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Model Simulations and ISCCP/Model Comparisons

Australian Cold Front Research Project (CFRP): Phase III

Overview

As part of the GCSS Working Group 3 effort, the CFRPIII storm case was simulated by a suite of atmospheric models. Several parameter fields produced by the atmospheric models are presented here and compared to the same fields from the ISCCP retrievals. The models used in the comparisons and the atmospheric parameters that are compared to the observations are listed below.

THE MODELS

  1. DARLAM is a limited area model that was run over a 30×20 degree domain centered on the experiment with a resolution of 30 km. Its output was sampled at 0.5 degree resolution and is compared to ISCCP CX retrievals sampled also at 0.5 degree resolution.
  2. MC2 is a cloud resolving model that was run over a 10×10 degree domain with a 5 km resolution. Its output was sampled at 0.5 degree resolution and is compared to ISCCP CX retrievals sampled also at 0.5 degree resolution.
  3. ECMWF is a global model that was run at approximately 1.5 degree resolution and its output was interpolated over 2.5 degree boxes. It is compared to the ISCCP C1 retrievals that represent averages over 2.5 degree boxes. The area of the comparison is a 35×30 degree region centered on the experiment.

THE PARAMETERS

Cloud Top Temperature is the temperature at the top of the cloud. In the ISCCP dataset it is derived from the infrared radiances measured by the satellites. In the models it represents the average top temperature of the clouds in a grid box.

Cloud Top Pressure is the atmospheric pressure at the level of the top of the cloud. In the ISCCP dataset it is derived from the infrared radiances measured by the satellites and the vertical temperature profile of the atmosphere. In the models it represents the average top pressure of the clouds in a grid box.

Cloud Optical Thickness is an index measuring of the ability of the cloud to reflect solar radiation. In the ISCCP data it is derived from the reflected visible radiances measured by the satellites. In the models it represents the column optical thickness of the clouds in a grid box.

Histogram is a two-dimensional plot that shows the number of clouds in the study area that have a particular optical thickness and top pressure. The combination of these two parameters defines the type of the cloud (e.g., cumulus, cirrus, etc.).


For information on this page contact:
George Tselioudis (gtselioudis@giss.nasa.gov)

Created by Evan Jacover.