regional-scale analysis of convective systems in the 2006 west african monsoon season nick guy...
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Regional-scale analysis of convective systems in the
2006 West African Monsoon season
Nick GuySteven Rutledge, Rob Cifelli,
and Timothy LangColorado State University
Tom RickenbachEast Carolina University
21 July 2009
Motivations
• Categorize MCS- and sub-MCS -scale convective systems in 2006 monsoon season
• Obtain statistics for MCS- and sub-MCS -designated convection on a regional scale
• Use of multiple platforms for analysis and verification of mesoscale model simulations
Radar LocationsTOGA
NPOL
MIT
Common Operating Period: 15 August – 16 September 2006
Seasonal Stats # Mean Time (hrs) Total Rain Fraction
Total Area Fraction
TOGA MCS 6 10.8 0.670 0.395
Maritime Sub-MCS 28 6.5 0.33 0.605
NPOL MCS 12 9.5 0.733 0.576
Coastal Sub-MCS 45 5.9 0.267 0.424
MIT MCS 37 12.1 0.923 0.873
Continental Sub-MCS 82 5.2 0.077 0.127
Precipitation Climatology
Anomaly – Deviation from TRMM climatological precipitation mean
WAM Region
TOGA (Maritime)[Mean ~ 1.0]
NPOL (Coastal)[Mean ~ 0.9]
MIT (Continental)[Mean ~ 1.1]
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Seasonal Rainrates
Good trend agreement between ground and satellite products
Track bands of precip associated with disturbances
1
2
Lightning Climatology
NPOL
MCS and Sub-MCS StatisticsSystem Stats Mean Conv
FractionMean CAPE
(Jkg-1)WWLLN
# Rain Area Before
Arrival
During Flashes
(CG)
TOGA MCS 6 0.614 0.149 1115 1006 107
Maritime Sub-MCS 28 0.613 0.126 658 654 1
NPOL MCS 12 0.688 0.187 1630 1299 98
Coastal Sub-MCS 45 0.759 0.238 1665 1528 14
MIT MCS 37 0.634 0.199 2276 1625 75
Continental Sub-MCS 82 0.676 0.253 2037 2221 3
Case StatisticsMCS Case Stats Mean Conv
FractionMean CAPE
(Jkg-1)WWLLN Tb < 233 K
Rain Area Before
Arrival
During Flashes
(CG)
Fraction
TOGA Case 1 0.794 0.140 1697 1544 385 0.281
Maritime Case 2 0.743 0.238 1585 779 10 0.175
NPOL Case 1 0.710 0.187 2712 1989 1 0.299
Coastal Case 2 0.605 0.173 1616 929 150 0.555
MIT Case 1 0.532 0.110 2446 903 220 0.356
Continental Case 2 0.736 0.248 2382 2344 11 0.320
Vertical Structure
Summary
• 2006 WAM season is “average” – Via TRMM rainfall and lightning climatology (domain: 0-30N,
30W-30E)
• Regional analysis defined via 3 radar sites represents continental, coastal, and maritime locations– TOGA (maritime) domain average for precipitation– NPOL (coastal) domain below average for precipitation– MIT (continental) domain slightly above average for precipitation– MCS scale events constitute greater fraction of rainfall inland
• Large precipitation events tracked across longitudinal domain
• No apparent first order correlation to environmental variables – must look at wave forcing as well
• Vertical structure varies with region, resembling typical “continental” and “maritime” structures
Future Work• AEWs: Define and calculate associated
convective statistics for each domain• Case Studies:
– 5-10 Sep 2006 possibly associated with non-developing wave
– 8-12 Sep 2006 possibly associated/interacts with wave that produced Hurricane Helene
– 12-14 Sep 2006
• Closer look at the satellite vs. ground products relationship
• Work with NASA Goddard Space Flight Center (Greenbelt, MD) to assess mesoscale model simulations of 2006 WAM events
Wave Passages
Wave definitions from Janicot et al (2008)
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