基于走航观测评估大气再分析中的南大洋大气河  

Evaluation of Southern Ocean Atmospheric Rivers in Atmospheric Reanalysis data Based on a Navigational Observation

作　　者：项旭 韩博 张功 刘长炜 梁凯昕 齐木荣 江可悦 林奕辰 钟锐 杨清华 XIANG Xu;HAN Bo;ZHANG Gong;LIU Changwei;LIANG Kaixin;QI Murong;JIANG Keyue;LIN Yinchen;ZHONG Rui;YANG Qinghua(School of Atmospheric Sciences,Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China)

机构地区：[1]中山大学大气科学学院和南方海洋科学与工程广东省实验室(珠海),广东珠海519082

出　　处：《高原气象》2025年第1期83-94,共12页Plateau Meteorology

基　　金：南方海洋科学与工程广东省实验室(珠海)自主项目(SML2023SP217,SML2023SP219,SML2020SP007,SML2021SP201);国家重点研发计划项目(2019YFA0607004,2020YFA0608804);广东省基础与应用基础研究基金项目(2020A1515110675);广东省自然资源厅重点项目(粤自然资合[2022]18号)。

摘　　要：大气河直接影响南极海-陆-冰-气相互作用,但对其开展的探空观测尚不多,造成数值模式和再分析数据的结论存在不确定性。本研究使用了中国第37次南极科考获得的走航探空数据,针对一次南大洋大气河事件评估了4种大气再分析数据——ERA5,CFSv2,JRA-55和MERRA-2。评估结果表明:虽然所有大气再分析数据对南大洋水汽通量(IVT)的描述都与观测比较接近——包括在大气河期间,但这部分是因为再分析数据高估了大气整层(地表至300 hPa)湿度场的同时低估了大气整层风速。进一步分析发现,大气湿度和风速在垂直方向的协变项被多数再分析数据显著低估甚至给出了与观测相反的结果;而协变项的偏差对IVT影响与整层大气湿度和风速相当。ERA5在协变项的表现显著优于其他再分析数据。与此同时,ERA5也给出了大气河期间与观测最为一致的逆湿和低空急流结构。因此,仅就本次观测而言ERA5对南大洋大气河的描述能力是最佳的。Atmospheric rivers significantly impact the ocean-land-ice-atmosphere interaction around Antarctica.However,the shortage of in situ observations limits people’s understanding,bringing considerable uncertainty in numerical simulation results and products.This study utilized ship-borne radiosonde data collected during the 37th Chinese Antarctic Expedition to evaluate four kinds of state-of-the-art atmospheric reanalysis datasets(ERA5,CFSv2,JRA-55,and MERRA-2)during an atmospheric river event in the Southern Ocean.All reanalysis provide acceptable descriptions of integrated water vapor transport(IVT)compared with the observation,even during the atmospheric river events.However,all reanalyses overestimated the humidity and underestimated the wind speed across the entire atmospheric column(from surface to 300 hPa).Moreover,all reanalyses,except for ERA5,failed to capture the variation in the covariance term between humidity and wind speed in the vertical direction;the latter contributes to a considerable bias in the IVT of reanalyses.The ERA5 demonstrates superior performance during the observation period,especially in humidity and low-level jet profiles when the atmospheric river arrives at the observation site.In this study,ERA5 seems to be the best atmospheric reanalysis for studying atmospheric rivers in the Southern Ocean.

关 键 词：南大洋 大气河 无线电探空 大气再分析 

分 类 号：P434.5[天文地球—大气科学及气象学]