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Melinda Webster

Research Scientist/Engineer - Principal

Email

melindaw@uw.edu

Phone

206-685-4551

Department Affiliation

Polar Science Center

Education

B.S. Oceanography, University of Washington, 2010

M.S. Oceanography, University of Washington, 2013

Ph.D. Oceanography, University of Washington, 2016

Publications

2000-present and while at APL-UW

Inter-comparison of melt pond products from optical satellite imagery

Lee, S., J. Stroeve, M. Webster, N. Fuchs, and D.K. Perovich, "Inter-comparison of melt pond products from optical satellite imagery," Remote Sens. Environ., 301, doi:10.1016/j.rse.2023.113920, 2024.

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1 Feb 2024

Given the importance that melt ponds have on the energy balance of summer sea ice, there have been several efforts to develop pan-Arctic datasets using satellite data. Here we intercompare three melt pond data sets that rely on multi-frequency optical satellite data. Early in the melt season, the three data sets have similar spatial patterns in melt pond fraction, but this agreement weakens as the melt season progresses despite relatively high interannual correlations in pond fractions between the data products. Most of the data sets do not exhibit trends towards increased melt pond fractions from 2002 to 2011 despite overall Arctic warming and earlier melt onset. Further comparisons are made against higher resolution optical data to assess relative accuracy. These comparisons reveal the challenges in retrieving melt ponds from coarse resolution satellite data, and the need to better discriminate between leads, small open water areas and melt ponds. Finally, we assess melt pond data sets as a function of ice type and how well they correlate with surface albedo. As expected, melt pond fractions are negatively correlated with surface albedo, though the strength of the correlation varies across products and regions. Overall, first-year ice has larger melt pond fractions than multi-year ice.

Rainy days in the Arctic

Boisvert, L.N., M.A. Webster, C.L. Parker, and R.M. Forbes, "Rainy days in the Arctic," J. Clim., 36, 6855-6878, doi:10.1175/JCLI-D-22-0428.1, 2023.

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1 Oct 2023

The Arctic is warming faster than anywhere on Earth, and with these warming temperatures, there is likely to be more precipitation falling as rain. This precipitation phase change will have profound impacts on the hydrologic cycle, energy balance, and snow and sea ice mass budgets. Here, we examine the number of rainfall days in the Arctic from three reanalysis: ERA-Interim, ERA5 and MERRA-2 over 1980-2016. We show that the number of rainfall days has increased over this period, predominantly in the autumn and in the North Atlantic and Peripheral Seas, and the length of the rain season has increased in all reanalyses. This is positively correlated to the number of days with above freezing air temperatures and a lengthening of the warm season. ERA-Interim produces significantly more rainfall days than other reanalyses and CloudSat observations, as well as significantly more rainfall when temperatures are below freezing. Investigation into the cloud microphysics schemes revealed that the scheme employed by ERA-Interim allowed for mixed-phase clouds to form rain at temperatures below freezing following a temperature-dependent phase partitioning function between 250K and 273K. This simple diagnostic treatment erroneously overestimates rain at temperatures below 273K and produces unrealistic rainfall compared to ERA5 and MERRA-2. This work highlights the importance of having accurate physics and improving microphysical schemes in models for simulating precipitation in the Arctic and the caution that is warranted for interpreting reanalysis trends.

Alaska terrestrial and marine climate trends, 1957–2021

Ballinger, T.J., and 9 others including M.A. Webster, "Alaska terrestrial and marine climate trends, 1957–2021," J. Clim., 36, 4375-4391, doi:10.1175/JCLI-D-22-0434.1, 2023.

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1 Jul 2023

Some of the largest climatic changes in the Arctic have been observed in Alaska and surrounding marginal seas. Near-surface air temperature (T2m), precipitation (P), snowfall, and sea ice changes have been previously documented, often in disparate studies. Here we provide an updated, long-term trend analysis (1957–2021; n=65 years) of such parameters in ERA5, NOAA NClimGrid, NOAA NCEI Alaska climate division, and composite sea ice products preceding the upcoming Fifth National Climate Assessment (NCA5) and other near-future climate reports. In the past half century, annual T2m has broadly increased across Alaska, and during winter, spring, and autumn on the North Slope and North Panhandle (T2m>0.50°C decade-1). P has also increased across climate divisions, and appears strongly interrelated with temperature-sea ice feedbacks on the North Slope, specifically with increased (decreased) open water (sea ice extent). Snowfall equivalent (SFE) has decreased in autumn and spring, perhaps aligned with a regime transition of snow to rain, while winter SFE has broadly increased across the state. Sea ice decline and melt season lengthening also have a pronounced signal around Alaska, with the largest trends in these parameters found in the Beaufort Sea. Alaska’s climatic changes are also placed in context against regional and contiguous U.S. air temperature trends, and show ~50% greater warming in Alaska relative to the lower-48 states. Alaska T2m increases also exceed those of any contiguous U.S. sub-region, positioning Alaska at the forefront of U.S. climate warming.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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