SSC regional climate zones

This page is a work in progress on the development of SSC climate zones, based on PCA decomposition of seasonal normals, and a k-means cluster analysis. All North American and European available stations were included. Nine zones were originally defined, and since zone 3 had nearly half of the stations, I ran a second cluster analysis to furhter divide the zone into 3 subzones. Jim Detwiler has produced the maps below depicting these zones.

		1 Southeast 60 stations Capital: Jackson, MS Stations in this zone experience a distinct seasonality, with a very variable winter calendar, during which time nearly all weather types are present. During the summer, the subtropical Bermuda High controls the weather, and Moist Tropical (and Moist Moderate on cloudier days) account for nearly 3/4ths of all days.
		2 Basin and range 34 stations Capital: Amarillo, TX This climate zone is found in elevated arid areas. Following Zone 7, it is the second-most affected by dry weather types, with nearly half of all days DM.
		3a Laurentian 58 stations Captial: Alpena, MI Of the three mid-latitude subzones, this zone features the most variability, with considerable difference between winter and summer, and the presence of all weather types throughout the summer, with limited tropical influence in the winter.
		3b Northern Rockies 33 stations Capital: Glasgow, MT Farther west of Zone 3a, this zone features much more limited MT-penetration. With high terrain nearby, there is some incidence of DT year-round, but also greater MP occurrence than in other temperate zones.
		3c True mid-latitude 54 stations Capital: Washington, DC Farther south of Zone 3a, this zone which borders Zone 1 contains a longer summer of significant MT occurrence, and more limited polar-weather type influcence than 3a or 3b. Its name derives from the fact that it's the only climate zone that is influenced by all weather types year-round.
		4 Arctic 37 stations Captial: Schefferville, QC This zone is most directly affected by the Arctic, with an abundance of polar weather types, with DP peaking in late winter, and MP peaking at the autumn ice minimum.
		5 Tropical 13 stations Capital: Key West, FL On the southern extreme of the continental US, and Puerto Rico and Hawaii, this zone features a virtual MT monopoly in the summer, with limited variability in the winter. This is the only zone with the same weather type making up more than 50% of the calendar in every month of the year.
		6 Boreal coast 15 stations Capital: Yakutat, AK Dominated by adjacent cold ocean waters, this climate zone is dominated by the MP weather type, which makes up over half of the average calendar. Dry Polar is common in the winter months, and MM occurence varies from station to station, based on proximity to a milder oceanic fetch on occasion.
		7 Sonoran 5 stations Capital: Phoenix, AZ The most distinct of the climate zones, this is the only climate zone dominated by DT. The five stations in this zone actually have two distinct summer patterns; Phoenix and Yuma heavily affected by the (MT) monsoon, and Las Vegas, Tucson, and Daggett not. The resulting climograph is midway between the two.
		8 Marine 16 stations Capital: Halfiax, NS This climate zone is quite similar to Zone 6, although with the stations farther south, warmer waters bring MM days more frequently, with MT occurring on occasion in summer. This climate zone also has the highest TR frequency of the lot.
		9 European 58 stations Capitals: Seattle, WA and Stuttgart, Germany Most of the stations within this climate type are in western Europe, with a few Pacific US stations included. Similar to zones 3a and 3c, all weather types have a presence, although due to Zone 9's maritime location, MM is more prominent here than in any other zone.