Variability of the boundary-layer depth over certain regions of the subtropical ocean from 3 years of COSMIC data

Global Positioning System (GPS) Radio Occultation (RO) remote sensing

with its high vertical resolution and sensitivity to moisture gradients

is an efficient method for monitoring Atmospheric Boundary Layer (ABL)

depth, particularly over the ocean. In previous studies by different

authors the ABL top was determined mainly from vertical gradients of

scalars retrieved from the GPS RO signals, such as bending angle,

refractivity, moisture, etc. In this study we apply the approach

developed at the COSMIC Data Analysis and Archiving Center at UCAR

for analysis of the spatial and temporal variability of the ABL depth

over the subtropical oceanic regions west of the coasts of North America,

South America and South Africa. These regions are characterized by a

relatively shallow stratocumulus-topped ABL with a strong capping

inversion. This study is based on 3 years of COSMIC data, which allows

investigation of the variability on different time scales, from annual

to diurnal.