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Title: Contributions to the implementation of the Arakawa-Schubert cumulus parameterization in the GLA GCM. [GCM (general circulation model)]

Abstract

Several integrations were made with a coarse version of the GLA GCM, which has the Arakawa-Schubert cumulus parameterization, predicted fractional cloud cover, and a parameterization of evaporation of falling rainfall. All model simulation experiments started from ECMWF analysis for 15 December 1982 and were integrated until 31 January 1983 using climatological boundary conditions. The first ten days of model integrations show that the model-simulated tropics dries and warms as a result of excessive precipitation. Three types of model development-cum-analysis studies were made with the cumulus scheme. First, the Critical Cloud Work Function (CCWF) dataset for different sigma layers were reworked using the Cloud Work Function (CWF) database of lord et al. as representative of time-average CWF and not the actual CCWF values as in the Arakawa-Schubert implementation of cumulus convection. The experiments with the new CCWF dataset helped to delineate influence of changing CCWF on model simulations. Larger values of CCWF partially alleviated the problem of excessive heating and drying during spinup and sharpened the tropical ITCZ (Intertropical Convergence Zone). Second, by comparing two simulations, one with and one without cumulus convection, the role of cumulus convection in maintaining observed tropical rainfall and 850 mb easterly winds is clarified. Third,more » relations between cloud radii and cumulus entrainment parameter, [lambda], realistic upper and lower bounds on [lambda] were obtained. This improvement had a great impact on the time evolution of tropical temperature and humidity simulation. It also suppressed excessive rainfall during spinup. Finally, by invoking [lambda][sub min] = 0.0002 m[sup [minus]1] (R[sub max] = 1.00 km) another simulation was made. In this simulation, not only the excessive initial rainfall was virtually eliminated, but a more realistic vertical distribution of specific humidity in the tropics was produced. 22 refs., 29 figs., 3 tabs.« less

Authors:
; ;  [1]
  1. NASA/Goddard Space Flight Center, Greenbelt, MD (United States)
Publication Date:
OSTI Identifier:
5572180
Resource Type:
Journal Article
Journal Name:
Journal of the Atmospheric Sciences; (United States)
Additional Journal Information:
Journal Volume: 48:13; Journal ID: ISSN 0022-4928
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ATMOSPHERIC CIRCULATION; COMPUTERIZED SIMULATION; CLOUDS; CONVECTION; GENERAL CIRCULATION MODELS; TROPICAL REGIONS; RAIN; METEOROLOGY; ATMOSPHERIC PRECIPITATIONS; ENERGY TRANSFER; HEAT TRANSFER; MASS TRANSFER; MATHEMATICAL MODELS; SIMULATION; 540110*

Citation Formats

Sud, Y C, Chao, W C, and Walker, G K. Contributions to the implementation of the Arakawa-Schubert cumulus parameterization in the GLA GCM. [GCM (general circulation model)]. United States: N. p., 1991. Web. doi:10.1175/1520-0469(1991)048<1573:CTTIOT>2.0.CO;2.
Sud, Y C, Chao, W C, & Walker, G K. Contributions to the implementation of the Arakawa-Schubert cumulus parameterization in the GLA GCM. [GCM (general circulation model)]. United States. https://doi.org/10.1175/1520-0469(1991)048<1573:CTTIOT>2.0.CO;2
Sud, Y C, Chao, W C, and Walker, G K. 1991. "Contributions to the implementation of the Arakawa-Schubert cumulus parameterization in the GLA GCM. [GCM (general circulation model)]". United States. https://doi.org/10.1175/1520-0469(1991)048<1573:CTTIOT>2.0.CO;2.
@article{osti_5572180,
title = {Contributions to the implementation of the Arakawa-Schubert cumulus parameterization in the GLA GCM. [GCM (general circulation model)]},
author = {Sud, Y C and Chao, W C and Walker, G K},
abstractNote = {Several integrations were made with a coarse version of the GLA GCM, which has the Arakawa-Schubert cumulus parameterization, predicted fractional cloud cover, and a parameterization of evaporation of falling rainfall. All model simulation experiments started from ECMWF analysis for 15 December 1982 and were integrated until 31 January 1983 using climatological boundary conditions. The first ten days of model integrations show that the model-simulated tropics dries and warms as a result of excessive precipitation. Three types of model development-cum-analysis studies were made with the cumulus scheme. First, the Critical Cloud Work Function (CCWF) dataset for different sigma layers were reworked using the Cloud Work Function (CWF) database of lord et al. as representative of time-average CWF and not the actual CCWF values as in the Arakawa-Schubert implementation of cumulus convection. The experiments with the new CCWF dataset helped to delineate influence of changing CCWF on model simulations. Larger values of CCWF partially alleviated the problem of excessive heating and drying during spinup and sharpened the tropical ITCZ (Intertropical Convergence Zone). Second, by comparing two simulations, one with and one without cumulus convection, the role of cumulus convection in maintaining observed tropical rainfall and 850 mb easterly winds is clarified. Third, relations between cloud radii and cumulus entrainment parameter, [lambda], realistic upper and lower bounds on [lambda] were obtained. This improvement had a great impact on the time evolution of tropical temperature and humidity simulation. It also suppressed excessive rainfall during spinup. Finally, by invoking [lambda][sub min] = 0.0002 m[sup [minus]1] (R[sub max] = 1.00 km) another simulation was made. In this simulation, not only the excessive initial rainfall was virtually eliminated, but a more realistic vertical distribution of specific humidity in the tropics was produced. 22 refs., 29 figs., 3 tabs.},
doi = {10.1175/1520-0469(1991)048<1573:CTTIOT>2.0.CO;2},
url = {https://www.osti.gov/biblio/5572180}, journal = {Journal of the Atmospheric Sciences; (United States)},
issn = {0022-4928},
number = ,
volume = 48:13,
place = {United States},
year = {Mon Jul 01 00:00:00 EDT 1991},
month = {Mon Jul 01 00:00:00 EDT 1991}
}