The vertical structure of the eastern Pacific ITCZs and associated circulation using the TRMM Precipitation Radar and in situ data

Abstract

The atmospheric circulation associated with the eastern Pacific single and double ITCZs, particularly its vertical structure, is little known due to the sparce observations. Using precipitation profiles from the Tropical Rainfall Measure Mission (TRMM) Precipitation Radar, with approximations to the liquid water and energy budget equations, we estimated vertical profiles of latent heating and vertical velocity in the far eastern Pacific (95°W–85°W) ITCZs in the 800–730 hPa layer. We combined this with Eastern Pacific Investigation of Climate campaign (EPIC2001) and other in situ data to produce a preliminary characterization of the meridional‐vertical circulation. We found evidence of a double‐cell structure in boreal fall between the ITCZ and the equator, with both shallow and upper level peaks in vertical velocity. In spring, the flow poleward of the two ITCZs has a single‐cell structure, although around the equator it shows some hints of the double cells. Reanalysis and satellite‐based data are shown to be unreliable for describing the vertical structure of the circulation.