Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product
Snow seasonality is expected to change as a result of planetary warming. Yet, how the timings of snow seasons have already shifted in mountain environments can be counterintuitive. Here, we update our 2018 analyses of snow seasonality in Kyrgyzstan (KG) using more data and improved methods. Using tw...
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| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | Environmental Research Letters |
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| Online Access: | https://doi.org/10.1088/1748-9326/ad9c98 |
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| author | Geoffrey M Henebry Monika A Tomaszewska |
| author_facet | Geoffrey M Henebry Monika A Tomaszewska |
| author_sort | Geoffrey M Henebry |
| collection | DOAJ |
| description | Snow seasonality is expected to change as a result of planetary warming. Yet, how the timings of snow seasons have already shifted in mountain environments can be counterintuitive. Here, we update our 2018 analyses of snow seasonality in Kyrgyzstan (KG) using more data and improved methods. Using two decades of MODIS snow-cover data, we investigated trends in four snow seasonality metrics: first date of snow (FDoS); last date of snow (LDoS); duration of the snow season (DoSS); and snow-covered days (SCDs). Our novel but conservative nonparametric approach analyzed trends within elevation ranges at two administrative levels: oblast and rayon. To attenuate the risk of false-positive trends, we reported as ‘notable’ only those significant ( p < 0.05) nonparametric trends that were also (i) strongly asymmetric (at least twice as many significant pixels in one direction) within an elevational range of the oblast or rayon and (ii) covering at least 5% of the elevation range in oblast or rayon and more than 10 pixels. We used both simple and advanced snow-cover metrics, with the latter exploiting the within-composite chronobyte detail available in the MOD10A2.061 product. We found notable trends to earlier FDoS below 3000 m in western KG and more SCD between 1500–3500 m in western KG. We also found the expected notable trends towards earlier LDoS at both oblast and rayon levels. In northwestern KG, DoSS was notably longer <3000 m, but notably shorter at 3500–4000 m. In our 2018 analyses, we found at the national level 160% more area trending to earlier FDoS than to earlier LDoS. Our comprehensive updated trend analysis was designed to be more conservative. It revealed more area (106%–130%) trending to earlier FDoS than earlier LDoS, reinforcing the counterintuitive finding of longer snow seasons starting earlier at lower elevations. |
| format | Article |
| id | doaj-art-55b61c88febe4e51bc5eedd5f7e174bd |
| institution | Kabale University |
| issn | 1748-9326 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | Environmental Research Letters |
| spelling | doaj-art-55b61c88febe4e51bc5eedd5f7e174bd2025-01-14T18:42:03ZengIOP PublishingEnvironmental Research Letters1748-93262025-01-0120202401810.1088/1748-9326/ad9c98Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow productGeoffrey M Henebry0https://orcid.org/0000-0002-8999-2709Monika A Tomaszewska1https://orcid.org/0000-0003-3641-323XDepartment of Geography, Environment, and Spatial Sciences, Michigan State University , East Lansing, MI, United States of America; Center for Global Change and Earth Observations - Michigan State University , East Lansing, MI, United States of AmericaCenter for Global Change and Earth Observations - Michigan State University , East Lansing, MI, United States of AmericaSnow seasonality is expected to change as a result of planetary warming. Yet, how the timings of snow seasons have already shifted in mountain environments can be counterintuitive. Here, we update our 2018 analyses of snow seasonality in Kyrgyzstan (KG) using more data and improved methods. Using two decades of MODIS snow-cover data, we investigated trends in four snow seasonality metrics: first date of snow (FDoS); last date of snow (LDoS); duration of the snow season (DoSS); and snow-covered days (SCDs). Our novel but conservative nonparametric approach analyzed trends within elevation ranges at two administrative levels: oblast and rayon. To attenuate the risk of false-positive trends, we reported as ‘notable’ only those significant ( p < 0.05) nonparametric trends that were also (i) strongly asymmetric (at least twice as many significant pixels in one direction) within an elevational range of the oblast or rayon and (ii) covering at least 5% of the elevation range in oblast or rayon and more than 10 pixels. We used both simple and advanced snow-cover metrics, with the latter exploiting the within-composite chronobyte detail available in the MOD10A2.061 product. We found notable trends to earlier FDoS below 3000 m in western KG and more SCD between 1500–3500 m in western KG. We also found the expected notable trends towards earlier LDoS at both oblast and rayon levels. In northwestern KG, DoSS was notably longer <3000 m, but notably shorter at 3500–4000 m. In our 2018 analyses, we found at the national level 160% more area trending to earlier FDoS than to earlier LDoS. Our comprehensive updated trend analysis was designed to be more conservative. It revealed more area (106%–130%) trending to earlier FDoS than earlier LDoS, reinforcing the counterintuitive finding of longer snow seasons starting earlier at lower elevations.https://doi.org/10.1088/1748-9326/ad9c98snowmeltsnow-covered dayssnow onsettrend analysislocal level analysis |
| spellingShingle | Geoffrey M Henebry Monika A Tomaszewska Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product Environmental Research Letters snowmelt snow-covered days snow onset trend analysis local level analysis |
| title | Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product |
| title_full | Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product |
| title_fullStr | Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product |
| title_full_unstemmed | Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product |
| title_short | Snow-cover seasonality in Kyrgyzstan: variation and change over 20 years (2001–2021) as observed by the MODIS Terra snow product |
| title_sort | snow cover seasonality in kyrgyzstan variation and change over 20 years 2001 2021 as observed by the modis terra snow product |
| topic | snowmelt snow-covered days snow onset trend analysis local level analysis |
| url | https://doi.org/10.1088/1748-9326/ad9c98 |
| work_keys_str_mv | AT geoffreymhenebry snowcoverseasonalityinkyrgyzstanvariationandchangeover20years20012021asobservedbythemodisterrasnowproduct AT monikaatomaszewska snowcoverseasonalityinkyrgyzstanvariationandchangeover20years20012021asobservedbythemodisterrasnowproduct |