| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | July 20, 2018 |
| Latest Amendment Date: | August 29, 2023 |
| Award Number: | 1803995 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Mea S. Cook
mcook@nsf.gov (703)292-7306 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2018 |
| End Date: | August 31, 2024 (Estimated) |
| Total Intended Award Amount: | $397,055.00 |
| Total Awarded Amount to Date: | $397,055.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
845 N PARK AVE RM 538 TUCSON AZ US 85721 (520)626-6000 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
888 N. Euclid Ave, Room 510 Tucson AZ US 85721-0158 |
| 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): | Paleoclimate |
| Primary Program Source: |
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| 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): | 47.050 |
ABSTRACT
Annual snowpack and snow meltwater supplies have deteriorated across the western United States since 1950. While climate projections indicate these trends will continue throughout the 21st century, short instrumental snow records prevent an assessment of whether these recent declines fall outside the natural range of long-term snowpack variability or if they are exceptional relative to prior centuries. A lack of long snow observations also makes it difficult to identify and characterize decadal-scale and longer-term climatic drivers of annual snow accumulation, changes in those drivers over time and space, and the magnitude of internal variability in the snow system. Yet information at these timescales are most important for effective climate change adaptation.
To address these critical knowledge gaps, this project will develop gridded spatial field reconstructions of snow water equivalent spanning the western United States that explicitly capture the period of negative snow trend within model calibrations using tree rings. The researchers aim to test the ability of climate models to simulate the range of forced and internal snow hydroclimate variability in western United States over the last millennium.
The potential Broader Impacts include the generation of long Snow Water Equivalent (SWE) tree ring chronologies to test different hypotheses of environmental forcing on the pre-industrial timescales and their comparison with last millennium climate model output; the testing of a possible anthropogenic fingerprint on changes in SWE over the last thirty years relative to pre-Industrial forcing and the possible implications for water resource management in the future; and support of an early-career scientist who has helped pioneer the tree-ring SWE discipline. The project also supports an undergraduate student, a post-doctoral research scientist, and outreach to water resource managers in Western North America.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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.
Climate projections indicate annual snowpack and snow meltwater supplies will continue to deteriorate throughout the 21st century; however, short instrumental snow records prevent an assessment of whether these recent declines already fall outside the natural range of long-term snowpack variability or if they are exceptional relative to prior centuries. A lack of long snow observations also makes it difficult to identify and characterize decadal-scale and longer-term climatic drivers of annual snow accumulation and the magnitude of internal variability in the snow system. To address these critical knowledge gaps, this project developed gridded spatial field reconstructions of snow water equivalent spanning the western United States using tree rings. We used these reconstructions to quantify the range of forced and internal snow hydroclimate variability over the last millennium.
Our reconstructions reveal a larger range of variability and extreme events than the short observational record alone. In fact, all the sub-regions in our reconstruction show a wider range of variability at interannual to decadal scales than is present in the limited instrumental period. Past analogs for the severe 2015 snow drought in the western United States do exist in the paleoclimate record, although in many regions recent snow drought years are indeed among the most severe of the last 600 years. In the Sierra Nevada in particular, there is evidence of more extreme 'whiplash' events in the past, with the system transitioning from drought to deep snowpack years repeatedly over the period of our reconstruction. Likewise, the paleoclimate record provides evidence for consecutive extreme heavy snow winters, calling our attention to the importance and potential hazards of anomalously deep snowpack in addition to the threat of drought. Our findings indicate that, even as rising temperatures and changes in atmospheric circulation are expected to cause continuing long-term trends toward reduced winter snow accumulation, variability across a range of shorter time scales, rapid transitions between drought and pluvial, and the potential for compounding extreme years will continue to be present and should be an important consideration for water resources management and hazard mitigation.
Last Modified: 04/21/2025
Modified by: Kevin J Anchukaitis
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