Monsoon Meteorology

  • View
    41

  • Download
    0

Embed Size (px)

DESCRIPTION

Monsoon Meteorology. ATS 553. Monsoon:. A reversal of the wind direction at the surface, usually accompanied by the change in the precipitation regime, that occurs in the tropics on a seasonal time scale. Caused by:. - PowerPoint PPT Presentation

Text of Monsoon Meteorology

  • Monsoon MeteorologyATS 553

  • Monsoon:A reversal of the wind direction at the surface, usually accompanied by the change in the precipitation regime, that occurs in the tropics on a seasonal time scale.

  • Caused by:the fact that water takes so much longer to heat up or cool down than land does.

  • Three Reasons

  • 1. Cooling by Evaporation

  • 1. Cooling by Evaporation

  • 2. Cooling by Mixing

  • 2. Cooling by Mixing

  • 2. Cooling by Mixing

  • 2. Cooling by Mixing

  • 3. High Specific Heat of Water

  • ThereforeIn the SUMMER hemisphere, tropical land masses are much hotter than the surrounding ocean.In the WINTER hemisphere, tropical land masses are much colder than the surrounding ocean.

    Formation of HEAT LOWS and POLAR HIGHS:

  • Heat Lows1000mb850mb700mb500mb

  • Heat Lows1000mb850mb700mb500mb

  • Heat Lows1000mb850mb700mb500mb

  • Heat Lows1000mb850mb700mb500mb

  • Heat Lows1000mb850mb700mb500mb

  • Heat Lows1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Polar Highs1000mb850mb700mb500mb

  • Fig 6-27 in Ramage

  • Fig 6-27 in Ramage

  • Fig 6-32 in Ramage

  • Monsoon Regions

  • Monsoon RegionsMajor shift or reversal of the circulation features.

  • Monsoon RegionsPrevailing wind isnt just a statistical averageit reflects the real flow in the atmosphere.

  • Monsoon RegionsThe prevailing wind needs to be reasonably robust.

  • Monsoon RegionsMonsoons are NOT just a shift in the storm track, bringing sequences of highs and lows.

  • Fig 6-28 in RamageIndia INDWest Africa WAFREast Africa EAFRSoutheast Asia SEASIAAustralia AUS

  • Where dont monsoons happen?South America1. Cold upwelling means that the land is ALWAYS warmer than the surrounding oceans.

  • Where dont monsoons happen?South America2. SAMER is too narrow at subtropical southern latitudes for a planetary scale anticyclone to form.

  • Where dont monsoons happen?South America3. In the NH, SAMER doesnt extend to regions of subsidence (which favor heat low formation).

  • Where dont monsoons happen?Mexico, SW US1. No region has a 120 wind shift

  • Where dont monsoons happen?Mexico, SW US2. Central America is too narrow for formation of polar highs.

  • Where dont monsoons happen?Mexico, SW US3. Weather is more driven by synoptic disturbances.

    However, a monsoon trough does form over the eastern Pacific..

  • Precipitation Regimes in the Wet Season

  • What You Dont Know About West Africa Is A LotATS 553

  • Political Geography

  • HistoricallyGrain CoastIvory CoastGold CoastSlave Coast

  • Vegetation

  • NDVI in WAFR

  • Sahara

  • Sahara

  • Sahel

  • Sahel

  • Savanna (Soudanian Zone)baobob trees

  • Soudanian Zone

  • Cotton Harvest in Burkina Faso

  • Rainforest

  • Niger River Basin

  • Inland DeltaGreat Mosque at Jenne

  • Landforms

  • Jos Plateau

  • Atakora Mountains

  • Ar Mountains

  • Oueme River Valley

  • Climatology of WAFR Monsoon

  • 925mb Winds in June

  • 925mb Winds in September

  • Time-latitude diagrams along 2.5E(Parakou, Benin)

  • V925mb along 2E

  • U925mb along 2E

  • OLR along 2.5E

  • Thermal Fields in the WAFR Monsoon

  • Surface TemperatureNCEP Climatology

  • Temperature on 2-sep-04

  • Vertical Cross-SectionBoundary between the warn and cold air mass is sloped with height, just like a cold front or a warm front.

  • Vertical Cross-SectionBoundary between the warn and cold air mass is sloped with height, just like a cold front or a warm front.Saharan Air Layer (SAL)Monsoon Layer

  • Vertical Cross-SectionIn the SAL, dry convection keeps the layer well-mixed:Saharan Air Layer (SAL)Monsoon Layer

  • Well-Mixed AirTemperature decreases according to the dry adiabatic lapse rate (DALR).Potential temperature is constant with height.Stability: Statically Neutral!Saharan Air Layer (SAL)Monsoon Layer

  • http://cimss.ssec.wisc.edu/tropic/real-time/wavetrak/sal-atl.html

  • Monsoon LayerTends to be CONDITIONALLY UNSTABLE due to cool conditions at the surface and higher potential temperatures aloft.Temperature decreases by the moist adiabatic lapse rate.Potential temperature increases slowly with height.Saharan Air Layer (SAL)Monsoon Layer

  • IsentropesSAL: Neutral at SFC, stable in upper trop, very stable above tropopauseMonsoon Layer: Conditionally unstable in lower trop, stable in upper trop, very stable above tropopause

    Low High

Recommended

View more >