Thermal Boundary Layer Retrievals over the Washington D.C. Metro Area using Satellite-Based NUCAPS-EDRs

The atmospheric boundary layer (ABL) is made up of layers defined by a characteristic scale that is proportional to the distance from the surface. The smallest scales are found near the surface and the larger scales are found in the upper layers. Most techniques of observing the ABL are based upon upward pointing remote sensors or radiosondes which provide information at a single locale. Satellite data, on the other hand, can provide important domain-wide context for such measurements.  Using the NOAA Unique Combined Atmospheric Processing System (NUCAPS), we examine profiles of the temperature and humidity profiles of the ABL for a wide area. In order to evaluate the sounding results from NUCAPS, 28 radiosonde launches were compared against the closest grid point to the Howard University launch site in Beltsville, Maryland. Each FOR is approximately 50 km in diameter. The statistics were calculated for the virtual potential temperature bias and standard deviation between NUCAPS and radisondes (NUCAPS – RAOB). Error statistics in the boundary layer, show the largest errors occur the region between 900-1000 hPa. The high errors in this region is most likely due to the difficulty in retrieving values near the inversion. Advancing further into the upper atmosphere the mean-absolute-error (MAE) decreases to less than one, and the standard deviation approaches the root-mean-square-error indicating that the dominant error source may be due to randomness, in the upper boundary layers, whereas the greater of value of the MAE indicates that lower boundary layer retrievals are more prone to systematic errors. The possibility of identifying urban heat islands is explored using NUCAPS-EDR using retrievals over Washington D.C. and New York City.