>>13963315Sensitivity of Satellite-Derived Tropospheric Temperature Trends
to the Diurnal Cycle Adjustment
CARL A. MEARS AND FRANK J. WENTZ
Remote Sensing Systems, Santa Rosa, California
(Manuscript received 23 October 2015, in final form 22 February 2016)
ABSTRACT
Temperature sounding microwave radiometers flown on polar-orbiting weather satellites provide a long-
term, global-scale record of upper-atmosphere temperatures, beginning in late 1978 and continuing to the
present. The focus of this paper is the midtropospheric measurements made by the Microwave Sounding Unit
(MSU) channel 2 and the Advanced Microwave Sounding Unit (AMSU) channel 5. Previous versions of the
Remote Sensing Systems (RSS) dataset have used a diurnal climatology derived from general circulation model
output to remove the effects of drifting local measurement time. This paper presents evidence that this previous
method is not sufficiently accurate and presents several alternative methods to optimize these adjustments using
information from the satellite measurements themselves. These are used to construct a number of candidate
climate data records using measurements from 15 MSU and AMSU satellites. The new methods result in
improved agreement between measurements made by different satellites at the same time.
