Post on 23-Dec-2015
Trend and Variability of East-Asian Precipitation: Linkage to Sea Surface Temperatures
Fanglin Yang
Environmental Modeling CenterNational Centers for Environmental Prediction
NOAA 32nd Climate Diagnostic and Prediction WorkshopCOAPS/FSU, October 22-27, 2007
Acknowledgment: This work was support by the NASA Modeling, Analysis and Prediction program while the author worked with William Lau at GFSC/NASA.
Possible causes:
1. South Asian black carbon emission
2. Climate regime shift3. Global warming4. Shift of Africa-North China
teleconncection5. SST trend
South China
Central China
North China
Questions?
• To what extent can the observed precipitation variability can be explained by SST variability?
• Does the precip-SST relation at the interannual timescale differ from that at the inter-decadal timescale?
Interannual Variability
Single Value Decomposition (SVD) applied to 7-year high-pass filtered precipitation and SSTs
SST Precip
MAM
SST Precip
JJA
SSTVariance
PrecipitationVariance
SST-PrecipitationCo-Variance
Correlation (PC_sst,
PC_precip)
MAM
SVD 1 31% 27% 27% 0.57
SVD 2 11% 15% 14% 0.64
JJA
SVD 1 43% 10% 24% – 0.77
SVD 2 7% 17% 13% 0.76
SST_PC Precip_PC
JJA, Regressions of wind850 and Z700 to PCs
JJA Climate, 1951-1998, NCEP R1
SVD Modes
SST_PC Precip_PC
MAM
Decadal Variation and Trend
SSTInterannual Mode
RainfallInterannual Mode
Projection of Obs to SVD modeArea-Mean Rainfall
ConclusionInterannual Variability• Precipitation over South China
in MAM and North China in JJA ENSO mode of SSTs
• Precipitation over central China in both MAM and JJA season SST in warm pool and northern Indian ocean;
• Features of the anomalous 850-hPa winds and 700-hPa geopotential height corresponding to these modes support a physical mechanism that explains the causal links between the modal variations of precipitation and SSTs.
Trend and decadal variation
• Upward South China MAM precipitation and downward JJA North China precipitation warming trend of the ENSO-like mode.
• Upward JJA central China precipitation warming trend of SSTs over the warm pool and Indian Ocean.
• Downward MAM South China precipitation downward central North Pacific SSTs (less robust)