Shouquan Cheng
Department of Geography
The Chinese University of Hong Kong
Shatin, New Territories, Hong Kong
Dr. Laurence S. Kalkstein
Synoptic Climatology Laboratory
Center for Climatic Research
Department of Geography
University of Delaware
ABSTRACT
This paper discusses the application of a year-round synoptic classification
procedure to define climatological seasons based upon the frequency occurrence
of seasonal air masses. The classification is developed through air mass 'seed
day' identification and discrminant function analysis, and assigns each day
to 1 of 18 air mass types for each of 14 stations along die East Coast of
the United States. Unlike the 'astronomical' definition of seasons, which
divides a year into 4 equal periods, the length of winter ranges from about
l 1/2 mo in Miami, Florida to more than 4 mo in Portland, Maine as determined
by air mass frequencies. The summer extends more than 5 mo in Florida, while
it only lasts 3 mo in Maine. In the mid-Atlantic region, there are 2 longer
seasons (summer and winter; about 4 mo each) and 2 shorter seasons (spring
and fall; about 2 mo each). The seasonal definition proposed here more closely
corresponds to phenological responses than do traditional definitions. The
information can be applied to numerous environmental assessment problems,
including aruinal demographics and habitat distributions, plant phenology
and subsequent pollen release. migration and hibernation patterns, human
health and psychological responses to climate, and agricultural planning activities.