Melinda Webster Research Scientist/Engineer - Principal melindaw@uw.edu Phone 206-685-4551 |
Education
B.S. Oceanography, University of Washington, 2010
M.S. Oceanography, University of Washington, 2013
Ph.D. Oceanography, University of Washington, 2016
Videos
Snow Accumulations on Arctic Sea Ice Snow plays a key role in the growth and decay of Arctic sea ice each year. APL-UW research assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge compared with in situ measurements taken in spring 2012 and historical data from the Soviet drifting ice stations of the mid-20th century. Snow depths have declined in the western Arctic and Beaufort and Chukchi seas. Thinning is correlated with the delayed onset of sea ice freeze-up during autumn. |
11 Sep 2014
|
Publications |
2000-present and while at APL-UW |
Summer snow on Arctic sea ice modulated by the Arctic Oscillation Webster, M.A., A. Riihelä, S. Kacimi, T.J. Ballinger, E. Blanchard-Wigglesworth, C.L. Parker, and L. Boisvert, "Summer snow on Arctic sea ice modulated by the Arctic Oscillation," Nat. Geosci., EOR, doi:10.1038/s41561-024-01525-y, 2024. |
More Info |
6 Sep 2024 |
|||||||
Since the 1970s, Arctic sea ice has undergone unprecedented change, becoming thinner, less extensive and less resilient to summer melt. Snow's high albedo greatly reduces solar absorption in sea ice and the upper ocean, which mitigates sea–ice melt and ocean warming. However, the drivers of summertime snow depth variability are unknown. The Arctic Oscillation is a mode of natural climate variability, influencing Arctic snowfall and air temperatures. Thus, it may affect summertime snow conditions on Arctic sea ice. Here we examine the role of the Arctic Oscillation in summer snow depth variability on Arctic sea ice in 19802020 using atmospheric reanalysis, snow modelling and satellite data. The positive phase leads to greater snow accumulation, ranging up to ~4.5 cm near the North Pole, and higher surface albedo in summer. There are more intense, frequent Arctic cyclones, cooler temperatures aloft and greater snowfall relative to negative and neutral phases; these conditions facilitate a more persistent summer snow cover, which may lessen sea-ice melt and ocean warming. The Arctic Oscillation influence on summertime snow weakens after 2007, which suggests that future warming and Arctic sea-ice loss might modify the relationship between the Arctic Oscillation and snow on Arctic sea ice. |
Model biases in simulating extreme sea ice loss associated with the record January 2022 Arctic cyclone Blanchard-Wigglesworth, E., S. Brenner, M. Webster, C. Horvat, Ø. Foss, and C.M. Bitz, "Model biases in simulating extreme sea ice loss associated with the record January 2022 Arctic cyclone," J. Geophys. Res., 129, doi:10.1029/2024JC021127, 2024. |
More Info |
24 Aug 2024 |
|||||||
In January 2022, the strongest Arctic cyclone on record resulted in a record weekly loss in sea ice cover in the Barents-Kara-Laptev seas. While ECMWF operational forecasts skillfully predicted the cyclone, the loss in sea ice was poorly predicted. We explore the ocean's response to the cyclone using observations from an Argo float that was profiling in the region, and investigate model biases in simulating the observed sea ice loss in a fully coupled GCM. The observations showed changes over the whole ocean column in the Barents Sea after the passage of the storm, cooling and mixing with enough implied heat release to melt roughly 1 m of sea ice. We replicate the observed cyclone in the GCM by nudging the model's winds to observations above the boundary layer. In these simulations, the associated loss of sea ice is only about 10%15% of the observed loss, and the ocean exhibits very small changes in response to the cyclone. With the use of a simple 1-D ice-ocean model, we find that the overly strong ocean stratification in the GCM may be a significant source of model bias in its simulated response to the cyclone. However, even initialized with observed stratification profiles, the 1-D model also underestimated mixing and sea ice melt relative to the observations. |
The effects of summer snowfall on Arctic sea ice radiative forcing Chapman-Dutton, H.R., and M.A. Webster, "The effects of summer snowfall on Arctic sea ice radiative forcing," J. Geophys. Res., 129, doi:10.1029/2023JD040667, 2024. |
More Info |
28 Jul 2024 |
|||||||
Snow is the most reflective natural surface on Earth. Since fresh snow on bare sea ice increases the surface albedo, the impact of summer snow accumulation can have a negative radiative forcing effect, which would inhibit sea ice surface melt and potentially slow sea-ice loss. However, it is not well known how often, where, and when summer snowfall events occur on Arctic sea ice. In this study, we used in situ and model snow depth data paired with surface albedo and atmospheric conditions from satellite retrievals to characterize summer snow accumulation on Arctic sea ice from 2003 to 2017. We found that, across the Arctic, ~2 snow accumulation events occurred on initially snow-free conditions each year. The average snow depth and albedo increases were ~2 cm and 0.08, respectively. 16.5% of the snow accumulation events were optically thick (>3 cm deep) and lasted 2.9 days longer than the average snow accumulation event (3.4 days). Based on a simple, multiple scattering radiative transfer model, we estimated a 0.086 ± 0.020 W m-2 change in the annual average top-of-the-atmosphere radiative forcing for summer snowfall events in 20032017. The following work provides new information on the frequency, distribution, and duration of observed snow accumulation events over Arctic sea ice in summer. Such results may be particularly useful in understanding the impacts of ephemeral summer weather on surface albedo and their propagating effects on the radiative forcing over Arctic sea ice, as well as assessing climate model simulations of summer atmosphereice processes. |
In The News
Arctic melt ponds influence sea ice extent each summer but how much? Mongabay, Michael C. Bradbury July marks the midpoint of the summer sea ice melt season, during which ice declines rapidly under the almost constant Arctic sun, and melt ponds form on ice floes. Scientists study melt ponds to better understand sea ice dynamics and to help forecast the annual sea ice minimum in September. |
20 Aug 2024
|
UW researchers attend sea ice conference above the Arctic Circle UW News and Information, Hannah Hickey University of Washington polar scientists are on Alaska’s North Slope this week for the 2016 Barrow Sea Ice Camp. Supported by the National Science Foundation, the event brings together U.S.-based sea ice observers, satellite experts and modelers at various career stages to collect data and discuss issues related to measuring and modeling sea ice. The goal is to integrate the research community in order to better observe and understand the changes in Arctic sea ice. |
1 Jun 2016
|
Snow has thinned on Arctic sea ice UW News and Information, Hannah Hickey From research stations drifting on ice floes to high-tech aircraft radar, scientists have been tracking the depth of snow that accumulates on Arctic sea ice for almost a century. Now that people are more concerned than ever about what is happening at the poles, research led by the University of Washington and NASA confirms that snow has thinned significantly in the Arctic, particularly on sea ice in western waters near Alaska. |
13 Aug 2014
|