The E1 Nifio-Southern Oscillation （ENSO） is emphasized the roles of wind stress and heat flux environmental forcing to the ocean; its effect and modulated by many factors; most previous studies have in the tropical ...The E1 Nifio-Southern Oscillation （ENSO） is emphasized the roles of wind stress and heat flux environmental forcing to the ocean; its effect and modulated by many factors; most previous studies have in the tropical Pacific. Freshwater flux （FWF） is another the related ocean salinity variability in the ENSO region have been of increased interest recently. Currently, accurate quantifications of the FWF roles in the climate remain challenging; the related observations and coupled ocean-atmosphere modeling involve large elements of uncertainty. In this study, we utilized satellite-based data to represent FWF-induced feedback in the tropical Pacific climate system; we then incorporated these data into a hybrid coupled ocean-atmosphere model （HCM） to quantify its effects on ENSO. A new mechanism was revealed by which interannual FWF forcing modulates ENSO in a significant way. As a direct forcing, FWF exerts a significant influence on the ocean through sea surface salinity （SSS） and buoyancy flux （QB） in the western-central tropical Pacific. The SSS perturbations directly induced by ENSO-related interannual FWF variability affect the stability and mixing in the upper ocean. At the same time, the ENSO-induced FWF has a compensating effect on heat flux, acting to reduce interannual Qs variability during ENSO cycles. These FWF-induced processes in the ocean tend to modulate the vertical mixing and entrainment in the upper ocean, enhancing cooling during La Nifia and enhancing warming during E1 Nifio, respectively. The interannual FWF forcing-induced positive feedback acts to enhance ENSO amplitude and lengthen its time scales in the tropical Pacific coupled climate system.展开更多
文摘针对GNSS(global navigation satellite system)数据分析中心对快速、超快速轨道产品精度及时效性的要求以及全球跟踪站分布不均匀性的现状,本文提出一种基于观测方程GDOP(geometric dilution of precision)值的优化选站SSS(selected step by step)模型。从理论上推导出精密定轨最小地面跟踪站数与地面最优跟踪站数的计算方法,分别通过s°×s°和k°×k°带全球网格划分,筛选最小跟踪站全球分布,以定轨观测方程GDOP值最小为准则,逐步累加筛选定轨全球跟踪站最优分布。连续6d的数据分析结果表明,本文提出的优化选站模型,在相同数据处理能力条件下,定轨精度可达整体处理的90%,处理时间缩短50%以上;与一般策略对比表明,SSS模型计算出的轨道精度相当,时间节约20%左右;此模型所选跟踪站为最优或次优,提高了分析中心数据处理效率。
基金supported in part by NSF Grant(ATM-0727668and AGS-1061998)NOAA Grant(NA08OAR4310885)+3 种基金NASA Grants(NNX08AI74G,NNX08AI76G,and NNX09AF41G)F.Zheng is supported by the National Basic Research Program of China(GrantNos.2012CB417404and2012CB955202)the Natural Science Foundation of China(Grant No.41075064)Pei is additionally supported by China Scholarship Coun-cil(CSC) with the Ocean University of China,Qingdao,China
文摘The E1 Nifio-Southern Oscillation （ENSO） is emphasized the roles of wind stress and heat flux environmental forcing to the ocean; its effect and modulated by many factors; most previous studies have in the tropical Pacific. Freshwater flux （FWF） is another the related ocean salinity variability in the ENSO region have been of increased interest recently. Currently, accurate quantifications of the FWF roles in the climate remain challenging; the related observations and coupled ocean-atmosphere modeling involve large elements of uncertainty. In this study, we utilized satellite-based data to represent FWF-induced feedback in the tropical Pacific climate system; we then incorporated these data into a hybrid coupled ocean-atmosphere model （HCM） to quantify its effects on ENSO. A new mechanism was revealed by which interannual FWF forcing modulates ENSO in a significant way. As a direct forcing, FWF exerts a significant influence on the ocean through sea surface salinity （SSS） and buoyancy flux （QB） in the western-central tropical Pacific. The SSS perturbations directly induced by ENSO-related interannual FWF variability affect the stability and mixing in the upper ocean. At the same time, the ENSO-induced FWF has a compensating effect on heat flux, acting to reduce interannual Qs variability during ENSO cycles. These FWF-induced processes in the ocean tend to modulate the vertical mixing and entrainment in the upper ocean, enhancing cooling during La Nifia and enhancing warming during E1 Nifio, respectively. The interannual FWF forcing-induced positive feedback acts to enhance ENSO amplitude and lengthen its time scales in the tropical Pacific coupled climate system.
