Identification

Title

Effects of surface heat and moisture exchange on ARW-WRF warm-season precipitation forecasts over the central United States

Abstract

The evolution of the daytime planetary boundary layer (PBL) and its association with warm-season precipitation is strongly impacted by land-atmosphere heat and moisture exchange (hereafter surface exchange). However, substantial uncertainty exists in the parameterization of surface exchange in numerical weather prediction (NWP) models. In the current study, we examine 0-24-h convection-permitting forecasts with different surface exchange strengths for a six-day period during the International H₂O Project (IHOP_2002). Results indicate sensitivity in the timing of simulated afternoon convection initiation and subsequent precipitation amounts to variations in surface exchange strength. Convection initiation in simulations with weak surface exchange was delayed by 2-3 h compared to simulations with strong surface exchange, and area-averaged total precipitation amounts were less by up to a factor of two. Over the western high plains (105°-100°W longitude), where deep convection is locally generated, simulations using a formulation for surface exchange that varied with vegetation category (height) produced area-averaged diurnal cycles of forecasted precipitation amounts in better agreement with observations than simulations that used the current ARW-WRF formulation. Parcel theory is used to diagnose mechanisms by which differences in surface exchange influence convection initiation in individual case studies. The more rapid initiation in simulations with strong surface exchange results from a more rapid removal of negative buoyancy beneath the level of free convection, which arises primarily from greater PBL warming.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d74t6kng

codeSpace

Dataset language

eng

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code identifying the spatial reference system

Classification of spatial data and services

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geoscientificInformation

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Text

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title

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reference date

date type

publication

effective date

2016-01-01T00:00:00Z

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date type

publication

effective date

2011-02-01T00:00:00Z

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Copyright 2011 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

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