Trends and Natural Variability of Spring Onset in the Coterminous United States as Evaluated by a New Gridded Dataset of Spring Indices

Toby Ault, Cornell University, Department of Earth and Atmospheric Science, Ithaca, NY, United States, Mark D Schwartz, University of Wisconsin Milwaukee, Milwaukee, WI, United States, Raul Zurita-Milla, University of Twente, Geo-Information Science and Earth Observation, Enschede, Netherlands, Jake F Weltzin, USA National Phenology Network, Tucson, AZ, United States and Julio L Betancourt, USGS Central Region Offices Denver, Denver, CO, United States