The US CLIVAR Working Group on Drought

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The US CLIVAR Working Group on Drought
USCLIVAR Annual Summit Annapolis, MD 15-17 July
2009

• Siegfried Schubert (NASA/GMAO) and Dave Gutzler
  (Univ New Mexico) Cochairs

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• U.S. Membership
• Tom Delworth NOAA GFDL
• Rong Fu Georgia Institute of Technology
• Dave Gutzler (co-chair) University of New
  Mexico
• Wayne Higgins NOAA/CPC
• Marty Hoerling NOAA/CDC
• Randy Koster NASA/GSFC
• Arun Kumar NOAA/CPC
• Dennis Lettenmaier University of Washington
• Kingtse Mo NOAA CPC
• Sumant Nigam University of Maryland
• Roger Pulwarty NOAA- NIDIS Director
• David Rind NASA - GISS
• Siegfried Schubert (co-chair) NASA GSFC
• Richard Seager Columbia University/LDEO
• Mingfang Ting Columbia University/LDEO
• Ning Zeng University of Maryland
• International Membership Ex Officio

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• Other interested participants
• Jin Huang Jin.Huang_at_noaa.gov
• Adam Sobel ltahs129_at_columbia.edugt
• Max Suarez ltMax.J.Suarez_at_nasa.govgt
• Phil Pegion pegion_at_gmao.gsfc.nasa.gov
• Entin, Jared K. ltjared.k.entin_at_nasa.govgt
• Donald Anderson ltdonald.anderson-1_at_nasa.govgt
• Rong Fu rf66_at_mail.gatech.edu
• Doug Lecomte Douglas.Lecomte_at_noaa.gov
• Hailan Wang hwang_at_climate.gsfc.nasa.gov
• Junye Chen jchen_at_gmao.gsfc.nasa.gov
• Eric Wood efwood_at_princeton.edu
• Aiguo Dai adai_at_ucar.edu
• Alfredo Ruiz-Barradas ltalfredo_at_atmos.umd.edugt
• Jae Kyung E Schemm Jae.Schemm_at_noaa.gov
• Kirsten L. Findell ltKirsten.Findell_at_noaa.govgt

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Accomplishments

• DWG Web page
• http//www.usclivar.org/Organization/drought-wg.ht
  ml
• List of relevant model simulations and
  observational data sets
• Coordinated Model simulations
• GMAO, GFDL, NCAR, CPC, Lamont, COLA/U Miami
• Impact of SST and Land/atmosphere feedbacks
• http//gmao.gsfc.nasa.gov/research/clivar_drought_
  wg/index.html
• Subset of data available to public
• ftp//gmaoftp.gsfc.nasa.gov/pub/data/clivar_drough
  t_wg/
• CDPW 2008 Focus workshop on drought (with
  DRICOMP)
• 08 Spring USCLIVAR Variations US CLIVAR
  Drought Working Group Workshop

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Publications

• U.S. CLIVAR VARIATIONS
• 07 Spring The U.S. CLIVAR Working Group on
  Long-term Drought D.Gutzler and S. Schubert
• 08 December Overview of the Drought Working
  Group
• 08 December Analysis of the multi-model U.S.
  CLIVAR Drought Working Group Simulations P.
  Pegion and A. Kumar
• Special Issue in JCLIM (DWG and DRICOMP)
• 10 publications in various stages of review from
  DWG (see next slide)
• 10 publications in various stages of review from
  DRICOMP
• Other
• Koster, R. D., Z. Guo, R. Yang, P. A. Dirmeyer,
  K. Mitchell, and M. J. Puma, 2009 On the nature
  of soil moisture in land surface models. J.
  Climate, in press.

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• 1) Siegfried Schubert, and the extended drought
  working group A USCLIVAR Project to Assess and
  Compare the Responses of Global Climate Models to
  Drought-Related SST Forcing Patterns Overview
  and Results. Accepted (pdf).
• 2) Kingtse C. Mo, Jae-Kyung E. Schemm and
  Soo-Hyun Yoo Influence of ENSO and the Atlantic
  multi-decadal Oscillation on Drought over the
  United States. Submitted (pdf).
• 3) Randal Koster, Hailan Wang, Siegfried
  Schubert, Max Suarez and Sarith Mahanama
  Drought-Induced warming in the continental United
  States under different SST regimes. Accepted.
• 4) Hailan Wang, Siegfried Schubert, Max Suarez
  and Randal Koster The Physical Mechanisms by
  which the Leading Patterns of SST Variability
  Impact U.S. Precipitation. Submitted (pdf).
• 5) Yochanan Kushnir, Richard Seager, Mingfang
  Ting, Naomi Naik, and Jennifer Nakamura
  Mechanisms of Tropical Atlantic SST Influence on
  North American Hydroclimate Variability.
  Submitted (pdf).
• 6) Philip Pegion and Arun Kumar Multi-model
  Estimates of Atmospheric Response to Modes of SST
  Variability and Implications for Droughts.
  Submitted (pdf).
• 7) Scott Weaver, Siegfried Schubert and Hailan
  Wang Warm Season Variations in the Low-Level
  Circulation and Precipitation over the Central
  U.S. in Observations, AMIP Simulations, and
  Idealized SST Experiments. Accepted (pdf).
• 8) Kirsten L. Findell and Thomas L. Delworth
  Impact of common sea surface temperature
  anomalies on global drought and pluvial
  frequency. Submitted (pdf).
• 9) Matias Mendez and Victor Magana Regional
  aspects of prolonged meteorological droughts over
  Mexico. Submitted (pdf).
• 10) Alfredo Ruiz-Barradas and Sumant Nigam AMIP
  Simulations of 20th Century North American
  Precipitation Variability by the Drought Working
  Group Models. Submitted.

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Leading EOFs and Time series (annual mean SST -
1901-2004)
Linear Trend Pattern (LT)
Pacific Pattern (Pac)
Atlantic Pattern (Atl)
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Idealized Experiments
NATL
PacInd
NATL
PacInd
SST Forcing patterns (warm phase)
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Annual Mean 200mb Height Response (m)
Pacific Warm
Pacific Cold
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(No Transcript)
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Global Spatial Correlations of Annual Mean
Responses
???
Precipitation
Agreement among models for response to Pacific is
high
???
Agreement is higher for z200 than it is for
precipitation
Agreement among models for response to Atlantic
is lower
?
?
???
???
z 200mb
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U.S. Precipitation Response (mm/day)
U.S. Tsfc Response (mm/day)
CCM3
NSIPP1
GFS
GFDL
CAM3.5
The annual and continental United States mean
responses for precipitation (top panel) and
surface temperature (bottom panel) for all 8
combinations of the Pacific and Atlantic patterns
for the 5 AGCMs
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Optimal SST Forcing for Drought in US
C
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Annual Precipitation (mm/day)
Pacific ColdAtlantic Warm
Pacific WarmAtlantic Cold
US Drought!
US Pluvials!
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Precipitation Response (mm/day) During SON PcAw
mm/day
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850mb Wind Speed (m/s) and Streamlines During SON
m/s
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Impact of Soil Moisture Feedbacks - Response to
Cold Pacific in JJA
No Soil Moisture Feedback
With Soil Moisture Feedback
Major drought in Great Plains
Reduced severity of drought in Great Plains
mm/day
Optimal SST Forcing for Drought in US
With Feedback
Without Feedback
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What Have We Learned?

• Important Role of SST in Droughts and Pluvials
  World-Wide
• Dominant role of tropical Pacific SST
• Important role of the tropical Atlantic/IAS
• Important role of land-atmosphere feedbacks
• Strong seasonality of responses
  (seasonally-changing impacts of planetary waves,
  jetstream dynamics/large-scale subsidence,
  weather, low level circulations/LLJs,
  land-atmosphere feedbacks, predictability)
• General agreement among models on global
  response, but substantial differences on regional
  scales
• Over the US
• Models agree that
• Cold PacificWarm Atlantic gt drought/warm
• Warm PacificCold Atlantic gt pluvial
  conditions/cold
• The models disagree on the regional details
• Sensitivity to errors in stationary waves
• Sensitivity to strength of land-atmosphere
  coupling
• Sensitivity to low level response in the
  IAS/Caribbean

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Future Directions

• Much more to study in current idealized and
  AMIP-style runs
• Physical mechanisms linking SST, Impact of land
• Other parts of the world (focus was on response
  over North America)
• ftp//gmaoftp.gsfc.nasa.gov/pub/data/clivar_drough
  t_wg/
• Continue Focus on
• Dependence on Time scales Seasonal,
  Inter-annual, Decadal/Climate Change
• AGCM response to SST, stationary waves, warm
  season precipitation, roles of different ocean
  basins including IAS, land-atmosphere coupling
  strength
• Coupled model issues realistic SST variability,
  AGCM issues
• Resolution issues e.g. diurnal cycle,
  mesoscale, LLJ, role of weather
• Role of land soil moisture, vegetation, aerosols
• Observations soil moisture monitoring and ICs
  role of LDAS, satellite measurements, improved
  information/inferences about coupling strength
• Other quantities (snow, run-off, temperature,
  etc)
• Programs/related activities
• Drought interest group (CLIVAR/GEWEX)
• VAMOS panel on extremes, IASCLIP
• AR5 IPCC runs including decadal simulations