Appendix 1: __________________________________________________________________ Regional climates, based on the Koppen system of classification (1931), as modified by G. T. Trewartha (1968) and Trewartha and others (1967). Koppen group and types Ecoregion equivalents A--Tropical Humid Climates Humid Tropical Domain (400) Tropical wet (Ar) Rainforest Division (420) Tropical wet-dry (Aw) Savanna division (410) B--Dry Climates Dry Domain (300) Tropical/subtropical Tropical/subtropical steppe semiarid (BSh) division (310) Tropical/subtropical Tropical/subtropical desert arid (BWk) division (320) Temperate semiarid (BSk) Temperate Steppe Division (330) Temperate arid (BWk) Temperate Desert Division (340) C--Subtropical Climates Humid Temperate Domain (200) Subtropical dry summer (Cs) Mediterranean Division (260) Humid subtropical (Cf) Subtropical Division (230) Prairie Division (250)* D--Temperate climates Temperate oceanic (Do) Marine Division (240) Temperate continental, warm Hot Continental Division (220) summer (Dca) Prairie Division (250)* Temperate continental, cool Warm Continental Division (210) summer (Dcb) Prairie Division (250)* E--Boreal climates Polar domain (100) Subarctic (E) Subarctic Division (130) F--Polar Climates Tundra (Ft) Tundra Division (120) Ice cap (Fi) *Koppen did not recognize the Prairie as a distinct climatic type. The ecoregion classification system represents it at the arid sides of the Cf, Dca, and Dcb types. Definitions and Boundaries of Koppen-Trewartha System Ar All months above 64F (18C) and no dry season. Aw Same as Ar, but with 2 months dry in winter. BSh Potential evaporation exceeds precipitation, and all months above 32F (0C). BWh One-half the precipitation of BSh, and all months above 32F (0C). BSk Same as BSh, but with at least 1 month below 32F (0C). BWk Same as BWh, but with at least 1 month below 32F (0C). Cs 8 months 50F (10C) or more, coldest month below 64F (18C), and summer dry. Cf Same as Cs, but no dry season. Do 4 to 7 months above 50F (10C), coldest month above 32F (0C). Dca 4 to 7 months above 50F (10C), coldest month below 32F (0C), and warmest month above 72F (22C). Dcb Same as Dca, but warmest month below 72F (22C). E Up to 3 months above 50F (10C). Ft All months below 50F (10C). Fi All months below 32F (0C). A/C boundary = Equatorial limits of frost; in marine locations, the isotherm of 64F (18C) for coolest month. C/D boundary = 8 months 50F (10C). D/E boundary = 4 months 50F (10C). E/F boundary = 50F (10C) for warmest month. B/A, B/C, B/D, B/E boundary = Potential evaporation equals precipitation.