PRISM Climate Mapping in Alaska Christopher Daly Director, PRISM Climate Group College of Engineering Oregon State University October 2016

Applied research team since 1991, founded and directed by Dr. Christopher Daly Housed within the Northwest Alliance for Computational Science and Engineering (NACSE), College of Engineering, Oregon State University Climate mapping center for the USDA; de facto climate mapping center for the US Sponsors cut across many federal departments and disciplines PRISM Climate Group Overview

What is PRISM? There are many locations for which no weather observations exist. To create a continuous weather or climate map, station observations are fed into a computer model called PRISM (Parameter-elevation Regressions on Independent Slopes Model). PRISM estimates weather and climate variables, such as temperature and precipitation, on a grid of millions of pixels, each measuring 30 arc- seconds (~800m in the CONUS, ~600m in Alaska)

How Does PRISM Work? For grid cells where no observations exist, PRISM mimics the thinking an expert meteorologist would follow. The model simulates how weather and climate varies with elevation, and accounts for coastal effects, temperature inversions, and terrain barriers that can cause rain shadows. Station PRISM Grid Cell Grand Canyon temperature map: PRISM incorporates the effects of elevation

Alaska Climate Mapping Objective Develop digital, baseline climatological maps of temperature and precipitation that reflect as closely as possible the state of knowledge of climate patterns across Alaska These maps provide the basis for a wide variety of spatial climate analyses and datasets

PRISM Alaska Mapping Timeline 2000: normals – VEMAP - EPRI, NASA, USFS – 2.5 arc-min (~3km) grid resolution 2009: normals – National Park Service (Pam Sousanes) – 30 arc-sec (~600m) grid resolution 2017: normals – National Park Service (Pam Sousanes) – 30 arc-sec (~600m) grid resolution – Increased station data, glacier/hydrologic studies

Arctic High Dominates Cold Air Pooling Coastal Zones

Interior warming Brooks Range Barrier Coastal Zones

Interior warming Coastal Zones Interior warming

Arctic High Strengthening Coastal Zones Interior Cooling

Dry North Slope Dry Interior Rain Shadows

Station Locations

Benefits of NPS Stations

Data Issues SNOTEL and NPS stations suffer from an incorrect equation that transforms YSI extended range probe resistance to temperature An adjustment curve has been developed. Adjustments will affect data mostly after about 2000 For details see poster by Ken Hill after this session +/- 1.2 º C

Improvements / Future Work Incorporate New Station Data – New NPS stations – Other stations/networks added since 2009 Review hydrologic/glacier/snow studies – OSU coastal AK hydrologic study (talk by Dave Hill) – UAF Juneau Ice Field study (Ziemen, Hock et al.) – NW AK Remote sensing analyses (snowcover; talk by Matt Macander) Monthly time series mapping? – Needed to assess trends and variations

CoCoRaHS Observers Needed in Alaska! Anyone can join: