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Title: Cloud transitions: comparison of temporal variation in the southeastern Pacific with the spatial variation in the northeastern Pacific at low latitudes

The seasonal variation of clouds in the southeastern equatorial Pacific (SEP) is analysed and compared with the spatial variation of clouds in the northeastern Pacific along the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/WGNE) Pacific Cross-Section Intercomparison (GPCI) transect. A ‘seasonal cloud transition’ – from stratocumulus to shallow cumulus and eventually to deep convection – is found in the SEP from September to April, which is similar to the spatial cloud transition along the GPCI transect from the California coast to the equator. It is shown that this seasonal cloud transition in the SEP is associated with increasing sea surface temperature (SST), decreasing lower tropospheric stability and large-scale subsidence, which are all similar to the spatial variation of these fields along the GPCI transect. There was a difference found such that the SEP cloud transition is associated with decreasing surface wind speed and surface latent heat flux, weaker larger-scale upward motion and convective instability, which lead to less deepening of the low clouds and less frequent deep convection than those in the GPCI transect. Finally, the seasonal cloud transition in the SEP provides a test for climate models to simulate the relationships betweenmore » clouds and large-scale atmospheric fields in a region that features a spurious double inter-tropical convergence zone (ITCZ) in most models.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [4]
  1. Stony Brook Univ., NY (United States). School of Marine and Atmospheric Sciences
  2. Stony Brook Univ., NY (United States). School of Marine and Atmospheric Sciences; Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Atmospheric Physics (IAP)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Atmospheric Physics (IAP); Univ. of Chinese Academy of Sciences, Beijing (China). College of Earth Science
Publication Date:
Report Number(s):
BNL-114209-2017-JA
Journal ID: ISSN 0899-8418
Grant/Contract Number:
SC0012704
Type:
Published Article
Journal Name:
International Journal of Climatology
Additional Journal Information:
Journal Volume: 37; Journal Issue: 6; Journal ID: ISSN 0899-8418
Publisher:
Royal Meteorological Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; cloud transition; GPCI; southeastern equatorial Pacific; marine boundary layer; deep convection
OSTI Identifier:
1328966
Alternate Identifier(s):
OSTI ID: 1328967; OSTI ID: 1392222