SAC Meeting - 12 April 2010

Land-Climate Interaction

Paul DirmeyerZhichang Guo, Dan Paolino, Jiangfeng Wei

SAC Meeting - 12 April 2010

Recent Activities• Hydrologic Cycle Feedbacks

– Synthesis of land-atmosphere interaction– Precipitation spectrum and predictability– Linking floods to remote moisture sources

• Land Impact on Prediction– GLACE2– Land feedbacks in coupled O-A models– Coupling AGCMs to multiple LSMs

• Land Surface Modeling– Multi-model skill, impact of forcing data on simulations– Role of land model in climate change projections

SAC Meeting - 12 April 2010

Recent Activities• Hydrologic Cycle Feedbacks

– Synthesis of land-atmosphere interaction– Precipitation spectrum and predictability– Linking floods to remote moisture sources

• Land Impact on Prediction– GLACE2– Land feedbacks in coupled O-A models– Coupling AGCMs to multiple LSMs

• Land Surface Modeling– Multi-model skill, impact of forcing data on simulations– Role of land model in climate change projections

SAC Meeting - 12 April 2010

Recent Activities• Hydrologic Cycle Feedbacks

– Synthesis of land-atmosphere interaction– Precipitation spectrum and predictability– Linking floods to remote moisture sources

• Land Impact on Prediction– GLACE2– Land feedbacks in coupled O-A models– Coupling AGCMs to multiple LSMs

• Land Surface Modeling– Multi-model skill, impact of forcing data on simulations– Role of land model in climate change projections

SAC Meeting - 12 April 2010

Land Group Collaborations

SAC Meeting - 12 April 2010

Coupling AGCMs to Multiple LSMs

GFS AGCMGFS

AGCMCOLA AGCMCOLA AGCM

SAC Meeting - 12 April 2010

Land-Atmosphere – Many Models•We have coupled 3 LSMs to both GFS and COLA AGCMs.•The GFS AGCM does not translate even strong ET signals into precipitation. NOAA’s operational global forecast model is unresponsive to the choice of LSM or the strength of SM/ET coupling.

Lead: Jiangfeng Wei

Coupling Strength – Soil Moisture to Precipitation

SAC Meeting - 12 April 2010

Maya Express•Moisture that supplies MJJ rainfall over US Plains evaporates from terrestrial and oceanic (GOM, Caribbean, Pacific)•Floods have a much larger fraction of moisture from western Gulf and Caribbean, less recycling.•Droughts have stagnant circulation, more local (already desiccated) land surface sources.

SAC Meeting - 12 April 2010

Twelve Rainiest Months

There is tremendous variation from case to case, but most show enhanced transport from the south. The fetch curves around, suggesting circulation about an extended or westward displaced subtropical ridge (Bermuda High).

SAC Meeting - 12 April 2010

Seasonal Reforecasts – Role of Land ICsCCSM3.0 (JFM, JAS; 1982-1998), T85, Eulerian Dynamics

Lead: Dan Paolino

SAC Meeting - 12 April 2010

CAM Seasonal Skill•Realistic initialization improves surface temperature simulation (top) compared to SST only (bottom)•Some of the early skill (first two weeks) comes from the atmospheric initialization.

Correlation to CAMS:

r2=0.155

r2=0.101r2=0.094

r2=0.131

SAC Meeting - 12 April 2010

Soil Moisture Memory

•GSWP2 MMA shows a large amount of persistence in column soil moisture (top)•This behavior is well reflected in CLM3, implying a source for predictability beyond the atmospheric ICs.

Correlation:

SAC Meeting - 12 April 2010

Precipitation Skill is Poorer•There are areas of improved skill with realistic ICs, especially in the extratropics.•Seasonal time scales may be too coarse to discern land surface impacts, which are largely confined to sub-seasonal periods.

Correlation to CMAP:

r2=0.080

r2=0.081

r2=0.089

r2=0.076

SAC Meeting - 12 April 2010