Preprints
https://doi.org/10.5194/acp-2021-345
https://doi.org/10.5194/acp-2021-345

  29 Apr 2021

29 Apr 2021

Review status: this preprint is currently under review for the journal ACP.

Water vapor anomaly over the tropical western Pacific in El Niño winters from radiosonde and satellite observations

Minkang Du1,2,3, Kaiming Huang1,2,3, Shaodong Zhang1,2, Chunming Huang1,2, Yun Gong1,2, and Fan Yi1,2,3 Minkang Du et al.
  • 1School of Electronic Information, Wuhan University, Wuhan, China
  • 2Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan, China
  • 3State Observatory for Atmospheric Remote Sensing, Wuhan, China

Abstract. Using radiosonde observations at five stations in the tropical western Pacific and reanalysis data for 15 years from 2005 to 2019, we report an extremely negative anomaly in atmospheric water vapor during the super El Niño winter of 2015/16, and compare the anomaly with that in the other three El Niño winters. Strong specific humidity anomaly is concentrated below 8 km of the troposphere with a peak at 2.5–3.5 km, and column integrated water vapor mass anomaly over the five radiosonde sites has a large negative correlation coefficient of −0.63 with oceanic Niño3.4 index, but with a lag of about 2–3 months. In general, the tropical circulation anomaly in the El Niño winter is characterized by divergence (convergence) in the lower troposphere over the tropical western (eastern) Pacific, thus the water vapor decreases over the tropical western Pacific as upward motion is suppressed. The variability of the Hadley circulation is quite small and has little influence on the observed water vapor anomaly. The anomaly of the Walker circulation makes a considerable contribution to the total anomaly in all the four El Niño winters, especially in the 2006/07 and 2015/16 eastern-Pacific (EP) El Niño events. The monsoon circulation shows a remarkable change from one to the other event, and its anomaly is large in the 2009/10 and 2018/19 central-Pacific (CP) El Niño winters and small in the two EP El Niño winters. The observed water vapor anomaly is caused mainly by the Walker circulation anomaly in the supper EP event of 2015/16 but by the monsoon circulation anomaly in the strong CP event of 2009/10. Owing to the anomalous decrease in upward transport of water vapor during the El Niño winter, less cloud amount and more outgoing longwave radiation over the five stations are clearly presented in satellite observation.

Minkang Du et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-345', Anonymous Referee #1, 27 May 2021
  • RC2: 'Comment on acp-2021-345', Anonymous Referee #2, 28 May 2021

Minkang Du et al.

Minkang Du et al.

Viewed

Total article views: 290 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
219 64 7 290 2 3
  • HTML: 219
  • PDF: 64
  • XML: 7
  • Total: 290
  • BibTeX: 2
  • EndNote: 3
Views and downloads (calculated since 29 Apr 2021)
Cumulative views and downloads (calculated since 29 Apr 2021)

Viewed (geographical distribution)

Total article views: 286 (including HTML, PDF, and XML) Thereof 286 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 29 Jul 2021
Download
Short summary
El Niño has an important influence on climate system. There is obviously negative water vapor anomaly from radiosonde observations in the tropical western Pacific during El Niño. The tropical Hadley, Walker and monsoon circulation variations are revealed to play different roles in the observed water vapor anomaly in different types of El Niños. The Walker (monsoon) circulation anomaly made a major contribution in the 2015/16 (2009/10) strong eastern-Pacific (central-Pacific) El Niño event.
Altmetrics