US Winters Arriving Earlier, Leaving Sooner
Following recent trends, 2016’s winter was a month shorter than the average winter last century. The 2016 winter was extraordinary, with the average first freeze occurring two weeks later than the 20th century average and the last frost occurring nine days earlier. Over the past ten years, weather stations nationwide have recorded the start of the winter a week later than winters from 1971 to1 980. In an article by Seth Borenstein, Associated Press Science Writer, experts are quoted on research looking at changes that signal later falls and earlier springs. Ken Kunkel, a meteorologist at the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information, pointed out a trend starting around 1980 in which freezes occur later and later. Kunkel compare data from 700 weather stations across the United States going back to 1895 and found that while in some places the first freeze may occur earlier in some years, on average the trend is toward later freezes. Theresa Crimmins, a University of Arizona ecologist and assistant director of the National Phenology Network, which studies how plants and animals adapt to changes in seasonal timing, said that these changes may be good for some organisms but bad for others. According to University of Oklahoma meteorology professor Jason Furtado, shorter winters have long been predicted by climate scientists and can be expected to occur more frequently in the coming decades as a result of climate change. The Borenstein article can be found at https://www.apnews.com/664a16182cbc4e3e9a26957f3cddc927
GRACE Satellite Mission Ends
Originally launched in 2002 for a planned five-year mission, the GRACE satellites exceeded expectations and the mission was only terminated in late 2017. The eighth of the GRACE-2 satellite’s twenty battery cells failed, causing the termination. The mission consisted of a pair of satellites designed to measure fractional changes in Earth’s gravity based on the position of the satellites relative to each other. Scientists around the world utilized this data to examine large-scale changes in water storage. Although its data could not capture small-scale changes in groundwater, it was effective in showing trends across large watersheds, such as the Colorado River Basin. A new satellite will soon take the place of the GRACE mission. GRACE Follow-On will make the same measurements and is set to launch in March 2018.
New Drought Index Uses GRACE Satellite Data
Drought monitoring is important for implementing drought mitigation plans and managing water supplies. Researchers have devised a new drought index incorporating groundwater storage into drought assessments, which they described in an article for the American Meteorological Society Journals Online. The index relies on data captured from NASA’s GRACE mission and the GRACE Follow-On mission, which is scheduled to be launched in early 2018. The GRACE-DSI provides for accurate and continuous drought monitoring, and because it is based on satellite gravity observations, it is able to retrieve data in remote areas. The new index performed favorably when compared with other popular drought indices. With the new index, researchers are confident in their ability to identify hydrological drought for both regional and global-scale monitoring. The journal article is accessible at http://journals.ametsoc.org/doi/10.1175/JCLI-D-16-0458.1.