53a4db44-indicator-start-of-spring-process

This indicator was developed using models that relate phenological observations (leaf and bloom dates) to weather and climate variables. These models were developed by analyzing the relationships between two types of measurements: 1) observations of the first leaf emergence and the first flower bloom of the season in lilacs and honeysuckles and 2) daily minimum and maximum temperature data. The models were developed using measurements collected throughout the portions of the Northern Hemisphere where lilacs and/or honeysuckles grow, then applied to temperature records from a larger set of stations throughout the contiguous 48 states. For more information about phonological data collection methods and procedures used to obtain temperature data, see Schwartz et al. (2013) and references cited therein. This indicator is based on the Extended Spring Indices (SI-x) which is an improved methodology from the original Spring Indices (SI) published in Schwartz et al. (2006). Data used are from January 1, 1900 to December 31, 2013. Data was accessed on September 17, 2014.

This activity resulted in the following :

• image 53a4db44-3a38-4234-a243-b1df283aaae4 was derived from dataset Global Historical Climatology Network - Daily
• image 53a4db44-3a38-4234-a243-b1df283aaae4 was derived from dataset Leafing and flowering data for lilacs and honeysuckles 1956-2014