Satellite measurements of the Earth’s microwave emission are crucial for long-term monitoring of atmospheric temperature, providing global spatial and uniform temporal coverage for the last 24 years. The Microwave Sounding Units (MSU) operating on NOAA polar-orbiting platforms have been the principal sources of satellite temperature profiles to date, with measurements of microwave radiance in four channels spanning the surface through the stratosphere extending over more than two decades, beginning in January 1979 and continuing through the present. The application of the MSU time series by Christy and Spencer to studies of climate change have played a high-profile and controversial role in the debate over the presence and magnitude of anthropogenic warming signals during the past decade. We have recently completed an independent, end-to-end analysis of the middle and upper tropospheric data from MSU Channel 2. Our results show trends approximately 0.1K/decade warmer than those found by Spencer and Christy. This difference arises primarily from slightly different choices for the merging parameters associated with the MSU mounted on the NOAA-9 satellite. We will explain and justify these differences in detail.