A cross-section of water vapor, convection, and circulation in the western Pacific
 

The light contours show water vapor mixing ratio (ppmv), derived from HALOE data.  The heavy
dashed line is the tropopause, the shading denotes coldest tropopause temperatures (near 100 mb),
and the vectors show the local mean meridional (Hadley) circulation (all derived from NCEP reanalyses).
The vectors are scaled to approximate displacements over a one day period.  The dark solid lines show
occurrence frequencies of  deep convective clouds at each level, derived from high resolution satellite
data (Gettelman et al., Distribution and effects of convection in the tropical tropopause region, in preparation).
The lines here denote frequencies of 0.5%, 1%, 3% and 10% (top to bottom).  All of these statistics
represent climatological structures in the Western Pacific region (averages over 120-180 E).

Note how the water vapor minimum above the tropopause is situated northward of the coldest
temperatures, in a sense consistent with the northward Hadley circulation in this region.