Climate mapping: temperatures are rising, especially daily lows | New
Oregon State University’s new 30-year ‘normal’ US climate maps show the area east of the Rockies is getting wetter, the southwest is getting drier, and temperatures are gradually rising – Daily minimums increasing faster than daily maximums.
“When we put out the normal news every 10 years, we take a decade out of a 30-year period and add another, which means the changes we’re seeing are subtle,” said geospatial climatologist Chris Daly, professor at the College of Engineering and founding director of OSU’s PRISM Climate group. “But temperatures are definitely rising and daily minimum temperatures are rising faster than the maximums.”
PRISM stands for Parameter-elevation Regressions on Independent Slopes Model, and the 30-year normals are the climate group’s signature product, one that is “uniquely precise and detailed,” says Daly.
“These maps are the flagship of our suite of digital weather and climate datasets that seamlessly cover all of the lower 48 states and are downloaded tens of thousands of times a day and used everywhere,” he said. -he declares. “PRISM datasets are used by many government agencies including NOAA, EPA and NASA and the Departments of Defense, Energy and Home Affairs. The private sector also relies on PRISM data, in a wide range of applications that include agriculture, hydrology, engineering, ecology and economics.
Private citizens can also use the maps to check the average conditions in their hometown by going to the normals page and selecting the data and month of interest, and the applicable color-coded map appears on the screen.
PRISM is a computer model, developed by Daly in 1991 while he was holding a doctorate. a student at Oregon State, who digitally mimicked techniques used by 20th-century climatologists who hand-drew climate maps for the U.S. Department of Agriculture’s Natural Resources Conservation Service.
Working in concert with NRCS hydrologist / climatologist Phil Pasteris of Tigard, Daly helped “bring USDA into the digital world” by creating a computerized replacement for a process so long that climate maps had not been put in place. Up to date for almost 30 years, Daly mentioned.
With funding from the NRCS, PRISM published its first 30-year normals, for the period 1961 to 1990.
Since then, PRISM, part of the OSU-based Northwest Alliance for Computational Science & Engineering, has released updated normals every 10 years, each time adding data and modeling from the most recent decade and removing the least recent. This latest update to normals, which covers the years 1991-2020, was sponsored by the USDA Risk Management Agency, which oversees the federal crop insurance program.
“What we try to do each time is to improve the technology and our data inputs to make the normals as close as possible to the current state of knowledge on average spatial climate models,” said Daly. “NOAA is the official provider of climate change statistics and we are staying out of it. We focus on the spatial aspect and creating a seamless coverage of climate models across the continental United States. This year, for the fourth time we’ve done this, we’ve made a big effort to add new data sources from new weather station networks. “
PRISM added 9,000 precipitation stations, for a total of 26,600; 3,000 temperature stations, bringing the total to 19,500; 2,400 dew point stations, for a total of 6,400; and 2,800 vapor pressure deficit stations, bringing the total to 6,400.
Solar radiation was added to climate normals for the first time, thanks to a three-year collaboration between the PRISM group and David Rupp of the OSU College of Earth, Ocean, and Atmospheric Sciences. Data on solar radiation reached PRISM through various sources, including the state’s agricultural networks and the Citizen Weather Observer Program, a public-private partnership with more than 7,000 stations in North America.
Daly said nearly 90% of precipitation data comes from citizen science programs, one of them, the Community Collaborative Rain, Hail & Snow Network, headquartered at Colorado State University, sending daily to the PRISM group thousands of reports from across the country.
While PRISM uses many data sources, Daly said one of the beauties of the advanced algorithm is that it helps fill information gaps.
“We can interpolate where we don’t have weather stations; the PRISM modeling system explains how the characteristics of the Earth affect spatial models of climate on the landscape, ”he said. “We programmed in mountains, valleys, rain shadows, coastlines and water body sources, so that we could make fairly accurate estimates of the average conditions in the lower 48. Our maps have dozens. millions of grid cells, half a mile by half a mile squares.
While the 30-year normals are the hallmark of PRISM, the group also has monthly climate maps of the same resolution dating back to 1895 and daily maps from 1981; these maps integrate the same variables as the normals, the information of which is omnipresent in climatology.
“Anytime you see a detailed map showing percentage of mean or deviation from mean, the PRISM normals are most likely underlying that calculation,” Daly said.