Performance evaluation of 20CRv3 downscaling using WRF over southern Alaska with focus on temperature and precipitation in glaciated areas
- 1School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, Australia.
- 2School of Environment, Geography and Geosciences, University of Portsmouth, Portsmouth, UK.
- 3Climate Change Research Centre, University of New South Wales, Sydney, Australia.
- 4ARC Centre of Excellence for Climate Extremes, University of New South Wales, Sydney, Australia.
- 5NOAA Physical Sciences Laboratory, Boulder, Colorado, USA.
Global warming has raised mean surface temperatures by 0.99 ± 0.15 °C from 1850-1900 to 2011-2020. The temperature rise has been greatest in the high latitudes. Alaska has one of the largest temperate and subarctic glaciated areas in the world, which is highly sensitive to climate change. Currently, the mass loss from these glaciers contributes to about a third of the global sea-level rise. For example, the tidewater glacier Columbia Glacier located within Prince William Sound is the largest single contributor to sea level rise through its rapid retreat, which started in the early 1980s. Although internal controls strongly influence the tidewater glacier cycle, the ubiquitous retreat of Alaskan tidewater glaciers indicates climatic forcing is involved. However, it is unlikely climate controls the rate of retreat. There are insufficient meteorological observations from this region to assess the role of climate across a whole tidewater cycle. This project reconstructs the regional climate of southern Alaska from 1836–2015 using dynamical downscaling of the NOAA-CIRES-DOE 20th Century Reanalysis (20CRv3). To do this, the Weather Research and Forecasting model (WRF) has been used to spatially downscale the reanalysis data to produce high-resolution 4 km (convection permitting) output for southcentral/southeastern Alaska. Five different physics parametrisations have been tested for the year 2010. The model output of these five configurations were evaluated using observational records from the Global Surface Summary of the Day (GSOD). The physics scheme that performed most realistically was identified using root mean square error, R squared and normalized mean error for temperature and precipitation. The study shows that 20CRv3 can successfully be downscaled for the study region. As a result, the leading parametrisation was used for a long-term simulation (179 years) to reconstruct local climate and weather over southern Alaska over a significant part of a tidewater glacier cycle. The results will be used to evaluate the influence of climate on these glaciers for the downscaling period from 1836 to 2015.
How to cite: Koenigseder, S., Barrows, T., Fisher, J., Evans, J., and MacColl, C.: Performance evaluation of 20CRv3 downscaling using WRF over southern Alaska with focus on temperature and precipitation in glaciated areas , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-10585, https://doi.org/10.5194/egusphere-egu23-10585, 2023.
