EAS 485 Content - Surface and Upper Air Climatology

1. Climatology Articles
   1. North American Surface
      1. Whittaker and Horn (1981, MWR) - Cyclogenesis only
         1. Shows areas prone to surface cyclogenesis
            1. Lee of mountains
               1. Near 30°N in spring and fall, then moves northward in summer
               2. Not a smooth transition
               3. Not as active in fall as in spring
            2. Western side of warm water bodies
               1. Peak activity in winter
               2. Natural baroclinic zone between warm ocean currents and cold air masses on eastern edge of continents
                  1. Favors creation and strengthening of jet streaks due to Thermal Wind Law
      2. Zishka and Smith (1980, MWR) - Genesis and Lysis areas for cyclones and anticyclones plus tracks
         1. Tracks shown by regions of relatively high variability
         2. January cyclones
            1. Cyclones mostly form in lee of mountains, western Gulf, and off northeast US coast
               1. Conservation of potential vorticity in a barotropic atmosphere produces lee troughing
            2. Cyclones dissipate off south coast of Alaska, Pacific Northwest, northern Appalachians
            3. Tend to move west to east or southwest to northeast.
         3. January anticyclones
            1. Far less frequent
            2. Form to lee of Rockies only or High Plains
               1. During +PNA pattern, can develop downwind of ridge
            3. Lysis in southern Rockies, southeastern US
            4. Track west to east or northwest to southeast
            5. Avoid Great Lakes while cyclones track over them
               1. QG effect of diabatic heating lowers pressure
            6. Bogus track within Intermountain region
               1. Residual of NWS Sea-Level Pressure error over mountains - maximum difference between station pressure and SLP occurs in January over central Rockies (3-5 mb)
         4. July cyclones
            1. Same trends but further north
            2. Colorado genesis region disappears
         5. July anticyclones
            1. Nearly all movement near US/Canadian border from Alberta to south of Great Lakes to northern Appalachians
   2. 500 mb short-waves
   1. Sanders (Dec. 1988, MWR)
      1. Subjective study using "wave analysis"
         1. Plot single representative height contour (552 dm at 500 mb)
         2. 9-year data set
      2. Life Cycle
         1. 8-15 present on any given day in NH
         2. Median duration of 12 days
         3. Mode of 5 days
      3. Births greater tendency downwind of major mountain ranges (Rockies, Alps, Urals, Himalayas)
      4. Deaths over eastern oceans (see Blackmon et al.), central Asia to west of mountains, and Middle East
      5. Note no births over high surface cyclone frequency areas, so most initiated by pre-existing shortwave trough
   2. Lefevre and Nielsen-Gammon (1995, Tellus)
      1. Objective study using 500 mb geostrophy curvature vorticity maxima
      2. 20-year data set
      3. Life Cycle
         1. Mean: 5.3 days with a maximum of 44 days
      4. Genesis Regions: north-central North America, Mediterranean Sea, southeast Asia
      5. Termination regions: extreme eastern Pacific, Mediterranean Sea, southwest Asia
      6. Genesis regions well upstream of areas of frequent surface cyclogenesis

Last updated: March 19, 2009

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