Journal articles: 'Variabilita interannuale'

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Navarro-Pérez, E., and E. D. Barton. "Seasonal and interannual variability of the Canary Current." Scientia Marina 65, S1 (July 30, 2001): 205–13. http://dx.doi.org/10.3989/scimar.2001.65s1205.

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Grandey, Benjamin S., Hsiang-He Lee, and Chien Wang. "Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires." Atmospheric Chemistry and Physics 16, no. 22 (November 23, 2016): 14495–513. http://dx.doi.org/10.5194/acp-16-14495-2016.

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Abstract. Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These “fire aerosols” can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of −1.0 W m−2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (−0.2 W m−2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (−1.2 W m−2), while over Boreal Asia the overestimation is +43 % (−1.9 W m−2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.

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Labitzke, K., B. Naujokat, and J. J. Barnett. "Interannual variability." Advances in Space Research 10, no. 12 (January 1990): 163–84. http://dx.doi.org/10.1016/0273-1177(90)90395-g.

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Cravatte, Sophie, Guillaume Serazin, Thierry Penduff, and Christophe Menkes. "Imprint of chaotic ocean variability on transports in the southwestern Pacific at interannual timescales." Ocean Science 17, no. 2 (March 18, 2021): 487–507. http://dx.doi.org/10.5194/os-17-487-2021.

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Abstract. The southwestern Pacific Ocean sits at a bifurcation where southern subtropical waters are redistributed equatorward and poleward by different ocean currents. The processes governing the interannual variability of these currents are not completely understood. This issue is investigated using a probabilistic modeling strategy that allows disentangling the atmospherically forced deterministic ocean variability and the chaotic intrinsic ocean variability. A large ensemble of 50 simulations performed with the same ocean general circulation model (OGCM) driven by the same realistic atmospheric forcing and only differing by a small initial perturbation is analyzed over 1980–2015. Our results show that, in the southwestern Pacific, the interannual variability of the transports is strongly dominated by chaotic ocean variability south of 20∘ S. In the tropics, while the interannual variability of transports and eddy kinetic energy modulation are largely deterministic and explained by the El Niño–Southern Oscillation (ENSO), ocean nonlinear processes still explain 10 % to 20 % of their interannual variance at large scale. Regions of strong chaotic variance generally coincide with regions of high mesoscale activity, suggesting that a spontaneous inverse cascade is at work from the mesoscale toward lower frequencies and larger scales. The spatiotemporal features of the low-frequency oceanic chaotic variability are complex but spatially coherent within certain regions. In the Subtropical Countercurrent area, they appear as interannually varying, zonally elongated alternating current structures, while in the EAC (East Australian Current) region, they are eddy-shaped. Given this strong imprint of large-scale chaotic oceanic fluctuations, our results question the attribution of interannual variability to the atmospheric forcing in the region from pointwise observations and one-member simulations.

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Katsura, Shota, Eitarou Oka, Bo Qiu, and Niklas Schneider. "Formation and Subduction of North Pacific Tropical Water and Their Interannual Variability." Journal of Physical Oceanography 43, no. 11 (November 1, 2013): 2400–2415. http://dx.doi.org/10.1175/jpo-d-13-031.1.

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Abstract Formation and subduction of the North Pacific Tropical Water (NPTW), its interannual variability, and its associated mechanisms were investigated by using gridded Argo-profiling float data and various surface flux data in 2003–11. The NPTW has two formation sites in the center of the North Pacific subtropical gyre, corresponding to two regional sea surface salinity maxima. Mixed layer salinity variations in these two NPTW formation sites were found to be significantly different. While seasonal variation was prominent in the eastern formation site, interannual variation was dominant in the western site. The mixed layer salinity variation in the eastern site was controlled mainly by evaporation, precipitation, and entrainment of fresher water below the mixed layer and was closely related to the seasonal variation of the mixed layer depth. In the western site, the effect of entrainment is small due to a small vertical difference in salinity across the mixed layer base, and excess evaporation over precipitation that tended to be balanced by eddy diffusion, whose strength varied interannually in association with the Pacific decadal oscillation. After subduction, denser NPTW that formed in the eastern site dissipated quickly, while the lighter one that formed in the western site was advected westward as far as the Philippine Sea, transmitting the interannual variation of salinity away from its formation region.

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Li, Feili, M. Susan Lozier, Gokhan Danabasoglu, Naomi P. Holliday, Young-Oh Kwon, Anastasia Romanou, Steve G. Yeager, and Rong Zhang. "Local and Downstream Relationships between Labrador Sea Water Volume and North Atlantic Meridional Overturning Circulation Variability." Journal of Climate 32, no. 13 (June 11, 2019): 3883–98. http://dx.doi.org/10.1175/jcli-d-18-0735.1.

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Abstract While it has generally been understood that the production of Labrador Sea Water (LSW) impacts the Atlantic meridional overturning circulation (MOC), this relationship has not been explored extensively or validated against observations. To explore this relationship, a suite of global ocean–sea ice models forced by the same interannually varying atmospheric dataset, varying in resolution from non-eddy-permitting to eddy-permitting (1°–1/4°), is analyzed to investigate the local and downstream relationships between LSW formation and the MOC on interannual to decadal time scales. While all models display a strong relationship between changes in the LSW volume and the MOC in the Labrador Sea, this relationship degrades considerably downstream of the Labrador Sea. In particular, there is no consistent pattern among the models in the North Atlantic subtropical basin over interannual to decadal time scales. Furthermore, the strong response of the MOC in the Labrador Sea to LSW volume changes in that basin may be biased by the overproduction of LSW in many models compared to observations. This analysis shows that changes in LSW volume in the Labrador Sea cannot be clearly and consistently linked to a coherent MOC response across latitudes over interannual to decadal time scales in ocean hindcast simulations of the last half century. Similarly, no coherent relationships are identified between the MOC and the Labrador Sea mixed layer depth or the density of newly formed LSW across latitudes or across models over interannual to decadal time scales.

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Hess, P., D. Kinnison, and Q. Tang. "Ensemble simulations of the role of the stratosphere in the attribution of northern extratropical tropospheric ozone variability." Atmospheric Chemistry and Physics 15, no. 5 (March 4, 2015): 2341–65. http://dx.doi.org/10.5194/acp-15-2341-2015.

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Abstract. Despite the need to understand the impact of changes in emissions and climate on tropospheric ozone, the attribution of tropospheric interannual ozone variability to specific processes has proven difficult. Here, we analyze the stratospheric contribution to tropospheric ozone variability and trends from 1953 to 2005 in the Northern Hemisphere (NH) mid-latitudes using four ensemble simulations of the free running (FR) Whole Atmosphere Community Climate Model (WACCM). The simulations are externally forced with observed time-varying (1) sea-surface temperatures (SSTs), (2) greenhouse gases (GHGs), (3) ozone depleting substances (ODS), (4) quasi-biennial oscillation (QBO), (5) solar variability (SV) and (6) stratospheric sulfate surface area density (SAD). A detailed representation of stratospheric chemistry is simulated, including the ozone loss due to volcanic eruptions and polar stratospheric clouds. In the troposphere, ozone production is represented by CH4–NOx smog chemistry, where surface chemical emissions remain interannually constant. Despite the simplicity of its tropospheric chemistry, at many NH measurement locations, the interannual ozone variability in the FR WACCM simulations is significantly correlated with the measured interannual variability. This suggests the importance of the external forcing applied in these simulations in driving interannual ozone variability. The variability and trend in the simulated 1953–2005 tropospheric ozone from 30 to 90° N at background surface measurement sites, 500 hPa measurement sites and in the area average are largely explained on interannual timescales by changes in the 30–90° N area averaged flux of ozone across the 100 hPa surface and changes in tropospheric methane concentrations. The average sensitivity of tropospheric ozone to methane (percent change in ozone to a percent change in methane) from 30 to 90° N is 0.17 at 500 hPa and 0.21 at the surface; the average sensitivity of tropospheric ozone to the 100 hPa ozone flux (percent change in ozone to a percent change in the ozone flux) from 30 to 90° N is 0.19 at 500 hPa and 0.11 at the surface. The 30–90° N simulated downward residual velocity at 100 hPa increased by 15% between 1953 and 2005. However, the impact of this on the 30–90° N 100 hPa ozone flux is modulated by the long-term changes in stratospheric ozone. The ozone flux decreases from 1965 to 1990 due to stratospheric ozone depletion, but increases again by approximately 7% from 1990 to 2005. The first empirical orthogonal function of interannual ozone variability explains from 40% (at the surface) to over 80% (at 150 hPa) of the simulated ozone interannual variability from 30 to 90° N. This identified mode of ozone variability shows strong stratosphere–troposphere coupling, demonstrating the importance of the stratosphere in an attribution of tropospheric ozone variability. The simulations, with no change in emissions, capture almost 50% of the measured ozone change during the 1990s at a variety of locations. This suggests that a large portion of the measured change is not due to changes in emissions, but can be traced to changes in large-scale modes of ozone variability. This emphasizes the difficulty in the attribution of ozone changes, and the importance of natural variability in understanding the trends and variability of ozone. We find little relation between the El Niño–Southern Oscillation (ENSO) index and large-scale tropospheric ozone variability over the long-term record.

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Hess, P., D. Kinnison, and Q. Tang. "Ensemble simulations of the role of the stratosphere in the attribution of tropospheric ozone variability." Atmospheric Chemistry and Physics Discussions 14, no. 14 (August 8, 2014): 20461–520. http://dx.doi.org/10.5194/acpd-14-20461-2014.

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Abstract. Despite the need to understand the impact of changes in emissions and climate on tropospheric ozone, attribution of tropospheric interannual ozone variability to specific processes has proved difficult. Here we analyze the stratospheric contribution to tropospheric ozone variability and trends from 1953–2005 in the Northern Hemisphere (N.~H.) mid-latitudes using four ensemble simulations of the Free Running (FR) Whole Atmosphere Community Climate Model (WACCM). The simulations are forced with observed time varying: (1) sea surface temperatures (SSTs), (2) greenhouse gases (GHGs), (3) ozone depleting substances (ODS), (4) Quasi-Biennial Oscillation (QBO); (5) solar variability (SV) and (6) stratospheric sulfate surface area density (SAD). Detailed representation of stratospheric chemistry is simulated including the ozone loss processes due to volcanic eruptions and polar stratospheric clouds. In the troposphere ozone production is represented by CH4-NOx smog chemistry, where surface chemical emissions remain interannually constant. Despite the simplicity of the tropospheric chemistry, the FR WACCM simulations capture the measured N. H. background interannual tropospheric ozone variability in many locations to a surprising extent, suggesting the importance of external forcing in driving interannual ozone variability. The variability and trend in the simulated 1953–2005 tropospheric ozone record from 30–90° N at background surface measurement sites, 500 hPa measurement sites and in the area average is largely explained on interannual timescales by changes in the 150 hPa 30–90° N ozone flux and changes in tropospheric methane concentrations. The average sensitivity of tropospheric ozone to methane (percent change in ozone to a percent change in methane) from 30–90° N is 0.17 at 500 hPa and 0.21 at the surface; the average sensitivity of tropospheric ozone to the 150 hPa ozone flux (percent change in ozone to a percent change in the ozone flux) from 30–90° N is 0.19 at 500 hPa and 0.11 at the surface. The 30–90° N simulated downward residual velocity at 150 hPa increased by 15% between 1953 and 2005. However, the impact of this on the 30–90° N 150 hPa ozone flux is modulated by the long-term changes in stratospheric ozone. The ozone flux decreases from 1965 to 1990 due to stratospheric ozone depletion, but increases again by approximately 7% from 1990–2005. The first empirical orthogonal function of interannual ozone variability explains from 40% (at the surface) to over 80% (at 150 hPa) of the simulated ozone interannual variability from 30–90° N. This identified mode of ozone variability shows strong stratosphere–troposphere coupling, demonstrating the importance of the stratosphere in an attribution of tropospheric ozone variability. The simulations, with no change in emissions, capture almost 50% of the measured ozone change during the 1990s at a variety of locations. This suggests that a large portion of the measured change is not due to changes in emissions, but can be traced to changes in large-scale modes of ozone variability. This emphasizes the difficulty in the attribution of ozone changes, and the importance of natural variability in understanding the trends and variability of ozone. We find little relation between the El Nino Southern Oscillation (ENSO) index and large-scale tropospheric ozone variability over the long-term record.

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Tandon, Neil F., Oleg A. Saenko, Mark A. Cane, and Paul J. Kushner. "Interannual Variability of the Global Meridional Overturning Circulation Dominated by Pacific Variability." Journal of Physical Oceanography 50, no. 3 (March 2020): 559–74. http://dx.doi.org/10.1175/jpo-d-19-0129.1.

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AbstractThe most prominent feature of the time-mean global meridional overturning circulation (MOC) is the Atlantic MOC (AMOC). However, interannual variability of the global MOC is shown here to be dominated by Pacific MOC (PMOC) variability over the full depth of the ocean at most latitudes. This dominance of interannual PMOC variability is robust across modern climate models and an observational state estimate. PMOC interannual variability has large-scale organization, its most prominent feature being a cross-equatorial cell spanning the tropics. Idealized experiments show that this variability is almost entirely wind driven. Interannual anomalies of zonal mean zonal wind stress produce zonally integrated Ekman transport anomalies that are larger in the Pacific Ocean than in the Atlantic Ocean, simply because the Pacific is wider than the Atlantic at most latitudes. This contrast in Ekman transport variability implies greater variability in the near-surface branch of the PMOC when compared with the near-surface branch of the AMOC. These near-surface variations in turn drive compensating flow anomalies below the Ekman layer. Because the baroclinic adjustment time is longer than a year at most latitudes, these compensating flow anomalies have baroclinic structure spanning the full depth of the ocean. Additional analysis reveals that interannual PMOC variations are the dominant contribution to interannual variations of the global meridional heat transport. There is also evidence of interaction between interannual PMOC variability and El Niño–Southern Oscillation.

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Qiu, Bo, and Shuiming Chen. "Interannual Variability of the North Pacific Subtropical Countercurrent and Its Associated Mesoscale Eddy Field." Journal of Physical Oceanography 40, no. 1 (January 1, 2010): 213–25. http://dx.doi.org/10.1175/2009jpo4285.1.

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Abstract Interannual changes in the mesoscale eddy field along the Subtropical Countercurrent (STCC) band of 18°–25°N in the western North Pacific Ocean are investigated with 16 yr of satellite altimeter data. Enhanced eddy activities were observed in 1996–98 and 2003–08, whereas the eddy activities were below average in 1993–95 and 1999–2002. Analysis of repeat hydrographic data along 137°E reveals that the vertical shear between the surface eastward-flowing STCC and the subsurface westward-flowing North Equatorial Current (NEC) was larger in the eddy-rich years than in the eddy-weak years. By adopting a 2½-layer reduced-gravity model, it is shown that the increased eddy kinetic energy level in 1996–98 and 2003–08 is because of enhanced baroclinic instability resulting from the larger vertical shear in the STCC–NEC’s background flow. The cause for the STCC–NEC’s interannually varying vertical shear can be sought in the forcing by surface Ekman temperature gradient convergence within the STCC band. Rather than El Niño–Southern Oscillation signals as previously hypothesized, interannual changes in this Ekman forcing field, and hence the STCC–NEC’s vertical shear, are more related to the negative western Pacific index signals.

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Räisänen, Jouni. "Energetics of interannual temperature variability." Climate Dynamics 52, no. 5-6 (June 18, 2018): 3139–56. http://dx.doi.org/10.1007/s00382-018-4306-0.

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Kane, R. P. "Interannual variability of precipitable water." Annales Geophysicae 14, no. 4 (April 30, 1996): 464–67. http://dx.doi.org/10.1007/s00585-996-0464-1.

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Abstract. The 12-month running means of the surface-to-500 mb precipitable water obtained from analysis of radiosonde data at seven selected locations showed three types of variability viz: (1) quasi-biennial oscillations; these were different in nature at different latitudes and also different from the QBO of the stratospheric tropical zonal winds; (2) decadal effects; these were prominent at middle and high latitudes and (3) linear trends; these were prominent at low latitudes, up trends in the Northern Hemisphere and downtrends in the Southern Hemisphere.

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Keenlyside, Noel S., and Mojib Latif. "Understanding Equatorial Atlantic Interannual Variability." Journal of Climate 20, no. 1 (January 1, 2007): 131–42. http://dx.doi.org/10.1175/jcli3992.1.

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Abstract An observational-based analysis of coupled variability in the equatorial Atlantic and its seasonality is presented. Regression analysis shows that the three elements of the Bjerknes positive feedback exist in the Atlantic and are spatially similar to those of the Pacific. The cross-correlation functions of the elements of the Bjerknes feedback are also similar and consistent with an ocean–atmosphere coupled mode. However, the growth rate in the Atlantic is up to 50% weaker, and explained variance is significantly lower. The Bjerknes feedback in the Atlantic is strong in boreal spring and summer, and weak in other seasons, which explains why the largest sea surface temperature anomalies (SSTAs) occur in boreal summer. Its seasonality is determined by seasonal variations in both atmospheric sensitivity to SSTA and SSTA sensitivity to subsurface temperature anomalies.

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Rasmusson, Eugene M. "Intraseasonal and interannual climate variability." Climatic Change 16, no. 2 (April 1990): 153–71. http://dx.doi.org/10.1007/bf00134654.

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Long, A. P., D. Haberlin, O. Lyashevska, D. Brophy, Brendan O’ Hea, C. O’Donnell, R. G. Scarrott, C. Lawton, and T. K. Doyle. "Interannual variability of gelatinous mesozooplankton in a temperate shelf sea: greater abundance coincides with cooler sea surface temperatures." ICES Journal of Marine Science 78, no. 4 (March 8, 2021): 1372–85. http://dx.doi.org/10.1093/icesjms/fsab030.

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Abstract Although gelatinous zooplankton are an important component of marine ecosystems, gelatinous mesozooplankton that are <2 cm are underrepresented in monitoring programmes. Here, the interannual variability of gelatinous mesozooplankton abundance and diversity was estimated from 167 zooplankton net samples that were collected in the Celtic Sea during seven fisheries surveys between 2007 and 2019 and analysed alongside environmental parameters. Compositional changes occurred interannually, including an overturn in the abundance ratio of two siphonophores (Muggiaea atlantica and Agalma elegans). Analysis of annual mean gelatinous abundance revealed no linear trend over time (Spearman, r = −0.09, p = 0.287); however, the interannual abundance varied by a factor of 33 (minimum mean abundance in 2013 = 7.36 ± 4.86 individuals m−3; maximum in 2017 = 244.82 ± 84.59 individuals m−3). Holoplanktonic taxa dominated the abundance of the gelatinous community (93.27%) and their abundance was negatively associated with summer sea surface temperature (represented by the 16°C isotherm in July), and the Eastern Atlantic Pattern index 3 months prior (April). Our data suggest that gelatinous mesozooplankton in the Celtic Sea may become less abundant with further ocean warming, and further highlight the need to monitor gelatinous mesozooplankton with a high taxonomic resolution moving forward.

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Jochum, Markus, Clara Deser, and Adam Phillips. "Tropical Atmospheric Variability Forced by Oceanic Internal Variability." Journal of Climate 20, no. 4 (February 15, 2007): 765–71. http://dx.doi.org/10.1175/jcli4044.1.

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Abstract Atmospheric general circulation model experiments are conducted to quantify the contribution of internal oceanic variability in the form of tropical instability waves (TIWs) to interannual wind and rainfall variability in the tropical Pacific. It is found that in the tropical Pacific, along the equator, and near 25°N and 25°S, TIWs force a significant increase in wind and rainfall variability from interseasonal to interannual time scales. Because of the stochastic nature of TIWs, this means that climate models that do not take them into account will underestimate the strength and number of extreme events and may overestimate forecast capability.

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Lu, Riyu, and Yuanhai Fu. "Intensification of East Asian Summer Rainfall Interannual Variability in the Twenty-First Century Simulated by 12 CMIP3 Coupled Models." Journal of Climate 23, no. 12 (June 15, 2010): 3316–31. http://dx.doi.org/10.1175/2009jcli3130.1.

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Abstract The authors examine the projected change in interannual variability of East Asian summer precipitation and of dominant monsoonal circulation components in the twenty-first century under scenarios A1B and A2 by analyzing the simulated results of 12 Coupled Model Intercomparison Project phase 3 (CMIP3) coupled models. Interannual standard deviation is used to depict the intensity of interannual variability. An evaluation indicates that these models can reasonably reproduce the essential features of the present-day interannual variability in both East Asian rainfall and the rainfall-related circulations. The models project an enhanced interannual variability of summer rainfall over East Asia in the twenty-first century, under both scenarios A1B and A2. Over the East Asian summer rain belt, 10 of the 12 models under scenario A1B and 9 of the 10 models under scenario A2 show enhanced variability in the twenty-first century relative to the twentieth century. The multimodel ensemble (MME) results in increased ratios of interannual standard deviation of precipitation averaged over this region of about 12% and 19% under scenarios A1B and A2, respectively. Furthermore, it is found that the interannual variability is intensified much more remarkably in comparison with mean precipitation. Two circulation factors, the western North Pacific subtropical high (WNPSH) and East Asian upper-tropospheric jet (EAJ), which are closely related to the interannual variability of East Asian summer rainfall, are also projected by the models to exhibit enhanced interannual variability in the twenty-first century. This provides more evidence for the enhancement of interannual variability in East Asian summer rainfall and implies intensified interannual variability of the whole East Asian summer monsoon system. On the other hand, the relationships of East Asian rainfall with the WNPSH and EAJ do not exhibit clear changes in the twenty-first century under scenarios A1B and A2, and there are great discrepancies in the changes of the relationships among the individual models.

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Vimont, Daniel J. "The Contribution of the Interannual ENSO Cycle to the Spatial Pattern of Decadal ENSO-Like Variability*." Journal of Climate 18, no. 12 (June 15, 2005): 2080–92. http://dx.doi.org/10.1175/jcli3365.1.

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Abstract A defining feature of Pacific decadal ENSO-like variability is the similarity between its spatial expression in sea surface temperature (SST) and the spatial structure of interannual ENSO variability. This similarity may indicate that the decadal variability is merely a long-term average over interannual ENSO variability. In contrast, subtle differences (namely the meridionally broadened tropical SST signature and emphasized midlatitude SST anomalies for the decadal ENSO-like pattern) may indicate that fundamentally different processes are responsible for generating variability on the decadal to interdecadal time scale. The present study attempts to reconcile the subtly different spatial structures of interannual ENSO and decadal ENSO-like variability by relating the decadal pattern to various SST patterns associated with the development of the interannual ENSO cycle. First, a statistical analysis is used to reconstruct the decadal ENSO-like SST pattern as a linear combination of interannual SST patterns. It is shown that the decadal ENSO-like pattern is well reconstructed in the absence of decadal spatial information. Next, these interannual patterns are physically interpreted in relation to the interannual ENSO cycle. The analysis reveals that the decadal ENSO-like SST pattern is obtained by averaging over three SST patterns associated with ENSO precursors, the peak of an ENSO event, and ENSO “leftovers.” The study provides a plausible physical explanation for the spatial structure of ENSO-like decadal variability as an average over variations in the interannual ENSO cycle. The results indicate that the prominent spatial features of decadal ENSO-like variability are generated by physical mechanisms that operate through the interannual ENSO cycle. This does not imply, however, that decadal processes are unimportant in altering the decadal properties of ENSO. Results may provide a framework for interpreting modeled decadal ENSO-like variability and for constraining plausible mechanisms of tropical decadal variability.

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Sun, Bo, and Huijun Wang. "Interannual Variation of the Spring and Summer Precipitation over the Three River Source Region in China and the Associated Regimes." Journal of Climate 31, no. 18 (September 2018): 7441–57. http://dx.doi.org/10.1175/jcli-d-17-0680.1.

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This study analyzes the interannual and interdecadal variability of spring and summer precipitation over the Three River Source (TRS) region in China using four datasets. A general consistency is revealed among the four datasets with regard to the interannual and interdecadal variability of TRS precipitation during 1979–2015, demonstrating a confidence of the four datasets in representing the precipitation variability over the TRS region. The TRS spring and summer precipitation shows distinct interannual and interdecadal variability, with an overall increasing trend in the spring precipitation and an interdecadal oscillation in the summer precipitation. The regimes associated with the interannual variability of TRS spring and summer precipitation are further investigated. The interannual variability of TRS spring precipitation is essentially modulated by an anomalous easterly water vapor transport (WVT) branch associated with the leading mode of Eurasian spring circulation. El Niño–Southern Oscillation (ENSO) may affect the interannual variability of TRS spring precipitation by causing southerly WVT anomalies toward the TRS region. The interannual variability of TRS summer precipitation is essentially modulated by an anomalous southwesterly WVT branch over the TRS region, which is mainly associated with a Eurasian wave train connected with the summer North Atlantic Oscillation. A strong East Asian summer monsoon and an El Niño–decaying summer may also contribute to the southwesterly WVT anomalies over the TRS region.

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Voulgarakis, A., N. H. Savage, P. Braesicke, O. Wild, G. D. Carver, and J. A. Pyle. "Interannual variability of tropospheric composition: the influence of changes in emissions, meteorology and clouds." Atmospheric Chemistry and Physics Discussions 9, no. 3 (June 26, 2009): 14023–57. http://dx.doi.org/10.5194/acpd-9-14023-2009.

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Abstract. We have run a chemistry transport model (CTM) to systematically examine the drivers of interannual variability of tropospheric composition. On a global scale, changing meteorology (winds, temperatures, humidity and clouds) is found to be the most important factor driving interannual variability of NO2 and ozone on the timescales considered. The strong influence of emissions is largely confined to areas where intense biomass burning events occur. For CO, interannual variability is almost solely driven by emission changes, while for OH meteorology dominates, with the radiative influence of clouds being a very strong contributor. Through a simple attribution analysis we conclude that changing cloudiness drives 25% of the interannual variability of OH over Europe by affecting shortwave radiation. Over Indonesia this figure is as high as 71%. Changes in cloudiness contribute a small but non-negligible amount (up to 6%) to the interannual variability of ozone over Europe and Indonesia. This suggests that future assessments of trends in tropospheric oxidizing capacity should account for interannual variability in cloudiness, a factor neglected in many previous studies. The approach followed in the current study can help explain observed tropospheric variability, such as the increases in ozone concentrations over Europe in 1998.

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Ford, Trent W., and Steven M. Quiring. "Influence of MODIS-Derived Dynamic Vegetation on VIC-Simulated Soil Moisture in Oklahoma." Journal of Hydrometeorology 14, no. 6 (November 22, 2013): 1910–21. http://dx.doi.org/10.1175/jhm-d-13-037.1.

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Abstract Soil moisture–vegetation interactions are an important component of land–atmosphere coupling, especially in semiarid regions such as the North American Great Plains. However, many land surface models parameterize vegetation using an interannually invariant leaf area index (LAI). This study quantifies how utilizing a dynamic vegetation parameter in the variability infiltration capacity (VIC) hydrologic model influences model-simulated soil moisture. Accuracy is assessed using in situ soil moisture observations from 20 stations from the Oklahoma Mesonet. Results show that VIC simulations generated with an interannually variant LAI parameter are not consistently more accurate than those generated with the invariant (static) LAI parameter. However, the static LAI parameter tends to overestimate LAI during anomalously dry periods. This has the greatest influence on the accuracy of the soil moisture simulations in the deeper soil layers. Soil moisture drought, as simulated with the static LAI parameter, tends to be more severe and persist for considerably longer than drought simulated using the interannually variant LAI parameter. Dynamic vegetation parameters can represent interannual variations in vegetation health and growing season length. Therefore, simulations with a dynamic LAI parameter better capture the intensity and duration of drought conditions and are recommended for use in drought monitoring.

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Lebedev, S. A., and A. G. Kostianoy. "Investigation of seasonal and interannual variability of water exchange through the Middle Caspian based on satellite altimetry." Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa 17, no. 6 (2020): 103–9. http://dx.doi.org/10.21046/2070-7401-2020-17-6-103-109.

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23

Martín-Rey, Marta, Irene Polo, Belén Rodríguez-Fonseca, and Fred Kucharski. "Changes in the interannual variability of the tropical Pacific as a response to an equatorial Atlantic forcing." Scientia Marina 76, S1 (September 3, 2012): 105–16. http://dx.doi.org/10.3989/scimar.03610.19a.

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24

Voulgarakis, A., N. H. Savage, O. Wild, P. Braesicke, P. J. Young, G. D. Carver, and J. A. Pyle. "Interannual variability of tropospheric composition: the influence of changes in emissions, meteorology and clouds." Atmospheric Chemistry and Physics 10, no. 5 (March 11, 2010): 2491–506. http://dx.doi.org/10.5194/acp-10-2491-2010.

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Abstract. We have run a chemistry transport model (CTM) to systematically examine the drivers of interannual variability of tropospheric composition during 1996–2000. This period was characterised by anomalous meteorological conditions associated with the strong El Niño of 1997–1998 and intense wildfires, which produced a large amount of pollution. On a global scale, changing meteorology (winds, temperatures, humidity and clouds) is found to be the most important factor driving interannual variability of NO2 and ozone on the timescales considered. Changes in stratosphere-troposphere exchange, which are largely driven by meteorological variability, are found to play a particularly important role in driving ozone changes. The strong influence of emissions on NO2 and ozone interannual variability is largely confined to areas where intense biomass burning events occur. For CO, interannual variability is almost solely driven by emission changes, while for OH meteorology dominates, with the radiative influence of clouds being a very strong contributor. Through a simple attribution analysis for 1996–2000 we conclude that changing cloudiness drives 25% of the interannual variability of OH over Europe by affecting shortwave radiation. Over Indonesia this figure is as high as 71%. Changes in cloudiness contribute a small but non-negligible amount (up to 6%) to the interannual variability of ozone over Europe and Indonesia. This suggests that future assessments of trends in tropospheric oxidizing capacity should account for interannual variability in cloudiness, a factor neglected in many previous studies.

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25

Good, Stephen P., Kaiyu Guan, and Kelly K. Caylor. "Global Patterns of the Contributions of Storm Frequency, Intensity, and Seasonality to Interannual Variability of Precipitation." Journal of Climate 29, no. 1 (December 22, 2015): 3–15. http://dx.doi.org/10.1175/jcli-d-14-00653.1.

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Abstract Interannual variation in precipitation totals is a critical factor governing the year-to-year availability of water resources, yet the connection between interannual precipitation variability and underlying event- and season-scale precipitation variability remains unclear. In this study, tropical and midlatitude precipitation characteristics derived from extensive station records and high-frequency satellite observations were analyzed to attribute the fraction of interannual variability arising as a result of individual variability in precipitation event intensity, frequency, and seasonality, as well as the cross-correlation between these factors at the global scale. This analysis demonstrates that variability in the length of the wet season is the most important factor globally, causing 52% of the total interannual variability, while variation in the intensity of individual rainfall events contributes 31% and variability in interstorm wait times contributes only 17%. Spatial patterns in the contribution of each of these intra-annual rainfall characteristics are informative, with regions such as Indonesia and southwestern North America primarily influenced by seasonality, while regions such as the eastern United States, central Africa, and the upper Amazon basin are strongly influenced by storm intensity and frequency. A robust cross-correlation between climate characteristics is identified in the equatorial Pacific, revealing an increased interannual variability over what is expected based on the variability of individual events. This decomposition of interannual variability identifies those regions where accurate representation of daily and seasonal rainfall statistics is necessary to understand and correctly model rainfall variability at longer time scales.

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SCHOTT, F., and R. ZANTOPP. "Florida Current: Seasonal and Interannual Variability." Science 227, no. 4684 (January 18, 1985): 308–11. http://dx.doi.org/10.1126/science.227.4684.308.

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27

Fedorov, V. M. "Interannual variability of the solar constant." Solar System Research 46, no. 2 (March 27, 2012): 170–76. http://dx.doi.org/10.1134/s0038094612020049.

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28

Lamb, Peter J., Randy A. Peppler, and Stefan Hastenrath. "Interannual variability in the tropical Atlantic." Nature 322, no. 6076 (July 1986): 238–40. http://dx.doi.org/10.1038/322238a0.

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Rajagopalan, B., and U. Lall. "Interannual variability in western US precipitation." Journal of Hydrology 210, no. 1-4 (September 1998): 51–67. http://dx.doi.org/10.1016/s0022-1694(98)00184-x.

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30

Fay, James A., and Dan Golomb. "Interannual variability of transboundary sulfur flux." Atmospheric Environment (1967) 23, no. 12 (January 1989): 2864–65. http://dx.doi.org/10.1016/0004-6981(89)90572-6.

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Olson, M. P., and K. K. Oikawa. "Interannual variability of transboundary sulphur flux." Atmospheric Environment (1967) 23, no. 2 (January 1989): 333–40. http://dx.doi.org/10.1016/0004-6981(89)90581-7.

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32

Kane, R. P., and D. Gobbi. "Interannual variability of United States cloudiness." Annales Geophysicae 13, no. 6 (June 30, 1995): 660–65. http://dx.doi.org/10.1007/s00585-995-0660-4.

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Abstract. United States cloudiness data for 1950–1992 show quasi-biennial (QBO) and quasi-triennial (QTO) oscillations which match partly with the QBO and QTO of the Southern Oscillation (SO) index (the Tahiti minus Darwin pressure), but not with the QBO of the 50-mb equatorial zonal wind. Cloudiness also shows significant periodicities near 4.2 and 7.5 years, and probably a sunspot cycle effect (periodicities 11–14 years), with minimum cloudiness at or soon after sunspot minima, though this could also be due to periodicities of 10 and 17 years observed in the SO index. During 1955–1970, cloudiness increased by about 1%. Thereafter, it remained almost steady for the eastern and central parts of the USA, but continued to rise until about 1980 for the western USA.

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33

Manning, James. "Middle Atlantic Bight salinity: interannual variability." Continental Shelf Research 11, no. 2 (February 1991): 123–37. http://dx.doi.org/10.1016/0278-4343(91)90058-e.

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34

Schultz, Colin. "Predicting interannual variability in evapotranspiration rates." Eos, Transactions American Geophysical Union 92, no. 45 (November 8, 2011): 408. http://dx.doi.org/10.1029/2011eo450011.

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35

L�thi, D., A. Cress, H. C. Davies, C. Frei, and C. Sch�r. "Interannual variability and regional climate simulations." Theoretical and Applied Climatology 53, no. 4 (1996): 185–209. http://dx.doi.org/10.1007/bf00871736.

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36

Frank, William M., and George S. Young. "The Interannual Variability of Tropical Cyclones." Monthly Weather Review 135, no. 10 (October 1, 2007): 3587–98. http://dx.doi.org/10.1175/mwr3435.1.

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Abstract This paper examines the interannual variability of tropical cyclones in each of the earth’s cyclone basins using data from 1985 to 2003. The data are first analyzed using a Monte Carlo technique to investigate the long-standing myth that the global number of tropical cyclones is less variable than would be expected from examination of the variability in each basin. This belief is found to be false. Variations in the global number of all tropical cyclones are indistinguishable from those that would be expected if each basin was examined independently of the others. Furthermore, the global number of the most intense storms (Saffir–Simpson categories 4–5) is actually more variable than would be expected because of an observed tendency for storm activity to be correlated between basins, and this raises important questions as to how and why these correlations arise. Interbasin correlations and factor analysis of patterns of tropical cyclone activity reveal that there are several significant modes of variability. The largest three factors together explain about 70% of the variance, and each of these factors shows significant correlation with ENSO, the North Atlantic Oscillation (NAO), or both, with ENSO producing the largest effects. The results suggest that patterns of tropical cyclone variability are strongly affected by large-scale modes of interannual variability. The temporal and spatial variations in storm activity are quite different for weaker tropical cyclones (tropical storm through category 2 strength) than for stronger storms (categories 3–5). The stronger storms tend to show stronger interbasin correlations and stronger relationships to ENSO and the NAO than do the weaker storms. This suggests that the factors that control tropical cyclone formation differ in important ways from those that ultimately determine storm intensity.

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Yamagami, Yoko, Tomoki Tozuka, and Bo Qiu. "Interannual Variability of the Natal Pulse." Journal of Geophysical Research: Oceans 124, no. 12 (December 2019): 9258–76. http://dx.doi.org/10.1029/2019jc015525.

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Chervin, Robert M. "Interannual Variability and Seasonal Climate Predictability." Journal of the Atmospheric Sciences 43, no. 3 (February 1986): 233–51. http://dx.doi.org/10.1175/1520-0469(1986)043<0233:ivascp>2.0.co;2.

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39

Thompson, R. L., E. Dlugokencky, F. Chevallier, P. Ciais, G. Dutton, J. W. Elkins, R. L. Langenfelds, et al. "Interannual variability in tropospheric nitrous oxide." Geophysical Research Letters 40, no. 16 (August 27, 2013): 4426–31. http://dx.doi.org/10.1002/grl.50721.

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Woollings, T., C. Franzke, D. L. R. Hodson, B. Dong, E. A. Barnes, C. C. Raible, and J. G. Pinto. "Contrasting interannual and multidecadal NAO variability." Climate Dynamics 45, no. 1-2 (July 31, 2014): 539–56. http://dx.doi.org/10.1007/s00382-014-2237-y.

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41

Jury, Mark R., and Ernesto Rodríguez. "Caribbean hurricanes: interannual variability and prediction." Theoretical and Applied Climatology 106, no. 1-2 (March 23, 2011): 105–15. http://dx.doi.org/10.1007/s00704-011-0422-z.

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42

Mapande, Amin T., and C. J. C. Reason. "Interannual rainfall variability over Western Tanzania." International Journal of Climatology 25, no. 10 (2005): 1355–68. http://dx.doi.org/10.1002/joc.1193.

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43

Mohr, Karen I., John Molinari, and Chris D. Thorncroft. "The Interannual Stability of Cumulative Frequency Distributions for Convective System Size and Intensity." Journal of Climate 22, no. 19 (October 1, 2009): 5218–31. http://dx.doi.org/10.1175/2009jcli2940.1.

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Abstract The characteristics of convective system populations in West Africa and the western Pacific tropical cyclone basin were analyzed to investigate whether interannual variability in convective activity in tropical continental and oceanic environments is driven by variations in the number of events during the wet season or by favoring large and/or intense convective systems. Convective systems were defined from Tropical Rainfall Measuring Mission (TRMM) data as a cluster of pixels with an 85-GHz polarization-corrected brightness temperature below 255 K and with an area of at least 64 km2. The study database consisted of convective systems in West Africa from May to September 1998–2007, and in the western Pacific from May to November 1998–2007. Annual cumulative frequency distributions for system minimum brightness temperature and system area were constructed for both regions. For both regions, there were no statistically significant differences between the annual curves for system minimum brightness temperature. There were two groups of system area curves, split by the TRMM altitude boost in 2001. Within each set, there was no statistically significant interannual variability. Subsetting the database revealed some sensitivity in distribution shape to the size of the sampling area, the length of the sample period, and the climate zone. From a regional perspective, the stability of the cumulative frequency distributions implied that the probability that a convective system would attain a particular size or intensity does not change interannually. Variability in the number of convective events appeared to be more important in determining whether a year is either wetter or drier than normal.

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44

Branstator, Grant, and Jorgen Frederiksen. "The Seasonal Cycle of Interannual Variability and the Dynamical Imprint of the Seasonally Varying Mean State." Journal of the Atmospheric Sciences 60, no. 13 (July 1, 2003): 1577–92. http://dx.doi.org/10.1175/3002.1.

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Abstract Various aspects of the seasonal cycle of interannual variability of the observed 300-hPa streamfunction are documented and related to dynamical influences of the seasonality of the mean circulation. The stochastically excited nondivergent barotropic vorticity equation linearized about upper-tropospheric climatological mean states from each month of the year is used to identify characteristics of interannual variability that the seasonal cycle of the mean state should modulate. The result is interannual variability with (a) extratropical centers of variance that are much stronger in winter than summer and that are confined to midlatitudes during the warm season, (b) an annual cycle of preferred scales in midlatitudes with largest scales occurring during winter and a semiannual cycle of scales in the subtropics, and (c) streamfunction tendencies from interannual fluxes that adjust to the seasonally varying climatological eddies in such a way as to damp them. Because these same properties are also shown to exist in nature, it is concluded that the linear framework is a useful means of understanding the seasonality of interannual disturbances and that seasonality of the mean state leaves a pronounced imprint on interannual variability. Analysis of an ensemble of general circulation model integrations indicates the signatures of seasonality produced in the stochastically driven linear framework are more useful for understanding intrinsic interannual variability than variability caused by seasonally varying sea surface temperature anomalies. Furthermore, it is found that the intrinsic variability of the GCM has properties very much like those in nature, another indication that organization resulting from anomalous forcing structure is not required for production of many aspects of the observed seasonality of interannual variability.

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45

Namboodiri, K. V. S., P. K. Dileep, and Koshy Mammen. "Climatic Variation at Thumba Equatorial Rocket Launching Station, India." Journal of Climatology 2013 (November 10, 2013): 1–16. http://dx.doi.org/10.1155/2013/680565.

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Long-term (45 years) diversified surface meteorological records from Thumba Equatorial Rocket Launching Station (TERLS), India, were collected and analysed to study the long-term changes in the overall climatology, climatology pertained to a particular observational time, mean daily climatology in temperature, inter-annual variability in temperature, interannual variability in surface pressure, and rainfall for the main Indian seasons—South West and North East monsoons and inter-annual mean monthly anomaly structure in temperature. Results on various analyses show strong and vivid features contributed by climate change for this South Peninsular Indian Arabian Sea Coastal Station, and this paper may be a first time venture which discusses climate change imparted perturbations in several meteorological parameters in different time domains, like a specific time, daily, monthly, and interannually over a station. Being a coastal rocket launching station, climatic change information is crucial for long-term planning of its facilities as well as for various rocket range operational demands.

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46

Kumar, Arun, Qin Zhang, J.-K. E. Schemm, Michelle L’Heureux, and K.-H. Seo. "An Assessment of Errors in the Simulation of Atmospheric Interannual Variability in Uncoupled AGCM Simulations." Journal of Climate 21, no. 10 (May 15, 2008): 2204–17. http://dx.doi.org/10.1175/2007jcli1743.1.

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Abstract For the uncoupled atmospheric general circulation model (AGCM) simulations, the quantification of errors due to the lack of coupled ocean–atmospheric evolution on the characteristics of the atmospheric interannual variability is important for various reasons including the following: 1) AGCM simulations forced with specified SSTs continue to be used for understanding atmospheric interannual variability and 2) there is a vast knowledge base quantifying the global atmospheric influence of tropical SSTs that traditionally has relied on the analysis of AGCM-alone simulations. To put such results and analysis in a proper context, it is essential to document errors that may result from the lack of a coupled ocean–atmosphere evolution in the AGCM-alone integrations. Analysis is based on comparison of tier-two (or uncoupled) and coupled hindcasts for the 1982–2005 period, and interannual variability for the December–February (DJF) seasonal mean is analyzed. Results indicate that for the seasonal mean variability, and for the DJF seasonal mean, atmospheric interannual variability between coupled and uncoupled simulations is similar. This conclusion is drawn from the analysis of interannual variability of rainfall and 200-mb heights and includes analysis of SST-forced interannual variability, analysis of El Niño and La Niña composites, and a comparison of hindcast skill between tier-two and coupled hindcasts.

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47

Jouanno, Julien, Olga Hernandez, and Emilia Sanchez-Gomez. "Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes." Earth System Dynamics 8, no. 4 (November 30, 2017): 1061–69. http://dx.doi.org/10.5194/esd-8-1061-2017.

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Abstract. The contributions of the dynamic and thermodynamic forcing to the interannual variability of the equatorial Atlantic sea surface temperature (SST) are investigated using a set of interannual regional simulations of the tropical Atlantic Ocean. The ocean model is forced with an interactive atmospheric boundary layer, avoiding damping toward prescribed air temperature as is usually the case in forced ocean models. The model successfully reproduces a large fraction (R2 = 0.55) of the observed interannual variability in the equatorial Atlantic. In agreement with leading theories, our results confirm that the interannual variations of the dynamical forcing largely contributes to this variability. We show that mean and seasonal upper ocean temperature biases, commonly found in fully coupled models, strongly favor an unrealistic thermodynamic control of the equatorial Atlantic interannual variability.

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48

Valsala, Vinu, Shamil Maksyutov, and Raghu Murtugudde. "Interannual to Interdecadal Variabilities of the Indonesian Throughflow Source Water Pathways in the Pacific Ocean." Journal of Physical Oceanography 41, no. 10 (October 1, 2011): 1921–40. http://dx.doi.org/10.1175/2011jpo4561.1.

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Abstract Some of the possible interannual to interdecadal variabilities of the Indonesian Throughflow (ITF) source water pathways in the Pacific Ocean are identified from an ocean reanalysis product provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) under the name Ocean Reanalysis, version S3 (ORA-S3). The data were used in an offline mode to evolve adjoint pathways of a passive tracer, which is injected from the key channels of the Indonesian straits where the ITF enters into the Indian Ocean. The adjoint pathways are simulated using interannually varying circulations for 41 yr starting from December 2000 to January 1960 with reversed currents and other physical parameters (control run). A climatological run for the 41 yr is produced with the reversed currents and other physical parameters as a monthly climatology. The adjoint pathway variability is found by subtracting the climatological run from the control run. The empirical orthogonal function (EOF) analysis carried out over the monthly differences between the tracer concentrations of the control run and the climatological run shows that the ITF is largely supplied from the northwestern tropical Pacific during a normal year, whereas the supply from the south equatorial Pacific is dominant during El Niño–Southern Oscillation (ENSO) years at a lag of 6 months. The interannual variability of the ITF source water pathways in the Pacific is largely determined by the ENSO variability and they are confined to the tropical Pacific, whereas the corresponding interdecadal variability is controlled by the meridional overturning circulations in the tropical and subtropical Pacific. The adjoint pathways hint that the ITF volume transport may have interdecadal variability; they are closely related to the variability of the subtropical cells (STCs) in the Pacific Ocean and can be quantified using the tropical convergence changes. The ITF is just an active member of the recharge–discharge of tropical warm waters at all time scales, and its role in the coupled climate variability of the Indo-Pacific needs to be assessed in that context.

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Huang, Yanyan, Huijun Wang, and Ke Fan. "Improving the Prediction of the Summer Asian–Pacific Oscillation Using the Interannual Increment Approach." Journal of Climate 27, no. 21 (October 24, 2014): 8126–34. http://dx.doi.org/10.1175/jcli-d-14-00209.1.

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Abstract The summer Asian–Pacific oscillation (APO) is a dominant teleconnection pattern over the extratropical Northern Hemisphere that links the large-scale atmospheric circulation anomalies over the Asian–North Pacific Ocean sector. In this study, the direct Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER) model outputs from 1960 to 2001, which are limited in predicting the interannual variability of the summer Asian upper-tropospheric temperature and the decadal variations, are applied using the interannual increment approach to improve the predictions of the summer APO. By treating the year-to-year increment as the predictand, the interannual increment scheme is shown to significantly improve the predictive ability for the interannual variability of the summer Asian upper-tropospheric temperature and the decadal variations. The improvements for the interannual and interdecadal summer APO variability predictions in the interannual increment scheme relative to the original scheme are clear and significant. Compared with the DEMETER direct outputs, the statistical model with two predictors of APO and sea surface temperature anomaly over the Atlantic shows a significantly improved ability to predict the interannual variability of the summer rainfall over the middle and lower reaches of the Yangtze River valley (SRYR). This study therefore describes a more efficient approach for predicting the APO and the SRYR.

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Donohoe, Aaron, John Marshall, David Ferreira, Kyle Armour, and David McGee. "The Interannual Variability of Tropical Precipitation and Interhemispheric Energy Transport." Journal of Climate 27, no. 9 (April 23, 2014): 3377–92. http://dx.doi.org/10.1175/jcli-d-13-00499.1.

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Abstract The interannual variability of the location of the intertropical convergence zone (ITCZ) is strongly (R = 0.75) correlated with the atmospheric heat transport across the equator (AHTEQ) over the satellite era (1979–2009). A 1° northward displacement of the ITCZ is associated with 0.34 PW of anomalous AHTEQ from north to south. The AHTEQ and precipitation anomalies are both associated with an intensification of the climatological Hadley cell that is displaced north of the equator. This relationship suggests that the tropical precipitation variability is driven by a hemispheric asymmetry of energy input to the atmosphere at all latitudes by way of the constraint that AHTEQ is balanced by a hemispheric asymmetry in energy input to the atmosphere. A 500-yr coupled model simulation also features strong interannual correlations between the ITCZ location and AHTEQ. The interannual variability of AHTEQ in the model is associated with a hemispheric asymmetry in the top of the atmosphere radiative anomalies in the tropics with the Northern Hemisphere gaining energy when the ITCZ is displaced northward. The surface heat fluxes make a secondary contribution to the interannual variability of AHTEQ despite the fact that the interannual variability of the ocean heat transport across the equator (OHTEQ) is comparable in magnitude to that in AHTEQ. The OHTEQ makes a minimal impact on the atmospheric energy budget because the vast majority of the interannual variability in OHTEQ is stored in the subsurface ocean and, thus, the interannual variability of OHTEQ does not strongly impact the atmospheric circulation.

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Journal articles on the topic 'Variabilita interannuale'

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