MSU temperature anomalies

Microwave Sounding Unit (MSU) temperature anomalies
December 1978 - March 2006

The MSU temperature data are provided by John Christy of the University of Alabama Huntsville ( christy@atmos.uah.edu ) and Roy Spencer of the National Aeronautics and Space Administration Marshall Space Flight Center ( roy.spencer@msfc.nasa.gov ).

Three MSU temperatures are available:

TLS (temperature lower stratosphere) (formerly known as channel 4), for which 90% of the emissions are from within 150 and 20 hPa.

TMT (temperature middle troposphere) (formerly known as channel 2), for which 90% of the emissions are below 120 hPa.

TLT (temperature lower troposphere) (formerly known as channel 2 LT), for which 90% of the emissions are below 400 hPa.

Weighting functions,
which are described above.

A larger version of this image is available.

Temperature anomaly maps for individual months can be viewed through this link. You will need to select "stratosphere" on the display to see the MSU LS maps. I'm not sure if the "troposphere" maps are TLT or TMT.

A large variety of phenomena can be studied with this data, for example the Quasi-Biennial Oscillation (QBO) and sudden stratospheric warmings. In the following, the dominant patterns of variability are documented in emiprical orthogonal functions (EOFs, spatial patterns) and associated principal components (PCs, amplitude time series) of correlation and covariance matrices of MSU LT, MT, and LS are presented.

1a) Leading EOF/PC of TLS anomalies calculated from the correlation matrix.

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The EOF is plotted as correlation coefficients with a contour interval of 0.2. MSU TLS variations are characterized by zonal wave number zero changes centered in the tropics with a weak tendency for anomalies of opposite polarity in the polar latitudes of the Northern Hemisphere. Fluctuations in the pattern explain 38% of the variance in the data set. This calculation was based on data for 1979-98.

The associated PC (normalized)

Digital values of the PC are linked here. The time series is characterized by significant persisent anomalies during 1982-83 and August 1991 - March 1993 which are consistent with a warming of the tropics. A general tendency of cooler tropical temperatures characterizes the data from mid-1993 through the end of the record (1998). The PC is similar to the global mean of "seasonally adjusted" MSU LT temperature anomalies shown by Roy Spencer at this link.

The difference map, 1994 minus 1992, is characterized by temperature differences in excess of -1.5C in the tropics and over northern Canada and Greenland.

1b) Leading EOF/PC of TLS anomalies calculated from the covariance matrix.

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The variance is largest in the extratropical latitudes (not shown). I am plotting the EOF as a correlation map as the EOF also explains significant amounts of variance outside of the extratropics.

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The PC exhibits its largest amplitudes in December through March.

2) Leading EOF/PC of TMT anomalies calculated from the covariance matrix.

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Variance is explained in the tropics and the Northern Hemisphere extratropics.

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3) Leading EOF/PC of TLT anomalies calculated from the covariance matrix.

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Data:

ASCII format

TLS in netCDF format (6.5 Mb)

TMT in netCDF format (6.5 Mb)

TLT in netCDF format (6.5 Mb)

Reference:
Christy, J. R., R. W. Spencer, W. B. Norris, W. D. Braswell, D. E. Parker, 2003: Error estimates of version 5.0 of MSU-AMSU bulk atmospheric temperatures. J. Atmos. Oceanic Technol., 20, 613-629.

March 2007

Todd Mitchell (mitchell@atmos.washington.edu)

JISAO data