A Global Surface Albedo Model

John R. Hummel Physics Department, General Motors Research Laboratories, Warren MI 48090

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Ruth A. Reck Physics Department, General Motors Research Laboratories, Warren MI 48090

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Abstract

We have shown in the past that the radiative-convective energy balance atmospheric model used at the General Motors Research Laboratories in our atmospheric physics research is extremely sensitive to the input value of surface albedo used. In response to this we developed a new global model of the surface albedo based on a detailed analysis of land use. The model has been used to determine the average surface albedo of the earth's surface in latitudinal bands for the four seasons of the year (January-March, April-June, July-September and October-December). In addition, global maps of surface albedo for elements 10° latitude by 10° longitude are provided. Our model involves: assigning one of 49 different types of surface to each of 77 040 areas for each of the four seasons. Each type of surface is assigned a different albedo for each season. The average surface albedo for a given latitudinal band is obtained by averaging the albedos for the areas in the desired latitudinal band. The average surface albedos are intended to be used for input data in our radiative-convective energy balance model of the earth's atmosphere in order to compute the atmospheric temperature profile. The average annual albedo values for 18 different latitudinal bands are compared with the predictions of three other studies. The values in this work tend to be slightly lower than the others from 30°N-30°S and! slightly higher from 90°-50°N and 50°-90°S. The annual global average albedo is calculated to be 15.40 as compared to 13.0 for the previous predictions.

Abstract

We have shown in the past that the radiative-convective energy balance atmospheric model used at the General Motors Research Laboratories in our atmospheric physics research is extremely sensitive to the input value of surface albedo used. In response to this we developed a new global model of the surface albedo based on a detailed analysis of land use. The model has been used to determine the average surface albedo of the earth's surface in latitudinal bands for the four seasons of the year (January-March, April-June, July-September and October-December). In addition, global maps of surface albedo for elements 10° latitude by 10° longitude are provided. Our model involves: assigning one of 49 different types of surface to each of 77 040 areas for each of the four seasons. Each type of surface is assigned a different albedo for each season. The average surface albedo for a given latitudinal band is obtained by averaging the albedos for the areas in the desired latitudinal band. The average surface albedos are intended to be used for input data in our radiative-convective energy balance model of the earth's atmosphere in order to compute the atmospheric temperature profile. The average annual albedo values for 18 different latitudinal bands are compared with the predictions of three other studies. The values in this work tend to be slightly lower than the others from 30°N-30°S and! slightly higher from 90°-50°N and 50°-90°S. The annual global average albedo is calculated to be 15.40 as compared to 13.0 for the previous predictions.

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