Title: Challenges and Limitations of regional climate model simulations in West Africa for Present and Future studies
1Challenges and Limitations of regional climate
model simulations in West Africa for Present and
Future studies
- Gregory S. Jenkins
- Penn State University
2Present and Future Climate issues in West Africa
- Present
- Climate Variability
- Land-Use Change
- Future
- Climate Variability
- Land-Use Change
- Climate change
3Issues 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
4Model integration
- Preprocessing
- Initial and Boundary conditions (observations and
models) - Grid Spacing
- Computing Power
- Storage
- Post-processing
5Regional Model parameterizations
- Land Surface-Atmosphere transfer parameterization
- PBL parameterization
- Cloud parameterization
- Precipitation schemes
- Radiation schemes
6The 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.
7MCSs 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).
8MCSs links to the Water Cycle
- MCSs reach their maximum coverage between
1800-0000 UTC. - The highest frequency of MCCs are over the Sahel.
9Nesbitt 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.
10MCSs are associated with high flash rates
(Nesbitt et al. 2000)
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13Model 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.
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15700 hPa AEJ simulations
16CCM/CCSM/Observational Air Temps.
17Sea Level Pressure comparison
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19ECMWF/CCM3 u,v spectrum
20ECMWF/CCSM spectrum of u,v
21CCM3/CCSM u,v spectrum
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23Regional Climate model driven by CCSM
24Evidence of AEWs from Meridional winds at .688s
25Evidence of AEWs from Rain rates
26Evidence of AEWs from Water vapor at .668s
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29Science topics
- Climate Variability
- Land-use Change
- Climate change
- Sensitivity Studies
30West African Precipitation Anomalies
31Africa is Highly Vulnerable to Climate
Change.IPCC 2001
32A1B scenario
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3621st century temp./prec. diff
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40Extension to other disciplines
- Agriculture
- Water Resources
- Health
- Economic Development
- Policy
41Limitations 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
42Challenges 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).