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Detecting the onset of spring: a possible application of phenological models

TitleDetecting the onset of spring: a possible application of phenological models
Publication TypeJournal Article
Year of Publication1990
AuthorsSchwartz, MD
JournalClimate Research
Page range23-29

The onset of the spring season is a phenomenon associated with systematic changes in theland surface-atmosphere interface, which will likely be modified by climate change. A measure of thiscomplex feature, or 'spring index', should reflect the variations in both weather events and plantphysiology usually identified with mid-latitude spring. In this study, variables representing plantphenology, synoptlc weather system frequency, surface temperature-thickness relationship 'breaks'(difference between surface maximum temperature and thickness-derived layer mean temperature),and last freeze date (0°C or lower) are compared and examined as components of a comprehensivemeasure of the onset of spnng. Two small networks of stations in the eastern and central United Statesare used as test data over the period 1961 to 1980. The phenology-synoptic weather component (P-SW),derived from regression-based models of first leaf emergence, has the strongest relationship lath othermeasures, and can be produced from generally available surface data. This component is proposed as afirst approximation of a comprehensive spring index, suitable for analyzing the impact of past and futureclimate changes on the onset of spring.