Thursday, 13 January 2005
Locating and removing problematic data in the DMSP SSM/I data sets
Daily averaged grids of brightness temperatures (TBs) from the Special Sensor Microwave Imager (SSM/I) on the Defense Meteorological Satellite Program (DMSP) F8, F11 and F13 platforms are available over the Arctic. As part of a quality control process, steps are taken to remove values determined to be physically unrealistic and to document scans that are missing from the data. Despite these efforts, TBs appear that are inconsistent with surrounding values though within a range of acceptable values and occur in arcs identical to the scanning pattern of the instrument. These bad arcs tend to appear in a single channel on a given day and are not necessarily collocated in time and space with anomalies in other channels. An automated process has been created to locate these bad arcs in order to remove them from the data set before making use of the DMSP SSM/I brightness temperatures. The detection technique incorporates TB’s in time and space to identify the bad arcs. Examples of the bad arcs and their removal will be presented. In addition, the detection technique has been applied to the SSM/I time series and days with bad arcs are identified and the actual pixels have been flagged for removal. The number of days and pixels identified will also be presented.