基于2014年6月全国14:00(北京时,下同)加密探空观测资料,设计了观测系统模拟试验(Observing System Simulation Experiments,OSSEs)和实际加密探空同化试验(Observing System Experiments,OSEs)来评估14:00加密探空对区域数值预报系统...基于2014年6月全国14:00(北京时,下同)加密探空观测资料,设计了观测系统模拟试验(Observing System Simulation Experiments,OSSEs)和实际加密探空同化试验(Observing System Experiments,OSEs)来评估14:00加密探空对区域数值预报系统的影响,并对14:00加密探空的观测布局进行了初步探索。结果表明:(1)理想模拟试验和实际同化试验中加入14:00加密探空对于提高区域模式的降水预报准确率均有积极影响,降水预报技巧评分在强降水量级提高更为明显,14:00起报结果优于20:00。(2)理想模拟试验中同化14:00加密探空能有效调整模式初始场中的动力、热力场结构和水汽分布,从而与"实况"更为接近。实际同化试验中增加14:00探空观测能修正模式风场,但对于温度和湿度分析在模式中低层略有负贡献,探空的湿度、温度观测本身存在观测偏差是一个可能的原因。(3)从观测布局来看,14:00加密探空对于数值预报具有基础作用,目前而言,GPS/PW等非常规资料不能取代14:00加密探空。综合考虑探空气球的施放成本,采用探测高度到300 h Pa、重点区域加密是一种经济的14:00增加高空观测方式。展开更多
An Acoustic Doppler Current Profiler （ADCP） observation site was set up in the Western South Yellow Sea from 2012 to 2013 to study the local suspended particle matters （SPM） distribution pattern. The SPM concentra...An Acoustic Doppler Current Profiler （ADCP） observation site was set up in the Western South Yellow Sea from 2012 to 2013 to study the local suspended particle matters （SPM） distribution pattern. The SPM concentration could be semi-quantitatively represented by backscatter intensity （Sv）, converted by the echo intensity （E/） of ADCP. Results show two types of SPM in the water column： the quasi-biological SPM and quasi-mineral SPM. The quasi-biological SPM mainly exists in summer half year and is con- centrated above the thermocline. It has periodically diurnal variations with high concentration at night and low concentration in the daytime. The quasi-mineral SPM is located in lower part of the water column, with similar relation to monthly tidal current variation all year round. However, the daily quasi-mineral SPM distribution patterns vary between summer and winter half year. The sunlight is thought to be the origin factor leading to the diurnally vertical motion of the biological features, which might cause the diurnal Sv variation. Unlike in winter half year when tidal current is relatively single driving force of the monthly SPM pattern, the high speed current near the thermocline is also responsible for the concentration of quasi-mineral SPM in summer half year. The sediment input difference between summer and winter half year contribute to the varied daily variation of quasi-mineral SPM with re-suspended SPM ir~ winter and sediments from Yellow Sea Mud Area （YSMA） in summer. The seasonal variations in hydrodynamics, water structure and heavy-wind incidents are the primary factors influencing the differential seasonal SPM distribution patterns.展开更多
In this paper,we studied the effect of spatial distribution of soil parameters on passive soil moisture retrieval at pixel scale.First,we evaluated the forward microwave emission model and soil moisture retrieval algo...In this paper,we studied the effect of spatial distribution of soil parameters on passive soil moisture retrieval at pixel scale.First,we evaluated the forward microwave emission model and soil moisture retrieval algorithm accuracy through the observa-tion of field experiments.Then,we used soil parameters in different spatial distribution patterns,including random,normal,and uniform distribution,to determine the different levels of heterogeneity on soil moisture retrieval,in order to seek the rela-tionship between heterogeneity and soil moisture retrieval error.Finally,we conducted a controlled heterogeneity effect ex-periment measurements using a Truck-mounted Multi-frequency Radiometer(TMMR) to validate our simulation results.This work has proved that the soil moisture retrieval algorithm had a high accuracy(RMSE=0.049 cm3 cm 3) and can satisfy the need of this research.The simulation brightness temperatures match well with observations,with RMSE=9.89 K.At passive microwave remote sensing pixel scale,soil parameters with different spatial distribution patterns could have different levels of error on soil moisture estimation.Overall,we found that soil moisture with a random distribution in a satellite pixel scale can cause the largest error,with a normal distribution being the second,and a uniform distribution the least due to the smallest het-erogeneity.展开更多
文摘基于2014年6月全国14:00(北京时,下同)加密探空观测资料,设计了观测系统模拟试验(Observing System Simulation Experiments,OSSEs)和实际加密探空同化试验(Observing System Experiments,OSEs)来评估14:00加密探空对区域数值预报系统的影响,并对14:00加密探空的观测布局进行了初步探索。结果表明:(1)理想模拟试验和实际同化试验中加入14:00加密探空对于提高区域模式的降水预报准确率均有积极影响,降水预报技巧评分在强降水量级提高更为明显,14:00起报结果优于20:00。(2)理想模拟试验中同化14:00加密探空能有效调整模式初始场中的动力、热力场结构和水汽分布,从而与"实况"更为接近。实际同化试验中增加14:00探空观测能修正模式风场,但对于温度和湿度分析在模式中低层略有负贡献,探空的湿度、温度观测本身存在观测偏差是一个可能的原因。(3)从观测布局来看,14:00加密探空对于数值预报具有基础作用,目前而言,GPS/PW等非常规资料不能取代14:00加密探空。综合考虑探空气球的施放成本,采用探测高度到300 h Pa、重点区域加密是一种经济的14:00增加高空观测方式。
基金supported by the National Natural Science Foundation of China (Grant No. 41030856)National 973 Project of China (Grant No. 2005CB422304)+1 种基金the Project of Taishan Scholarsupport of the R/V Dongfanghong 2 and Shared Voyage of the National Nature Science Foundation of China
文摘An Acoustic Doppler Current Profiler （ADCP） observation site was set up in the Western South Yellow Sea from 2012 to 2013 to study the local suspended particle matters （SPM） distribution pattern. The SPM concentration could be semi-quantitatively represented by backscatter intensity （Sv）, converted by the echo intensity （E/） of ADCP. Results show two types of SPM in the water column： the quasi-biological SPM and quasi-mineral SPM. The quasi-biological SPM mainly exists in summer half year and is con- centrated above the thermocline. It has periodically diurnal variations with high concentration at night and low concentration in the daytime. The quasi-mineral SPM is located in lower part of the water column, with similar relation to monthly tidal current variation all year round. However, the daily quasi-mineral SPM distribution patterns vary between summer and winter half year. The sunlight is thought to be the origin factor leading to the diurnally vertical motion of the biological features, which might cause the diurnal Sv variation. Unlike in winter half year when tidal current is relatively single driving force of the monthly SPM pattern, the high speed current near the thermocline is also responsible for the concentration of quasi-mineral SPM in summer half year. The sediment input difference between summer and winter half year contribute to the varied daily variation of quasi-mineral SPM with re-suspended SPM ir~ winter and sediments from Yellow Sea Mud Area （YSMA） in summer. The seasonal variations in hydrodynamics, water structure and heavy-wind incidents are the primary factors influencing the differential seasonal SPM distribution patterns.
基金supported by National Natural Science Foun-dation of China (Grant No.41030534)National Basic Research Program of China (Grant No. 2007CB714403)The European Commission Under FP7 Topic ENV.2007.4.1.4.2 "Improving Observing Systems for Water Resource Management"
文摘In this paper,we studied the effect of spatial distribution of soil parameters on passive soil moisture retrieval at pixel scale.First,we evaluated the forward microwave emission model and soil moisture retrieval algorithm accuracy through the observa-tion of field experiments.Then,we used soil parameters in different spatial distribution patterns,including random,normal,and uniform distribution,to determine the different levels of heterogeneity on soil moisture retrieval,in order to seek the rela-tionship between heterogeneity and soil moisture retrieval error.Finally,we conducted a controlled heterogeneity effect ex-periment measurements using a Truck-mounted Multi-frequency Radiometer(TMMR) to validate our simulation results.This work has proved that the soil moisture retrieval algorithm had a high accuracy(RMSE=0.049 cm3 cm 3) and can satisfy the need of this research.The simulation brightness temperatures match well with observations,with RMSE=9.89 K.At passive microwave remote sensing pixel scale,soil parameters with different spatial distribution patterns could have different levels of error on soil moisture estimation.Overall,we found that soil moisture with a random distribution in a satellite pixel scale can cause the largest error,with a normal distribution being the second,and a uniform distribution the least due to the smallest het-erogeneity.
