MSU Tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons

Abstract

Two deep-layer tropospheric temperature products, one for the lower troposphere (T 2LT) and one for the midtroposphere (T 2 , which includes some stratospheric emissions), are based on the observations of channel 2 of the microwave sounding unit on National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites. Revisions to version C of these datasets have been explicitly applied to account for the effects of orbit decay (loss of satellite altitude) and orbit drift (east-west movement). Orbit decay introduces an artificial cooling in T 2LT , while the effects of orbit drift introduce artificial warming in both T 2LT and T 2. The key issues for orbit drift are 1) accounting for the diurnal cycle and 2) the adjustment needed to correct for spurious effects related to the temperature of the instrument. In addition, new calibration coefficients for NOAA-12 have been applied. The net global effect of these revisions (version D) is small, having little impact on the year-to-year anomalies. The change in global trends from C to D for 1979-98 for T 2LT is an increase from ϩ0.03 to ϩ0.06 K decade Ϫ1 , and a decrease for T 2 from ϩ0.08 to ϩ0.04 K decade Ϫ1 .

Melting of major Glaciers in the western Himalayas: evidence of climatic changes from long term MSU derived tropospheric temperature trend (1979–2008)

“…The MSU data suffer from a number of inter-calibration issues, time and diurnal biases. Several groups (Remote Sensing Systems (RSS), the University of Maryland (UMD), the University of Alabama at Huntsville (UAH), the NOAA National Environmental Satellite, Data, and Information Service (NOAA/NESDIS)) have merged the data available from these MSU/AMSU instruments to produce a long-term atmospheric temperature record (Christy et al, 2000(Christy et al, , 2003Grody et al, 2004;Mears et al, 2002Mears et al, , 2003Mears and Wentz, 2009;Prabhakara et al, 2000;Vinnikov et al, 2005;Zou et al, 2006). We have used the atmospheric temperature (microwave lower and mid tropospheric) records from the MSU and AMSU-derived temperature data that are available from Remote Sensing Systems (RSS).…”

The Role of Volcanic Activity in Climate and Global Change

“…Santer et al [77] developed an iterative regression procedure to separate a volcanic effect from an El Niño signal using microwave sounding unit (MSU) brightness temperature observations from the lower tropospheric channel 2LT [80]. The globally averaged synthetic 2LT temperature for the Pinatubo ensemble runs is calculated using model output and compared with the response from Santer et al [77].…”

Uncertainty of the stratospheric/tropospheric temperature trends in 1979–2008: multiple satellite MSU, radiosonde, and reanalysis datasets

“…The first MSU temperature dataset (Christy et al, 2000) was created by Christy's group at the University of Alabama in Huntsville (UAH) based on 12 different satellites. The data used in this study includes the UAH MSU data for the lower stratosphere (MSU channel 4: CH4) and troposphere (MSU channel 2: CH2).…”

“…For example, the MSU data come from 12 different satellites and the data quality is significantly affected by intersatellite biases, uncertainties in each instrument's calibration coefficients, changes in instrument body temperature, Correspondence to: J. Xu (jianjun.xu@noaa.gov) drift in sampling of the diurnal cycle, roll biases and decay of orbital altitude (Christy and Spencer, 2000;Zou et al, 2008). Many previous studies (Santers et al, 1999;Seidel et al, 2004;Xu and Powell, 2010;and many others) show that climate analysis depends critically on the selection and implementation of the data sources.…”