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Differences Between the HUT Snow Emission Model and MEMLS and Their Effects on Brightness Temperature SimulationMicrowave emission models are a critical component of snow water equivalent retrieval algorithms applied to passive microwave measurements. Several such emission models exist, but their differences need to be systematically compared. This paper compares the basic theories of two models: the multiple-layer HUT (Helsinki University of Technology) model and MEMLS (Microwave Emission Model of Layered Snowpacks). By comparing the mathematical formulation side-by-side, three major differences were identified: (1) by assuming the scattered intensity is mostly (96) in the forward direction, the HUT model simplifies the radiative transfer (RT) equation into 1-flux; whereas MEMLS uses a 2-flux theory; (2) the HUT scattering coefficient is much larger than MEMLS; (3 ) MEMLS considers the trapped radiation inside snow due to internal reflection by a 6-flux model, which is not included in HUT. Simulation experiments indicate that, the large scattering coefficient of the HUT model compensates for its large forward scattering ratio to some extent, but the effects of 1-flux simplification and the trapped radiation still result in different T(sub B) simulations between the HUT model and MEMLS. The models were compared with observations of natural snow cover at Sodankyl, Finland; Churchill, Canada; and Colorado, USA. No optimization of the snow grain size was performed. It shows that HUT model tends to under estimate T(sub B) for deep snow. MEMLS with the physically-based improved Born approximation performed best among the models, with a bias of -1.4 K, and an RMSE of 11.0 K.
Document ID
20170003726
Document Type
Reprint (Version printed in journal)
Authors
Pan, Jinmei
(Ohio State Univ. Columbus, OH, United States)
Durand, Michael
(Ohio State Univ. Columbus, OH, United States)
Sandells, Melody
(Reading Univ. United Kingdom)
Lemmetyinen, Juha
(Finnish Meteorological Inst. Sodankyla, Finland)
Kim, Edward J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Pulliainen, Jouni
(Finnish Meteorological Inst. Sodankyla, Finland)
Kontu, Anna
(Finnish Meteorological Inst. Sodankyla, Finland)
Derksen, Chris
(Environment Canada Toronto, Canada)
Date Acquired
April 20, 2017
Publication Date
November 10, 2015
Publication Information
Publication: IEEE Transactions on Geoscience and Remote Sensing
Volume: 54
Issue: 4
ISSN: 0196-2892
Subject Category
Geosciences (General)
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN41698
TGRS-2015-00132
Funding Number(s)
CONTRACT_GRANT: NNX13AB63G
Distribution Limits
Public
Copyright
Other
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