An Improved Convective Ice Parameterization for the NASA GISS Global Climate Model and Impacts on Cloud Ice Simulation

January 2017
Journal of Climate;Jan2017, Vol. 30 Issue 1, p317
Academic Journal
Partitioning of convective ice into precipitating and detrained condensate presents a challenge for GCMs since partitioning depends on the strength and microphysics of the convective updraft. It is an important issue because detrainment of ice from updrafts influences the development of stratiform anvils, impacts radiation, and can affect GCM climate sensitivity. Recent studies have shown that the CM1P5 configurations of the Goddard Institute for Space Studies (GISS) GCM simulated upper-tropospheric ice water content (IWC) that exceeded an estimated upper bound by a factor of 2. Partly in response to this bias, a new GCM parameterization of convective cloud ice has been developed that incorporates new ice particle fall speeds and convective outflow particle size distributions (PSDs) from the NASA African Monsoon Multidisciplinary Analyses (NAMMA), NASA Tropical Composition Cloud and Climate Coupling (TC4), DOE ARM-NASA Midlatitude Continental Convective Clouds Experiment (MC3E), and DOE ARM Small Particles in Cirrus (SPARTICUS) field campaigns The new parameterization assumes a normalized gamma PSD with two novel developments: no explicit assumption for particle habit in the calculation of mass distributions, and a formulation for translating ice particle fall speeds as a function of maximum diameter intofall speeds as a function of melted-equivalent diameter. Two parameters (particle volume- and projected area-weighted equivalent diameter) are diagnosed as a function of temperature and IWC in the convective plume, and these parameters constrain the shape and scale of the normalized gamma PSD. The diagnosed fall speeds and PSDs are combined with the GCM's parameterized convective updraft vertical velocity to partition convective updraft condensate into precipitating and detrained components. A 5-yr prescribed sea surface temperature GCM simulation shows a 30%-50% decrease in upper-tropospheric deep convective IWC, bringing the tropical and global mean ice water path into closer agreement with CloudSat best estimates.


Related Articles

  • Long-Lived Mesoscale Systems in a Low-Convective Inhibition Environment. Part II: Downshear Propagation. Moncrieff, Mitchell W.; Lane, Todd P. // Journal of the Atmospheric Sciences;Nov2015, Vol. 72 Issue 11, p4319 

    Part II of this study of long-lived convective systems in a tropical environment focuses on forward-tilted, downshear-propagating systems that emerge spontaneously from idealized numerical simulations. These systems differ in important ways from the standard mesoscale convective system that is...

  • Attribution of Decadal-Scale Lake-Level Trends in the Michigan-Huron System. Hanrahan, Janel; Roebber, Paul; Kravtsov, Sergey // Water (20734441);Aug2014, Vol. 6 Issue 8, p2278 

    This study disentangles causes of the Michigan-Huron system lake-level variability. Regional precipitation is identified as the primary driver of lake levels with sub-monthly time lag, implying that the lake-level time series can be used as a proxy for regional precipitation throughout most of...

  • Temporal and spatial scaling impacts on extreme precipitation. Eggert, B.; Berg, P.; Haerter, J. O.; Jacob, D.; Moseley, C. // Atmospheric Chemistry & Physics Discussions;2015, Vol. 15 Issue 2, p2157 

    Both in the current climate and in the light of climate change, understanding of the causes and risk of precipitation extremes is essential for protection of human life and adequate design of infrastructure. Precipitation extreme events depend qualitatively on the temporal and spatial scales at...

  • Aerosol-cloud-land surface interactions within tropical convection simulations. Grant, Leah D.; van den Heever, Susan C.; Lu, Lixin // AIP Conference Proceedings;May2013, Vol. 1527 Issue 1, p739 

    Mutual impacts of enhanced aerosol concentrations and reductions to surface roughness length on convective rainfall patterns are investigated within idealized simulations of tropical convection focused along a sea-breeze convergence zone. Results indicate that enhanced aerosol concentrations...

  • Exploratory High-Resolution Climate Simulations using the Community Atmosphere Model (CAM). Bacmeister, Julio T.; Wehner, Michael F.; Neale, Richard B.; Gettelman, Andrew; Hannay, Cecile; Lauritzen, Peter H.; Caron, Julie M.; Truesdale, John E. // Journal of Climate;May2014, Vol. 27 Issue 9, p3073 

    Extended, high-resolution (0.23° latitude × 0.31° longitude) simulations with Community Atmosphere Model versions 4 and 5 (CAM4 and CAM5) are examined and compared with results from climate simulations conducted at a more typical resolution of 0.9° latitude × 1.25° longitude....

  • Scale Issues in the Development of Future Precipitation Scenarios. Schoof, Justin T. // Journal of Contemporary Water Research & Education;Mar2012, Vol. 147 Issue 1, p8 

    Many of the processes that govern precipitation occurrence and intensity occur at spatial and temporal scales that remain unresolved by the current generation of climate models. The resulting mismatch between the information reliably provided by such models and the needs of researchers assessing...

  • Sensitivity of different convection schemes in RegCM4.0 for simulation of precipitation during the Septembers of 1989 and 1998 over West Africa. Adeniyi, Mojisola // Theoretical & Applied Climatology;Jan2014, Vol. 115 Issue 1/2, p305 

    The regional climate model of the International Centre for Theoretical Physics (RegCM4.0) was used to simulate the climate of West Africa. The convective schemes Kuo, Massachusetts Institute of Technology-Emanuel (Ema) and Grell with closures Arakawa-Schubert (Grell 1) and Fritch Chappel (Grell...

  • Extreme Precipitation Indices over China in CMIP5 Models. Part I: Model Evaluation. Jiang, Zhihong; Li, Wei; Xu, Jianjun; Li, Laurent // Journal of Climate;Nov2015, Vol. 28 Issue 21, p8603 

    Compared to precipitation extremes calculated from a high-resolution daily observational dataset in China during 1960-2005, simulations in 31 climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) have been quantitatively assessed using skill-score metrics. Four extreme...

  • Seasonality of Precipitation over Himalayan Watersheds in CORDEX South Asia and their Driving CMIP5 Experiments. Hasson, Shabeh ul // Atmosphere;Oct2016, Vol. 7 Issue 10, p123 

    Since the Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments exhibit limited skill in reproducing the statistical properties of prevailing precipitation regimes over the major Himalayan watersheds (Indus, Ganges, Brahmaputra and Mekong), this study evaluates the anticipated added...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics