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Sara Q. Zhang
,
Milija Zupanski
,
Arthur Y. Hou
,
Xin Lin
, and
Samson H. Cheung

Abstract

Assimilation of remotely sensed precipitation observations into numerical weather prediction models can improve precipitation forecasts and extend prediction capabilities in hydrological applications. This paper presents a new regional ensemble data assimilation system that assimilates precipitation-affected microwave radiances into the Weather Research and Forecasting Model (WRF). To meet the challenges in satellite data assimilation involving cloud and precipitation processes, hydrometeors produced by the cloud-resolving model are included as control variables and ensemble forecasts are used to estimate flow-dependent background error covariance. Two assimilation experiments have been conducted using precipitation-affected radiances from passive microwave sensors: one for a tropical storm after landfall and the other for a heavy rain event in the southeastern United States. The experiments examined the propagation of information in observed radiances via flow-dependent background error auto- and cross covariance, as well as the error statistics of observational radiance. The results show that ensemble assimilation of precipitation-affected radiances improves the quality of precipitation analyses in terms of spatial distribution and intensity in accumulated surface rainfall, as verified by independent ground-based precipitation observations.

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Dusanka Zupanski
,
Sara Q. Zhang
,
Milija Zupanski
,
Arthur Y. Hou
, and
Samson H. Cheung

Abstract

In the near future, the Global Precipitation Measurement (GPM) mission will provide precipitation observations with unprecedented accuracy and spatial/temporal coverage of the globe. For hydrological applications, the satellite observations need to be downscaled to the required finer-resolution precipitation fields. This paper explores a dynamic downscaling method using ensemble data assimilation techniques and cloud-resolving models. A prototype ensemble data assimilation system using the Weather Research and Forecasting Model (WRF) has been developed. A high-resolution regional WRF with multiple nesting grids is used to provide the first-guess and ensemble forecasts. An ensemble assimilation algorithm based on the maximum likelihood ensemble filter (MLEF) is used to perform the analysis. The forward observation operators from NOAA–NCEP’s gridpoint statistical interpolation (GSI) are incorporated for using NOAA–NCEP operational datastream, including conventional data and clear-sky satellite observations. Precipitation observation operators are developed with a combination of the cloud-resolving physics from NASA Goddard cumulus ensemble (GCE) model and the radiance transfer schemes from NASA Satellite Data Simulation Unit (SDSU). The prototype of the system is used as a test bed to optimally combine observations and model information to produce a dynamically downscaled precipitation analysis. A case study on Tropical Storm Erin (2007) is presented to investigate the ability of the prototype of the WRF Ensemble Data Assimilation System (WRF-EDAS) to ingest information from in situ and satellite observations including precipitation-affected radiance. The results show that the analyses and forecasts produced by the WRF-EDAS system are comparable to or better than those obtained with the WRF-GSI analysis scheme using the same set of observations. An experiment was also performed to examine how the analyses and short-term forecasts of microphysical variables and dynamical fields are influenced by the assimilation of precipitation-affected radiances. The results highlight critical issues to be addressed in the next stage of development such as model-predicted hydrometeor control variables and associated background error covariance, bias estimation, and correction in radiance space, as well as the observation error statistics. While further work is needed to optimize the performance of WRF-EDAS, this study establishes the viability of developing a cloud-scale ensemble data assimilation system that has the potential to provide a useful vehicle for downscaling satellite precipitation information to finer scales suitable for hydrological applications.

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Peter Bissolli
,
Catherine Ganter
,
Tim Li
,
Ademe Mekonnen
,
Ahira Sánchez-Lugo
,
Eric J. Alfaro
,
Lincoln M. Alves
,
Jorge A. Amador
,
B. Andrade
,
Francisco Argeñalso
,
P. Asgarzadeh
,
Julian Baez
,
Reuben Barakiza
,
M. Yu. Bardin
,
Mikhail Bardin
,
Oliver Bochníček
,
Brandon Bukunt
,
Blanca Calderón
,
Jayaka D. Campbell
,
Elise Chandler
,
Ladislaus Chang’a
,
Vincent Y. S. Cheng
,
Leonardo A. Clarke
,
Kris Correa
,
Catalina Cortés
,
Felipe Costa
,
A.P.M.A. Cunha
,
Mesut Demircan
,
K. R. Dhurmea
,
A. Diawara
,
Sarah Diouf
,
Dashkhuu Dulamsuren
,
M. ElKharrim
,
Jhan-Carlo Espinoza
,
A. Fazl-Kazem
,
Chris Fenimore
,
Steven Fuhrman
,
Karin Gleason
,
Charles “Chip” P. Guard
,
Samson Hagos
,
Mizuki Hanafusa
,
H. R. Hasannezhad
,
Richard R. Heim Jr.
,
Hugo G. Hidalgo
,
J. A. Ijampy
,
Gyo Soon Im
,
Annie C. Joseph
,
G. Jumaux
,
K. R. Kabidi
,
P-H. Kamsu-Tamo
,
John Kennedy
,
Valentina Khan
,
Mai Van Khiem
,
Philemon King’uza
,
Natalia N. Korshunova
,
A. C. Kruger
,
Hoang Phuc Lam
,
Mark A. Lander
,
Waldo Lavado-Casimiro
,
Tsz-Cheung Lee
,
Kinson H. Y. Leung
,
Gregor Macara
,
Jostein Mamen
,
José A. Marengo
,
Charlotte McBride
,
Noelia Misevicius
,
Aurel Moise
,
Jorge Molina-Carpio
,
Natali Mora
,
Awatif E. Mostafa
,
Habiba Mtongori
,
Charles Mutai
,
O. Ndiaye
,
Juan José Nieto
,
Latifa Nyembo
,
Patricia Nying’uro
,
Xiao Pan
,
Reynaldo Pascual Ramírez
,
David Phillips
,
Brad Pugh
,
Madhavan Rajeevan
,
M. L. Rakotonirina
,
Andrea M. Ramos
,
M. Robjhon
,
Camino Rodriguez
,
Guisado Rodriguez
,
Josyane Ronchail
,
Benjamin Rösner
,
Roberto Salinas
,
Hirotaka Sato
,
Hitoshi Sato
,
Amal Sayouri
,
Joseph Sebaziga
,
Serhat Sensoy
,
Sandra Spillane
,
Katja Trachte
,
Gerard van der Schrier
,
F. Sima
,
Adam Smith
,
Jacqueline M. Spence
,
O. P. Sreejith
,
A. K. Srivastava
,
José L. Stella
,
Kimberly A. Stephenson
,
Tannecia S. Stephenson
,
S. Supari
,
Sahar Tajbakhsh-Mosalman
,
Gerard Tamar
,
Michael A. Taylor
,
Asaminew Teshome
,
Wassila M. Thiaw
,
Skie Tobin
,
Adrian R. Trotman
,
Cedric J. Van Meerbeeck
,
A. Vazifeh
,
Shunya Wakamatsu
,
Wei Wang
,
Fei Xin
,
F. Zeng
,
Peiqun Zhang
, and
Zhiwei Zhu
Free access
Peter Bissolli
,
Catherine Ganter
,
Ademe Mekonnen
,
Ahira Sánchez-Lugo
,
Zhiwei Zhu
,
A. Abida
,
W. Agyakwah
,
Laura S. Aldeco
,
Eric J. Alfaro
,
Teddy Allen
,
Lincoln M. Alves
,
Jorge A. Amador
,
B. Andrade
,
P. Asgarzadeh
,
Grinia Avalos
,
Julian Baez
,
M. Yu. Bardin
,
E. Bekele
,
Renato Bertalanic
,
Oliver Bochníček
,
Brandon Bukunt
,
Blanca Calderón
,
Jayaka D. Campbell
,
Elise Chandler
,
Candice S Charlton
,
Vincent Y. S. Cheng
,
Leonardo A. Clarke
,
Kris Correa
,
Catalina R. Cortés Salazar
,
Felipe Costa
,
Lenka Crhová
,
Ana Paula Cunha
,
Mesut Demircan
,
K. R. Dhurmea
,
Diana A. Domínguez
,
Dashkhuu Dulamsuren
,
M. ElKharrim
,
Jhan-Carlo Espinoza
,
A. Fazl-Kezemi
,
Nava Fedaeff
,
Chris Fenimore
,
Steven Fuhrman
,
Karin Gleason
,
Charles “Chip” P. Guard
,
Samson Hagos
,
Mizuki Hanafusa
,
Richard R. Heim Jr.
,
John Kennedy
,
Sverker Hellström
,
Hugo G. Hidalgo
,
I. A. Ijampy
,
Gyo Soon Im
,
G. Jumaux
,
K. Kabidi
,
Kenneth Kerr
,
Yelena Khalatyan
,
Valentina Khan
,
Mai Van Khiem
,
Tobias Koch
,
Gerbrand Koren
,
Natalia N. Korshunova
,
A. C. Kruger
,
Mónika Lakatos
,
Jostein Mamen
,
Hoang Phuc Lam
,
Mark A. Lander
,
Waldo Lavado-Casimiro
,
Tsz-Cheung Lee
,
Kinson H. Y. Leung
,
Xuefeng Liu
,
Rui Lu
,
José A. Marengo
,
Mohammadi Marjan
,
Ana E. Martínez
,
Charlotte McBride
,
Mirek Mietus
,
Noelia Misevicius
,
Aurel Moise
,
Jorge Molina-Carpio
,
Natali Mora
,
Awatif E. Mostafa
,
O. Ndiaye
,
Juan J. Nieto
,
Kristin Olafsdottir
,
Reynaldo Pascual Ramírez
,
David Phillips
,
Amos Porat
,
Esteban Rodriguez Guisado
,
Madhavan Rajeevan
,
Andrea M. Ramos
,
Cristina Recalde Coronel
,
Alejandra J. Reyes Kohler
,
M. Robjhon
,
Josyane Ronchail
,
Roberto Salinas
,
Hirotaka Sato
,
Hitoshi Sato
,
Amal Sayouri
,
Serhat Sensoy
,
Amsari Mudzakir Setiawan
,
F. Sima
,
Adam Smith
,
Matthieu Sorel
,
Sandra Spillane
,
Jacqueline M. Spence
,
O. P. Sreejith
,
A. K. Srivastava
,
Tannecia S. Stephenson
,
Kiyotoshi Takahashi
,
Michael A. Taylor
,
Wassila M. Thiaw
,
Skie Tobin
,
Lidia Trescilo
,
Adrian R. Trotman
,
Cedric J. Van Meerbeeck
,
A. Vazifeh
,
Shunya Wakamatsu
,
M. F. Zaheer
,
F. Zeng
, and
Peiqun Zhang
Free access