Effect of Teleconnected Land–Atmosphere Coupling on Northeast China Persistent Drought in Spring–Summer of 2017

• DOI: 10.1175/jcli-d-19-0175.1
• Publication Date: 2019-08-01T18:40:12Z
• Authors: Dingwen Zeng; Xing Yuan; Joshua K. Roundy
• Keywords: Teleconnection; Anomaly (physics); Anticyclone; Diabatic

Northeast China (NEC) suffered a severe drought that persisted from March to July of 2017 with profound impacts on agriculture and society, raising an urgent need understand the mechanism for persistent droughts over midlatitudes. Previous studies focused either large-scale teleconnections or local land–atmosphere coupling, while less attention was paid their synergistic effects persistence. Here we show NEC triggered by strong positive phase Arctic Oscillation in March, maintained anticyclone area south Lake Baikal (ASLB) through quasi-stationary Rossby wave April–July, accompanied sinking motion north wind anomaly. By using coupling index based persistence feedbacks between boundary layer land surface, find states ASLB shifted wet persistently strengthened dry April–July. Over ASLB, increased surface sensible heat, decreased cloud cover, weakened longwave absorption, resulting diabatic heating anomaly lower atmosphere cooling upper atmosphere. This anomalous vertical profile led negative potential vorticity at low levels, indicating had phase-lock effect train originating upstream areas, therefore downstream regions. Our study suggests pattern should be considered diagnosing droughts, especially northern