Chapter 15
Climate-Scale Oceanic Rainfall Based on Passive
Microwave Radiometry
Long S. Chiu, Si Gao, and Dong-Bin Shin
Abstract In the microwave regime, the relatively low and stable emissivity of the
sea surface serves as an excellent background over which brightly emitting
hydrometeors can be distinguished. Space/time oceanic rainfall has been estimated
from microwave radiometry using a simple radiative transfer model of an atmospheric rain column, a rain rate distribution to account for sampling deficiencies,
and an empirical correction of the nonuniformly filled field of view of the microwave sensor. The microwave emission-based brightness temperature histogram
(METH) technique has been applied to the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) to produce over 25 years
of monthly oceanic rainfall. The METH technique is described and the retrieved
parameters are assessed. The inter-satellite calibration of microwave and DMSP
SSM/I sensors provided a climate-scale oceanic rainfall time series capable of
examining climate trends and variabilities.
Keywords Microwave radiometry • SSM/I • Oceanic rainfall • Rain frequency •
Mixed lognormal distribution • Inter-satellite calibration • Climate trend
15.1 Introduction
Accurate measurements of global rainfall are crucial for advancing our understanding of the climate system such as the water and energy cycles. The lack of global
gauge networks, especially over the ocean, in mountainous terrains, or in remote
L.S. Chiu (*) • S. Gao
Department of Atmospheric, Oceanic and Atmospheric Sciences, College of Science,
George Mason University, Fairfax, VA 22030, USA
e-mail: lchiu@gmu.edu; sgao2@gmu.edu
D.-B. Shin
Department of Atmospheric Science, Yonsei University, Seoul, South Korea
e-mail: dbshin@yonsei.ac.kr
J.J. Qu et al. (eds.), Satellite-based Applications on Climate Change,
DOI 10.1007/978-94-007-5872-8_15, # Springer Science+Business Media Dordrecht 2013
225
Climate-Scale Oceanic Rainfall Based on Passive
Microwave Radiometry
Long S. Chiu, Si Gao, and Dong-Bin Shin
Abstract In the microwave regime, the relatively low and stable emissivity of the
sea surface serves as an excellent background over which brightly emitting
hydrometeors can be distinguished. Space/time oceanic rainfall has been estimated
from microwave radiometry using a simple radiative transfer model of an atmospheric rain column, a rain rate distribution to account for sampling deficiencies,
and an empirical correction of the nonuniformly filled field of view of the microwave sensor. The microwave emission-based brightness temperature histogram
(METH) technique has been applied to the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) to produce over 25 years
of monthly oceanic rainfall. The METH technique is described and the retrieved
parameters are assessed. The inter-satellite calibration of microwave and DMSP
SSM/I sensors provided a climate-scale oceanic rainfall time series capable of
examining climate trends and variabilities.
Keywords Microwave radiometry • SSM/I • Oceanic rainfall • Rain frequency •
Mixed lognormal distribution • Inter-satellite calibration • Climate trend
15.1 Introduction
Accurate measurements of global rainfall are crucial for advancing our understanding of the climate system such as the water and energy cycles. The lack of global
gauge networks, especially over the ocean, in mountainous terrains, or in remote
L.S. Chiu (*) • S. Gao
Department of Atmospheric, Oceanic and Atmospheric Sciences, College of Science,
George Mason University, Fairfax, VA 22030, USA
e-mail: lchiu@gmu.edu; sgao2@gmu.edu
D.-B. Shin
Department of Atmospheric Science, Yonsei University, Seoul, South Korea
e-mail: dbshin@yonsei.ac.kr
J.J. Qu et al. (eds.), Satellite-based Applications on Climate Change,
DOI 10.1007/978-94-007-5872-8_15, # Springer Science+Business Media Dordrecht 2013
225