Simulations ofregional, extreme monthly precipitation by the NARCCAP RCMs

Authors:

W. J. Gutowski, Jr., Iowa State University, Linda O. Mearns, NCAR,

Ray Arritt; Iowa State, Sebastien Biner, OURANOS, Daniel Caya, OURANOS; David Flory, Iowa State, Richard Jones, Hadley Centre, Rene Laprise, UQAM; Ruby Leung, PNNL; Wilfran Moufouma-Okia, Hadley Centre,Ana Nunez, Scripps, Yun Qian, PNNL, John Roads, Scripps; Lisa Sloan, UC Santa Cruz; Mark Snyder, UCSC, Gene Takle, Iowa State

We analyze the ability of the NARCCAP ensemble of regional climate models (RCMs) to simulate extreme monthly precipitation and its supporting circulation for regions of North America, comparing18 years of simulations driven by the NCEP-DOE reanalysis with observations. Analysis focuses the wettest 10% of months during the cold half of the year (October-March), when we assume that synoptic circulation governs precipitation. For a coastal California region where the precipitation is largely topographic, the models individually and collectively replicate well the months of greatest extremes, the amount of extreme precipitation and the 500 hPa circulation anomaly associated with the extremes. The simulated top 10% wettest months average less than 3% more precipitation than the observed wettest 10%. The models also replicate very well the statistics of the interannual variability of occurrences of extremes: 98% of all simulated monthly extremes among the models occur in a year with an observed extreme. For an interior region containing the Upper Mississippi River Basin, where precipitation is more dependent on internally generated storms, the models still show agreement with observations, though not as closely. Circulation anomalies for extreme months are roughly similar in the models and observations, and the simulated top 10% wettest months average about 5% less precipitation than observed wettest 10%. The models also replicate fairly well for this region the interannual variability of extreme monthly precipitation: 80% of all simulated monthly extremes among the models occur in a year with an observed extreme.

Abstract Text Entered.

Simulations of regional, extreme monthly precipitation by the NARCCAP RCMs

William J. Gutowski Jr., Iowa State University, Ames, IA; and L. O. Mearns, R. Arritt, S. Biner, D. Caya, D. Flory, R. Jones, R. Laprise, R. Leung, W. Moufouma-Okia, A. Nunez, Y. Qian, J. Roads, L. Sloan, M. Snyder, and G. Takle

We analyze the ability of the NARCCAP ensemble of regional climate models (RCMs) to simulate extreme monthly precipitation and its supporting circulation for regions of North America, comparing 18 years of simulations driven by the NCEP-DOE reanalysis with observations. Analysis focuses the wettest 10% of months during the cold half of the year (October-March), when we assume that synoptic circulation governs precipitation. For a coastal California region where the precipitation is largely topographic, the models individually and collectively replicate well the months of greatest extremes, the amount of extreme precipitation and the 500 hPa circulation anomaly associated with the extremes. The simulated top 10% wettest months average less than 3% more precipitation than the observed wettest 10%. The models also replicate very well the statistics of the interannual variability of occurrences of extremes: 98% of all simulated monthly extremes among the models occur in a year with an observed extreme. For an interior region containing the Upper Mississippi River Basin, where precipitation is more dependent on internally generated storms, the models still show agreement with observations, though not as closely. Circulation anomalies for extreme months are roughly similar in the models and observations, and the simulated top 10% wettest months average about 5% less precipitation than observed wettest 10%. The models also replicate fairly well for this region the interannual variability of extreme monthly precipitation: 80% of all simulated monthly extremes among the models occur in a year with an observed extreme.

Abstract ID#: 146023

Password: 836540

Program Selection: 21st Conference on Climate Variability and Change

Topic Selection: Regional climate modeling, especially with urban applications

Title: Simulations of regional, extreme monthly precipitation by the NARCCAP RCMs

Comments to Organizer: This presentation is intended to be part of the NARCCAP session.

Presentation Format: Oral

Withdraw if not accepted for preferred format: N

Paper Submitted by a Student: N

Paper Entered in Competition, if Appropriate: Y

First Author

Presenting

William J. Gutowski, Jr.

Department of Geological and Atmospheric Sci.

Iowa State University

3010 Agronomy

Iowa State University

Ames, IA 50011

Phone Number: 1-515-294-5632

Fax Number: 1-515-294-2619

Email:

* AMS Member

* Membership Number 011441

Second Author

Linda O. Mearns

IMAGe

NCAR

P.O. Box 3000

Boulder, CO 80307-3000

Phone Number: 303-497-8139

Email:

Third Author

Ray Arritt

Agronomy

Iowa State University

3010 Agronomy

Iowa State University

Ames, IA 50011

Fourth Author

Sébastien Biner

OURANOS

Fifth Author

D. Caya

Ouranos Consortium/Université du Québec à Montréal

Montreal, QB

Canada

Sixth Author

David Flory

Geological & Atmospheric Sciences

Iowa State University

3010 Agronomy

Iowa State University

Ames, IA 50011

Seventh Author

Richard Jones

Hadley Centre

Eighth Author

R. Laprise

Université du Québec à Montréal

Montreal, QB

Canada

Ninth Author

Ruby Leung

Climate Physics group

PNNL

P.O. Box 999

Richland, WA 99352

Phone Number: 509-372-6463

Email:

Tenth Author

Wilfran Moufouma-Okia

Hadley Centre

Eleventh Author

Ana Nunez

SIO/Univ. Of California

Twelfth Author

Yun Qian

Department of Atmospheric Science and Global Change

PNNL

P.O. Box 999

Richland, WA 99352

Phone Number: 509-372-6182

Fax Number: 509-372-6168

Email:

Thirteenth Author

John Roads

Scripps of institution of oceanography

SIO/Univ. Of California

9500 Gilman La Jolla, CA

California, CA 92037

Phone Number: 534-4507

Email:

Fourteenth Author

Lisa Sloan

University of California/Santa Cruz

Fifteenth Author

Mark Snyder

University of California/Santa Cruz

Sixteenth Author

Gene Takle

Geological & Atmospheric Sciences

Iowa State University

3010 Agronomy

Iowa State University

Ames, IA 50011 Next step: