Structure of an Atmospheric River Over Australia and the Southern Ocean. Part I: Tropical and Midlatitude Water Vapor Fluxes
Structure of an Atmospheric River Over Australia and the Southern Ocean. Part I: Tropical and Midlatitude Water Vapor Fluxes
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DOI：
10.1029/2020jd032513
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发表时间：
2020-09
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通讯作者：
R. Rauber;Huancui Hu;F. Dominguez;S. Nesbitt;G. McFarquhar;T. J. Zaremba;Joseph A. Finlon
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作者：
R. Rauber;Huancui Hu;F. Dominguez;S. Nesbitt;G. McFarquhar;T. J. Zaremba;Joseph A. Finlon
利用模拟和观测方法分析了2018年1月28日至29日南大洋云、辐射、气溶胶输送实验研究活动期间影响塔斯马尼亚、澳大利亚和南大洋的一条大气河（AR）。Gulfstream - V下沉探空仪测量和全球降水测量雷达分析，结合使用水汽示踪剂的天气研究与预报模式模拟，研究了热带和中纬度湿气源对AR的相对贡献。与季风热带低气压相关的湿气被带入延伸至60°S的中纬度锋系统。到达离南极洲海岸850公里的相关低压系统，有效地连接了热带和极地地区。当气流在塔斯马尼亚附近的南大洋上空移动时，热带湿气贡献了AR内约50%的可降水量。热带对降水的贡献随纬度的变化而减少，从澳大利亚上空的约70%，到澳大利亚海岸的约50%，到55°S的极地地区的不到5%。在1月28日1200 UTC至1月29日0600 UTC期间，通过AR核心的综合水汽输送（IVT）达到500 kg m−1 s−1以上，是世界上最大的陆地河流亚马逊河平均输送量的1.29倍。高IVT强度可能归因于澳大利亚和南大洋南部夏季较暖的温度导致较高的水蒸气含量。
An atmospheric river (AR) impacting Tasmania, Australia, and the Southern Ocean during the austral summer on 28–29 January 2018 during the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study campaign is analyzed using a modeling and observational approach. Gulfstream‐V dropsonde measurements and Global Precipitation Measurement radar analyses were used in conjunction with Weather Research and Forecasting model simulations with water vapor tracers to investigate the relative contributions of tropical and midlatitude moisture sources to the AR. Moisture associated with a monsoonal tropical depression became entrained into a midlatitude frontal system that extended to 60°S, reaching the associated low‐pressure system 850 km off the coast of Antarctica—effectively connecting the tropics and the polar region. Tropical moisture contributed to about 50% of the precipitable water within the AR as the flow moved over the Southern Ocean near Tasmania. The tropical contribution to precipitation decreased with latitude, from >70% over Australia, to ~50% off the Australian coast, to less than 5% poleward of 55°S. The integrated vapor transport (IVT) through the core of the AR reached above 500 kg m−1 s−1 during 1200 UTC 28 January to 0600 UTC 29 January, 1.29 times the average amount of water carried by the world's largest terrestrial river, the Amazon. The high IVT strength might be attributed to the higher water vapor content associated with the warmer temperatures across Australia and the Southern Ocean in austral summer.