Effects of Saharan dusts on weather and climate
- Slides: 14
Effects of Saharan dusts on weather and climate over the Atlantic: How Nature foiled the 2006 hurricane forecasts William K. M. Lau NASA/GSFC Laboratory for Atmospheres Co-author: K. M. Kim/GEST
Effects of Saharan dusts on weather and climate over the Atlantic • Annual emission of Saharan dust is estimated to be 4 billion tons • Increased Saharan dust outbreak since the 1970’s, associated with the prolonged drought in Sahel and increased dust storm over the Sahara desert Possible weather and climate impacts: • SAL dry air may suppress tropical cyclogenesis, and/or hurricane formation • Microphysics effects: suppress warm rain; increase ice-nucleation and deep convection • • Solar Dimming Effect “ Elevated Heat Pump” Effect MODIS Images
How did nature foil the 2006 hurricane forecasts? 2005 15 H, 12 TS, 2 TD, 1 STS, 1 STD 2006 5 H, 4 TS
El Nino-SST effect Dust-SST “Solar Dimming” effect Dust appears to be the primary cause for SST cooling in the MDR; El Nino is associated with reduced SST (and increased vertical shear) in the eastern equatorial Atlantic, suppresses cyclogensis
More dust means lesser number of days of tropical cyclones
Correlations of HC/TS statistics with a) Barbados dust and b) El Nino SST, 1980 -2007 • TS = sustained wind speed > 34 knts (17 m/s) HC = sustained wind speed >64 knts (33 m/s)
The “Elevated Heat Pump” effect : fv. GCM simulation of radiative Effect on circulation and climate of the West African region Caribbean Africa
Gulf of Guinea Africa
Short wave flux = -30. 4 Wm-2 Longwave flux = 5. 9 Wm-2 Sensible heat flux = 2. 1 Wm-2 Latent heat flux = 8. 6 Wm-2 Net surface flux = -14. 1 Wm-2 Estimate of anomalous (aerosol+ water cycle feedback) surface energy flux over the N. Atlantic/Caribbean region
Anomalous Overturning Circulation induced by “Elevated Heat Pump” effect for WAM increased upper level clouds reduced upper level clouds induced subsidence suppresses convection increased low level clouds increased moisture influx reduced SW Caribbean Region cools ocean reduced SW cools land Africa dust source
West Africa East Atlantic Caribbean
Great zimbabwe spice chart
Galactic city model
Trans saharan trade route map
Trade routes in the 1500s
Sub saharan africa physical features
Trans saharan trade
African city model
Sub saharan africa landforms
Trans saharan trade route
Sub-saharan africa
Sub saharan africa ap world history
Climate change 2014 mitigation of climate change
How does wind affect weather and climate
Clim 101
How do prevailing winds affect climate
