Assessing Heating in Climate Models

Top: Atmospheric diabatic heating estimates from the TRMM satellite quantify the response of regional energy budgets in the Tropical Pacific to the 1998 El Niño event.

Right: Similar fields extracted from the latest IPCC climate models indicate that today’s GCMs still have difficulty modeling the response of diabatic heating in the Tropical West Pacific to ENSO.

In general, vertical profiles of radiative heating on large scales developed under NEWS enable the assessment of global climate models to be evaluated.

T. S. L’Ecuyer, G. L. Stephens, Z. Luo

WestWestPacificPacific

EastEastPacificPacific

EquatorialEquatorialPacificPacific

Feb. 1998Feb. 1998(El Ni(El Niñño)o)

Feb. 1999Feb. 1999(La Ni(La Niñña)a)

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EquatorialEquatorialPacificPacific

Latent HeatingLatent HeatingNet Heating/CoolingNet Heating/Cooling

Clear-sky SWClear-sky SWCloudy-sky SWCloudy-sky SWPrecipitating SWPrecipitating SW

Clear-sky LWClear-sky LWCloudy-sky LWCloudy-sky LWPrecipitating LWPrecipitating LW

Observed Regional Heat Budgets

(-0.6) (0.43) (-0.6) (0.67) (0.51) (0.87) (-0.1) (0.47) (-0.4) (0.54)

TRMM ECHAM5 IPSL-CM4 MIROC-m UKMOCNRM INM-CM3 MIROC-h CCSM3 CGCM2

(0.68) (0.94) (1.78) (1.26) (1.09) (1.24) (1.36) (1.71) (0.77) (1.31)

TRMM ECHAM5 IPSL-CM4 MIROC-m UKMOCNRM INM-CM3 MIROC-h CCSM3 CGCM2

Latent Heating SW Heating LW Cooling

Latent Heating SW Heating LW Cooling

February 1999 (La Niña)

February 1998 (El Niño)

IPCC-AR4 Model Heat Budgets

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D. Posselt, T. S. L’Ecuyer, G. L. Stephens

Extension to Cloud Resolving Scale

NEWS energy and water cycle datasets also allow the fidelity of cloud resolving model simulations of the energy and water cycle to be assessed.

When compared against corresponding products from TRMM (red curves), PDFs of energy and water cycle parameters from CRM simulations (blue curves) over the SCSMEX region suggest that the model is too moist (upper left), predicts rainfall that is too intense (lower left), and exhibits too much shortwave cloud radiative forcing at TOA (upper right) during the active monsoon period.

Increasing (green curves) or decreasing (black curves) the modeled particle size distribution and fall velocities demonstrates that model performance is affected by varying its parameterizations over a reasonable range suggesting that NEWS products could be used to refine model microphysics.

Color Key

TRMM

Control Run

Increased Particle Size

Decreased Particle Size

Probing the Energy and WaterCycle With A-Train Measurements

T. S. L’Ecuyer, J. M. Haynes, and G. L. Stephens

NEWS research, is also being used in combination with that from other focus areas to provide a new perspective on the global energy and water cycle.

Energy and water cycle products from CloudSat , for example, are yielding insights into the vertical distributions of radiative heating associated with a variety of different cloud systems as well as the importance of light and frozen precipitation in the global hydrologic cycle (shown here as a function of latitude and surface type).

July 2006 - Jan. 2007

Latest Publications

Papers:

L’Ecuyer, T. S. and G. L. Stephens, 2007. “The Tropical Atmospheric Energy Budget from the TRMM Perspective. Part II: Evaluating GCM Representations of the Sensitivity of Regional Energy and Water Cycles to the 1998 ENSO Event”, J. Climate, in press.

Posselt, D. J., T. S. L’Ecuyer, W.-K. Tao, A. Y. Hou, and G. L. Stephens, 2007. “Evaluation of the Cloud-resolving Model Component of a Multi-scale Modeling Framework Using Observations from TRMM”, submitted to J. Climate.

Presentations:

T. S. L’Ecuyer and G. L. Stephens: “Radiative Heating Profile Products from TRMM and CloudSat”, DOE-ARM Radiative Heating Profile Workshop, San Diego, CA, January, 2007.

T. S. L'Ecuyer. “A Satellite Energy and Water Cycle Dataset for Climate Studies in the Southern Hemisphere”, 8th Conference on Southern Hemisphere Meteorology and Oceanography, Iguassu Falls, Brazil, April, 2006.