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Supplementary Materials
Temporal and Spatial Variability of Precipitation from Observations and Models
James H. Trammell1, Xun Jiang1,*, Liming Li2, Angela Kao1, Guang J. Zhang3,
Edmund K. M. Chang4, and Yuk L. Yung5
1 Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX,
USA
2 Department of Physics, University of Houston, Houston, TX, USA
3 Climate, Atmospheric Science and Physical Oceanography Division, Scripps Institution
of Oceanography, La Jolla, CA, USA
4 ITPA/SoMAS, Stony Brook University, Stony Brook, NY, USA
5 Division of Geological & Planetary Sciences, California Institute of Technology,
Pasadena, CA, USA
To explore the possible relationship between precipitation and storm track activities, we
regressed PC1 of precipitation with storm track data, which is calculated as the variance
of ECMWF-Interim sea level pressure filtered by the 24-hour difference (Chang and Fu,
2002). PC1 of Arctic precipitation is used to regress with storm track data in the northern
hemisphere. Result is shown in Figure S1a. There are positive storm track anomalies over
north Pacific, North America, north Atlantic, and Europe in the northern hemisphere. In
the southern hemisphere, PC1 of Antarctic precipitation is used to regress with storm
track data. As shown in Figure S1b, there are positive storm track anomalies over south
Pacific Ocean. Regressed storm track magnitudes are up to 10 hPa2, which is close to
10% of the local storm track climatological value. The positive storm track anomalies are
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consistent with the positive precipitation anomalies in the first leading modes of
precipitation in both hemispheres.
References:
Chang, E. K. M., and Y. Fu, 2002: Interdecadal variations in northern hemisphere winter
storm track intensity. J. Climate, 15, 642-658.
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TRAMMELL ET AL.
Figure S1: (a) Regression of ECMWF-Interim storm track data with PC1 of Arctic
precipitation. (b) Regression of ECMWF-Interim storm track data with PC1 of Antarctic
precipitation. Units are hPa2.
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