Journal articles on the topic 'Diurnal heating'
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1
Jiang, Qingfang. "On Offshore Propagating Diurnal Waves." Journal of the Atmospheric Sciences 69, no. 5 (May 1, 2012): 1562–81. http://dx.doi.org/10.1175/jas-d-11-0220.1.
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Abstract Characteristics and dynamics of offshore diurnal waves induced by land–sea differential heating are examined using linear theory. Two types of heating profiles are investigated, namely a shallow heating source confined within an atmospheric boundary layer (BL) and a deep heating source located above the boundary layer. It is demonstrated that a boundary layer top inversion or a more stable layer aloft tends to partially trap diurnal waves in the BL and consequently extend perturbations well offshore. The wave amplitude decays with offshore distance due to BL friction and leakage of energy into the free atmosphere. The dependence of trapped waves on the inversion height and strength, atmosphere stratification, latitude, BL friction, and background winds is investigated. Diurnal waves generated by a deep heating source extending well above the BL are characterized by longer wavelengths, faster propagation, and substantially longer e-folding decay distances than waves induced by a BL source. For the latter, BL friction has little impact on the e-folding decay distance, as waves are mostly located in the free atmosphere rather than in a frictional BL.
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Navarro, Erika L., Gregory J. Hakim, and Hugh E. Willoughby. "Balanced Response of an Axisymmetric Tropical Cyclone to Periodic Diurnal Heating." Journal of the Atmospheric Sciences 74, no. 10 (September 27, 2017): 3325–37. http://dx.doi.org/10.1175/jas-d-16-0279.1.
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Abstract A modified version of the Sawyer–Eliassen equation is applied to determine the impact of periodic diurnal heating on a balanced vortex. The TC diurnal cycle is a coherent signal that arises in the cirrus canopy. However, despite thorough documentation in the literature, the dynamical mechanism remains unknown. Recent work demonstrates that periodic radiative heating in the TC outflow layer is linked with an anomalous upper-level circulation; this heating is also associated with a cycle of latent heating in the lower troposphere that corresponds to a cycle in storm intensity. Using a method that is analogous to the Sawyer–Eliassen equation, but for solutions having the same time scale as time-periodic forcing, these distributions are analyzed to determine the effect of periodic diurnal heating on an axisymmetric vortex. Results for periodic heating in the lower troposphere show an overturning circulation that resembles the Sawyer–Eliassen solution. The model simulates positive perturbations in the azimuthal wind field of 2.5 m s−1 near the radius of maximum wind. Periodic heating near the top of the vortex produces a local overturning response in the region of heating and an inertia–buoyancy wave response in the storm environment. Comparison of the results from the modified Sawyer–Eliassen equation to those of an idealized axisymmetric solution for both heating distributions shows similarities in the structure of the perturbation wind fields, suggesting that the axisymmetric TC diurnal cycle is primarily a balanced response driven by periodic heating.
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Johnson, Richard H., Paul E. Ciesielski, Tristan S. L’Ecuyer, and Andrew J. Newman. "Diurnal Cycle of Convection during the 2004 North American Monsoon Experiment." Journal of Climate 23, no. 5 (March 1, 2010): 1060–78. http://dx.doi.org/10.1175/2009jcli3275.1.
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Abstract The diurnal cycle of summer monsoon convection in the coastal, mountainous region of northwestern Mexico is investigated using data from the 2004 North American Monsoon Experiment (NAME). Data from a special sounding network consisting of research and operational sites have been quality controlled and combined with surface, wind profiler, and pibal observations to create a gridded dataset over the NAME domain. This study concentrates on results from the interior portion of the NAME sounding network, where gridded analysis fields are independent of model data. Special attention is given to surface and pibal observations along the western slope of the Sierra Madre Occidental (SMO) in order to obtain an optimal analysis of the diurnally varying slope flows. Results show a prominent sea-breeze–land-breeze cycle along the western slopes of the SMO. There is a deep return flow above the afternoon sea breeze as a consequence of the elevated SMO immediately to the east. The upslope flow along the western slope of the SMO is delayed until late morning, likely in response to early morning low clouds over the SMO crest and reduced morning insolation over the west-facing slopes. The diurnal cycle of the net radiative heating rate is characterized by a net cooling during most of the daytime except for net heating in the lower and upper troposphere at midday. The diurnal cycle of the apparent heat source Q1 minus the radiative heating rate QR (providing a measure of net condensational heating) and the apparent moisture sink Q2 over the SMO is indicative of shallow convection around noon, deep convection at 1800 LT, evolving to stratiform precipitation by midnight, consistent with the radar-observed diurnal evolution of precipitation over this coastal mountainous region as well as the typical evolution of tropical convective systems across a wide range of spatial and temporal scales. Convection over the Gulf of California is strikingly different from that over land, namely, heating and moistening are confined principally to the lower troposphere below 700 hPa, peaking during the nighttime hours.
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Evans, Rebecca C., and David S. Nolan. "Balanced and Radiating Wave Responses to Diurnal Heating in Tropical Cyclone–Like Vortices Using a Linear Nonhydrostatic Model." Journal of the Atmospheric Sciences 76, no. 8 (August 1, 2019): 2575–97. http://dx.doi.org/10.1175/jas-d-18-0361.1.
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Abstract The diurnal cycle (DC) in the cirrus canopy of tropical cyclones (TCs) is a well-documented phenomenon. While early studies linked the DC in the area of the cirrus canopy to a DC in the strength of eyewall convection, later studies considered it a direct response to the DC of radiation in the cirrus canopy. In this study, an idealized linear model is used to examine the extent to which linear dynamics can capture the DC in TCs, in particular the transition between balanced and radiating responses to diurnal heating. The model heat forcing is physically motivated by the diabatic heating output from a realistic simulation, which illustrates the presence of a DC in moist convective heating and radiative heating in the eyewall, and a DC in radiative heating in the cirrus canopy. This study finds that the DCs of heating in the eyewall yield a response that is restricted to inside the RMW by the high inertial stability in the inner core. The DC of radiative heating in the cirrus canopy yields a response throughout the entire cyclone. Lower-frequency responses, of diurnal and semidiurnal frequency, are balanced throughout much of the cyclone. High-frequency waves with periods under 8 h, created at sunrise and sunset, can radiate outward and downward. These results indicate that diurnal responses are balanced in the majority of a TC and originate in the cirrus canopy, instead of the eyewall. The DC in cirrus canopy vertical motion also appears to originate in the cirrus canopy.
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VICHARE, GEETA, and R. RAJARAM. "Diurnal and semi-diurnal tidal structures due to O2, O3 and H2O heating." Journal of Earth System Science 122, no. 5 (October 2013): 1207–17. http://dx.doi.org/10.1007/s12040-013-0353-4.
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Wall, Casey J., Joel R. Norris, Blaž Gasparini, William L. Smith, Mandana M. Thieman, and Odran Sourdeval. "Observational Evidence that Radiative Heating Modifies the Life Cycle of Tropical Anvil Clouds." Journal of Climate 33, no. 20 (October 15, 2020): 8621–40. http://dx.doi.org/10.1175/jcli-d-20-0204.1.
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AbstractA variety of satellite and ground-based observations are used to study how diurnal variations of cloud radiative heating affect the life cycle of anvil clouds over the tropical western Pacific Ocean. High clouds thicker than 2 km experience longwave heating at cloud base, longwave cooling at cloud top, and shortwave heating at cloud top. The shortwave and longwave effects have similar magnitudes during midday, but only the longwave effect is present at night, so high clouds experience a substantial diurnal cycle of radiative heating. Furthermore, anvil clouds are more persistent or laterally expansive during daytime. This cannot be explained by variations of convective intensity or geographic patterns of convection, suggesting that shortwave heating causes anvil clouds to persist longer or spread over a larger area. It is then investigated if shortwave heating modifies anvil development by altering turbulence in the cloud. According to one theory, radiative heating drives turbulent overturning within anvil clouds that can be sufficiently vigorous to cause ice nucleation in the updrafts, thereby extending the cloud lifetime. High-frequency air motion and ice-crystal number concentration are shown to be inversely related near cloud top, however. This suggests that turbulence depletes or disperses ice crystals at a faster rate than it nucleates them, so another mechanism must cause the diurnal variation of anvil clouds. It is hypothesized that radiative heating affects anvil development primarily by inducing a mesoscale circulation that offsets gravitational settling of cloud particles.
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Kelly, Patrick, and Brian Mapes. "Land Surface Heating and the North American Monsoon Anticyclone: Model Evaluation from Diurnal to Seasonal." Journal of Climate 23, no. 15 (August 1, 2010): 4096–106. http://dx.doi.org/10.1175/2010jcli3332.1.
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Abstract Data from several regional and global models (including model-based analysis data) are compared with field data from the North American Monsoon Experiment (NAME), from observational sites as well as satellite retrievals. On the regional scale (NAME tier 1.5), sensible heating is shown to exceed latent and is furthermore concentrated in the lower half of the troposphere, so in considering the North American monsoon (NAM) midlevel anticyclone, the authors focus on radiative and turbulent energy fluxes at the surface. Models exhibit large discrepancies in their simulation of the mean diurnal cycle of these fluxes as well as in their sensitivity of evaporative fraction to recent rainfall. Most of the models examined have too much net radiation due to excessive shortwave surface flux (too little cloud) and too much sensible heating. These high biases in sensible heating appear to drive overpredictions of both the daily and seasonal rise of 500-hPa heights in the NAM anticyclone. This diurnal–seasonal resemblance suggests that calibrating surface heating processes using readily field-observed diurnal variations could lead to improvements in seasonal-time-scale NAM simulations.
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Hughes, Kenneth G., James N. Moum, and Emily L. Shroyer. "Heat Transport through Diurnal Warm Layers." Journal of Physical Oceanography 50, no. 10 (October 1, 2020): 2885–905. http://dx.doi.org/10.1175/jpo-d-20-0079.1.
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AbstractPenetration of solar radiation in the upper few meters of the ocean creates a near-surface, stratified diurnal warm layer. Wind stress accelerates a diurnal jet in this layer. Turbulence generated at the diurnal thermocline, where the shear of the diurnal jet is concentrated, redistributes heat downward via mixing. New measurements of temperature and turbulence from fast thermistors on a surface-following platform depict the details of this sequence in both time and depth. Temporally, the sequence at a fixed depth follows a counterclockwise path in logϵ–logN parameter space. This path also captures the evolution of buoyancy Reynolds number (a proxy for the anisotropy of the turbulence) and Ozmidov scale (a proxy for the outer vertical length scale of turbulence in the absence of the free surface). Vertically, the solar heat flux always leads to heating of fluid parcels in the upper few meters, whereas the turbulent heat flux divergence changes sign across the depth of maximum vertical temperature gradient, cooling fluid parcels above and heating fluid parcels below. In general, our measurements of fluid parcel heating or cooling rates of order 0.1°C h−1 are consistent with our estimates of heat flux divergence. In weak winds (<2 m s−1), sea surface temperature (SST) is controlled by the depth-dependent absorption of solar radiation. In stronger winds, turbulent mixing controls SST.
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Li, Yanping, and Ronald B. Smith. "Observation and Theory of the Diurnal Continental Thermal Tide." Journal of the Atmospheric Sciences 67, no. 9 (September 1, 2010): 2752–65. http://dx.doi.org/10.1175/2010jas3384.1.
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Abstract Harmonic analysis of summer Automated Surface Observing System (ASOS) data over North America shows sun-following diurnal temperature and pressure oscillations with amplitudes increasing in the western United States (i.e., 5–8 K and 60–120 hPa, respectively) due to larger sensible heating in the dryer western terrains. The phases of temperature and pressure (i.e., 220° and 110°) are constant with longitude after an interfering eastward propagating wave is subtracted. Tidal amplitudes and phases shift significantly with season. A linear Boussinesq model with thermal forcing can reproduce these observed oscillations with properly selected parameters. The model neglects global effects to focus on a single transect across a single ideal continent. A damping parameter α ranging from 5 × 10−5 to 9 × 10−5 s−1, comparable to the inertia and Coriolis parameters, is needed to explain the temperature phase lag relative to local solar noon (40°–50°C). The phase lag between surface pressure minimum and temperature maximum (45°–70°C) requires a 3–5-h time delay between surface and elevated heating. The ratio of pressure and temperature amplitude requires a heating depth varying between 550 (winter) and 1250 m (summer). Both the heating delay and depth are consistent with a vertical heat diffusivity of about K = 10 m2 s−1 in winter, but K theory gives inconsistent summer K values. The observed tide amplitude requires diurnal heating amplitudes in the range of 100–250 W m−2. When the model is applied to an inhomogeneous continent, it is possible to obtain a clearer idea of how wide a region must be to approach the tidal (i.e., long-wave) limit. Traveling diurnal heating generates gentle tides over the large uniform interior regions but causes vigorous sea breezes and mountain–plain circulations in regions of heating gradient. These gradient regions have significant vertical motions and are moderately sensitive to the Coriolis force and the mean wind speed. Surprisingly, these local circulations do not alter the phases of the temperature and pressure oscillations, in agreement with observations.
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Ushijima, Yusuke, and Yutaka Yoshikawa. "Mixed Layer Depth and Sea Surface Warming under Diurnally Cycling Surface Heat Flux in the Heating Season." Journal of Physical Oceanography 49, no. 7 (July 2019): 1769–87. http://dx.doi.org/10.1175/jpo-d-18-0230.1.
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AbstractIn the present study, large-eddy simulations (LESs) were performed to investigate mixed layer depth (MLD) and sea surface warming (SSW) under diurnally cycling surface heat flux in the heating season, in which a mixed layer (ML) is shoaling on intraseasonal time scales. The LES results showed that the diurnal cycle makes the MLD greater (smaller) at lower (higher) latitudes than the MLD without the cycle. Time scales of the wind-induced shear and the surface heat are a key to understand this latitudinal dependence of the diurnal cycle effects. The wind-induced shear-driven turbulence developed from early morning and became strongest at half the inertial period (Ti/2), while nighttime cooling weakened the ML stratification until the end of the nighttime (T24 = 24 h). At lower latitudes where Ti/2 > T24 (lower than 15°), the shear-driven turbulence continued to grow after T24 and determined the time of the greatest MLD. Thus, the shear-driven turbulence shaped the latitudinal dependence of the MLD, though convective turbulence helped further deepening of the ML. At higher latitudes (Ti/2 < T24), on the other hand, the shear-driven turbulence ceased growing before the nighttime cooling ended. However, reduced stratification due to the nighttime cooling supported the shear-driven turbulence to continue deepening the ML. Thus, the nighttime cooling shaped the latitudinal dependence of the MLD at higher latitudes. The MLD change induced by the diurnal cycle altered the SSW rate. At higher latitudes, the diurnal cycle is expected to reduce the MLD and increase the SSW by 10% in the heating season.
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Gao, Shouting, Yushu Zhou, and Xiaofan Li. "Effects of Diurnal Variations on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study." Journal of the Atmospheric Sciences 64, no. 2 (February 1, 2007): 656–64. http://dx.doi.org/10.1175/jas3835.1.
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Abstract Effects of diurnal variations on tropical heat and water vapor equilibrium states are investigated based on hourly data from two-dimensional cloud-resolving simulations. The model is integrated for 40 days and the simulations reach equilibrium states in all experiments. The simulation with a time-invariant solar zenith angle produces a colder and drier equilibrium state than does the simulation with a diurnally varied solar zenith angle. The simulation with a diurnally varied sea surface temperature generates a colder equilibrium state than does the simulation with a time-invariant sea surface temperature. Mass-weighted mean temperature and precipitable water budgets are analyzed to explain the thermodynamic differences. The simulation with the time-invariant solar zenith angle produces less solar heating, more condensation, and consumes more moisture than the simulation with the diurnally varied solar zenith angle. The simulation with the diurnally varied sea surface temperature produces a colder temperature through less latent heating and more IR cooling than the simulation with the time-invariant sea surface temperature.
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Clark, John H. E. "Gravity Waves Driven by Diurnal Fluctuations in Mesoscale Heating." Journal of the Atmospheric Sciences 56, no. 5 (March 1999): 769–83. http://dx.doi.org/10.1175/1520-0469(1999)056<0769:gwdbdf>2.0.co;2.
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Liu, Jing, Zhiwen Luo, Taoyao Zhao, and Jing Shui. "Ventilation in a Street Canyon under Diurnal Heating Conditions." International Journal of Ventilation 11, no. 2 (September 2012): 141–54. http://dx.doi.org/10.1080/14733315.2012.11683977.
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Lieberman, R. S., D. A. Ortland, and E. S. Yarosh. "Climatology and interannual variability of diurnal water vapor heating." Journal of Geophysical Research: Atmospheres 108, no. D3 (February 12, 2003): n/a. http://dx.doi.org/10.1029/2002jd002308.
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Woolnough, S. J., J. M. Slingo, and B. J. Hoskins. "The Diurnal Cycle of Convection and Atmospheric Tides in an Aquaplanet GCM." Journal of the Atmospheric Sciences 61, no. 21 (November 1, 2004): 2559–73. http://dx.doi.org/10.1175/jas3290.1.
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Abstract The diurnal cycle of tropical convection and its relationship to the atmospheric tides is investigated using an aquaplanet GCM. The diurnal and semidiurnal harmonics of precipitation are both found to contribute significantly to the total diurnal variability of precipitation in the model, which is broadly consistent with observations of the diurnal cycle of convection over the open ocean. The semidiurnal tide is found to be the dominant forcing for the semidiurnal harmonic of precipitation. In contrast the diurnal tide plays only a small role in forcing the diurnal harmonic of precipitation, which is dominated by the variations in shortwave and longwave heating. In both the diurnal and semidiurnal harmonics, the feedback onto the convection by the humidity tendencies due to the convection is found to be important in determining the phase of the harmonics. Further experiments show that the diurnal cycle of precipitation is sensitive to the choice of closure in the convection scheme. While the surface pressure signal of the simulated atmospheric tides in the model agree well with both theory and observations in their magnitude and phase, sensitivity experiments suggest that the role of the stratospheric ozone in forcing the semidiurnal tide is much reduced compared to theoretical predictions. Furthermore, the influence of the cloud radiative effects seems small. It is suggested that the radiative heating profile in the troposphere, associated primarily with the water vapor distribution, is more important than previously thought for driving the semidiurnal tide. However, this result may be sensitive to the vertical resolution and extent of the model.
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Kukulka, Tobias, Kara L. Law, and Giora Proskurowski. "Evidence for the Influence of Surface Heat Fluxes on Turbulent Mixing of Microplastic Marine Debris." Journal of Physical Oceanography 46, no. 3 (March 2016): 809–15. http://dx.doi.org/10.1175/jpo-d-15-0242.1.
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AbstractBuoyant microplastic marine debris (MPMD) is a pollutant in the ocean surface boundary layer (OSBL) that is submerged by wave-driven turbulent transport processes. This study analyzes observed MPMD surface concentrations in the Atlantic and Pacific Oceans to reveal a significant increase in concentrations during surface heating and a decrease during surface cooling. Turbulence-resolving large-eddy simulations of the OSBL for an idealized diurnal heating cycle suggest that turbulent downward fluxes of buoyant tracers are enhanced at night, facilitating deep submergence of plastics, and suppressed in heating conditions, resulting in surface-trapped MPMD. Simulations agree better with observations if enhanced mixing due to wave-driven Langmuir turbulence (LT) is included. The simulated time-dependent OSBL response results in hysteresis effects so that surface concentrations depend also on the phase of the diurnal heating cycle. The results demonstrate the controlling influence of surface heat fluxes and LT on turbulent transport in the OSBL and on vertical distributions of buoyant marine particles.
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Jiang, Qingfang. "A Linear Theory of Three-Dimensional Land–Sea Breezes." Journal of the Atmospheric Sciences 69, no. 6 (June 1, 2012): 1890–909. http://dx.doi.org/10.1175/jas-d-11-0137.1.
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Abstract Land–sea breezes (LSBs) induced by diurnal differential heating are examined using a three-dimensional linear model employing fast Fourier transform with emphasis on the complex coastline shape and geometry, the earth’s rotation, and background wind effects. It has been demonstrated that the low-level vertical motion associated with LSB can be significantly enhanced over a bay (peninsula) because of convergence of perturbations induced by differential heating along a seaward concave (convex) coastline. The dependence of surface winds and vertical motion patterns and their evolutions on the coastline geometries such as the width and the aspect ratio of the bay, the earth’s rotation, and the background winds are investigated. The LSB induced by an isolated tropical island is characterized by onshore flow and ascent over the island in the afternoon to early evening, with a reversal of direction from midnight to early morning. The diurnal heating–induced vertical motion is greatly enhanced over the island and weakened offshore because of the convergence and divergence of perturbations. In the presence of background flow, stronger diurnal perturbations are found at the downwind side of the island, which can extend far downstream associated with inertia–gravity waves.
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Gasparini, Blaž, Adam B. Sokol, Casey J. Wall, Dennis L. Hartmann, and Peter N. Blossey. "Diurnal Differences in Tropical Maritime Anvil Cloud Evolution." Journal of Climate 35, no. 5 (March 1, 2022): 1655–77. http://dx.doi.org/10.1175/jcli-d-21-0211.1.
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Abstract Satellite observations of tropical maritime convection indicate an afternoon maximum in anvil cloud fraction that cannot be explained by the diurnal cycle of deep convection peaking at night. We use idealized cloud-resolving model simulations of single anvil cloud evolution pathways, initialized at different times of the day, to show that tropical anvil clouds formed during the day are more widespread and longer lasting than those formed at night. This diurnal difference is caused by shortwave radiative heating, which lofts and spreads anvil clouds via a mesoscale circulation that is largely absent at night, when a different, longwave-driven circulation dominates. The nighttime circulation entrains dry environmental air that erodes cloud top and shortens anvil lifetime. Increased ice nucleation in more turbulent nighttime conditions supported by the longwave cloud-top cooling and cloud-base heating dipole cannot compensate for the effect of diurnal shortwave radiative heating. Radiative–convective equilibrium simulations with a realistic diurnal cycle of insolation confirm the crucial role of shortwave heating in lofting and sustaining anvil clouds. The shortwave-driven mesoscale ascent leads to daytime anvils with larger ice crystal size, number concentration, and water content at cloud top than their nighttime counterparts. Significance Statement Deep convective activity and rainfall peak at night over the tropical oceans. However, anvil clouds that originate from the tops of deep convective clouds reach their largest extent in the afternoon hours. We study the underlying physical mechanisms that lead to this discrepancy by simulating the evolution of anvil clouds with a high-resolution model. We find that the absorption of sunlight by ice crystals lofts and spreads the daytime anvil clouds over a larger area, increasing their lifetime, changing their properties, and thus influencing their impact on climate. Our findings show that it is important not only to simulate the correct onset of deep convection but also to correctly represent anvil cloud evolution for skillful simulations of the tropical energy balance.
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Li, Yanping, and R. E. Carbone. "Offshore Propagation of Coastal Precipitation." Journal of the Atmospheric Sciences 72, no. 12 (November 19, 2015): 4553–68. http://dx.doi.org/10.1175/jas-d-15-0104.1.
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Abstract This work focuses on the seaward propagation of coastal precipitation with and without mountainous terrain nearby. Offshore of India, diurnal propagation of precipitation is observed over the Bay of Bengal. On the eastern side of the bay, a diurnal but nonpropagating signal is observed near the west coast of Burma. This asymmetry is consistent with the inertio-gravity wave mechanism. Perturbations generated by diurnal heating over the coastal mountains of India propagate offshore, amplify in the upwind direction, and dissipate in the downwind direction relative to the steering wind, owing to critical-level considerations. A linear model is applied to evaluate sensitivity to gravity waves, as these affect deep moist convection and propagation. Analyses are performed for various heating depths, mountain widths, stability, Coriolis effect, background mean wind, and friction. Calculations reveal how these factors affect the amplitude, dissipation, initiation phase, and propagation speed of the diurnal disturbance. The propagation of precipitation triggered by land–sea breezes is distinguishable from that triggered by a mountain–plains circulation. Convection resulting purely from mountain heating begins earlier, propagates slower, and damps faster than that of the land–sea breeze. For mountains near a coast, slower propagation and stronger earlier convection result from a resonance-like combination of two dynamical mechanisms. The propagation of precipitation is initially triggered by the mountain breeze near the coastal mountain. Over the open ocean, the dominant signal propagates as that of the land breeze but with stronger convection.
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Svensen, Jan Lorenz. "Peak Shaving in District Heating Utilizing Adaptive Predictive Control." Energies 15, no. 22 (November 16, 2022): 8555. http://dx.doi.org/10.3390/en15228555.
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District heating systems (DHS) are driven by the heat demands of their consumers, with higher demands giving a higher load on the heat production. While heat demands are human-dependent, they contain diurnal behaviors and weather dependencies. The diurnal behaviors contain periods with high demands causing peak loads on the heat production, which is operationally costly. This is especially true for heat pumps, a solution for DHS to include green energy, as the cost depends directly on the needed temperature. This paper presents a formulation of adaptive model predictive control (MPC) for inducing peak shaving on the production load to handle the peak load problem by using the DHS distribution network as a heat storage. It also presents a simulator model to describe the DHS. The MPC was applied to data from a case study of the DHS in Brønderslev, Denmark, showing a peak reduction of around 8%.
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Cohen, R. R., D. M. Tanton, S. D. Probert, and D. J. Nevrala. "Diurnal thermal energy storage in gas-fired central heating systems." Building Services Engineering Research and Technology 7, no. 1 (February 1986): 33–36. http://dx.doi.org/10.1177/014362448600700105.
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Ruppert, James H., Xingchao Chen, and Fuqing Zhang. "Convectively Forced Diurnal Gravity Waves in the Maritime Continent." Journal of the Atmospheric Sciences 77, no. 3 (March 1, 2019): 1119–36. http://dx.doi.org/10.1175/jas-d-19-0236.1.
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Abstract Long-lived, zonally propagating diurnal rainfall disturbances are a highly pronounced and common feature in the Maritime Continent (MC). A recent study argues that these disturbances can be explained as diurnally phase-locked gravity waves. Here we explore the origins of these waves through regional cloud-permitting numerical model experiments. The gravity waves are reproduced and isolated in the model framework through the combined use of realistic geography and diurnally cyclic lateral boundary conditions representative of both characteristic easterly and westerly background zonal flow regimes. These flow regimes are characteristic of the Madden–Julian oscillation (MJO) suppressed and active phase in the MC, respectively. Tests are conducted wherein Borneo, Sumatra, or both islands and/or their orography are removed. These tests imply that the diurnal gravity waves are excited and maintained directly by latent heating from the vigorous mesoscale convective systems (MCSs) that form nocturnally in both Borneo and Sumatra. Removing orography has only a secondary impact on both the MCSs and the gravity waves, implying that it is not critical to these waves. We therefore hypothesize that diurnal gravity waves are fundamentally driven by mesoscale organized deep convection, and are only sensitive to orography to the measure that the convection is affected by the orography and its mesoscale flows. Factor separation further reveals that the nonlinear interaction of synchronized diurnal cycles in Sumatra and Borneo slightly amplifies this gravity wave mode compared to if either island existed in isolation. This nonlinear feedback appears most prominently at longitudes directly between the two islands.
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Rutan, David A., G. Louis Smith, and Takmeng Wong. "Diurnal Variations of Albedo Retrieved from Earth Radiation Budget Experiment Measurements." Journal of Applied Meteorology and Climatology 53, no. 12 (December 2014): 2747–60. http://dx.doi.org/10.1175/jamc-d-13-0119.1.
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AbstractFive years of measurements from the Earth Radiation Budget Satellite (ERBS) have been analyzed to define the diurnal cycle of albedo from 55°N to 55°S. The ERBS precesses through all local times every 72 days so as to provide data regarding the diurnal cycles for Earth radiation. Albedo together with insolation at the top of the atmosphere is used to compute the heating of the Earth–atmosphere system; thus its diurnal cycle is important in the energetics of the climate system. A principal component (PC) analysis of the diurnal variation of top-of-atmosphere albedo using these data is presented. The analysis is done separately for ocean and land because of the marked differences of cloud behavior over ocean and over land. For ocean, 90%–92% of the variance in the diurnal cycle is described by a single component; for land, the first PC accounts for 83%–89% of the variance. Some of the variation is due to the increase of albedo with increasing solar zenith angle, which is taken into account in the ERBS data processing by a directional model, and some is due to the diurnal cycle of cloudiness. The second PC describes 2%–4% of the variance for ocean and 5% for land, and it is primarily due to variations of cloudiness throughout the day, which are asymmetric about noon. These terms show the response of the atmosphere to the cycle of solar heating. The third PC for ocean is a two-peaked curve, and the associated map shows high values in cloudy regions.
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Price, James F., Robert A. Weller, and Robert Pinkel. "Diurnal cycling: Observations and models of the upper ocean response to diurnal heating, cooling, and wind mixing." Journal of Geophysical Research 91, no. C7 (1986): 8411. http://dx.doi.org/10.1029/jc091ic07p08411.
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Sutherland, Graig, Louis Marié, Gilles Reverdin, Kai H. Christensen, Göran Broström, and Brian Ward. "Enhanced Turbulence Associated with the Diurnal Jet in the Ocean Surface Boundary Layer." Journal of Physical Oceanography 46, no. 10 (October 2016): 3051–67. http://dx.doi.org/10.1175/jpo-d-15-0172.1.
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AbstractDetailed observations of the diurnal jet, a surface intensification of the wind-driven current associated with the diurnal cycle of sea surface temperature (SST), were obtained during August and September 2012 in the subtropical Atlantic. A diurnal increase in SST of 0.2° to 0.5°C was observed, which corresponded to a diurnal jet of 0.15 m s−1. The increase in near-surface stratification limits the vertical diffusion of the wind stress, which in turn increases the near-surface shear. While the stratification decreased the turbulent dissipation rate ε below the depth of the diurnal jet, there was an observed increase in ε within the diurnal jet. The diurnal jet was observed to increase the near-surface shear by a factor of 5, which coincided with enhanced values of ε. The diurnal evolution of the Richardson number, which is an indicator of shear instability, is less than 1, suggesting that shear instability may contribute to near-surface turbulence. While the increased stratification due to the diurnal heating limits the depth of the momentum flux due to the wind, shear instability provides an additional source of turbulence that interacts with the enhanced shear of the diurnal jet to increase ε within this shallow layer.
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Schmidli, Juerg, and Richard Rotunno. "Mechanisms of Along-Valley Winds and Heat Exchange over Mountainous Terrain." Journal of the Atmospheric Sciences 67, no. 9 (September 1, 2010): 3033–47. http://dx.doi.org/10.1175/2010jas3473.1.
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Abstract The physical mechanisms leading to the formation of diurnal along-valley winds are investigated over idealized three-dimensional topography. The topography used in this study consists of a valley with a horizontal floor enclosed by two isolated mountain ridges on a horizontal plain. A diagnostic equation for the along-valley pressure gradient is developed and used in combination with numerical model simulations to clarify the relative role of various forcing mechanisms such as the valley volume effect, subsidence heating, and surface sensible heat flux effects. The full diurnal cycle is simulated using comprehensive model physics including radiation transfer, land surface processes, and dynamic surface–atmosphere interactions. The authors find that the basic assumption of the valley volume argument of no heat exchange with the free atmosphere seldom holds. Typically, advective and turbulent heat transport reduce the heating of the valley during the day and the cooling of the valley during the night. In addition, dynamically induced valley–plain contrasts in the surface sensible heat flux can play an important role. Nevertheless, the present analysis confirms the importance of the valley volume effect for the formation of the diurnal along-valley winds but also clarifies the role of subsidence heating and the limitations of the valley volume effect argument. In summary, the analysis brings together different ideas of the valley wind into a unified picture.
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Chung, E. S., B. J. Sohn, J. Schmetz, and M. Koenig. "Diurnal variation of upper tropospheric humidity and its relations to convective activities over tropical Africa." Atmospheric Chemistry and Physics 7, no. 10 (May 14, 2007): 2489–502. http://dx.doi.org/10.5194/acp-7-2489-2007.
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Abstract. Diurnal variations of upper tropospheric humidity (UTH) as well as middle tropospheric humidity (MTH) were examined in conjunction with the diurnal cycle of convection over tropical Africa and the adjacent tropical Atlantic Ocean using Meteosat-8 measurements. Cloud and humidity features were also tracked to document the diurnal variations of humidity and clouds in the Lagrangian framework. A distinct diurnal variation of UTH (and MTH) is noted over regions where tropical deep convective cloud systems are commonly observed. The amplitude of the UTH diurnal variation is larger over land, while its variations over convectively inactive subtropical regions are much smaller. The diurnal variation of UTH tends to reach a maximum during nighttime over land, lagging deep convection and high cloud whose maxima occurred in the late afternoon and evening, respectively. It was revealed that these diurnal variations over the African continent are likely associated with continental-scale daytime solar heating and topography, in which topographically-induced signals develop earlier around the mid-afternoon and merge into stronger and broader continental-scale convection clusters later, forming a precipitation maximum in the late afternoon. It was also revealed that advection effect on the diurnal variation appears to be insignificant.
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Radell, David B., and Clinton M. Rowe. "An Observational Analysis and Evaluation of Land Surface Model Accuracy in the Nebraska Sand Hills." Journal of Hydrometeorology 9, no. 4 (August 1, 2008): 601–21. http://dx.doi.org/10.1175/2007jhm913.1.
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Abstract In this study, the influence of subsurface water on the energy budget components of three locations with heterogeneous land surfaces in the Nebraska Sand Hills are examined through observations and use of the Noah land surface model (LSM). Observations of the four primary components of the surface energy budget are compared for a wet interdunal meadow valley, a dry interdunal valley, and a dunal upland location. With similar atmospheric forcing at each site, it was determined that differences in the partitioning of the mean diurnal net radiation (Rnet) existed among the three locations due to the influence of varied soil moisture and vegetation through the year. At the wet valley, observations indicated that almost 65% of the mean daily peak Rnet was used for latent heating, due to the relatively higher soil moisture content resulting from an annual upward gradient of subsurface water and denser vegetation. In sharp contrast, the dunal upland site yielded only 21% of the mean daily peak Rnet going to latent heating, and a greater mean diurnal soil heat flux with typically drier soils and sparser vegetation than at the wet valley. The dry valley partition of the peak Rnet fell between the wet valley and dunal upland site, with approximately 50% going to sensible heating and 50% toward latent heating. In addition to the observational analysis, an uncoupled land surface model was forced with the observations from each site to simulate the energy budgets, with no tuning of the model’s fundamental equations and with little adjustment of the model parameters to improve results. While the model was able to reasonably simulate the mean diurnal and annual energy budget components at all locations, in most instances with root-mean-square errors within 20%–25% of the observed values, the lack of explicit treatment of subsurface water within the model limited predictability, particularly at the wet valley site. For instance, only 25% of the peak mean diurnal Rnet went toward latent heating in the model simulation of the wet valley, compared to 65% as estimated by observations. Model evaluation statistics are presented to document the land surface model’s ability to capture the annual and mean diurnal variations in the surface energy budget terms at the dry valley and dunal upland sites, but the absence of subsurface water results in large errors in the wet valley simulation. From these results, a case is made for the future inclusion of the explicit treatment of subsurface water within the Noah LSM to better approximate the prediction of the surface energy budget in such environments.
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Tang, Xiaodong, Zhe-Min Tan, Juan Fang, Y. Qiang Sun, and Fuqing Zhang. "Impact of the Diurnal Radiation Cycle on Secondary Eyewall Formation." Journal of the Atmospheric Sciences 74, no. 9 (August 31, 2017): 3079–98. http://dx.doi.org/10.1175/jas-d-17-0020.1.
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Abstract The sensitivity of the secondary eyewall formation (SEF) of Hurricane Edouard (2014) to the diurnal solar insolation cycle is examined with convection-permitting simulations. A control run with a real diurnal radiation cycle and a sensitivity experiment without solar insolation are conducted. In the control run, there is an area of relatively weak convection between the outer rainbands and the primary eyewall, that is, a moat region. This area is highly sensitive to solar shortwave radiative heating, mostly in the mid- to upper levels in the daytime, which leads to a net stabilization effect and suppresses convective development. Moreover, the heated surface air weakens the wind-induced surface heat exchange (WISHE) feedback between the surface fluxes (that promote convection) and convective heating (that feeds into the secondary circulation and then the tangential wind). Consequently, a typical SEF with a clear moat follows. In the sensitivity experiment, in contrast, net radiative cooling leads to persistent active inner rainbands between the primary eyewall and outer rainbands, and these, along with the absence of the rapid filamentation zone, are detrimental to moat formation and thus to SEF. Sawyer–Eliassen diagnoses further suggest that the radiation-induced difference in diabatic heating is more important than the vortex wind structure for moat formation and SEF. These results suggest that the SEF is highly sensitive to solar insolation.
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Hansen, Zachary R., Larissa E. Back, and Peigen Zhou. "Boundary Layer Quasi-Equilibrium Limits Convective Intensity Enhancement from the Diurnal Cycle in Surface Heating." Journal of the Atmospheric Sciences 77, no. 1 (December 16, 2019): 217–37. http://dx.doi.org/10.1175/jas-d-18-0346.1.
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Abstract A combination of cloud-permitting model (CPM) simulations, satellite, and reanalysis data are used to test whether the diurnal cycle in surface temperature has a significant impact on the intensity of deep convection as measured by high-percentile updraft velocities, lightning, and CAPE. The land–ocean contrast in lightning activity shows that convective intensity varies between land and ocean independently from convective quantity. Thus, a mechanism that explains the land–ocean contrast must be able to do so even after controlling for precipitation variations. Motivated by the land–ocean contrast, we use idealized CPM simulations to test the impact of the diurnal cycle on high-percentile updrafts. In simulations, updrafts are somewhat enhanced due to large-scale precipitation enhancement by the diurnal cycle. To control for large-scale precipitation, we use statistical sampling techniques. After controlling for precipitation enhancement, the diurnal cycle does not affect convective intensities. To explain why sampled updrafts are not enhanced, we note that CAPE is also not increased, likely due to boundary layer quasi equilibrium (BLQE) occurring over our land area. Analysis of BLQE in terms of net positive and negative mass flux finds that boundary layer entrainment, and even more importantly downdrafts, account for most of the moist static energy (MSE) sink that is balancing surface fluxes. Using ERA-Interim data, we also find qualitative evidence for BLQE over land in the real world, as high percentiles of CAPE are not greater over land than over ocean.
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Parish, Thomas R., and Larry D. Oolman. "On the Role of Sloping Terrain in the Forcing of the Great Plains Low-Level Jet." Journal of the Atmospheric Sciences 67, no. 8 (August 1, 2010): 2690–99. http://dx.doi.org/10.1175/2010jas3368.1.
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Abstract The summertime Great Plains low-level jet (LLJ) has been the subject of numerous investigations during the past several decades. Characteristics of the LLJ include nighttime development of a pronounced wind maximum of typically 15–20 m s−1 at levels 300–800 m above the surface and a clockwise rotation of the wind maximum during the course of the night. Maximum frequency of occurrence of the LLJ is found in the southern Great Plains. Theories proposed to explain the diurnal wind maximum of the Great Plains LLJ include inertial oscillation of the ageostrophic wind, the diurnal oscillation of the horizontal pressure field associated with heating and cooling of the sloping terrain, and the western boundary current interpretations. A simple equation system and output from the 12-km horizontal resolution Weather Research and Forecasting Nonhydrostatic Mesoscale Model (NAM) for July 2008 are used to provide evidence as to the importance of the Great Plains topography in driving the LLJ. Summertime heating of the sloping terrain is critical in establishing the climatological position for the Great Plains LLJ. Heating enhances the background geostrophic flow associated with the Bermuda high, resulting in a maximum low-level mean summertime flow over the Great Plains region. Maximum geostrophic winds in the NAM are found during late afternoon, providing a large background wind on which frictional decoupling can act. The nighttime LLJ maximum is the result of an inertial oscillation of the unbalanced components that arise fundamentally from frictional decoupling. Diurnal heating of the sloping terrain forces a cycle in the geostrophic wind that is out of phase with the wind maximum.
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Ciesielski, Paul E., Richard H. Johnson, Wayne H. Schubert, and James H. Ruppert. "Diurnal Cycle of the ITCZ in DYNAMO." Journal of Climate 31, no. 11 (May 17, 2018): 4543–62. http://dx.doi.org/10.1175/jcli-d-17-0670.1.
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Abstract During the 2011 special observing period of the Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment, two sounding arrays were established over the central Indian Ocean, one north and one south of the equator, referred to here as the NSA and SSA, respectively. Three-hourly soundings from these arrays augmented by observations of radiation and rainfall are used to investigate the diurnal cycle of ITCZ convection during the MJO suppressed phase. During the first half of October, when convection was suppressed over the NSA but prominent over the SSA, the circulation over the sounding arrays could be characterized as a local Hadley cell. Strong rising motion was present within the ITCZ extending across the SSA with compensating subsidence over the NSA. A prominent diurnal pulsing of this cell was observed, impacting conditions on both sides of the equator, with the cell running strongest in the early morning hours (0500–0800 LT) and notably weakening later in the day (1700–2000 LT). The declining daytime subsidence over the NSA may have assisted the moistening of the low to midtroposphere there during the pre-onset stage of the MJO. Apparent heating Q1 within the ITCZ exhibited a diurnal evolution from early morning bottom-heavy profiles to weaker daytime top-heavy profiles, indicating a progression from convective to stratiform precipitation. Making use of the weak temperature gradient approximation, results suggest that both horizontal radiative heating gradients and direct cloud radiative forcing have an important influence on diurnal variations of vertical motion and convection within the ITCZ.
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Lieberman, Ruth S., Conway B. Leovy, Byron A. Boville, and Bruce P. Briegleb. "Diurnal Heating and Cloudiness in the NCAR Community Climate Model (CCM2)." Journal of Climate 7, no. 6 (June 1994): 869–89. http://dx.doi.org/10.1175/1520-0442(1994)007<0869:dhacit>2.0.co;2.
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Gent, M. P. N., and Y. Z. Ma. "311 Growth and Mineral Nutrition of Tomato Seedlings under Diurnal Temperature Variation of the Root and Shoot." HortScience 34, no. 3 (June 1999): 496C—496. http://dx.doi.org/10.21273/hortsci.34.3.496c.
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Does heating roots only in the day improve growth and nutrient status of seedlings grown under a day-to-night difference (DIF) in air temperature? To answer this question, tomato seedlings (Lycopersicon esculentum Mill) were grown in early March or April in greenhouses heated to give either a 14 °C DIF or a 5 °C DIF with a 18 °C mean. The roots were in peat-vermiculite medium that was unheated or heated to 21 °C, constantly or only in the day, or only in the night. Growth was faster and there were higher concentrations of elements in leaves under 5 °C compared to 14 °C air DIF. Any root-zone heating increased growth and nutrition compared to no heating. Under both air conditions, the trend in root temperature treatments was constant > day > night. In general, there was no benefit of heating the roots only in the day, compared to constant heating of the root zone, even with a large diurnal variation in temperature of the shoot. The only nutrient to respond differently to root heating under 5 °C compared to 14 °C air DIF was nitrate in leaves. Under a 14 °C air DIF, heating roots in the day resulted in the highest nitrate concentration, whereas constant root heating was optimal under a 5 °C DIF. Research supported in part by grant 93-37100-9101 from NRI Competitive grants program/USDA.
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Navarro, Erika L., and Gregory J. Hakim. "Idealized Numerical Modeling of the Diurnal Cycle of Tropical Cyclones." Journal of the Atmospheric Sciences 73, no. 10 (October 1, 2016): 4189–201. http://dx.doi.org/10.1175/jas-d-15-0349.1.
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Abstract A numerical experiment is performed to evaluate the role of the daily cycle of radiation on axisymmetric hurricane structure. Although a diurnal response in high cloudiness has been well documented previously, the link to tropical cyclone (TC) structure and intensity remains unknown. Previous modeling studies attributed differences in results to experimental setup (e.g., initial and boundary conditions) as well as to radiative parameterizations. Here, a numerically simulated TC in a statistically steady state is examined for 300 days to quantify the TC response to the daily cycle of radiation. Fourier analysis in time reveals a spatially coherent diurnal signal in the temperature, wind, and latent heating tendency fields. This signal is statistically different from random noise and accounts for up to 62% of the variance in the TC outflow and 28% of the variance in the boundary layer. Composite analysis of each hour of the day reveals a cycle in storm intensity: a maximum is found in the morning and a minimum in the evening, with magnitudes near 1 m s−1. Anomalous latent heating forms near the inner core of the storm in the late evening, which persists throughout the early morning. Examination of the radial–vertical wind suggests two distinct circulations: 1) a radiatively driven circulation in the outflow layer due to absorption of solar radiation and 2) a convectively driven circulation in the lower and middle troposphere due to anomalous latent heating. These responses are coupled and are periodic with respect to the diurnal cycle.
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Ryu, Young-Hee, James A. Smith, and Elie Bou-Zeid. "On the Climatology of Precipitable Water and Water Vapor Flux in the Mid-Atlantic Region of the United States." Journal of Hydrometeorology 16, no. 1 (February 1, 2015): 70–87. http://dx.doi.org/10.1175/jhm-d-14-0030.1.
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Abstract The seasonal and diurnal climatologies of precipitable water and water vapor flux in the mid-Atlantic region of the United States are examined. A new method of computing water vapor flux at high temporal resolution in an atmospheric column using global positioning system (GPS) precipitable water, radiosonde data, and velocity–azimuth display (VAD) wind profiles is presented. It is shown that water vapor flux exhibits striking seasonal and diurnal cycles and that the diurnal cycles exhibit rapid transitions over the course of the year. A particularly large change in the diurnal cycle of meridional water vapor flux between spring and summer seasons is found. These features of the water cycle cannot be resolved by twice-a-day radiosonde observations. It is also shown that precipitable water exhibits a pronounced seasonal cycle and a less pronounced diurnal cycle. There are large contrasts in the climatology of water vapor flux between precipitation and nonprecipitation conditions in the mid-Atlantic region. It is hypothesized that the seasonal transition of large-scale flow environments and the change in the degree of differential heating in the mountainous and coastal areas are responsible for the contrasting diurnal cycle between spring and summer seasons.
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Du, Yu, and Richard Rotunno. "Thermally Driven Diurnally Periodic Wind Signals off the East Coast of China." Journal of the Atmospheric Sciences 72, no. 7 (July 2015): 2806–21. http://dx.doi.org/10.1175/jas-d-14-0339.1.
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The characteristics of thermally driven diurnally periodic wind signals off the east coast of China are studied using hourly model data for the period June 2006–11 simulated with a mesoscale model. Analysis of these model data indicates low-level diurnally periodic wind signals propagate eastward off the southeast coast, whereas diurnal wind variations off the northeast coast are nearly in phase. It is found that a simple 2D linear land–sea-breeze model with friction can capture this main difference in propagation character with respect to latitude. Idealized simulations using a simplified version of the mesoscale model that includes surface heating and terrain are found to explain certain features not captured by the present linear theory such as the absolute time phase and cross-coast location of the maximum amplitude of the diurnally periodic winds.
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Sanjana, M. C., G. Latha, M. Ashokan, and R. R. Rao. "Diurnal Variability of Ambient Noise in Shallow Tropical Waters, South Western Bay of Bengal." Fluctuation and Noise Letters 14, no. 02 (May 4, 2015): 1550016. http://dx.doi.org/10.1142/s0219477515500169.
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Ambient noise recorded at shallow southwestern Bay of Bengal during September 2010 has been analyzed for spectral characteristics in the band 0.1–5.0 kHz. The noise level (NL) exhibits diurnal periodicity in the band 0.5–2.0 kHz, during most of the day. The in situ wind data at the site correlates well with the NL, which also shows a diurnal cycle. Wavelet analysis further carried out establishes of the diurnal periodicity in wind/NL pattern during fair weather conditions under the influence of local wind effects. Wavelet coherence shows wind and noise to be in phase or wind leading noise. Diurnal variation in wind is more frequently observed along the coast in tropical regions due to differential heating of land and sea, and this has attributed to the NL pattern at the site. The period of measurement is also favorable for the formation of such localized circulation since it is the sunny unclouded period prior to the Bay of Bengal cyclone season and the northeast monsoon.
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Mayr, Georg J., and Laurence Armi. "The Influence of Downstream Diurnal Heating on the Descent of Flow across the Sierras." Journal of Applied Meteorology and Climatology 49, no. 9 (September 1, 2010): 1906–12. http://dx.doi.org/10.1175/2010jamc2516.1.
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Abstract The potential for a stably stratified air mass upstream of the Sierra Nevada (California) to descend as foehn into the nearly 3-km-deep Owens Valley was studied for the 2 March 2006 case with observations from sondes, weather stations, and two aircraft flights. While upstream conditions remained almost unchanged throughout the day, strong diurnal heating on the downstream side warmed the valley air mass sufficiently to permit flow through the passes to descend to the valley floor only in the late afternoon. Potential temperatures of air crossing the crest were too warm to descend past a virtual floor formed by the strong potential temperature step at the top of the valley air mass, the height of which changed throughout the day primarily due to diurnal heating in the valley. The descending stably stratified flow and its rebound with vertical velocities as high as 8 m s−1 were shaped by the underlying topography and the virtual valley floor.
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Farrow, D. E., and J. C. Patterson. "On the response of a reservoir sidearm to diurnal heating and cooling." Journal of Fluid Mechanics 246 (January 1993): 143–61. http://dx.doi.org/10.1017/s0022112093000072.
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During the day, the shallower regions of a reservoir sidearm absorb more heat per unit volume than the deeper parts, leading to a horizontal pressure gradient that drives a circulation in the sidearm. At night, the shallow regions cool more rapidly, leading to a circulation in the opposite direction. Since the spin-up time of a typical sidearm is at least of the same order as a day, the flow within a diurnally forced sidearm is principally an inertia–buoyancy balance. In this paper, a diurnally forced sidearm is modelled by periodically forced natural convection in a triangular cavity. The periodic forcing enters the model via an internal heating/cooling term in the temperature equation. Reservoir sidearms typically have small bottom slopes and this fact can be exploited to obtain asymptotic solutions of the resulting equations. These solutions clearly demonstrate the transition from the viscous-dominated flow in the shallows to the inertia-dominated flow in the deeper parts. In the inertia-dominated region, the flow response significantly lags the forcing. Numerical solutions of the full nonlinear problem are consistent with the asymptotic solutions.
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Ising, Jan, Michael Lewis Kaplan, and Yuh-Lang Lin. "Effects of Density Current, Diurnal Heating, and Local Terrain on the Mesoscale Environment Conducive to the Yarnell Hill Fire." Atmosphere 13, no. 2 (January 28, 2022): 215. http://dx.doi.org/10.3390/atmos13020215.
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The Yarnell Hill Fire, triggered by dry lightning on 28 June 2013, was initiated by hot and dry westerly winds, which rapidly shifted to north-northeast by convective-induced outflows. This sudden wind shift led to the demise of 19 firefighters. This study focuses on the environment and its predictive potential in terms of erratically changing the fire spread. Three numerical sensitivity tests are performed investigating the evolving synoptic-meso-β scale environmental wind flow: (1) deactivating the evaporative cooling, (2) deactivating surface-driven diurnal heating/cooling, and (3) removing the mountain. Results show the strong north-northeasterly wind induced by the density current(s) and the diurnal surface sensible heating played the most significant roles in enhancing the mesoscale environment conducive to the rapid change in the fire spread direction. While the mountain played a less significant role in weakening the magnitude of the airflow affecting the fire, it still had an impact. Additionally, the Hot-Dry-Windy (HDW) index is calculated to determine its predictor role with respect to the atmosphere affecting the fire. The focus is not on feedback from explicit fire heating on the larger environment but rather the role of the environmental physical processes in causing the convectively induced rapid wind shifts.
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Chen, Jinghua, Xiaoqing Wu, Yan Yin, Qian Huang, and Hui Xiao. "Characteristics of Cloud Systems over the Tibetan Plateau and East China during Boreal Summer." Journal of Climate 30, no. 9 (May 2017): 3117–37. http://dx.doi.org/10.1175/jcli-d-16-0169.1.
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Constrained by ERA-Interim, a cloud-resolving model is employed to characterize cloud systems over the Tibetan Plateau (TP) and east China. The authors focus on analyzing the role of different physical processes on cloud macro- and microscale properties of the cloud systems, especially convective cloud systems between east China and the TP. It is found that convective clouds over the TP are thinner than over east China. This difference is also reflected in the albedo at the top of the atmosphere, where smaller albedos are found for the clouds over the TP. Furthermore, the lifetimes of the deep cloud systems over the TP are shorter than over east China. For the entire simulated period, the latent heat released by phase transitions contributes the most to the total heating and moisture budget, followed by eddy transport over all regions. In addition, radiative heating also plays a nonnegligible role in the total heating effects over the TP. These results also suggest that the influence of ice phase processes is more important over the TP than east China, especially during deep convective periods. Affected by strong surface heat flux, the cloud-top height of convective clouds over the TP exhibits a diurnal cycle, leading to a diurnal cycle of rainfall.
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Tang, Shuaiqi, Shaocheng Xie, Yunyan Zhang, Minghua Zhang, Courtney Schumacher, Hannah Upton, Michael P. Jensen, et al. "Large-scale vertical velocity, diabatic heating and drying profiles associated with seasonal and diurnal variations of convective systems observed in the GoAmazon2014/5 experiment." Atmospheric Chemistry and Physics 16, no. 22 (November 16, 2016): 14249–64. http://dx.doi.org/10.5194/acp-16-14249-2016.
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Abstract. This study describes the characteristics of large-scale vertical velocity, apparent heating source (Q1) and apparent moisture sink (Q2) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) that were conducted from 15 February to 26 March 2014 (wet season) and from 1 September to 10 October 2014 (dry season) near Manaus, Brazil, during the Green Ocean Amazon (GoAmazon2014/5) experiment. The derived large-scale fields have large diurnal variations according to convective activity in the GoAmazon region and the morning profiles show distinct differences between the dry and wet seasons. In the wet season, propagating convective systems originating far from the GoAmazon region are often seen in the early morning, while in the dry season they are rarely observed. Afternoon convective systems due to solar heating are frequently seen in both seasons. Accordingly, in the morning, there is strong upward motion and associated heating and drying throughout the entire troposphere in the wet season, which is limited to lower levels in the dry season. In the afternoon, both seasons exhibit weak heating and strong moistening in the boundary layer related to the vertical convergence of eddy fluxes. A set of case studies of three typical types of convective systems occurring in Amazonia – i.e., locally occurring systems, coastal-occurring systems and basin-occurring systems – is also conducted to investigate the variability of the large-scale environment with different types of convective systems.
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Schumacher, Courtney, Minghua H. Zhang, and Paul E. Ciesielski. "Heating Structures of the TRMM Field Campaigns." Journal of the Atmospheric Sciences 64, no. 7 (July 1, 2007): 2593–610. http://dx.doi.org/10.1175/jas3938.1.
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Abstract Heating profiles calculated from sounding networks and other observations during three Tropical Rainfall Measuring Mission (TRMM) field campaigns [the Kwajalein Experiment (KWAJEX), TRMM Large-Scale Biosphere–Atmosphere Experiment in Amazonia (LBA), and South China Sea Monsoon Experiment (SCSMEX)] show distinct geographical differences between oceanic, continental, and monsoon regimes. Differing cloud types (both precipitating and nonprecipitating) play an important role in determining the total diabatic heating profile. Variations in the vertical structure of the apparent heat source, Q1, can be related to the diurnal cycle, large-scale forcings such as atmospheric waves, and rain thresholds at each location. For example, TRMM-LBA, which occurred in the Brazilian Amazon, had mostly deep convection during the day while KWAJEX, which occurred in the western portion of the Pacific intertropical convergence zone, had more shallow and moderately deep daytime convection. Therefore, the afternoon height of maximum heating was more bottom heavy (i.e., heating below 600 hPa) during KWAJEX compared to TRMM-LBA. More organized convective systems with extensive stratiform rain areas and upper-level cloud decks tended to occur in the early and late morning hours during TRMM-LBA and KWAJEX, respectively, thereby causing Q1 profiles to be top heavy (i.e., maxima from 600 to 400 hPa) at those times. SCSMEX, which occurred in the South China Sea during the monsoon season, had top-heavy daytime and nighttime heating profiles suggesting that mesoscale convective systems occurred throughout the diurnal cycle, although more precipitation and upper-level cloud in the afternoon caused the daytime heating maximum to be larger. A tendency toward bottom- and top-heavy heating profile variations is also associated with the different cloud types that occurred before and after the passage of easterly wave troughs during KWAJEX, the easterly and westerly regimes during TRMM-LBA, and the monsoon onset and postonset active periods during SCSMEX. Rain thresholds based on heavy, moderate, and light/no-rain amounts can further differentiate top-heavy heating, bottom-heavy heating, and tropospheric cooling. These budget studies suggest that model calculations and satellite retrievals of Q1 must account for a large number of factors in order to accurately determine the vertical structure of diabatic heating associated with tropical cloud systems.
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Evans, Rebecca C., and David S. Nolan. "The Spatiotemporal Evolution of the Diurnal Cycle in Two WRF Simulations of Tropical Cyclones." Journal of the Atmospheric Sciences 79, no. 4 (April 2022): 1021–43. http://dx.doi.org/10.1175/jas-d-21-0100.1.
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Abstract The properties of diurnal variability in tropical cyclones (TCs) and the mechanisms behind them remain an intriguing aspect of TC research. This study provides a comprehensive analysis of diurnal variability in two simulations of TCs to explore these mechanisms. One simulation is a well-known Hurricane Nature Run (HNR1), which is a realistic simulation of a TC produced using the Weather Research and Forecasting (WRF) Model. The other simulation is a realistic simulation produced using WRF of Hurricane Florence (2018) using hourly ERA5 data as input. Empirical orthogonal functions and Fourier filtering are used to analyze diurnal variability in the TCs. In both simulations a diurnal squall forms at sunrise in the inner core and propagates radially outward and intensifies until midday. At midday the upper-level outflow strengthens, surface inflow weakens, and the cirrus canopy reaches its maximum height and radial extent. At sunset and overnight, the surface inflow is stronger, and convection inside the RMW peaks. Therefore, two diurnal cycles of convection exist in the TCs with different phases of maxima: eyewall convection at sunset and at night, and rainband convection in the early morning. This study finds that the diurnal pulse in the cirrus canopy is not advectively driven, nor can it be attributed to weaker inertial stability at night; rather, the results indicate direct solar heating as a mechanism for cirrus canopy lifting and enhanced daytime outflow. These results show a strong diurnal modulation of tropical cyclone structure, and are consistent with other recent observational and modeling studies of the TC diurnal cycle.
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Sun, Jianhua, and Fuqing Zhang. "Impacts of Mountain–Plains Solenoid on Diurnal Variations of Rainfalls along the Mei-Yu Front over the East China Plains." Monthly Weather Review 140, no. 2 (February 2012): 379–97. http://dx.doi.org/10.1175/mwr-d-11-00041.1.
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Convection-permitting numerical experiments using the Weather Research and Forecasting (WRF) model are performed to examine the impact of a thermally driven mountain–plains solenoid (MPS) on the diurnal variations of precipitation and mesoscale convective vortices along the mei-yu front over the east China plains during 1–10 July 2007. The focus of the analyses is a 10-day simulation that used the 10-day average of the global analysis at 0000 UTC as the initial condition and the 10-day averages every 6 h as lateral boundary conditions (with diurnal variations only). Despite differences in the rainfall intensity and location, this idealized experiment successfully simulated the observed diurnal variation and eastward propagation of rainfall and mesoscale convective vortices along the mei-yu front. It was found that the upward branch of the MPS, along with the attendant nocturnal low-level jet, is primarily responsible for the midnight-to-early-morning rainfall enhancement along the mei-yu front. The MPS is induced by differential heating between the high mountain ranges in central China and the low-lying plains in east China. Diabatic heating from moist convection initiated and/or enhanced by the solenoid circulation subsequently leads to the formation of a mesoscale convective vortex that further organizes and amplifies moist convection while propagating eastward along the mei-yu front. The downward branch of the MPS, on the other hand, leads to the suppression of precipitation over the plains during the daytime. The impacts of this regional MPS on the rainfall diurnal variations are further attested to by another idealized WRF simulation that uses fixed lateral boundary conditions.
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Lee, Myong-In, Siegfried D. Schubert, Max J. Suarez, Isaac M. Held, Arun Kumar, Thomas L. Bell, Jae-Kyung E. Schemm, et al. "Sensitivity to Horizontal Resolution in the AGCM Simulations of Warm Season Diurnal Cycle of Precipitation over the United States and Northern Mexico." Journal of Climate 20, no. 9 (May 1, 2007): 1862–81. http://dx.doi.org/10.1175/jcli4090.1.
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Abstract This study examines the sensitivity of the North American warm season diurnal cycle of precipitation to changes in horizontal resolution in three atmospheric general circulation models, with a primary focus on how the parameterized moist processes respond to improved resolution of topography and associated local/regional circulations on the diurnal time scale. It is found that increasing resolution (from approximately 2° to ½° in latitude–longitude) has a mixed impact on the simulated diurnal cycle of precipitation. Higher resolution generally improves the initiation and downslope propagation of moist convection over the Rockies and the adjacent Great Plains. The propagating signals, however, do not extend beyond the slope region, thereby likely contributing to a dry bias in the Great Plains. Similar improvements in the propagating signals are also found in the diurnal cycle over the North American monsoon region as the models begin to resolve the Gulf of California and the surrounding steep terrain. In general, the phase of the diurnal cycle of precipitation improves with increasing resolution, though not always monotonically. Nevertheless, large errors in both the phase and amplitude of the diurnal cycle in precipitation remain even at the highest resolution considered here. These errors tend to be associated with unrealistically strong coupling of the convection to the surface heating and suggest that improved simulations of the diurnal cycle of precipitation require further improvements in the parameterizations of moist convection processes.
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Noh, Yign, and Yeonju Choi. "Comments on “Langmuir Turbulence and Surface Heating in the Ocean Surface Boundary Layer”." Journal of Physical Oceanography 48, no. 2 (February 2018): 455–58. http://dx.doi.org/10.1175/jpo-d-17-0135.1.
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AbstractUsing large-eddy simulations (LES) it is shown that the depth of a diurnal thermocline h should be scaled by the Zilitinkevich scale LZ, not by the Monin–Obukhov length scale LMO, contrary to the proposition by Pearson et al. Their argument to explain the slower increase of h than LMO using the effect of the preexisting thermocline is also invalid.
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Gajendiran, M., and N. Nallusamy. "Application of Solar Thermal Energy Storage for Industrial Process Heating." Advanced Materials Research 984-985 (July 2014): 725–29. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.725.
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A massive deployment of solar thermal technology is required in those industries which use large quantities of low temperature hot water for the economic operation. With the rise in fuel cost and scarcity now, there is a significant research, development and application in solar industrial process heating. Due to the unavailability of solar energy during non sunny days and diurnal changes throughout the day, storage of thermal energy is inevitable. Recent developments nationally and internationally may rekindle new applications of solar thermal energy use by industry. This paper reviews the application of solar industrial process heating in paper industry.
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Wu, Shanshan, Haibo Zou, and Junjie Wu. "The Diurnal Variations of GPS PWV near Poyang Lake in China during Midsummer." Advances in Meteorology 2020 (July 21, 2020): 1–11. http://dx.doi.org/10.1155/2020/6241507.
Full textAbstract:
With the 1 h-averaged data of atmospheric precipitable water vapor (PWV) for 2015–2018 retrieved from 18 ground-based Global Positioning System (GPS) observation stations near Poyang Lake (PL), China, the diurnal variations of the PWV during midsummer (July-August) are studied by the harmonic method. Results show that significant diurnal variations of PWV are found at the 18 GPS stations. The harmonics with 24 h cycle (diurnal cycle) over PL (i.e., Duchang and Poyang) and Nanchang city only have about 50% (or even smaller than 50%) of variance contribution with the amplitude of about 0.2 mm, while above 70% (or even 80%) of variance contribution occurs elsewhere around PL, with the amplitude of about 0.9 mm. The harmonics with diurnal cycles in most stations peak from afternoon to evening (i.e., 1200-2000 LST), but one exception is Duchang site, where the diurnal cycle peaks in the morning (i.e., 1000 LST). Moreover, the harmonics with 12 h cycle (semidiurnal cycle) have the relatively uniform amplitude of about 0.2 mm, but their variance contributions show uneven distribution, with the contributions of about or above 50% in PL and Nanchang city (the semidiurnal cycles peak about 0000 LST or 1200 LST) and below 30% (or even 10%) in other areas. The preliminary diagnosis analysis shows that the diurnal variation of the low-level (below 850 hPa) air temperature (increasing after the sunrise, decreasing after the sunset, and peaking around 1400-1800 LST) may be responsible for the diurnal cycle. Moreover, in PL (Duchang and Poyang) and Nanchang city, the effects (heating or cooling) of lake and urban, the diurnal variation of the 10 m wind over PL, and the acceleration of PL on overlying air also contributed to the diurnal variation of PWV.