caa a22 4500 605471568 CHVBK 20210128100333.0 cr unu---uuuuu 210128e20151001xx s 000 0 eng 10.1007/s00382-014-2439-3 doi (NATIONALLICENCE)springer-10.1007/s00382-014-2439-3 Influences of ENSO on the vertical coupling of atmospheric circulation during the onset of South Asian summer monsoon [Elektronische Daten] [Boqi Liu, Guoxiong Wu, Roncai Ren] Based on multiple sources of atmospheric and oceanic data, this study performs a series of composite analysis of the South Asian summer monsoon (SASM) onset against ENSO events, and indicates that warm/cold ENSO events induce later/earlier onset of the SASM by modulating the vertical coupling of the upper- and lower-level circulation over the South Asia. Specifically, during the monsoon onset of Bay of Bengal (BOB), the ENSO-induced convection anomalies over the southern Philippines can modulate the position of South Asian high (SAH) in late April in the upper troposphere, which evolves to affect the monsoon onset convection by changing the upper divergence-pumping effect. In the lower troposphere, ENSO induces an anomalous zonal gradient of sea surface temperature (SST) over the Indian-western Pacific Ocean to alter the barotropic instability which further affects the formation of BOB monsoon onset convection. During the Indian summer monsoon onset, the anomalous convection over northeastern BOB and Indochina Peninsula in late May act to change the SAH position and its relevant upper divergence-pumping over the Arabian Sea (AS). Meanwhile, the Indian monsoon onset convection is also modulated by the ENSO-induced changes in intensity of the inertial instability and the forced convection over the AS, which are related to an ENSO-induced anomalous cross-equatorial SST gradient and zonally asymmetric meridional gradient of sea level pressure, and an anomalous westerly over the central AS in the lower troposphere. Results demonstrate that during the BOB and India monsoon onset, the influences of ENSO on the upper circulation are similar, but are distinctly different on the lower-level circulation. Springer-Verlag Berlin Heidelberg, 2014 South Asian summer monsoon onset nationallicence ENSO nationallicence South Asian high nationallicence Inertial instability nationallicence Forced convection nationallicence Liu Boqi State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China aut Wu Guoxiong State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China aut Ren Roncai State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China aut Climate Dynamics Springer Berlin Heidelberg 45/7-8(2015-10-01), 1859-1875 0930-7575 45:7-8<1859 2015 45 382 https://doi.org/10.1007/s00382-014-2439-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-014-2439-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Liu Boqi State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China aut NATIONALLICENCE 700 1- Wu Guoxiong State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China aut NATIONALLICENCE 700 1- Ren Roncai State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/7-8(2015-10-01), 1859-1875 0930-7575 45:7-8<1859 2015 45 382