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Alba, Richard, et Victor Nee. « Rethinking Assimilation Theory for a New Era of Immigration ». International Migration Review 31, no 4 (décembre 1997) : 826–74. http://dx.doi.org/10.1177/019791839703100403.
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Assimilation theory has been subject to intensive critique for decades. Yet no other framework has provided the social science community with as deep a corpus of cumulative findings concerning the incorporation of immigrants and their descendants. We argue that assimilation theory has not lost its utility for the study of contemporary immigration to the United States. In making our case, we review critically the canonical account of assimilation provided by Milton Gordon and others; we refer to Shibutani and Kwan's theory of ethnic stratification to suggest some directions to take in reformulating assimilation theory. We also examine some of the arguments frequently made to distinguish between the earlier mass immigration of Europeans and the immigration of the contemporary era and find them to be inconclusive. Finally, we sift through some of the evidence about the socioeconomic and residential assimilation of recent immigrant groups. Though the record is clearly mixed, we find evidence consistent with the view that assimilation is taking place, albeit unevenly.
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Lin, Liao-Fan, Ardeshir M. Ebtehaj, Rafael L. Bras, Alejandro N. Flores et Jingfeng Wang. « Dynamical Precipitation Downscaling for Hydrologic Applications Using WRF 4D-Var Data Assimilation : Implications for GPM Era ». Journal of Hydrometeorology 16, no 2 (1 avril 2015) : 811–29. http://dx.doi.org/10.1175/jhm-d-14-0042.1.
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Abstract The objective of this study is to develop a framework for dynamically downscaling spaceborne precipitation products using the Weather Research and Forecasting (WRF) Model with four-dimensional variational data assimilation (4D-Var). Numerical experiments have been conducted to 1) understand the sensitivity of precipitation downscaling through point-scale precipitation data assimilation and 2) investigate the impact of seasonality and associated changes in precipitation-generating mechanisms on the quality of spatiotemporal downscaling of precipitation. The point-scale experiment suggests that assimilating precipitation can significantly affect the precipitation analysis, forecast, and downscaling. Because of occasional overestimation or underestimation of small-scale summertime precipitation extremes, the numerical experiments presented here demonstrate that the wintertime assimilation produces downscaled precipitation estimates that are in closer agreement with the reference National Centers for Environmental Prediction stage IV dataset than similar summertime experiments. This study concludes that the WRF 4D-Var system is able to effectively downscale a 6-h precipitation product with a spatial resolution of 20 km to hourly precipitation with a spatial resolution of less than 10 km in grid spacing—relevant to finescale hydrologic applications for the era of the Global Precipitation Measurement mission.
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Tall, Moustapha, Clément Albergel, Bertrand Bonan, Yongjun Zheng, Françoise Guichard, Mamadou Dramé, Amadou Gaye et al. « Towards a Long-Term Reanalysis of Land Surface Variables over Western Africa : LDAS-Monde Applied over Burkina Faso from 2001 to 2018 ». Remote Sensing 11, no 6 (26 mars 2019) : 735. http://dx.doi.org/10.3390/rs11060735.
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This study focuses on the ability of the global Land Data Assimilation System, LDAS-Monde, to improve the representation of land surface variables (LSVs) over Burkina-Faso through the joint assimilation of satellite derived surface soil moisture (SSM) and leaf area index (LAI) from January 2001 to June 2018. The LDAS-Monde offline system is forced by the latest European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis ERA5 as well as ERA-Interim former reanalysis, leading to reanalyses of LSVs at 0.25° × 0.25° and 0.50° × 0.50° spatial resolution, respectively. Within LDAS-Monde, SSM and LAI observations from the Copernicus Global Land Service (CGLS) are assimilated with a simplified extended Kalman filter (SEKF) using the CO2-responsive version of the ISBA (Interactions between Soil, Biosphere, and Atmosphere) land surface model (LSM). First, it is shown that ERA5 better represents precipitation and incoming solar radiation than ERA-Interim former reanalysis from ECMWF based on in situ data. Results of four experiments are then compared: Open-loop simulation (i.e., no assimilation) and analysis (i.e., joint assimilation of SSM and LAI) forced by either ERA5 or ERA-Interim. After jointly assimilating SSM and LAI, it is noticed that the assimilation is able to impact soil moisture in the first top soil layers (the first 20 cm), and also in deeper soil layers (from 20 cm to 60 cm and below), as reflected by the structure of the SEKF Jacobians. The added value of using ERA5 reanalysis over ERA-Interim when used in LDAS-Monde is highlighted. The assimilation is able to improve the simulation of both SSM and LAI: The analyses add skill to both configurations, indicating the healthy behavior of LDAS-Monde. For LAI in particular, the southern region of the domain (dominated by a Sudan-Guinean climate) highlights a strong impact of the assimilation compared to the other two sub-regions of Burkina-Faso (dominated by Sahelian and Sudan-Sahelian climates). In the southern part of the domain, differences between the model and the observations are the largest, prior to any assimilation. These differences are linked to the model failing to represent the behavior of some specific vegetation species, which are known to put on leaves before the first rains of the season. The LDAS-Monde analysis is very efficient at compensating for this model weakness. Evapotranspiration estimates from the Global Land Evaporation Amsterdam Model (GLEAM) project as well as upscaled carbon uptake from the FLUXCOM project and sun-induced fluorescence from the Global Ozone Monitoring Experiment-2 (GOME-2) are used in the evaluation process, again demonstrating improvements in the representation of evapotranspiration and gross primary production after assimilation.
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Dethof, A., et E. V. Hólm. « Ozone assimilation in the ERA-40 reanalysis project ». Quarterly Journal of the Royal Meteorological Society 130, no 603 (1 octobre 2004) : 2851–72. http://dx.doi.org/10.1256/qj.03.196.
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Aarnes, Ole Johan, Saleh Abdalla, Jean-Raymond Bidlot et Øyvind Breivik. « Marine Wind and Wave Height Trends at Different ERA-Interim Forecast Ranges ». Journal of Climate 28, no 2 (15 janvier 2015) : 819–37. http://dx.doi.org/10.1175/jcli-d-14-00470.1.
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Abstract Trends in marine wind speed and significant wave height are investigated using the global reanalysis ERA-Interim over the period 1979–2012, based on monthly-mean and monthly-maximum data. Besides the traditional reanalysis, the authors include trends obtained at different forecast range, available up to 10 days ahead. Any model biases that are corrected differently over time are likely to introduce spurious trends of variable magnitude. However, at increased forecast range the model tends to relax, being less affected by assimilation. Still, there is a trade-off between removing the impact of data assimilation at longer forecast range and getting a lower level of uncertainty in the predictions at shorter forecast range. Because of the sheer amount of assimilations made in ERA-Interim, directly and indirectly affecting the data, it is difficult, if not impossible, to distinguish effects imposed by all updates. Here, special emphasis is put on the introduction of wave altimeter data in August 1991, the only type of data directly affecting the wave field. From this, it is shown that areas of higher model bias introduce quite different trends depending on forecast range, most apparent in the North Atlantic and eastern tropical Pacific. Results are compared with 23 in situ measurements, Envisat altimeter winds, and two stand-alone ECMWF operational wave model (EC-WAM) runs with and without wave altimeter assimilation. Here, the 48-h forecast is suggested to be a better candidate for trend estimates of wave height, mainly due to the step change imposed by altimeter observations. Even though wind speed seems less affected by undesirable step changes, the authors believe that the 24–48-h forecast more effectively filters out any unwanted effects.
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Polovyi, Mykola. « Specifics of USSR era migrants’ adaptation in the modern Russian Federation ». Bibliotekarz Podlaski Ogólnopolskie Naukowe Pismo Bibliotekoznawcze i Bibliologiczne 47, no 2 (10 juillet 2020) : 203–16. http://dx.doi.org/10.36770/bp.478.
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The task of this paper is a quantitative assessment of the possible fact and speed of assimilation of Ukrainian migrants in the modern Russian Federation according to the data of all-Russian censuses of 2002 and 2010. In all regions of the Russian Federation, and even in regions where the absolute number of the population has increased, we note the decrease in the number of Ukrainians significantly exceeded the overall rate of depopulation. The share of the decrease in the number of Ukrainians, which goes beyond the general rate of depopulation in a relevant region, can characterize the rate of assimilation of Ukrainian migrants in Russia. Thus, the annual rate of assimilation of Ukrainian migrants in the Russian Federation varies in different regions from 2.38% to 6.25%. The average rate of Ukrainian migrants’ assimilation is estimated for regions of the Russian Federation as 3.78% per year. Some assumptions are made about the main factors of such an unexpectedly rapid rate of peaceful assimilation of Ukrainians. Related factors include the tradition of Russians’ scornful attitude towards foreigners and “younger brothers” (a terms used to refer to Ukrainians); the Russian Federation’s disregard towards the cultural and educational needs of national minorities that do not have their territorial administrative formations on the territory of the Russian Federation; as well as a disregard of Ukrainian society and the Ukrainian state towards Ukrainians living on the territory of the Russian Federation.
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Alba, Richard, et Victor Nee. « Rethinking Assimilation Theory for a New Era of Immigration ». International Migration Review 31, no 4 (1997) : 826. http://dx.doi.org/10.2307/2547416.
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Woods, Thomas E. « Assimilation and Resistance : Catholic Intellectuals and the Progressive Era ». Catholic Social Science Review 5 (2000) : 297–312. http://dx.doi.org/10.5840/cssr2000527.
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Wang, Yuanbing, Jieying He, Yaodeng Chen et Jinzhong Min. « The Potential Impact of Assimilating Synthetic Microwave Radiances Onboard a Future Geostationary Satellite on the Prediction of Typhoon Lekima Using the WRF Model ». Remote Sensing 13, no 5 (26 février 2021) : 886. http://dx.doi.org/10.3390/rs13050886.
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Geostationary meteorological satellites can provide continuous observations of high-impact weather events with a high temporal and spatial resolution. Sounding the atmosphere using a microwave instrument onboard a geostationary satellite has aroused great study interests for years, as it would increase the observational efficiency as well as provide a new perspective in the microwave spectrum to the measuring capability for the current observational system. In this study, the capability of assimilating future geostationary microwave sounder (GEOMS) radiances was developed in the Weather Research and Forecasting (WRF) model’s data assimilation (WRFDA) system. To investigate if these frequently updated and widely distributed microwave radiances would be beneficial for typhoon prediction, observational system simulation experiments (OSSEs) using synthetic microwave radiances were conducted using the mesoscale numerical model WRF and the advanced hybrid ensemble–variational data assimilation method for the Lekima typhoon that occurred in early August 2019. The results show that general positive forecast impacts were achieved in the OSSEs due to the assimilation of GEOMS radiances: errors of analyses and forecasts in terms of wind, humidity, and temperature were both reduced after assimilating GEOMS radiances when verified against ERA-5 data. The track and intensity predictions of Lekima were also improved before 68 h compared to the best track data in this study. In addition, rainfall forecast improvements were also found due to the assimilation impact of GEOMS radiances. In general, microwave observations from geostationary satellites provide the possibility of frequently assimilating wide-ranging microwave information into a regional model in a finer resolution, which can potentially help improve numerical weather prediction (NWP).
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Eick, Caroline, et Linda Valli. « TEACHERS AS CULTURAL MEDIATORS : A COMPARISON OF THE ACCOUNTABILITY ERA TO THE ASSIMILATION ERA ». Critical Inquiry in Language Studies 7, no 1 (26 février 2010) : 54–77. http://dx.doi.org/10.1080/15427580903524613.
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White, Michael J., et Erica Jade Mullen. « Socioeconomic Attainment in the Ellis Island Era ». Social Science History 40, no 1 (2016) : 147–81. http://dx.doi.org/10.1017/ssh.2015.84.
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Contemporary discussions of immigrant assimilation in the United States often take the experience of the late nineteenth and early twentieth centuries as a benchmark, yet significant gaps remain in our understanding of the generality and rate of immigrant progress during that era. Using four decades of Integrated Public Use Microdata Samples census microdata, we utilize both ordinary least squares microdata regression and double cohort methodology to examine socioeconomic assimilation across arrival cohort and country of origin during the Ellis Island era. Our results show, contrary to some writing, that while the first generation (the foreign born) exhibit decidedly inferior labor market outcomes, socioeconomic attainment (measured by Socio-Economic Index points) increased quickly with duration in the United States. Persons of the second generation and those of mixed parentage show much less penalty than immigrants. At the same time, we uncover differences in outcome by European region that do not disappear over the decades we examine.
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Albergel, Clement, Simon Munier, Aymeric Bocher, Bertrand Bonan, Yongjun Zheng, Clara Draper, Delphine Leroux et Jean-Christophe Calvet. « LDAS-Monde Sequential Assimilation of Satellite Derived Observations Applied to the Contiguous US : An ERA-5 Driven Reanalysis of the Land Surface Variables ». Remote Sensing 10, no 10 (12 octobre 2018) : 1627. http://dx.doi.org/10.3390/rs10101627.
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Land data assimilation system (LDAS)-Monde, an offline land data assimilation system with global capacity, is applied over the CONtiguous US (CONUS) domain to enhance monitoring accuracy for water and energy states and fluxes. LDAS-Monde ingests satellite-derived surface soil moisture (SSM) and leaf area index (LAI) estimates to constrain the interactions between soil, biosphere, and atmosphere (ISBA) land surface model (LSM) coupled with the CNRM (Centre National de Recherches Météorologiques) version of the total runoff integrating pathways (CTRIP) continental hydrological system (ISBA-CTRIP). LDAS-Monde is forced by the ERA-5 atmospheric reanalysis from the European Center for Medium Range Weather Forecast (ECMWF) from 2010 to 2016 leading to a seven-year, quarter degree spatial resolution offline reanalysis of land surface variables (LSVs) over CONUS. The impact of assimilating LAI and SSM into LDAS-Monde is assessed over North America, by comparison to satellite-driven model estimates of land evapotranspiration from the Global Land Evaporation Amsterdam Model (GLEAM) project, and upscaled ground-based observations of gross primary productivity from the FLUXCOM project. Taking advantage of the relatively dense data networks over CONUS, we have also evaluated the impact of the assimilation against in situ measurements of soil moisture from the USCRN (US Climate Reference Network), together with river discharges from the United States Geological Survey (USGS) and the Global Runoff Data Centre (GRDC). Those data sets highlight the added value of assimilating satellite derived observations compared with an open-loop simulation (i.e., no assimilation). It is shown that LDAS-Monde has the ability not only to monitor land surface variables but also to forecast them, by providing improved initial conditions, which impacts persist through time. LDAS-Monde reanalysis also has the potential to be used to monitor extreme events like agricultural drought. Finally, limitations related to LDAS-Monde and current satellite-derived observations are exposed as well as several insights on how to use alternative datasets to analyze soil moisture and vegetation state.
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Bromwich, David H., et Ryan L. Fogt. « Strong Trends in the Skill of the ERA-40 and NCEP–NCAR Reanalyses in the High and Midlatitudes of the Southern Hemisphere, 1958–2001* ». Journal of Climate 17, no 23 (1 décembre 2004) : 4603–19. http://dx.doi.org/10.1175/3241.1.
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Abstract The European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) and the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis (NCEP1) data are compared with Antarctic and other mid- to high-latitude station observations for the complete years of overlap, 1958–2001. Overall, it appears that ERA-40 more closely follows the observations; however, a more detailed look at the presatellite era reveals many shortcomings in ERA-40, particularly in the austral winter. By calculating statistics in 5-yr moving windows for June–July–August (JJA), it is shown that ERA-40 correlations with observed MSLP and surface (2 m) temperatures are low and even negative during the mid-1960s. A significant trend in skill in ERA-40 is observed in conjunction with the assimilation of satellite data during winter, eventually reaching a high level of skill after 1978 that is superior to NCEP1. NCEP1 shows consistency in its correlation with observations throughout time in this season; however, the biases in the NCEP1 MSLP fields decrease significantly with time. Similar problems are also found in the 500-hPa geopotential height fields above the direct influences of the mountainous topography. The height differences between ERA-40 and NCEP1 over the South Pacific are substantial before the modern satellite era throughout the depth of the troposphere. The ability for ERA-40 to be more strongly constrained by the satellite data compared to NCEP1, which is largely constrained by the station observational network, suggests that the differing assimilation schemes between ERA-40 and NCEP1 lead to the large discrepancies seen here. Thus, both reanalyses must be used with caution over high southern latitudes during the nonsummer months prior to the assimilation of satellite sounding data.
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Gao, Yanqiu, Ting Liu, Xunshu Song, Zheqi Shen, Youmin Tang et Dake Chen. « An extension of LDEO5 model for ENSO ensemble predictions ». Climate Dynamics 55, no 11-12 (28 août 2020) : 2979–91. http://dx.doi.org/10.1007/s00382-020-05428-7.
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Abstract This study provided an extension to the latest version of Lamont-Doherty Earth Observation (LDEO5) prediction system. First, an ensemble coupled data assimilation (CDA) system, based on the Ensemble Kalman Filter, was established. Both the Kaplan sea surface temperature (SST) data from January 1856 to December 2018 and the ECMWF twentieth century reanalysis (ERA-20C) wind data from January 1900 to February 2010 were assimilated for prediction initialization. Second, an ensemble prediction (EP) system was established using stochastic optimal perturbation that represented the uncertainty in the physical process. The assimilation experiments showed that assimilating multi-source data yielded better results than assimilating single-source data. The analyses of Niño3.4 SST anomalies and zonal wind stress (ZWS) anomalies were in good agreement with the observed counterparts, respectively. The root mean square errors of both Niño3.4 SST anomalies and ZWS anomalies were found to be significantly reduced, compared to the values obtained before assimilation. The modeled upper layer depth anomalies along the equator, and subsurface temperature anomalies in the Niño3.4 region were also found to be similar to the observed counterparts. A long-term ensemble hindcast was conducted using the EP system for the past 163 years, from January 1856 to December 2018. Results showed that the predictions initialized by assimilating multi-source data yielded best deterministic skill, reaching the international advanced level. A comparative analysis revealed that the EP system predicted the warm events well, followed by cold and neutral events.
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Draper, Clara, et Rolf H. Reichle. « Assimilation of Satellite Soil Moisture for Improved Atmospheric Reanalyses ». Monthly Weather Review 147, no 6 (23 mai 2019) : 2163–88. http://dx.doi.org/10.1175/mwr-d-18-0393.1.
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Abstract A newly developed, weakly coupled land and atmosphere data assimilation system for NASA’s Global Earth Observing System model is presented, and used to demonstrate the benefit of assimilating satellite soil moisture into an atmospheric reanalysis. Specifically, Advanced Scatterometer and Soil Moisture Ocean Salinity soil moisture retrievals are assimilated into a system that uses the same model, atmospheric assimilation system, and atmospheric observations as the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). The atmosphere is sensitive to soil moisture only under certain conditions. Hence, while the globally averaged model improvements were small, regionally, the soil moisture assimilation induced some substantial improvements. For example, in a large region spanning from western Europe across southern Russia, the soil moisture assimilation decreased the RMSE against independent station observations of daily maximum 2-m temperature () by up to 0.4 K, and of 2-m specific humidity (q2m) by up to 0.5 g kg−1. Over all available stations, the mean RMSE was reduced from 2.82 to 2.79 K, while the mean q2m RMSE was reduced from 1.25 to 1.20 g kg−1. The soil moisture assimilation also reduced the mean RMSE across 29 flux tower sites from 34.2 to 32.6 W m−2 for latent heating, and from 37.7 to 36.5 W m−2 for sensible heating. For all variables evaluated, the soil moisture assimilation improved the model at monthly to seasonal, rather than daily, time scales. Based on the above experiments, it is recommended that satellite soil moisture be assimilated into future reanalyses, including the follow-on to MERRA-2.
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Hou, Arthur Y., et Sara Q. Zhang. « Assimilation of Precipitation Information Using Column Model Physics as a Weak Constraint ». Journal of the Atmospheric Sciences 64, no 11 (1 novembre 2007) : 3865–78. http://dx.doi.org/10.1175/2006jas2028.1.
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Abstract Currently, operational weather forecasting systems use observations to optimize the initial state of a forecast without considering possible model deficiencies. For precipitation assimilation, this could be an issue since precipitation observations, unlike conventional data, do not directly provide information on the atmospheric state but are related to the state variables through parameterized moist physics with simplifying assumptions. Precipitation observation operators are comparatively less accurate than those for conventional data or observables in clear-sky regions, which can limit data usage not because of issues with observations, but with the model. The challenge lies in exploring new ways to make effective use of precipitation data in the presence of model errors. This study continues the investigation of variational algorithms for precipitation assimilation using column model physics as a weak constraint. The strategy is to develop techniques to make online estimation and correction of model errors to improve the precipitation observation operator during the assimilation cycle. Earlier studies have shown that variational continuous assimilation (VCA) of tropical rainfall using moisture tendency correction can improve Goddard Earth Observing System 3 (GEOS-3) global analyses and forecasts. Here results are presented from a 4-yr GEOS-3 reanalysis assimilating Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Special Sensor Microwave Imager (SSM/I) tropical rainfall using the VCA scheme. Comparisons with NCEP operational analysis and the 40-yr ECMWF Re-Analysis (ERA-40) show that the GEOS-3 reanalysis is significantly better at replicating the intensity and variability of tropical precipitation systems ranging from a few days to interannual time scales. As a further refinement of rainfall assimilation using the VCA scheme, a variational algorithm for assimilating TMI latent heating retrievals using semiempirical parameters in the model moist physics as control variables is described and initial test results are presented.
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Luo, Yiqi, Kiona Ogle, Colin Tucker, Shenfeng Fei, Chao Gao, Shannon LaDeau, James S. Clark et David S. Schimel. « Ecological forecasting and data assimilation in a data-rich era ». Ecological Applications 21, no 5 (juillet 2011) : 1429–42. http://dx.doi.org/10.1890/09-1275.1.
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Morgan, George. « Memory and Marginalisation—Aboriginality and Education in the Assimilation Era ». Australian Journal of Education 50, no 1 (avril 2006) : 40–49. http://dx.doi.org/10.1177/000494410605000104.
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In the mid-twentieth century many Aboriginal Australians moved to live in Australian cities in search of life opportunities that were not available to them in rural areas. This article explores the life history narratives of three Indigenous people who were brought to live in Sydney as children during this period. It considers the processes by which, in spite of the dominant policy position of assimilation at the time, they were alienated from the school education system and failed to make the most of their talents. None of them could recognise themselves in the meritocratic narratives held up to them. In addition, each experienced obligations to family and/or to home country that were incompatible with the rhythms of life associated with school education.
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Vasquez, Jessica M. « THE BUMPY ROAD OF ASSIMILATION : GENDER, PHENOTYPE, AND HISTORICAL ERA ». Sociological Spectrum 31, no 6 (6 octobre 2011) : 718–48. http://dx.doi.org/10.1080/02732173.2011.606728.
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Stuart, Paul H. « Interventions in Native American communities during an era of assimilation ». Journal of Community Practice 28, no 4 (1 octobre 2020) : 296–308. http://dx.doi.org/10.1080/10705422.2020.1847593.
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Ahmad, Jawairia A., Barton A. Forman et Sujay V. Kumar. « Soil moisture estimation in South Asia via assimilation of SMAP retrievals ». Hydrology and Earth System Sciences 26, no 8 (29 avril 2022) : 2221–43. http://dx.doi.org/10.5194/hess-26-2221-2022.
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Abstract. A soil moisture retrieval assimilation framework is implemented across South Asia in an attempt to improve regional soil moisture estimation as well as to provide a consistent regional soil moisture dataset. This study aims to improve the spatiotemporal variability of soil moisture estimates by assimilating Soil Moisture Active Passive (SMAP) near-surface soil moisture retrievals into a land surface model. The Noah-MP (v4.0.1) land surface model is run within the NASA Land Information System software framework to model regional land surface processes. NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA2) and Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals (IMERG) provide the meteorological boundary conditions to the land surface model. Assimilation is carried out using both cumulative distribution function (CDF)-corrected (DA-CDF) and uncorrected SMAP retrievals (DA-NoCDF). CDF matching is applied to correct the statistical moments of the SMAP soil moisture retrieval relative to the land surface model. Comparison of assimilated and model-only soil moisture estimates with publicly available in situ measurements highlights the relative improvement in soil moisture estimates by assimilating SMAP retrievals. Across the Tibetan Plateau, DA-NoCDF reduced the mean bias and RMSE by 8.4 % and 9.4 %, even though assimilation only occurred during less than 10 % of the study period due to frozen (or partially frozen) soil conditions. The best goodness-of-fit statistics were achieved for the IMERG DA-NoCDF soil moisture experiment. The general lack of publicly available in situ measurements across irrigated areas limited a domain-wide direct model validation. However, comparison with regional irrigation patterns suggested correction of biases associated with an unmodeled hydrologic phenomenon (i.e., anthropogenic influence via irrigation) as a result of SMAP soil moisture retrieval assimilation. The greatest sensitivity to assimilation was observed in cropland areas. Improvements in soil moisture potentially translate into improved spatiotemporal patterns of modeled evapotranspiration, although limited influence from soil moisture assimilation was observed on modeled processes within the carbon cycle such as gross primary production. Improvement in fine-scale modeled estimates by assimilating coarse-scale retrievals highlights the potential of this approach for soil moisture estimation over data-scarce regions.
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Majumdar, Sharanya J. « A Review of Targeted Observations ». Bulletin of the American Meteorological Society 97, no 12 (1 décembre 2016) : 2287–303. http://dx.doi.org/10.1175/bams-d-14-00259.1.
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Abstract It has long been conceived that numerical weather forecasts will benefit from the assimilation of supplementary observations that augment the conventional observational network. In particular, the concept of “targeting” observations in selected regions to improve a forecast of a high-impact weather event had been promoted and tested prior to and during the World Meteorological Organization/World Weather Research Programme’s The Observing System Research and Predictability Experiment (THORPEX) era (2005–14), through field campaigns and assimilation experiments. The end of the THORPEX era provided an appropriate opportunity to review the outcomes and, in particular, the evaluations of the influence of assimilating targeted observations on numerical weather predictions. The main outcome in the extratropics was that the influence of the targeted observations was positive though small (typically an average forecast error reduction of less than 10%). In the tropics, the targeted observations usually improved tropical cyclone track forecasts. Significantly, the results from these and other experiments were found to be sensitive to the sample chosen, the method of verification, and the numerical weather prediction system including the data assimilation scheme and the treatment of observations. Recommendations for the future include innovations to optimize the use of the Global Observing System via better exploitation of routinely available resources together with new instrumentation; expanding into the convective scale and mesoscale; investing quantitative evaluations and improving our understanding of how observations affect forecasts; and assessing the socioeconomic value of improved forecasts. A comprehensive bibliography of approximately 200 papers is provided in the online supplement to this paper.
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Liu, Hongyan. « Carbon–Water Relationships of the Forest Ecosystem under a Changing Climate ». Forests 12, no 5 (30 avril 2021) : 563. http://dx.doi.org/10.3390/f12050563.
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Brennan, M. Kathleen, et Gregory J. Hakim. « Reconstructing Arctic Sea Ice over the Common Era Using Data Assimilation ». Journal of Climate 35, no 4 (15 février 2022) : 1231–47. http://dx.doi.org/10.1175/jcli-d-21-0099.1.
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Abstract Arctic sea ice decline in recent decades has been dramatic; however, few long-term records of Arctic sea ice exist to put such a decline in context. Here we employ an ensemble Kalman filter data assimilation approach to reconstruct Arctic sea ice concentration over the last two millennia by assimilating temperature-sensitive proxy records with ensembles drawn from last millennium climate model simulations. We first test the efficacy of this method using pseudoproxy experiments. Results show good agreement between the target and reconstructed total Arctic sea ice extent (R2 value and coefficient of efficiency values of 0.51 and 0.47 for perfect model experiments and 0.43 and 0.43 for imperfect model experiments). Imperfect model experiments indicate that the reconstructions inherit some bias from the model prior. We assimilate 487 temperature-sensitive proxy records with two climate model simulations to produce two gridded reconstructions of Arctic sea ice over the last two millennia. These reconstructions show good agreement with satellite observations between 1979 and 1999 CE for total Arctic sea ice extent with an R2 value and coefficient of efficiency of about 0.60 and 0.50, respectively, for both models. Regional quantities derived from these reconstructions show encouraging similarities with independent reconstructions and sea ice sensitive proxy records from the Barents Sea, Baffin Bay, and East Greenland Sea. The reconstructions show a positive trend in Arctic sea ice extent between around 750 and 1820 CE, and increases during years with large volcanic eruptions that persist for about 5 years. Trend analysis of total Arctic sea ice extent reveals that for time periods longer than 30 years, the satellite era decline in total Arctic sea ice extent is unprecedented over the last millennium. Significance Statement Areal coverage of Arctic sea ice is a critical aspect of the climate system that has been changing rapidly in recent decades. Prior to the advent of satellite observations, sparse observations of Arctic sea ice make it difficult to put the current changes in context. Here we reconstruct annual averages of Arctic sea ice coverage for the last two millennia by combining temperature-sensitive proxy records (i.e., ice cores, tree rings, and corals) with climate model simulations using a statistical technique called data assimilation. We find large interannual changes in Arctic sea ice coverage prior to 1850 that are associated with volcanic eruptions, with a steady rise in Arctic sea ice coverage between 750 and 1820 CE. The satellite-period loss of sea ice has no analog during the last millennium.
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Newman, Kathryn M., Craig S. Schwartz, Zhiquan Liu, Hui Shao et Xiang-Yu Huang. « Evaluating Forecast Impact of Assimilating Microwave Humidity Sounder (MHS) Radiances with a Regional Ensemble Kalman Filter Data Assimilation System ». Weather and Forecasting 30, no 4 (1 août 2015) : 964–83. http://dx.doi.org/10.1175/waf-d-14-00091.1.
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Abstract This study examines the impact of assimilating Microwave Humidity Sounder (MHS) radiances in a limited-area ensemble Kalman filter (EnKF) data assimilation system. Two experiments spanning 11 August–13 September 2008 were run over a domain featuring the Atlantic basin using a 6-h full cycling analysis and forecast system. Deterministic 72-h forecasts were initialized at 0000 and 1200 UTC for a comparison of forecast impact. The two experiments were configured identically with the exception of the inclusion of the MHS radiances (AMHS) in the second to isolate the impacts of the MHS radiance data. The results were verified against several sources, and statistical significance tests indicate the most notable differences are in the midlevel moisture fields. Both configurations were characterized by high moisture biases when compared to the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim, also known as ERA-I) specific humidity fields, as well as precipitable water vapor from an observationally based product. However, the AMHS experiment has midlevel moisture fields closer to the ERA-I and observation datasets. When reducing the verification domain to focus on the subtropical and easterly wave regions of the North Atlantic Ocean, larger improvements in midlevel moisture at nearly all lead times is seen in the AMHS simulation. Finally, when considering tropical cyclone forecasts, the AMHS configuration shows improvement in intensity forecasts at several lead times as well as improvements at early to intermediate lead times for minimum sea level pressure forecasts.
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Randles, C. A., A. M. da Silva, V. Buchard, P. R. Colarco, A. Darmenov, R. Govindaraju, A. Smirnov et al. « The MERRA-2 Aerosol Reanalysis, 1980 Onward. Part I : System Description and Data Assimilation Evaluation ». Journal of Climate 30, no 17 (septembre 2017) : 6823–50. http://dx.doi.org/10.1175/jcli-d-16-0609.1.
Texte intégralRésumé :
The Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), updates NASA’s previous satellite-era (1980 onward) reanalysis system to include additional observations and improvements to the Goddard Earth Observing System, version 5 (GEOS-5), Earth system model. As a major step toward a full Integrated Earth Systems Analysis (IESA), in addition to meteorological observations, MERRA-2 now includes assimilation of aerosol optical depth (AOD) from various ground- and space-based remote sensing platforms. Here, in the first of a pair of studies, the MERRA-2 aerosol assimilation is documented, including a description of the prognostic model (GEOS-5 coupled to the GOCART aerosol module), aerosol emissions, and the quality control of ingested observations. Initial validation and evaluation of the analyzed AOD fields are provided using independent observations from ground, aircraft, and shipborne instruments. The positive impact of the AOD assimilation on simulated aerosols is demonstrated by comparing MERRA-2 aerosol fields to an identical control simulation that does not include AOD assimilation. After showing the AOD evaluation, this paper takes a first look at aerosol–climate interactions by examining the shortwave, clear-sky aerosol direct radiative effect. The companion paper (Part II) evaluates and validates available MERRA-2 aerosol properties not directly impacted by the AOD assimilation (e.g., aerosol vertical distribution and absorption). Importantly, while highlighting the skill of the MERRA-2 aerosol assimilation products, both studies point out caveats that must be considered when using this new reanalysis product for future studies of aerosols and their interactions with weather and climate.
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Routray, A., S. C. Kar, P. Mali et K. Sowjanya. « Simulation of Monsoon Depressions Using WRF-VAR : Impact of Different Background Error Statistics and Lateral Boundary Conditions ». Monthly Weather Review 142, no 10 (19 septembre 2014) : 3586–613. http://dx.doi.org/10.1175/mwr-d-13-00285.1.
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Abstract In a variational data assimilation system, background error statistics (BES) spread the influence of the observations in space and filter analysis increments through dynamic balance or statistical relationships. In a data-sparse region such as the Bay of Bengal, BES play an important role in defining the location and structure of monsoon depressions (MDs). In this study, the Indian-region-specific BES have been computed for the Weather Research and Forecasting (WRF) three-dimensional variational data assimilation system. A comparative study using single observation tests is carried out using the computed BES and global BES within the WRF system. Both sets of BES are used in the assimilation cycles and forecast runs for simulating the meteorological features associated with the MDs. Numerical experiments have been conducted to assess the relative impact of various BES in the analysis and simulations of the MDs. The results show that use of regional BES in the assimilation cycle has a positive impact on the prediction of the location, propagation, and development of rainbands associated with the MDs. The track errors of MDs are smaller when domain-specific BES are used in the assimilation cycle. Additional experiments have been conducted using data from the Interim European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim) as initial and boundary conditions (IBCs) in the assimilation cycle. The results indicate that the use of domain-dependent BES and high-resolution ERA-I data as IBCs further improved the initial conditions for the model leading to better forecasts of the MDs.
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Milner, Lisa. « “An Unpopular Cause” : The Union of Australian Women’s Support for Aboriginal Rights ». Labour History 116, no 1 (1 mai 2019) : 167–88. http://dx.doi.org/10.3828/jlh.2019.8.
Texte intégralRésumé :
The Union of Australian Women (UAW) was a national organisation for left-wing women between World War II and the emergence of the women’s liberation movement. Along with other left-wing activists, UAW members supported Aboriginal rights, through their policies, publications and actions. They also attracted a number of Aboriginal members including Pearl Gibbs, Gladys O’Shane, Dulcie Flower and Faith Bandler. Focusing on NSW activity in the assimilation period, this article argues that the strong support of UAW members for Aboriginal rights drew upon the group’s establishment far-left politics, its relations with other women’s groups and the activism of its Aboriginal members. Non-Aboriginal members of the UAW gave practical and resourceful assistance to their Aboriginal comrades in a number of campaigns through the assimilation era, forming productive and collaborative relationships. Many of their campaigns aligned with approaches of the Communist Party of Australia and left-wing trade unions. In assessing the relationship between the UAW and Aboriginal rights, this article addresses a gap in the scholarship of assimilation era activism.
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Hawker, Ronald W. « Transformed or Transformative ? Two Northwest Coast Artists in the Era of Assimilation ». American Indian Culture and Research Journal 25, no 2 (1 janvier 2001) : 37–61. http://dx.doi.org/10.17953/aicr.25.2.531038554752v803.
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Dee, D. P., S. M. Uppala, A. J. Simmons, P. Berrisford, P. Poli, S. Kobayashi, U. Andrae et al. « The ERA-Interim reanalysis : configuration and performance of the data assimilation system ». Quarterly Journal of the Royal Meteorological Society 137, no 656 (avril 2011) : 553–97. http://dx.doi.org/10.1002/qj.828.
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Decker, Mark, Michael A. Brunke, Zhuo Wang, Koichi Sakaguchi, Xubin Zeng et Michael G. Bosilovich. « Evaluation of the Reanalysis Products from GSFC, NCEP, and ECMWF Using Flux Tower Observations ». Journal of Climate 25, no 6 (14 mars 2012) : 1916–44. http://dx.doi.org/10.1175/jcli-d-11-00004.1.
Texte intégralRésumé :
Abstract Reanalysis products produced at the various centers around the globe are utilized for many different scientific endeavors, including forcing land surface models and creating surface flux estimates. Here, flux tower observations of temperature, wind speed, precipitation, downward shortwave radiation, net surface radiation, and latent and sensible heat fluxes are used to evaluate the performance of various reanalysis products [NCEP–NCAR reanalysis and Climate Forecast System Reanalysis (CFSR) from NCEP; 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) and ECMWF Interim Re-Analysis (ERA-Interim) from ECMWF; and Modern-Era Retrospective Analysis for Research and Applications (MERRA) and Global Land Data Assimilation System (GLDAS) from the Goddard Space Flight Center (GSFC)]. To combine the biases and standard deviation of errors from the separate stations, a ranking system is utilized. It is found that ERA-Interim has the lowest overall bias in 6-hourly air temperature, followed closely by MERRA and GLDAS. The variability in 6-hourly air temperature is again most accurate in ERA-Interim. ERA-40 is found to have the lowest overall bias in latent heat flux, followed closely by CFSR, while ERA-40 also has the lowest 6-hourly sensible heat bias. MERRA has the second lowest and is close to ERA-40. The variability in 6-hourly precipitation is best captured by GLDAS and ERA-Interim, and ERA-40 has the lowest precipitation bias. It is also found that at monthly time scales, the bias term in the reanalysis products are the dominant cause of the mean square errors, while at 6-hourly and daily time scales the dominant contributor to the mean square errors is the correlation term. Also, it is found that the hourly CFSR data have discontinuities present due to the assimilation cycle, while the hourly MERRA data do not contain these jumps.
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Mendes, Monica Cristina Damião, Iracema F. A. Cavalcanti et Dirceu Luis Herdies. « Southern Hemisphere atmospheric blocking diagnostic by ECMWF and NCEP/NCAR data ». Revista Brasileira de Meteorologia 27, no 3 (septembre 2012) : 263–71. http://dx.doi.org/10.1590/s0102-77862012000300001.
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An assessment of blocking episodes over the Southern Hemisphere, selected from the Era-40 and NCEP/NCAR reanalysis are presented in this study. Blocking can be defined by an objective index based on two 500 hPa geopotential height meridional gradients. The seasonal cycle and preferential areas of occurrence are well reproduced by the two data sets. In both reanalysis used in this study, South Pacific and Oceania were the preferred regions for blocking occurrence, followed by the Atlantic Ocean. However the results revealed differences in frequencies of occurrences, which may be related to the choice of assimilation scheme employed to produce the reanalysis data sets. It is important to note that the ERA 40 and NCEP/NCAR reanalysis were produced using consistent models and assimilation schemes throughout the whole reanalyzed period, which are different for each set.
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Bromwich, David H., Julien P. Nicolas et Andrew J. Monaghan. « An Assessment of Precipitation Changes over Antarctica and the Southern Ocean since 1989 in Contemporary Global Reanalyses* ». Journal of Climate 24, no 16 (15 août 2011) : 4189–209. http://dx.doi.org/10.1175/2011jcli4074.1.
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Abstract This study evaluates the temporal variability of the Antarctic surface mass balance, approximated as precipitation minus evaporation (P − E), and Southern Ocean precipitation in five global reanalyses during 1989–2009. The datasets consist of the NCEP/U.S. Department of Energy (DOE) Atmospheric Model Intercomparison Project 2 reanalysis (NCEP-2), the Japan Meteorological Agency (JMA) 25-year Reanalysis (JRA-25), ECMWF Interim Re-Analysis (ERA-Interim), NASA Modern Era Retrospective-Analysis for Research and Application (MERRA), and the Climate Forecast System Reanalysis (CFSR). Reanalyses are known to be prone to spurious trends and inhomogeneities caused by changes in the observing system, especially in the data-sparse high southern latitudes. The period of study has seen a dramatic increase in the amount of satellite observations used for data assimilation. The large positive and statistically significant trends in mean Antarctic P − E and mean Southern Ocean precipitation in NCEP-2, JRA-25, and MERRA are found to be largely spurious. The origin of these artifacts varies between reanalyses. Notably, a precipitation jump in MERRA in the late 1990s coincides with the start of the assimilation of radiances from the Advanced Microwave Sounding Unit (AMSU). ERA-Interim and CFSR do not exhibit any significant trends. However, the potential impact of the assimilation of rain-affected radiances in ERA-Interim and inhomogeneities in CFSR pressure fields over Antarctica cast some doubt on the reliability of these two datasets. The authors conclude that ERA-Interim likely offers the most realistic depiction of precipitation changes in high southern latitudes during 1989–2009. The range of the trends in Antarctic P − E among the reanalyses is equivalent to 1 mm of sea level over 21 years, which highlights the improvements still needed in reanalysis simulations to better assess the contribution of Antarctica to sea level rise. Finally, this work argues for continuing cautious use of reanalysis datasets for climate change assessment.
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El Akkraoui, Amal, David Carvalho, Ronald M. Errico, Nikki C. Privé et Michael G. Bosilovich. « The Role of Analysis Error in the Convergence of Reanalysis Production Streams in MERRA-2 ». Monthly Weather Review 149, no 4 (avril 2021) : 1041–54. http://dx.doi.org/10.1175/mwr-d-20-0256.1.
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ABSTRACTDue to production time constraints, most reanalyses are produced in multiple parallel streams instead of a single continuous one. These streams cover separate segments of the reanalysis time period with short overlaps to allow reconstruction of the official record. A fundamental assumption justifying this approach is that the streams will be assimilating the same observations during the periods where they overlap, and so will eventually converge to a similar atmospheric state, making discontinuities at stream junctions negligible. This assumption is revisited in this work by examining the impact of analysis error on the differences between MERRA-2 overlapping streams in three historical periods. Comparison results are shown in terms of standard deviations of stream differences as well as the spectral decomposition of the variance of their differences. Residual differences were found at the end of each year of overlap, with larger values observed in the earlier segments of the presatellite era. By drawing parallels with analysis error statistics estimated from the GMAO OSSE system, these differences are shown to reflect the varying constraint of data with the varying observing network, and to further carry the imprint of errors that the data assimilation process is not able to mitigate. As such, they are unlikely to be reduced by longer spinup periods. The ability of data assimilation to ensure continuity in the parallel streams is put into question when the observing system coverage is inadequate or simply when the data assimilation system as a whole is suboptimal.
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Yung (容启聪), Kenneth Kai-chung. « Diaspora of Chinese Intellectuals in the Cold War Era ». Journal of Chinese Overseas 15, no 2 (13 novembre 2019) : 145–70. http://dx.doi.org/10.1163/17932548-12341400.
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Abstract On the eve of the Communist takeover in 1949, a considerable number of Chinese intellectuals were reluctant to live under Communist rule. They began their self-exile and the search for a new home outside China. Many travelled to places on China’s periphery such as Taiwan and Hong Kong. Others continued their journey and finally settled down in Southeast Asia and North America. Sojourning abroad, most of these self-exiled intellectuals still kept a close eye on Chinese politics and society. They were eager to promote their political ideal for a liberal-democratic China in the overseas Chinese communities. However, they were at the same time facing the challenge of assimilation into local society. This article traces the journey of the self-exiles in the 1950s and 1960s from Hong Kong to Southeast Asia and North America. It examines several representative figures and studies their activities in their new place of settlement. It argues that, although the self-exiles largely maintained a strong commitment to the future of their homeland, they varied in their degree of assimilation into their new homes. Age was not a key factor in their decision to adapt to the local community. Instead, the existence of a politically and economically influential Chinese population played a more important role in such a decision. Intellectuals who lived in Hong Kong or Southeast Asia were more willing to adjust their life to the locality, while those who went to North America were less attached to the local society.
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Guo, Yanjuan, et Edmund K. M. Chang. « Impacts of Assimilation of Satellite and Rawinsonde Observations on Southern Hemisphere Baroclinic Wave Activity in the NCEP–NCAR Reanalysis ». Journal of Climate 21, no 13 (1 juillet 2008) : 3290–309. http://dx.doi.org/10.1175/2007jcli2189.1.
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Abstract In this study, the impacts of the assimilation of satellite and rawinsonde observations on Southern Hemisphere (SH) baroclinic wave activity in the NCEP–NCAR reanalysis are examined by comparing analyses made with and without the assimilation of satellite data (SAT and NOSAT, respectively) for the year 1979, as well as by comparing analyses to the corresponding first guesses from 1958 to 1999. Comparing the eddy kinetic energy (EKE) computed based on the SAT and NOSAT analyses, it is found that the assimilation of satellite data generally decreases the EKE in the SH, which is the opposite of the findings for the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) in previous studies. The decrease of EKE by satellite data in the NCEP–NCAR reanalysis can be traced back to a low bias in retrieved satellite temperature (SATEMP) variance. The eddy available potential energy (EPE) is decreased even more than the EKE with the assimilation of SATEMP, making the waves more barotropic in the SAT analysis. The EKE analysis increment, that is, the difference between the EKE based on analysis and first guess, is a good quantity to indicate the impacts of all observations assimilated. In the NOSAT analysis, positive EKE analysis increments are found around the SH rawinsonde stations, indicating that the assimilation of rawinsonde data increases EKE significantly from the first guess. This also suggests that the NCEP–NCAR first guess is probably biased low. Positive analysis increments around the rawinsonde stations become even larger in the SAT analysis compared with the NOSAT, suggesting that with the assimilation of low-biased SATEMP data, the EKE in the analysis (the initial condition for next time) and hence the first guess is reduced, therefore the rawinsonde observations have to further increase the EKE from the first guess. The patterns of EKE increment from the presatellite (1958–77) and satellite (1979–99) eras show high degrees of similarities to the NOSAT and SAT reanalysis patterns, respectively, lending further support to these findings. The impact of the assimilation of satellite data on the trend of SH baroclinic wave activity is discussed. Positive trends in the SH EKE are found in both the NCEP–NCAR and ERA-40 reanalyses during 1958–99. After taking the impacts of satellite data into account, the EKE trend in the NCEP–NCAR reanalysis gets stronger, while that in the ERA-40 is largely weakened, which adds complications to assessing the real trend in SH baroclinic wave activity. Comparisons among the variances based on the two reanalyses, NCEP–NCAR first guess, SATEMP, and rawinsonde observations are presented to substantiate some of the findings discussed above, such as the low bias in energy in NCEP–NCAR first guess and SATEMP variance.
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Golovanova, Elena I. « Dynamic Processes in the Russian Language of the Coronavirus Era ». Vestnik of Northern (Arctic) Federal University. Series Humanitarian and Social Sciences, no 5 (15 novembre 2021) : 33–39. http://dx.doi.org/10.37482/2687-1505-v128.
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This article considers the active processes occurring in the Russian language during the coronavirus pandemic. Specific changes in the vocabulary are described, new phenomena in lexical semantics in various spheres of communication are identified. Primary attention is given to the changes in the active vocabulary of the literary language, the sources of new words, and the assimilation of foreign borrowings that are highly relevant for communication in this period. According to the author, the most important processes taking place in the Russian language include intellectualization of the common literary language, i.e. the introduction of highly specialized terms of medicine, virology, and immunotherapy (saturation, contagiousness, antibodies, etc.); activation of a number of words due to the current events (regime, quarantine, vaccine, etc.) and expansion of their collocations; active derivational processes in the course of assimilation of loan words (covid, coronavirus, pandemic, etc.) and adaptation of existing words to the new reality (remote working, distance learning, etc.); actualization of individual lexical and grammatical categories of words (substantivized adjectives and nouns ending in -tion); dynamic processes in lexical semantics (semantic neologisms, enantiosemy); formation of multicomponent synonym sets and variants of nomination (covid, coronavirus, new coronavirus infection, etc.); widespread use of figurative names (red zone, peak in morbidity, immune response, viral load, second wave, etc.). Concrete examples show that the new reality has expanded the range of social practices, whose language reflects the values and pragmatic attitudes characteristic of the current moment.
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Kowal, Rebekah J. « “Indian Ballerinas Toe Up” : Maria Tallchief and Making Ballet “American” in the Tribal Termination Era ». Dance Research Journal 46, no 2 (août 2014) : 73–96. http://dx.doi.org/10.1017/s0149767714000291.
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Ballet faced formidable obstacles in establishing itself as a “home-grown” transplant at mid-century. Scholars have emphasized choreographic efforts to cultivate a nationally identifiable style during the period, focusing primarily on the emergence of Balanchine and neo-classicism. Yet the role of dancers in the Americanization of ballet largely has not been probed. This article examines the part that Maria Tallchief, daughter of a “full-blooded” Osage Indian father and Scotch-Irish mother, and the first American ballerina to reach prima status, played in changing public perceptions of ballet in the mid-twentieth century. Between 1952 and 1954, national magazines such asDancemagazine,Holiday, andNewsweekfeatured images of Tallchief on their covers, lending visual credibility to claims that ballet, which many at the time considered a “foreign” dance form, had come of age in the U.S. I argue that iconographic portrayals of Tallchief's face, legs, and feet, which illustrated the dancer's physical assimilation of Balanchine's approach to dance technique, along with narratives of her personal story, advanced an account of ballet's Americanization that placed the dancer, as much as if not more than Balanchine, at center stage. I then illuminate how Tallchief's exemplification of self-discipline and initiative bolstered nostalgic arguments about the successful “citizenship” of white ethnic immigrants, while also promoting arguments about the viability of Indian assimilation during the tribal termination era. When seen in the contemporaneous contexts of ballet's Americanization and societal debates over Native American citizenship, Tallchief's story is seen to complicate the meanings of “assimilation” and “citizenship” in postwar America.
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Ding, Lihong, Jirarat Sitthiworachart et John Morris. « PAD Class Teaching in Undergraduate English Courses in the Era of Information Technology ». World Journal of English Language 13, no 1 (21 décembre 2022) : 286. http://dx.doi.org/10.5430/wjel.v13n1p286.
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We studied the teaching effect of Zhang’s Presentation - Assimilation – Discussion (or PAD) class mode in undergraduate English class. Taking undergraduates of Lanzhou University of Arts and Sciences in China as an example, we studied the teaching of undergraduate English using PAD in the information technology era. The new PAD mode has three well defined components: teacher presentation, student assimilation and discussion. Using experimental and control oral English classes, with similar input skill, after eight weeks, we found the English proficiency of both groups increased, but the PAD class was significantly better in scores for content and expression, With PAD style teaching, the experimental group improved their mean scores from 74.2 to 80.1 (median 74 to 81.5), whereas the traditional class only improved from 75.4 to 76.8 (median 74 to 79). A t-test confirmed that the results were significant.Assessments, based on questionnaires and interviews, also showed that PAD class teaching improved attitude and learning habits. After the experiment, interviews with some students in the experimental class further confirmed this. Thus the improved learning effect is worth applying in more classrooms to improve undergraduate English ability.
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McMahon, Edmund. « Psychiatry at the Frontier : Surveying Aboriginal Mental Health in the Era of Assimilation ». Health and History 9, no 2 (2007) : 22–47. http://dx.doi.org/10.1353/hah.2007.0017.
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McMahon, Edmund. « Psychiatry at the Frontier : Surveying Aboriginal Mental Health in the Era of Assimilation ». Health and History 9, no 2 (2007) : 22. http://dx.doi.org/10.2307/40111574.
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Faisal, F., Abdul Munir Mulkhan, Achmad Nurmandi et Hasse Jubba. « From Conflict to Assimilation : Strategies of Muslim Immigrants in Papua Special Autonomy Era ». Wawasan : Jurnal Ilmiah Agama dan Sosial Budaya 4, no 1 (30 juillet 2019) : 103–16. http://dx.doi.org/10.15575/jw.v4i1.5190.
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This paper aims to explain the forms of Muslim immigrant strategies in Papua in the era of special autonomy. After the implementation of special autonomy in Papua, migrants feel the increasing tension or competition in the economic and political fields. Data obtained through the method of observation, interviews, and literature studies. Observations focused on the economic practices of Muslim migrants in places such as the market in Jayapura, Papua. Interviews were conducted with a number of parties, both Muslim migrants and local Papuans, to obtain information on many things including their response to the presence of Muslim migrants. In addition, data was also obtained through the documentation of literature related to the topic of this paper. The data obtained were then analyzed through the steps of qualitative analysis, namely data reduction, data presentation, drawing conclusions/verification. This paper confirms that Muslim migrants made various efforts to deal with various obstacles in the era of Special Autonomy in Papua in three ways. First, Muslim migrants strengthen the economy, especially the informal sector. Secondly, the political sector is not the main objective of the existence of Muslim migrants. Third, Muslim migrants are not exclusive, especially in establishing communication with indigenous people.
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Slivka, Kevin. « Art, Craft, and Assimilation : Curriculum for Native Students during the Boarding School Era ». Studies in Art Education 52, no 3 (avril 2011) : 225–42. http://dx.doi.org/10.1080/00393541.2011.11518837.
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Luo, Bingkun, Peter J. Minnett, Malgorzata Szczodrak, Nicholas R. Nalli et Vernon R. Morris. « Accuracy Assessment of MERRA-2 and ERA-Interim Sea Surface Temperature, Air Temperature, and Humidity Profiles over the Atlantic Ocean Using AEROSE Measurements ». Journal of Climate 33, no 16 (15 août 2020) : 6889–909. http://dx.doi.org/10.1175/jcli-d-19-0955.1.
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AbstractSatellite and in situ measurements of the sea surface and the atmosphere often have inadequate sampling frequencies and often lack consistent global coverage. Because of such limitations, reanalysis model output is frequently used in atmospheric and oceanographic research endeavors to complement satellite and in situ data. The National Aeronautics and Space Administration’s (NASA’s) Goddard Earth Sciences Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) and the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim) datasets provide accurate, complete fields through the assimilation of many atmospheric and surface observations. Still, the reanalysis output data must be rigorously and continuously evaluated to understand their strengths and weaknesses. To this end, this study evaluates sea surface skin temperature (SSTskin) and atmospheric temperature and humidity profiles in MERRA-2 and ERA-Interim data through comparisons with independent Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) and radiosonde data from the Aerosols and Ocean Science Expeditions (AEROSE) cruises, focusing on the representation of spatial and temporal variability. SSTskin values are generally in good agreement with corresponding M-AERI measurements, with the average differences on the order of 0.1 K. Comparisons between MERRA-2 and ERA-Interim relative humidity and air temperature profiles with a total of 553 radiosondes that have been withheld from data assimilation schemes show good correspondence below 500 hPa: the average air temperature difference is <2 K and the average relative humidity discrepancy is within 10%. These results support the use of these MERRA-2 and ERA-Interim reanalysis fields in a variety of research applications.
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Liu, Qing, Rolf H. Reichle, Rajat Bindlish, Michael H. Cosh, Wade T. Crow, Richard de Jeu, Gabrielle J. M. De Lannoy, George J. Huffman et Thomas J. Jackson. « The Contributions of Precipitation and Soil Moisture Observations to the Skill of Soil Moisture Estimates in a Land Data Assimilation System ». Journal of Hydrometeorology 12, no 5 (1 octobre 2011) : 750–65. http://dx.doi.org/10.1175/jhm-d-10-05000.1.
Texte intégralRésumé :
Abstract The contributions of precipitation and soil moisture observations to soil moisture skill in a land data assimilation system are assessed. Relative to baseline estimates from the Modern Era Retrospective-analysis for Research and Applications (MERRA), the study investigates soil moisture skill derived from (i) model forcing corrections based on large-scale, gauge- and satellite-based precipitation observations and (ii) assimilation of surface soil moisture retrievals from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E). Soil moisture skill (defined as the anomaly time series correlation coefficient R) is assessed using in situ observations in the continental United States at 37 single-profile sites within the Soil Climate Analysis Network (SCAN) for which skillful AMSR-E retrievals are available and at 4 USDA Agricultural Research Service (“CalVal”) watersheds with high-quality distributed sensor networks that measure soil moisture at the scale of land model and satellite estimates. The average skill of AMSR-E retrievals is R = 0.42 versus SCAN and R = 0.55 versus CalVal measurements. The skill of MERRA surface and root-zone soil moisture is R = 0.43 and R = 0.47, respectively, versus SCAN measurements. MERRA surface moisture skill is R = 0.56 versus CalVal measurements. Adding information from precipitation observations increases (surface and root zone) soil moisture skills by ΔR ~ 0.06. Assimilating AMSR-E retrievals increases soil moisture skills by ΔR ~ 0.08. Adding information from both sources increases soil moisture skills by ΔR ~ 0.13, which demonstrates that precipitation corrections and assimilation of satellite soil moisture retrievals contribute important and largely independent amounts of information.
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Luque-Almagro, Víctor M., Andrew J. Gates, Conrado Moreno-Vivián, Stuart J. Ferguson, David J. Richardson et M. Dolores Roldán. « Bacterial nitrate assimilation : gene distribution and regulation ». Biochemical Society Transactions 39, no 6 (21 novembre 2011) : 1838–43. http://dx.doi.org/10.1042/bst20110688.
Texte intégralRésumé :
In the context of the global nitrogen cycle, the importance of inorganic nitrate for the nutrition and growth of marine and freshwater autotrophic phytoplankton has long been recognized. In contrast, the utilization of nitrate by heterotrophic bacteria has historically received less attention because the primary role of these organisms has classically been considered to be the decomposition and mineralization of dissolved and particulate organic nitrogen. In the pre-genome sequence era, it was known that some, but not all, heterotrophic bacteria were capable of growth on nitrate as a sole nitrogen source. However, examination of currently available prokaryotic genome sequences suggests that assimilatory nitrate reductase (Nas) systems are widespread phylogenetically in bacterial and archaeal heterotrophs. Until now, regulation of nitrate assimilation has been mainly studied in cyanobacteria. In contrast, in heterotrophic bacterial strains, the study of nitrate assimilation regulation has been limited to Rhodobacter capsulatus, Klebsiella oxytoca, Azotobacter vinelandii and Bacillus subtilis. In Gram-negative bacteria, the nas genes are subjected to dual control: ammonia repression by the general nitrogen regulatory (Ntr) system and specific nitrate or nitrite induction. The Ntr system is widely distributed in bacteria, whereas the nitrate/nitrite-specific control is variable depending on the organism.
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Haimberger, Leopold. « Homogenization of Radiosonde Temperature Time Series Using Innovation Statistics ». Journal of Climate 20, no 7 (1 avril 2007) : 1377–403. http://dx.doi.org/10.1175/jcli4050.1.
Texte intégralRésumé :
Abstract Radiosonde temperature records contain valuable information for climate change research from the 1940s onward. Since they are affected by numerous artificial shifts, time series homogenization efforts are required. This paper introduces a new technique that uses time series of temperature differences between the original radiosonde observations (obs) and background forecasts (bg) of an atmospheric climate data assimilation system for homogenization. These obs − bg differences, the “innovations,” are a by-product of the data assimilation process. They have been saved during the 40-yr ECMWF Re-Analysis (ERA-40) and are now available for each assimilated radiosonde record back to 1958. It is demonstrated that inhomogeneities in the obs time series due to changes in instrumentation can be automatically detected and adjusted using daily time series of innovations at 0000 and 1200 UTC. The innovations not only reveal problems of the radiosonde records but also of the data assimilation system. Although ERA-40 used a frozen data assimilation system, the time series of the bg contains some breaks as well, mainly due to changes in the satellite observing system. It has been necessary to adjust the global mean bg temperatures before the radiosonde homogenization. After this step, homogeneity adjustments, which can be added to existing raw radiosonde observations, have been calculated for 1184 radiosonde records. The spatiotemporal consistency of the global radiosonde dataset is improved by these adjustments and spuriously large day–night differences are removed. After homogenization the climatologies of the time series from certain radiosonde types have been adjusted. This step reduces temporally constant biases, which are detrimental for reanalysis purposes. Therefore the adjustments applied should yield an improved radiosonde dataset that is suitable for climate analysis and particularly useful as input for future climate data assimilation efforts. The focus of this paper relies on the lower stratosphere and on the internal consistency of the homogenized radiosonde dataset. Implications for global mean upper-air temperature trends are touched upon only briefly.
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Garbus, Julie. « “My Good Italian Friends” : Vida Scudder and Boston's Circolo Italo-Americano ». New England Quarterly 94, no 4 (décembre 2021) : 531–63. http://dx.doi.org/10.1162/tneq_a_00915.
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Abstract The Circolo Italo-Americano, a Progressive-era group of educated Italian immigrants and affluent Bostonians, was founded by settlement movement pioneer Vida Dutton Scudder to integrate Italians into American life through “friendly personal contacts,” social events, and educational opportunities. The Circolo included Italian leadership and focused on immigrants’ contributions, not on “assimilation.”
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Egamberganova, Matluba. « CHANGES IN THE TRADITIONAL IDENTITY OF THE TURKMENS OF THE KHOREZM OASIS ». JOURNAL OF LOOK TO THE PAST 4, no 10 (30 octobre 2021) : 60–65. http://dx.doi.org/10.26739/2181-9599-2021-10-22.
Texte intégralRésumé :
In this article, changes in the traditional identity of the Turkmens of the Khorezm oasis in the Soviet era are studied on the example of household life, customs and wedding ceremonies. At the same time, changes in the way of life of the Turkmen populationduring the Khiva Khanate and the Soviet era, the struggle for independence, the consequences of the policy of collectivization, the consequences of national-territorial demarcation, the way of life of the population during World War II.Index Terms:National identity,turkmens, national-territorial delimitation, weddings, кomsomol weddings, assimilation
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Aalstad, Kristoffer, Sebastian Westermann, Thomas Vikhamar Schuler, Julia Boike et Laurent Bertino. « Ensemble-based assimilation of fractional snow-covered area satellite retrievals to estimate the snow distribution at Arctic sites ». Cryosphere 12, no 1 (23 janvier 2018) : 247–70. http://dx.doi.org/10.5194/tc-12-247-2018.
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Abstract. With its high albedo, low thermal conductivity and large water storing capacity, snow strongly modulates the surface energy and water balance, which makes it a critical factor in mid- to high-latitude and mountain environments. However, estimating the snow water equivalent (SWE) is challenging in remote-sensing applications already at medium spatial resolutions of 1 km. We present an ensemble-based data assimilation framework that estimates the peak subgrid SWE distribution (SSD) at the 1 km scale by assimilating fractional snow-covered area (fSCA) satellite retrievals in a simple snow model forced by downscaled reanalysis data. The basic idea is to relate the timing of the snow cover depletion (accessible from satellite products) to the peak SSD. Peak subgrid SWE is assumed to be lognormally distributed, which can be translated to a modeled time series of fSCA through the snow model. Assimilation of satellite-derived fSCA facilitates the estimation of the peak SSD, while taking into account uncertainties in both the model and the assimilated data sets. As an extension to previous studies, our method makes use of the novel (to snow data assimilation) ensemble smoother with multiple data assimilation (ES-MDA) scheme combined with analytical Gaussian anamorphosis to assimilate time series of Moderate Resolution Imaging Spectroradiometer (MODIS) and Sentinel-2 fSCA retrievals. The scheme is applied to Arctic sites near Ny-Ålesund (79° N, Svalbard, Norway) where field measurements of fSCA and SWE distributions are available. The method is able to successfully recover accurate estimates of peak SSD on most of the occasions considered. Through the ES-MDA assimilation, the root-mean-square error (RMSE) for the fSCA, peak mean SWE and peak subgrid coefficient of variation is improved by around 75, 60 and 20 %, respectively, when compared to the prior, yielding RMSEs of 0.01, 0.09 m water equivalent (w.e.) and 0.13, respectively. The ES-MDA either outperforms or at least nearly matches the performance of other ensemble-based batch smoother schemes with regards to various evaluation metrics. Given the modularity of the method, it could prove valuable for a range of satellite-era hydrometeorological reanalyses.