| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | July 25, 2016 |
| Latest Amendment Date: | July 25, 2016 |
| Award Number: | 1602720 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Gregory Anderson
greander@nsf.gov (703)292-4693 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | July 15, 2016 |
| End Date: | June 30, 2021 (Estimated) |
| Total Intended Award Amount: | $186,911.00 |
| Total Awarded Amount to Date: | $186,911.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
2145 N TANANA LOOP FAIRBANKS AK US 99775-0001 (907)474-7301 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
930 Koyukuk Drive Fairbanks AK US 99775-7340 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
PREEVENTS - Prediction of and, ARCSS-Arctic System Science |
| Primary Program Source: |
0100XXXXDB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
Arctic cyclones are an important contributor to sea ice deformation and oceanic mixing. Changes
in storm activity, and associated atmospheric feedbacks, have been linked to increased seasonality of the high north in the last decade, and with sea ice depletion during summer months. Cyclones are also likely to respond to changes in Arctic ice cover and ocean state indicating that
the atmosphere-ocean-ice system is tightly coupled through processes related to cyclones. Previous Arctic modeling studies typically used regional model simulations without full coupling
of the atmosphere-ocean-ice system, or fully coupled global climate models that do not permit year-on-year comparison with the observational record. This study will avoid such limitations by using
the Regional Arctic System Model (RASM), for which output corresponds directly with month-on-month observational records. This
will allow assessment of the ice-ocean-atmosphere coupling processes on multiple temporal
and spatial scales, and to relate them to limited Arctic Ocean measurements to build a more complete understanding of how increased cyclone activity may be helping to shift the surface climate of the Arctic to a new, warmer state with seasonal sea ice cover, and of how cyclones
will respond to this new Arctic Ocean state.
The impact of cyclones on Arctic stakeholder sectors in northern and western Alaska, including coastal communities and marine transport, will be assessed through a partnership with the Alaska Center for Climate Assessment and Policy and the project's inventory of Arctic cyclones and associated ocean and sea ice conditions will be archived at the National Snow and Ice Data Center. Historical time series of annual and seasonal Arctic cyclone activity, maps of tracks and intensities of Arctic cyclones, and case studies of intense or impactful cyclones will be made available on a project web page. The project will engage graduate students and a post-doctoral fellow,
and results will be used in atmospheric and oceanic science undergraduate and graduate level courses at the project institutions. Outcomes from this work will be address priorities in the US National Strategy for the Arctic Region and will address key uncertainties in understanding extreme events and their role in the Arctic climate system.
The recent loss of Arctic sea ice has increased the potential for ocean-atmosphere coupling
in the Arctic, especially in areas of low ice concentration or where the ice edge has receded. An important aspect of increased ocean-atmosphere Arctic coupling is the
potential increase
of the ocean's response to storms. Where once mitigated by thick ice, wind-induced ice deformation and oceanic mixing are increasing as the ice pack thins. The decreasing Arctic ice cover and associated warming of the Arctic Ocean may also impact cyclone intensity and frequency. This grant will support investigation of changes in atmosphere-ice-ocean coupling in the presence of cyclones in the Arctic. It will advance our understanding of coupled atmosphere-ocean-ice processes with a focus on the role and response of cyclones in altering the state of the Arctic system. A cyclone tracking scheme will be applied to reanalyses, yielding an inventory of Arctic cyclone locations, tracks, and intensities that will provide a framework for analysis of ice and upper-ocean responses to storms. The responses of ice concentration, ocean temperature and salinity, and associated ice mass balance before, during, and after cyclones at a variety of intensities will be documented. The same analysis will be applied
to output from the high-resolution Regional Arctic System Model (RASM) and to output from
a suite of global climate models (GCMs). Using a novel set of metrics computed from the output of RASM, peak temporal and spatial scales of oceanic mixing, sea ice deformation, and turbulent fluxes associated with the passage of storms in the Arctic will be determined, in order to assess coupled cyclone-ocean-sea ice processes. Changes in the cyclone climatology between pairs of coupled RASM simulations, that differ only in sea ice and ocean state, and in current and end of the 21st century CMIP5 simulations will allow for assessment of cyclone response to changing ocean and ice state. This award is made by the Arctic Section of NSF Polar Programs and co-funded by the NSF GEO effort PREEVENTS.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The overarching goal of this project was to increase understanding of the role of Arctic cyclones in a changing climate, especially the ways in which Arctic cyclones affect, and are affected by, sea ice and the ocean. Work at the University of Alaska Fairbanks included evaluations of changes in overall storminess and in the occurrences of high-wind events in the Arctic relative to the presence or absence of a sea ice cover; case studies of linkages between seasonal-scale storm activity and sea ice motion and loss; diagnosis of drivers of changes in atmosphere-ice-ocean coupling in the Arctic; evaluation of precursors of polar low activity; and assessment the strength of evidence for historical trends, and confidence in future trends, of Arctic cyclone activity. The results were reported in nine peer-reviewed journal publications and two book chapters. Notable findings are described below under ?Intellectual Merit?.
Intellectual Merit
Over the past several decades, there is no statistically significant trend in the frequency of cyclones in the central Arctic and the North Atlantic subarctic. However, there has been a northward shift in the track of North Pacific storms into the Arctic. Importantly for impacts, storm activity over open water along the western and northern Alaskan coasts has increased, with nearly a tripling of such events at Utqiagvik (Barrow), increasing vulnerability to coastal flooding and erosion. The increase is due primarily to the loss of sea ice, and only secondarily to changes in storminess.
We documented examples of seasonal-scale anomalies of storm activity contributing to (a) a record low late-winter sea ice cover in the Baring Sea (2018-19) and (b) a collapse of the Beaufort High. In the latter case, highly unusual eastward ice drift north of Alaska impacted the distribution of multiyear ice for the following seasons.
Analysis of simulations by several global climate models showed that, as the Arctic warms, the thinner sea ice results in more uniform ice production and smaller spatial heterogeneity of thickness. Withe higher temperatures, there is also a damping of the response of sea ice growth to the thermodynamic forcing. In this way, the atmospheric forcing is projected to contribute less to change daily variations of sea ice growth rates in the future climate.
We found that wintertime sudden stratosphere warming events are followed by periods of reduced polar low activity in the Labrador Sea region. Cold air outbreaks at the surface provide the linkage. However, polar low activity in the Nordic Seas is tied more closely to the location and intensity of synoptic-scale cyclones.
Based on the results of this collaborative NSF project and a review of the published literature, Arctic cyclones were rated below most other types of high-latitude extreme events in terms of both the evidence for historical changes and the confidence in future changes. This assessment was included in a review paper on extreme events in the Arctic.
Broader Impacts
We incorporated the project results into a module entitled ?Arctic Storms? for a Massive Open Online Course (MOOC), "Climate Change in Arctic Environments". The course was developed by P.I. Walsh and R. Thoman in collaboration with University of Alaska Fairbanks eCampus department and is hosted by the edX platform. The course began accepting applications In October 2021 and will go live on November 9, 2021. The URL for the course is https://www.edx.org/course/climate-change-in-arctic-environments
P.I. Walsh mentored two REU (Research Experience for Undergraduate) on research topics under this grant. The first REU project (summer 2019, Sarah Pearl, Dartmouth College) was a study of variations and trends of high-wind events affecting Alaska, with a focus on coastal sites at which sea ice has diminished. The second REU project (summer 2021, Claire Bachand, U. California-Berkeley) was a study of warm-season flood events associated with cyclones in the Alaska region.
The journal publications on the results summarized above, as well as the book chapters, disseminate the results to the science community. The MOOC module on Arctic storms targets the broader public. An intermediate audience, decision-makers who need wind information, is the intended audience for an online wind tool that is an outgrowth of the 2019 REU project on high-wind events. More specifically, we have developed a website at which users can explore historical and future (model-projected) wind threshold exceedance frequencies. The site uses historical hourly wind data from more than 65 sites in Alaska, together with corresponding projections downscaled from two global climate models for several future time slices (through 2100). The thresholds for the exceedance vary by location, as the average wind speeds vary widely across Alaska. The website was motivated by the need of coastal stakeholders for information on the frequencies of high-wind events, including ongoing trends as well as future changes. The website is available at http://windtool.accap.uaf.edu/
Last Modified: 10/25/2021
Modified by: John E Walsh
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