Title: Evaluating and Improving Scale–Awareness of a Convective Parameterization Closure Using Cloud–Resolving Model Simulations of Convection

Abstract

Abstract This study aims to evaluate a revised closure of the Zhang‐McFarlane (ZM) scheme for deep convection and to further improve its scale awareness. Output from two cloud‐resolving model (CRM) simulations of both midlatitude organized (MC3E) and tropical unorganized (TWP‐ICE) convection are used for the evaluation. By averaging the CRM output over different subdomain sizes from 64 to 4 km, convection‐associated fields are obtained to represent the fields at different horizontal resolutions of global climate models (GCMs). The convection parameterization closure is then tested using these fields. Results show that the cloud base mass flux M _b determined from the closure has a relatively good relationship with CRM‐simulated convection at coarse resolutions for both MC3E and TWP‐ICE, but their correlation degrades at higher resolutions, especially when approaching the gray zone scale under 10 km. The fluctuation of CAPE consumption rate per unit cloud base mass flux for different convective events is found to be an important factor affecting the correlation. When averaged over the base domain, the cloud base mass flux determined by the closure is found to increase with decreasing subdomain size, implying that the closure is not scale‐aware. To improve its scale‐awareness, a modified closure is designed tomore » alleviate the overprediction of convection at high GCM resolutions. Results show that the modified closure has the scale‐aware ability to suppress the overprediction problem at high GCM resolutions for both MC3E and TWP‐ICE.« less

Authors:

Wang, Xu  ^[1];

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Zhang, Guang J.  ^[1];

• Search DOE PAGES for author "Zhang, Guang J."
• Search DOE PAGES for ORCID "0000-0002-9712-5226"

Wang, Yong ^[2]

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+ Show Author Affiliations

1. Scripps Inst. of Oceanography, La Jolla, CA (United States)
2. Tsinghua Univ., Beijing (China)

Publication Date:

Tue Jan 11 00:00:00 EST 2022

Research Org.:

Univ. of California, San Diego, La Jolla, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1865244

Alternate Identifier(s):

OSTI ID: 1841301

Grant/Contract Number:  

SC0022064

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research: Atmospheres

Additional Journal Information:

Journal Volume: 127; Journal Issue: 2; Journal ID: ISSN 2169-897X

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; convection parameterization; scale-awareness; simulation of convection