NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Validation of Satellite-Based Objective Overshooting Cloud-Top Detection Methods Using CloudSat Cloud Profiling Radar ObservationsTwo satellite infrared-based overshooting convective cloud-top (OT) detection methods have recently been described in the literature: 1) the 11-mm infrared window channel texture (IRW texture) method, which uses IRW channel brightness temperature (BT) spatial gradients and thresholds, and 2) the water vapor minus IRW BT difference (WV-IRW BTD). While both methods show good performance in published case study examples, it is important to quantitatively validate these methods relative to overshooting top events across the globe. Unfortunately, no overshooting top database currently exists that could be used in such study. This study examines National Aeronautics and Space Administration CloudSat Cloud Profiling Radar data to develop an OT detection validation database that is used to evaluate the IRW-texture and WV-IRW BTD OT detection methods. CloudSat data were manually examined over a 1.5-yr period to identify cases in which the cloud top penetrates above the tropopause height defined by a numerical weather prediction model and the surrounding cirrus anvil cloud top, producing 111 confirmed overshooting top events. When applied to Moderate Resolution Imaging Spectroradiometer (MODIS)-based Geostationary Operational Environmental Satellite-R Series (GOES-R) Advanced Baseline Imager proxy data, the IRW-texture (WV-IRW BTD) method offered a 76% (96%) probability of OT detection (POD) and 16% (81%) false-alarm ratio. Case study examples show that WV-IRW BTD.0 K identifies much of the deep convective cloud top, while the IRW-texture method focuses only on regions with a spatial scale near that of commonly observed OTs. The POD decreases by 20% when IRW-texture is applied to current geostationary imager data, highlighting the importance of imager spatial resolution for observing and detecting OT regions.
Document ID
20130000799
Acquisition Source
Langley Research Center
Document Type
Reprint (Version printed in journal)
Authors
Bedka, Kristopher M.
(Science Systems and Applications, Inc. Hampton, VA, United States)
Dworak, Richard
(Wisconsin Univ. Madison, WI, United States)
Brunner, Jason
(Wisconsin Univ. Madison, WI, United States)
Feltz, Wayne
(Wisconsin Univ. Madison, WI, United States)
Date Acquired
August 27, 2013
Publication Date
October 1, 2012
Publication Information
Publication: Journal of Applied Meteorology and Climatology
Volume: 51
Issue: 10
Subject Category
Meteorology And Climatology
Report/Patent Number
NF1676L-15626
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available