combining glm and abi data for enhanced goes-r rainfall estimates
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Combining GLM and ABI Data for Enhanced GOES-R Rainfall Estimates Robert F. Adler, Weixin Xu, and Nai-Yu Wang CICS, University of Maryland, College Park, MD. Email: [email protected]. Combining Infrared and Lightning Information for Rainfall Estimates (Applied to TRMM data) . - PowerPoint PPT PresentationTRANSCRIPT
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Combining GLM and ABI Data for Enhanced GOES-R Rainfall EstimatesRobert F. Adler, Weixin Xu, and Nai-Yu Wang
CICS, University of Maryland, College Park, MD. Email: [email protected]
This study uses TRMM data to develop the basis and eventually the
algorithms to combine GOES-R ABI Infrared (IR), Geostationary
Lightning Mapper (GLM) data to provide an improved geosynchronous
rainfall product. A simple IR-lightning rainfall algorithm is developed
through coupling lightning measurements into the Convective/Stratiform
(C/S) technique (CST) proposed by Adler and Negri (1988). Preliminary results show that CST is improved by more than 30% in retrieving convective (or heavy) rainfall after lightning observations are coupled. Specifically, lightning information can aid in identifying convective cores missed by the IR-only technique (improving detection), eliminate misidentified convective cores (lowering false alarms), and more correctly assign heavy convective rainfall rates.
Combining Infrared and Lightning Information for Rainfall Estimates (Applied to TRMM data)
2. IR-based C/S Technique (CST)
3. Lightning-enhanced CST (CSTL)
4. Evaluation on CST and CSTL Estimates
B. Estimates on Instantaneous Rainrate
C. Comparison with SCaMPR (GOES)
1. Introduction
a. Conv. cores w/o lightning in mature systems are removed; b. Conv. areas (with flashes) missed by CST are added;c. Rain rates are derived from both IR and lightning density;
CST algorithm tuned from Adler and Negri (1988)a. Conv. core defined by local Tb minima that pass slope test;b. Conv. core area is an empirical function of Tb minima.
CST ( and most IR techniques) does a GOOD job in catching young convective cells.
CST ( and most IR techniques) becomes VAGUE as mesoscale convective systems mature (too many convective cores).
Lightning is very
valuable in helping
IR technique to
correctly identify
heavy rainfall.
PWM RR Radar RR
IR+L RRSCaMPR RR
CST C/SRadar C/S
TMI C/S (10mm/hr) CST C/S
IR Tb
IR Tb + lightning
CST RR CST + L RR
PR RRTMI RR
Dependent data (used to train the algorithm):2002-2004, May-AugustIndependent data: 2005-2008, May-AugustBoth datasets include only storms > 5 flashes per minute
A. Estimates on Convective Rain
20 km res.
May 2007
100 cases(> 5 flash/min)
CST
PR
CST
TMI
CSTL
PR
TMI
POD
FAR CSI
CSTL
Correlation Coefficient (CC)
BIAS &RMSE
20 km res.May-Aug 2002-20083500 cases(> 5 flash/min)