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191.
The problem of tracking the directions-of-arrival (DOAs) of multiple moving sonar targets with an array of passive sensors is complicated by sensor movement. An algorithm for the joint tracking of source DOAs and sensor positions is presented to address this problem. Initial maximum-likelihood estimates of source DOAs and sensor positions are refined by Kalman filtering. Spatio-temporally correlated array movement is considered. Source angle dynamics are used to achieve correct data association. The new technique is capable of performing well for the difficult cases of sources that cross in angle as well as for fully coherent sources. Computer simulations show that the approach is robust in the presence of array motion modeling uncertainty and effectively reduces dependence on expensive and possibly unreliable hardware 相似文献
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Steven Desch 《Meteoritics & planetary science》2015,50(8):1489-1490
195.
Matthew A.LAZZARA Sophie A.ORENDORF Taylor P.NORTON Jordan G.POWERS David H.BROMWICH Scott CARPENTIER John J.CASSANO Steven R.COLWELL Arthur M.CAYETTE Kirstin WERNER 《大气科学进展》2020,37(5):423-430
1.Overview In July 2018,the Antarctic community came together to meet at the 13th Workshop on Antarctic Meteorology and Climate(WAMC)in Madison,Wisconsin,USA(Fig.1);and in the following year in June 2019,the 14th WAMC was held in Charleston,South Carolina,USA(Fig.2).With a growing history,the WAMC addresses the topics of Antarctic meteorology and climate(Kameda et al.,2008;Colwell et al.,2016;Lazzara et al.,2018)as well as weather-related issues of scientific and operational support.The workshops bring together researchers,operational forecasters,numerical modelers,observational specialists,and students.The themes of both workshops included Antarctic meteorological observations,Antarctic atmospheric numerical modeling,Antarctic meteorological and climate research,and Antarctic weather forecasting and operational services.The 2018 and 2019 WAMC were both followed by a one-day focus on the Year of Polar Prediction-Southern Hemisphere(YOPP-SH),when preparations and follow-up discussions were made with regard to the YOPP Special Observing Period from 16 November 2018 to 15 February 2019. 相似文献
196.
Li Xiao-Feng Blenkinsop Stephen Barbero Renaud Yu Jingjing Lewis Elizabeth Lenderink Geert Guerreiro Selma Chan Steven Li Yafei Ali Haider Villalobos Herrera Roberto Kendon Elizabeth Fowler Hayley J. 《Climate Dynamics》2020,54(11):4823-4839
Climate Dynamics - We investigate the global distribution of hourly precipitation and its connections with the El Niño–Southern Oscillation (ENSO) using both satellite precipitation... 相似文献
197.
Mantsis Damianos F. Sherwood Steven Dixit Vishal Morrison Hugh Thompson Greg 《Climate Dynamics》2020,54(7):3425-3439
Climate Dynamics - The simulation of Saharan mid tropospheric clouds is investigated with the weather research and forecasting (WRF) regional atmospheric model at convection permitting... 相似文献
198.
Abstract The medium‐scale wave regime, consisting largely of zonal wavenumbers 5–7, frequently dominates the summer Southern Hemisphere tropospheric circulation. We perform a diagnostic study of this circulation as simulated by the Canadian Climate Centre (CCC) general circulation model (GCM). The analysis of Hövmöller diagrams, space‐time and zonal wavenumber spectra shows that the CCC GCM is able to simulate the observed medium‐scale wave regime. The zonally averaged meridional eddy heat and momentum transports and the associated baroclinic and barotropic energy conversions are also examined. The distributions of the transports on the vertical plane agree well with the observations. After comparison with the observed December‐January‐February 1979 distributions, some quantitative differences remain: the heat transport is too weak aloft and too large near the surface, whereas the momentum transport tends to be too weak. The baroclinic and barotropic conversions show a maximum in the medium‐scale waves. The time evolution of the Richardson number of the mean flow suggests that the medium‐scale wave is due to a baroclinic instability. 相似文献
199.
Steven J. Smith Joseph Karas Jae Edmonds Jiyong Eom Andrew Mizrahi 《Climatic change》2013,117(4):663-675
The Global Warming Potential (GWP) index is currently used to create CO2-equivalent emission totals for multi-gas greenhouse targets. While many alternatives have been proposed, it is not possible to uniquely define a metric that captures the different impacts of emissions of substances with widely disparate atmospheric lifetimes, which leads to a wide range of possible index values. We examine the sensitivity of emissions and climate outcomes to the value of the index used to aggregate methane emissions using a technologically detailed integrated assessment model. The methane index is varied between 4 and 70, with a central value of 21, which is the 100-year GWP value currently used in policy contexts. We find that the sensitivity to index value is, at most, 10–18 % in terms of methane emissions but only 2–3 % in terms of the maximum total radiative forcing change, with larger regional emissions differences in some cases. The choice of index also affects estimates of the cost of meeting a given end of century forcing target, with total two-gas mitigation cost increasing by 7–9 % if the index is increased, and increasing in most scenarios from 4 to 23 % if the index is lowered, with a slight (1 %) decrease in total cost in one case. We find that much of the methane abatement occurs as the induced effect of CO2 abatement rather than explicit abatement, which is one reason why climate outcomes are relatively insensitive to the index value. We also find that the near-term climate benefit of increasing the methane index is small. 相似文献
200.
Multi-factor impact analysis of agricultural production in Bangladesh with climate change 总被引:1,自引:0,他引:1
Alex C. Ruane David C. Major Winston H. Yu Mozaharul Alam Sk. Ghulam Hussain Abu Saleh Khan Ahmadul Hassan Bhuiya Md. Tamim Al Hossain Richard Goldberg Radley M. Horton Cynthia Rosenzweig 《Global Environmental Change》2013,23(1):338-350
Diverse vulnerabilities of Bangladesh's agricultural sector in 16 sub-regions are assessed using experiments designed to investigate climate impact factors in isolation and in combination. Climate information from a suite of global climate models (GCMs) is used to drive models assessing the agricultural impact of changes in temperature, precipitation, carbon dioxide concentrations, river floods, and sea level rise for the 2040–2069 period in comparison to a historical baseline. Using the multi-factor impacts analysis framework developed in Yu et al. (2010), this study provides new sub-regional vulnerability analyses and quantifies key uncertainties in climate and production. Rice (aman, boro, and aus seasons) and wheat production are simulated in each sub-region using the biophysical Crop Environment REsource Synthesis (CERES) models. These simulations are then combined with the MIKE BASIN hydrologic model for river floods in the Ganges-Brahmaputra-Meghna (GBM) Basins, and the MIKE21 Two-Dimensional Estuary Model to determine coastal inundation under conditions of higher mean sea level. The impacts of each factor depend on GCM configurations, emissions pathways, sub-regions, and particular seasons and crops. Temperature increases generally reduce production across all scenarios. Precipitation changes can have either a positive or a negative impact, with a high degree of uncertainty across GCMs. Carbon dioxide impacts on crop production are positive and depend on the emissions pathway. Increasing river flood areas reduce production in affected sub-regions. Precipitation uncertainties from different GCMs and emissions scenarios are reduced when integrated across the large GBM Basins’ hydrology. Agriculture in Southern Bangladesh is severely affected by sea level rise even when cyclonic surges are not fully considered, with impacts increasing under the higher emissions scenario. 相似文献