Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022
The seasonal mountain snowpack of the Western US (WUS) is a key water resource to millions of people and an important component of the regional climate system. Impurities at the snow surface can affect snowmelt timing and rate through snow radiative forcing (RF), resulting in earlier streamflow, sno...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | Environmental Research: Climate |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/2752-5295/ad285a |
| _version_ | 1797289571163045888 |
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| author | Anna S Jensen Karl Rittger Mark S Raleigh |
| author_facet | Anna S Jensen Karl Rittger Mark S Raleigh |
| author_sort | Anna S Jensen |
| collection | DOAJ |
| description | The seasonal mountain snowpack of the Western US (WUS) is a key water resource to millions of people and an important component of the regional climate system. Impurities at the snow surface can affect snowmelt timing and rate through snow radiative forcing (RF), resulting in earlier streamflow, snow disappearance, and less water availability in dry months. Predicting the locations, timing, and intensity of impurities is challenging, and little is known concerning whether snow RF has changed over recent decades. Here we analyzed the relative magnitude and spatio-temporal variability of snow RF across the WUS at three spatial scales (pixel, watershed, regional) using remotely sensed RF from spatially and temporally complete (STC) MODIS data sets (STC-MODIS Snow Covered Area and Grain Size/MODIS Dust Radiative Forcing on Snow) from 2001 to 2022. To quantify snow RF impacts, we calculated a pixel-integrated metric over each snowmelt season (1st March–30th June) in all 22 years. We tested for long-term trend significance with the Mann–Kendall test and trend magnitude with Theil–Sen’s slope. Mean snow RF was highest in the Upper Colorado region, but notable in less-studied regions, including the Great Basin and Pacific Northwest. Watersheds with high snow RF also tended to have high spatial and temporal variability in RF, and these tended to be near arid regions. Snow RF trends were largely absent; only a small percent of mountain ecoregions (0.03%–8%) had significant trends, and these were typically decreasing trends. All mountain ecoregions exhibited a net decline in snow RF. While the spatial extent of significant RF trends was minimal, we found declining trends most frequently in the Sierra Nevada, North Cascades, and Canadian Rockies, and increasing trends in the Idaho Batholith. This study establishes a two-decade chronology of snow impurities in the WUS, helping inform where and when RF impacts on snowmelt may need to be considered in hydrologic models and regional hydroclimate studies. |
| first_indexed | 2024-03-07T19:06:54Z |
| format | Article |
| id | doaj.art-04e5b588d9de45cab3f770493d370aa5 |
| institution | Directory Open Access Journal |
| issn | 2752-5295 |
| language | English |
| last_indexed | 2024-03-07T19:06:54Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research: Climate |
| spelling | doaj.art-04e5b588d9de45cab3f770493d370aa52024-03-01T07:59:15ZengIOP PublishingEnvironmental Research: Climate2752-52952024-01-013202500110.1088/2752-5295/ad285aSpatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022Anna S Jensen0https://orcid.org/0009-0000-0790-6604Karl Rittger1https://orcid.org/0000-0002-8733-434XMark S Raleigh2https://orcid.org/0000-0002-1303-3472College of Earth, Ocean, and Atmospheric Sciences, Oregon State University , Corvallis, OR, United States of AmericaInstitute of Arctic and Alpine Research, University of Colorado , Boulder, CO, United States of AmericaCollege of Earth, Ocean, and Atmospheric Sciences, Oregon State University , Corvallis, OR, United States of AmericaThe seasonal mountain snowpack of the Western US (WUS) is a key water resource to millions of people and an important component of the regional climate system. Impurities at the snow surface can affect snowmelt timing and rate through snow radiative forcing (RF), resulting in earlier streamflow, snow disappearance, and less water availability in dry months. Predicting the locations, timing, and intensity of impurities is challenging, and little is known concerning whether snow RF has changed over recent decades. Here we analyzed the relative magnitude and spatio-temporal variability of snow RF across the WUS at three spatial scales (pixel, watershed, regional) using remotely sensed RF from spatially and temporally complete (STC) MODIS data sets (STC-MODIS Snow Covered Area and Grain Size/MODIS Dust Radiative Forcing on Snow) from 2001 to 2022. To quantify snow RF impacts, we calculated a pixel-integrated metric over each snowmelt season (1st March–30th June) in all 22 years. We tested for long-term trend significance with the Mann–Kendall test and trend magnitude with Theil–Sen’s slope. Mean snow RF was highest in the Upper Colorado region, but notable in less-studied regions, including the Great Basin and Pacific Northwest. Watersheds with high snow RF also tended to have high spatial and temporal variability in RF, and these tended to be near arid regions. Snow RF trends were largely absent; only a small percent of mountain ecoregions (0.03%–8%) had significant trends, and these were typically decreasing trends. All mountain ecoregions exhibited a net decline in snow RF. While the spatial extent of significant RF trends was minimal, we found declining trends most frequently in the Sierra Nevada, North Cascades, and Canadian Rockies, and increasing trends in the Idaho Batholith. This study establishes a two-decade chronology of snow impurities in the WUS, helping inform where and when RF impacts on snowmelt may need to be considered in hydrologic models and regional hydroclimate studies.https://doi.org/10.1088/2752-5295/ad285aMODISsnow hydrologyradiative forcingspatiotemporal trendsremote sensinglight absorbing particles |
| spellingShingle | Anna S Jensen Karl Rittger Mark S Raleigh Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022 Environmental Research: Climate MODIS snow hydrology radiative forcing spatiotemporal trends remote sensing light absorbing particles |
| title | Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022 |
| title_full | Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022 |
| title_fullStr | Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022 |
| title_full_unstemmed | Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022 |
| title_short | Spatio-temporal patterns and trends in MODIS-retrieved radiative forcing by snow impurities over the Western US from 2001 to 2022 |
| title_sort | spatio temporal patterns and trends in modis retrieved radiative forcing by snow impurities over the western us from 2001 to 2022 |
| topic | MODIS snow hydrology radiative forcing spatiotemporal trends remote sensing light absorbing particles |
| url | https://doi.org/10.1088/2752-5295/ad285a |
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