The GHCC generates several products in real-time from both GOES-12 Imager and Sounder data. The Imager and Sounder single pixel retrievals cover most of the CONtinental United States (CONUS) and have resolutions of 4 km and 10 km, respectively.

The products currently created operationally at GHCC are:

Skin temperature is the radiating temperature of the soil, vegetation, buildings, water etc. (often defined as land/sea surface temperature), and an image of it describes the spatial variability of surface thermal emission over the region. During periods of solar heating, the time tendency of skin temperature is related to the surface moisture availiability and is a useful parameter to assimilate into a numerical forecast model. Skin temperature is derived simultaneously with total precipitable water using data from at least two split window channels in a physical technique to solve the radiative transfer equation.

Total precipitable water is the total amount of water vapor contained in a vertical column of unit cross-sectional area extending from the surface to the top of the atmosphere, and an image of it describes the spatial variability of the total water vapor in the atmosphere, and is useful for isolating regions of potential convective development. Total precipitable water is derived simultaneously with skin temperature using a physical split-window technique.

Cloud top pressure images describe the spatial variation of height and type of clouds over a region, and are useful for nowcasting and forecast-model data assimilation. The presence or lack of clouds over a region is very important for modeling and diagnostic studies. When a cloud is present in a satellite image, it's height (or cloud top pressure) is an important additional parameter. Cloud top pressure is derived using a method that correlates the cloud top temperature in an infrared window channel to a thermodynamic profile from the MM5 forecast model. The cloud top pressure product incorporates the GHCC operational cloud mask, produced using a technique that relies upon a 11 - 3.7 micron difference image to enhance surface versus cloud contrast to delineate cloudy pixels from clear.

The cloud mask algorithm has undergone several changes in the past year, with significant improvements seen. The Jedlovec and Laws (2001 - PDF version) and Jedlovec and Laws (2003 - PDF version) conference papers describe the method. In summary, the cloud mask method applies two spatial tests and one threshold test on a 11 - 3.7 micron difference image. An additional test implemented since the writing of the paper is a temperature threshold test. This fourth test compares the temperature from the 11 micron channel to a 20-day clear-sky composite of 11 micron temperatures, and labels the pixel as cloudy if the difference is greater than the threshold. This additional test is intended to produce improvements mainly during the nighttime hours.

The 20-day clear-sky visible composite is the minimum visible channel radiance value for each pixel from the past 20 days, and is an intermediate product that provides an estimate of the minimum in surface reflectivity for each pixel, assuming no pixel is cloud covered for all 20 days. It is used to produce the surface albedo and insolation products.

Surface insolation is the amount of solar radiation reaching the surface, and an image of it describes the variation of direct and indirect (scattered) solar radiation reaching the ground, and is assimilated into regional forecast models to improve the surface energy balance. Surface insolation is derived from the visible channel's measurements of reflectance. The insolation is calculated as the sum of solar radiation incident on the surface from both direct and indirect sources and also includes the effect of attenuation by clouds.

Surface albedo is the ratio of the radiation reflected by the surface to the incoming solar radiation, and an image of it describes the variation of the amount of solar radiation absorbed by the surface over a region. Surface albedo is derived from the visible channel's measurements of reflectance. Albedo is determined using the clear-sky composite image.

Click on an image below to see the corresponding products from today or the past two weeks