Modification of the atmospheric surface layer and upper ocean by synoptic disturbances in the east Pacific ITCZ

The tropical east Pacific ITCZ is a region with pronounced synoptic variability (3-5 day periods) in lower tropospheric winds. Low-level clouds form along the troughline of these disturbances, creating inverted V structures in visible satellite imagery. Mesoscale systems form within this chain of low-level clouds, with some of these systems appearing to spin off as hurricanes. The purpose of this study is to better understand the role of the upper ocean and atmospheric surface layer in coupling these synoptic disturbances to convection. We use spectral and cospectral techniques to quantify the magnitude of the synoptic variability in upper ocean and atmospheric surface layer quantities. The data used for this aspect of our study are provided by the TAO buoys along 95W enhanced for the East Pacific Investigation of Climate (EPIC) program from early 2001 to late 2003. Additional EPIC buoys deployed along 95W specifically for EPIC also provide data for this same time period. The synoptic activity at the moorings is placed in the context of the larger scale convective activity represented by GOES satellite outgoing longwave radiation (OLR) filtered for synoptic periods. We also explore possible feedbacks of the sea surface temperature and atmospheric stability on these disturbances. Boundary layer stability is provided by NCEP reanalyses, as well as by ship-board soundings available for the fall of 2001.