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Title: The Role of Convective Gustiness in Reducing Seasonal Precipitation Biases in the Tropical West Pacific

Abstract

Precipitation is an important climate quantity that is critically relevant to society. In spite of intense efforts, significant precipitation biases remain in most climate models. One pervasive and persistent bias found in many general circulation models occurs in the Tropical West Pacific where northern hemisphere summer-time precipitation is often underestimated compared to observations. Using the DOE-E3SM model, the inclusion of a missing process, convective gustiness, is shown to reduce those biases through a net increase in surface evaporation. Gustiness in surface wind fields is assumed to arise empirically in proportion to the intensity of convective precipitation. The increased evaporation can be treated as an increase in the moist static energy forcing into the atmosphere. A Normalized Gross Moist Stability (NGMS) framework (which characterizes the relationship between convective forcing and convective response) is used to explore the processes responsible for the precipitation bias, and the impact of the gustiness parameterization in reducing that bias. Because the NGMS of the Tropical West Pacific is less than unity in the E3SMv1 model, the increase in energy forcing amplifies the increase in precipitation to exceed that of the evaporative flux. Convective gustiness favors increased precipitation in regions where the resolved surface winds are weakmore » and convection is present.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2];  [2]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. National Center for Atmospheric Research, Boulder, CO (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1432724
Alternate Identifier(s):
OSTI ID: 1432727; OSTI ID: 1438988
Report Number(s):
PNNL-SA-128772
Journal ID: ISSN 1942-2466; KP1703020
Grant/Contract Number:
AC05-76RL01830; AC02-05CH11231
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 10; Journal Issue: 4; Journal ID: ISSN 1942-2466
Publisher:
American Geophysical Union (AGU)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; precipitation; convective; tropical; circulation; model; rainfall

Citation Formats

Harrop, Bryce E., Ma, Po -Lun, Rasch, Philip J., Neale, Richard B., and Hannay, Cecile. The Role of Convective Gustiness in Reducing Seasonal Precipitation Biases in the Tropical West Pacific. United States: N. p., 2018. Web. doi:10.1002/2017MS001157.
Harrop, Bryce E., Ma, Po -Lun, Rasch, Philip J., Neale, Richard B., & Hannay, Cecile. The Role of Convective Gustiness in Reducing Seasonal Precipitation Biases in the Tropical West Pacific. United States. doi:10.1002/2017MS001157.
Harrop, Bryce E., Ma, Po -Lun, Rasch, Philip J., Neale, Richard B., and Hannay, Cecile. Mon . "The Role of Convective Gustiness in Reducing Seasonal Precipitation Biases in the Tropical West Pacific". United States. doi:10.1002/2017MS001157.
@article{osti_1432724,
title = {The Role of Convective Gustiness in Reducing Seasonal Precipitation Biases in the Tropical West Pacific},
author = {Harrop, Bryce E. and Ma, Po -Lun and Rasch, Philip J. and Neale, Richard B. and Hannay, Cecile},
abstractNote = {Precipitation is an important climate quantity that is critically relevant to society. In spite of intense efforts, significant precipitation biases remain in most climate models. One pervasive and persistent bias found in many general circulation models occurs in the Tropical West Pacific where northern hemisphere summer-time precipitation is often underestimated compared to observations. Using the DOE-E3SM model, the inclusion of a missing process, convective gustiness, is shown to reduce those biases through a net increase in surface evaporation. Gustiness in surface wind fields is assumed to arise empirically in proportion to the intensity of convective precipitation. The increased evaporation can be treated as an increase in the moist static energy forcing into the atmosphere. A Normalized Gross Moist Stability (NGMS) framework (which characterizes the relationship between convective forcing and convective response) is used to explore the processes responsible for the precipitation bias, and the impact of the gustiness parameterization in reducing that bias. Because the NGMS of the Tropical West Pacific is less than unity in the E3SMv1 model, the increase in energy forcing amplifies the increase in precipitation to exceed that of the evaporative flux. Convective gustiness favors increased precipitation in regions where the resolved surface winds are weak and convection is present.},
doi = {10.1002/2017MS001157},
journal = {Journal of Advances in Modeling Earth Systems},
number = 4,
volume = 10,
place = {United States},
year = {Mon Mar 12 00:00:00 EDT 2018},
month = {Mon Mar 12 00:00:00 EDT 2018}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1002/2017MS001157

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