Brittany is a senior studying Environmental Engineering at Colorado State
University. She spent her summer with us working with Professor Thomas Vonder
Haar and mentors John Forsythe and Janice Bytheway analyzing precipitable
The NASA Water Vapor Project (NVAP) has been creating a daily water vapor
dataset spanning 1987-2010. One device used to collect the total precipitable
water (TPW) data is the Special Sensor Microwave/Imager (SSM/I). The SSM/I is
most accurate when collecting TPW data over oceans. Land contamination is a
large source of error when using SSM/I, so a landmask is used to run data
through to filter the land out. Therefore, it is critical to test the accuracy
of the SSM/I.
Global Positioning System (GPS) is being used to interpret the more globally
available SSM/I satellites. Data from three SSM/I satellites (F13, F14, and F15)
and GPS receivers from January 2003 were used in this analysis. The SSM/I data
was matched to GPS stations based on location and the time the data was
collected. This ensured that the TPW data being compared was from the same time
The GPS TPW was plotted against the SSM/I TPW to analyze the accuracy of the
SSM/I readings. Then GPS island stations were isolated with a landmask and used
as the source of SSM/I comparison as well.
The relationship between the GPS and SSM/I data was found to be linear with some
scatter. SSM/I F15 has a greater problem with scatter and most of those problem
stations were found to be in Japan. There is still error involved with SSM/I
water vapor data. A better understanding of water vapor will help with creating
more accurate hydrological, weather and climate models in the future.
Brittany's summer research poster,
Comparing and Analyzing Total Precipitable Water from Ground-Based GPS and SSM/I Satellite Remote Sensing, may be downloaded here (5MB).
Brittany's research interests include severe storms, mesoscale meteorology and
remote sensing. She enjoys drawing, reading fiction, gardening and hiking.