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Challenges and Limitations of regional climate model simulations in West Africa for Present and Future studies

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Challenges and Limitations of regional climate model simulations in West Africa for Present and Future studies Gregory S. Jenkins Penn State University – PowerPoint PPT presentation

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Title: Challenges and Limitations of regional climate model simulations in West Africa for Present and Future studies


1
Challenges and Limitations of regional climate
model simulations in West Africa for Present and
Future studies
  • Gregory S. Jenkins
  • Penn State University

2
Present and Future Climate issues in West Africa
  • Present
  • Climate Variability
  • Land-Use Change
  • Future
  • Climate Variability
  • Land-Use Change
  • Climate change

3
Issues in Regional Modeling for West Africa
  • Model integration
  • Regional Model parameterizations
  • The state of knowledge in regional climate
    systems and observations for verification.
  • Science topics
  • Extension to other disciplines

4
Model integration
  • Preprocessing
  • Initial and Boundary conditions (observations and
    models)
  • Grid Spacing
  • Computing Power
  • Storage
  • Post-processing

5
Regional Model parameterizations
  • Land Surface-Atmosphere transfer parameterization
  • PBL parameterization
  • Cloud parameterization
  • Precipitation schemes
  • Radiation schemes

6
The state of knowledge in regional climate
systems and observations for verification.
  • West Africa
  • Precipitation Processes (trigger,
    characteristics)
  • Low level southwesterly winds
  • 600-700 hPa African Easterly Jet
  • African Easterly Waves (AEWs)
  • 200 hPa Tropical Easterly Jet
  • Meridional surface temperature gradients.

7
MCSs links to the Water Cycle
  • MCSs (squall lines, MCCs, non-squall clusters)
    are responsible for most of West Africas rain.
  • MCSs are found primarily in the Sahel
    regiondownstream of mountains.
  • A significant fraction of the MCSs are long-lived
    (gt 24 hrs) Mathon and Laurent, (2001).

8
MCSs links to the Water Cycle
  • MCSs reach their maximum coverage between
    1800-0000 UTC.
  • The highest frequency of MCCs are over the Sahel.

9
Nesbitt et al. 2000 for Aug-Oct. 1998
  • MCSs are a small fraction of precipitation
    features in Africa (lt 3) but account for more
    than 50 of rain.

10
MCSs are associated with high flash rates
(Nesbitt et al. 2000)
11
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13
Model Simulations
  • CCM3.6 forced by Observed SSTs (AMIP)
  • CCSM (A1B scenario) SSTs computed from fully
    dynamic ocean
  • RegCM 60km and 90 km runs forced by CCSM.

14
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15
700 hPa AEJ simulations
16
CCM/CCSM/Observational Air Temps.
17
Sea Level Pressure comparison
18
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19
ECMWF/CCM3 u,v spectrum
20
ECMWF/CCSM spectrum of u,v
21
CCM3/CCSM u,v spectrum
22
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23
Regional Climate model driven by CCSM
24
Evidence of AEWs from Meridional winds at .688s
25
Evidence of AEWs from Rain rates
26
Evidence of AEWs from Water vapor at .668s
27
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29
Science topics
  • Climate Variability
  • Land-use Change
  • Climate change
  • Sensitivity Studies

30
West African Precipitation Anomalies
31
Africa is Highly Vulnerable to Climate
Change.IPCC 2001
32
A1B scenario
33
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36
21st century temp./prec. diff
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40
Extension to other disciplines
  • Agriculture
  • Water Resources
  • Health
  • Economic Development
  • Policy

41
Limitations of Regional climate modeling for West
Africa
  • Resource to complete science (computers, storage,
    boundary conditions)--especially for climate
    change integrations.
  • Recognition that regional modeling results are
    very dependent on input of boundary conditions
    (poor results can be anticipated !).
  • Critical mass of scientists to address various
    science questions.
  • Observations to compare to model results.
  • Forum to discuss/publish results and issues

42
Challenges of Regional climate modeling for West
Africa
  • Formation of working groups to pool resources for
    examining scientific issues (climate variability,
    land-use, climate change, sensitivity tests,
    improvements in model parameterization).
  • Recognition that regional climate models may need
    to undergoe significant modification to be a
    useful tool in a particular region.
  • Develop tools that will ease the use of climate
    modeling (pre-processing, integration,
    post-processing) on multiple platforms (PCs,
    workstations, supercomputers).
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