Next-Day Convection-Allowing WRF Model Guidance: A Second Look at 2-km versus 4-km Grid SpacingSource: Monthly Weather Review:;2009:;volume( 137 ):;issue: 010::page 3351Author:Schwartz, Craig S.
,
Kain, John S.
,
Weiss, Steven J.
,
Xue, Ming
,
Bright, David R.
,
Kong, Fanyou
,
Thomas, Kevin W.
,
Levit, Jason J.
,
Coniglio, Michael C.
DOI: 10.1175/2009MWR2924.1Publisher: American Meteorological Society
Abstract: During the 2007 NOAA Hazardous Weather Testbed (HWT) Spring Experiment, the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma produced convection-allowing forecasts from a single deterministic 2-km model and a 10-member 4-km-resolution ensemble. In this study, the 2-km deterministic output was compared with forecasts from the 4-km ensemble control member. Other than the difference in horizontal resolution, the two sets of forecasts featured identical Advanced Research Weather Research and Forecasting model (ARW-WRF) configurations, including vertical resolution, forecast domain, initial and lateral boundary conditions, and physical parameterizations. Therefore, forecast disparities were attributed solely to differences in horizontal grid spacing. This study is a follow-up to similar work that was based on results from the 2005 Spring Experiment. Unlike the 2005 experiment, however, model configurations were more rigorously controlled in the present study, providing a more robust dataset and a cleaner isolation of the dependence on horizontal resolution. Additionally, in this study, the 2- and 4-km outputs were compared with 12-km forecasts from the North American Mesoscale (NAM) model. Model forecasts were analyzed using objective verification of mean hourly precipitation and visual comparison of individual events, primarily during the 21- to 33-h forecast period to examine the utility of the models as next-day guidance. On average, both the 2- and 4-km model forecasts showed substantial improvement over the 12-km NAM. However, although the 2-km forecasts produced more-detailed structures on the smallest resolvable scales, the patterns of convective initiation, evolution, and organization were remarkably similar to the 4-km output. Moreover, on average, metrics such as equitable threat score, frequency bias, and fractions skill score revealed no statistical improvement of the 2-km forecasts compared to the 4-km forecasts. These results, based on the 2007 dataset, corroborate previous findings, suggesting that decreasing horizontal grid spacing from 4 to 2 km provides little added value as next-day guidance for severe convective storm and heavy rain forecasters in the United States.
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contributor author | Schwartz, Craig S. | |
contributor author | Kain, John S. | |
contributor author | Weiss, Steven J. | |
contributor author | Xue, Ming | |
contributor author | Bright, David R. | |
contributor author | Kong, Fanyou | |
contributor author | Thomas, Kevin W. | |
contributor author | Levit, Jason J. | |
contributor author | Coniglio, Michael C. | |
date accessioned | 2017-06-09T16:32:08Z | |
date available | 2017-06-09T16:32:08Z | |
date copyright | 2009/10/01 | |
date issued | 2009 | |
identifier issn | 0027-0644 | |
identifier other | ams-69560.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4211242 | |
description abstract | During the 2007 NOAA Hazardous Weather Testbed (HWT) Spring Experiment, the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma produced convection-allowing forecasts from a single deterministic 2-km model and a 10-member 4-km-resolution ensemble. In this study, the 2-km deterministic output was compared with forecasts from the 4-km ensemble control member. Other than the difference in horizontal resolution, the two sets of forecasts featured identical Advanced Research Weather Research and Forecasting model (ARW-WRF) configurations, including vertical resolution, forecast domain, initial and lateral boundary conditions, and physical parameterizations. Therefore, forecast disparities were attributed solely to differences in horizontal grid spacing. This study is a follow-up to similar work that was based on results from the 2005 Spring Experiment. Unlike the 2005 experiment, however, model configurations were more rigorously controlled in the present study, providing a more robust dataset and a cleaner isolation of the dependence on horizontal resolution. Additionally, in this study, the 2- and 4-km outputs were compared with 12-km forecasts from the North American Mesoscale (NAM) model. Model forecasts were analyzed using objective verification of mean hourly precipitation and visual comparison of individual events, primarily during the 21- to 33-h forecast period to examine the utility of the models as next-day guidance. On average, both the 2- and 4-km model forecasts showed substantial improvement over the 12-km NAM. However, although the 2-km forecasts produced more-detailed structures on the smallest resolvable scales, the patterns of convective initiation, evolution, and organization were remarkably similar to the 4-km output. Moreover, on average, metrics such as equitable threat score, frequency bias, and fractions skill score revealed no statistical improvement of the 2-km forecasts compared to the 4-km forecasts. These results, based on the 2007 dataset, corroborate previous findings, suggesting that decreasing horizontal grid spacing from 4 to 2 km provides little added value as next-day guidance for severe convective storm and heavy rain forecasters in the United States. | |
publisher | American Meteorological Society | |
title | Next-Day Convection-Allowing WRF Model Guidance: A Second Look at 2-km versus 4-km Grid Spacing | |
type | Journal Paper | |
journal volume | 137 | |
journal issue | 10 | |
journal title | Monthly Weather Review | |
identifier doi | 10.1175/2009MWR2924.1 | |
journal fristpage | 3351 | |
journal lastpage | 3372 | |
tree | Monthly Weather Review:;2009:;volume( 137 ):;issue: 010 | |
contenttype | Fulltext |