Extended Spring Indices, Continental United States, 1981 - Current Year

The USA National Phenology Network has available a series of gridded products enabling researchers to analyze historical and contemporary data related to the Extended Spring Indices. The Extended Spring Indices are mathematical models that predict the "start of spring" (timing of leaf out or bloom for species active in early spring) at a particular location (Schwartz 1997, Schwartz et al. 2006, Schwartz et al. 2013). These models were constructed using historical observations of the timing of first leaf and first bloom in a cloned lilac cultivar (Syringa x chinensis 'Red Rothomagensis') and two cloned honeysuckle cultivars (Lonicera tatarica 'Arnold Red' and L. korolkowii 'Zabelii'). Primary inputs to the model are temperature and weather events, beginning January 1 of each year (Ault et al. 2015). The model output is the day of year that a particular location met the requirements of one of the Spring Index models (First Leaf or First Bloom).As the Extended Spring Index models are based on individual models for each of three calibration species, model output is available for each of these species individually, or as an average of the three species. The original Spring Indices (Schwartz 1997) included a chilling requirement. In a more recent version of the model (Schwartz et al. 2013), referred to as the Extended Spring Indices, the chilling requirement was excluded, allowing the index to be extended across the entire U.S. Spring index products in the USA National Phenology Network's gridded data product suite are based on the Extended Spring Indices.The data are accessible via the USA-NPN Geoserver (user access facilitated by the Geoserver Request Builder: https://www.usanpn.org/geoserver-request-builder), and a subset can be viewed in the USA-NPN Visualization Tool (https://www.usanpn.org/data/visualizations).For all inquiries regarding this dataset, please contact the USA-NPN. This data is subject to the USA-NPN's Data Use Policy.

美国国家物候学网络（USA National Phenology Network，简称USA-NPN）公开了一系列网格化产品，可供研究人员开展与扩展春季指数（Extended Spring Indices）相关的历史与当代数据分析工作。扩展春季指数是一类数学模型，用于预测特定地点的“春季起始时间”——即早春活跃物种的展叶或开花物候期（Schwartz 1997、Schwartz等2006、Schwartz等2013）。该类模型基于克隆紫丁香栽培品种（Syringa x chinensis 'Red Rothomagensis'）与两个克隆金银花栽培品种（Lonicera tatarica 'Arnold Red'、L. korolkowii 'Zabelii'）的首次展叶、首次开花物候观测数据构建。模型的核心输入为气温与天气事件，数据序列起始于每年1月1日（Ault等2015）。模型输出为特定地点满足某一春季指数模型（首次展叶或首次开花）要求的年积日（Day of Year, DOY）。由于扩展春季指数模型针对三个校准物种分别构建了独立子模型，因此其输出可分别对应三个物种，或取三个物种的均值。原始春季指数（Schwartz 1997）包含低温需求模块，而在后续更新的模型版本（Schwartz等2013，即扩展春季指数）中，该低温需求模块被移除，使得该指数可覆盖美国全境。USA-NPN的网格化数据集产品套件中的所有春季指数产品，均基于扩展春季指数模型构建。该数据集可通过USA-NPN地理服务器获取，用户可借助地理服务器请求构建工具（Geoserver Request Builder）完成访问，访问地址为https://www.usanpn.org/geoserver-request-builder；部分数据可通过USA-NPN可视化工具预览，访问地址为https://www.usanpn.org/data/visualizations。有关该数据集的所有咨询，请联系USA-NPN。本数据需遵循USA-NPN的数据使用政策。