Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product

<p>This study presents a spatio-temporal continuous data set for snow cover in Iceland based on the Moderate Resolution Imaging Spectroradiometer (MODIS) from 2000 to 2018. Cloud cover and polar darkness are the main limiting factors for data availability of remotely sensed optical data at hig...

Full description

Bibliographic Details
Main Authors: A. Gunnarsson, S. M. Garðarsson, Ó. G. B. Sveinsson
Format: Article
Language:English
Published: Copernicus Publications 2019-07-01
Series:Hydrology and Earth System Sciences
Online Access:https://www.hydrol-earth-syst-sci.net/23/3021/2019/hess-23-3021-2019.pdf
_version_ 1818695675082178560
author A. Gunnarsson
A. Gunnarsson
S. M. Garðarsson
Ó. G. B. Sveinsson
author_facet A. Gunnarsson
A. Gunnarsson
S. M. Garðarsson
Ó. G. B. Sveinsson
author_sort A. Gunnarsson
collection DOAJ
description <p>This study presents a spatio-temporal continuous data set for snow cover in Iceland based on the Moderate Resolution Imaging Spectroradiometer (MODIS) from 2000 to 2018. Cloud cover and polar darkness are the main limiting factors for data availability of remotely sensed optical data at higher latitudes. In Iceland the average cloud cover is 75&thinsp;% with some spatial variations, and polar darkness reduces data availability from the MODIS sensor from late November until mid January. In this study MODIS snow cover data were validated over Iceland with comparison to manned in situ observations and Landsat 7/8 and Sentinel 2 data. Overall a good agreement was found between in situ observed snow cover, with an average agreement of 0.925. Agreement of Landsat 7/8 and Sentinel 2 was found to be acceptable, with <span class="inline-formula"><i>R</i><sup>2</sup></span> values 0.96, 0.92 and 0.95, respectively, and in agreement with other studies. By applying daily data merging from Terra and Aqua and a temporal aggregation of 7&thinsp;d, unclassified pixels were reduced from 75&thinsp;% to 14&thinsp;%. The remaining unclassified pixels after daily merging and temporal aggregation were removed with classification learners trained with classified data, pixel location, aspect and elevation. Various snow cover characteristic metrics were derived for each pixel such as snow cover duration, first and last snow-free dates, deviation and dynamics of snow cover and trends during the study period. On average the first snow-free date in Iceland is 27 June, with a standard deviation of 19.9&thinsp;d. For the study period a trend of increasing snow cover duration was observed for all months except October and November. However, statistical testing of the trends indicated that there was only a significant trend in June.</p>
first_indexed 2024-12-17T13:49:14Z
format Article
id doaj.art-06542fd49f5342e28f2e12c73e3f569c
institution Directory Open Access Journal
issn 1027-5606
1607-7938
language English
last_indexed 2024-12-17T13:49:14Z
publishDate 2019-07-01
publisher Copernicus Publications
record_format Article
series Hydrology and Earth System Sciences
spelling doaj.art-06542fd49f5342e28f2e12c73e3f569c2022-12-21T21:46:05ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382019-07-01233021303610.5194/hess-23-3021-2019Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover productA. Gunnarsson0A. Gunnarsson1S. M. Garðarsson2Ó. G. B. Sveinsson3University of Iceland, Civil and Environmental Engineering, Hjardarhagi 2–6, IS-107 Reykjavik, IcelandLandsvirkjun, Department of Research and Development, IS-107 Reykjavík, IcelandUniversity of Iceland, Civil and Environmental Engineering, Hjardarhagi 2–6, IS-107 Reykjavik, IcelandLandsvirkjun, Department of Research and Development, IS-107 Reykjavík, Iceland<p>This study presents a spatio-temporal continuous data set for snow cover in Iceland based on the Moderate Resolution Imaging Spectroradiometer (MODIS) from 2000 to 2018. Cloud cover and polar darkness are the main limiting factors for data availability of remotely sensed optical data at higher latitudes. In Iceland the average cloud cover is 75&thinsp;% with some spatial variations, and polar darkness reduces data availability from the MODIS sensor from late November until mid January. In this study MODIS snow cover data were validated over Iceland with comparison to manned in situ observations and Landsat 7/8 and Sentinel 2 data. Overall a good agreement was found between in situ observed snow cover, with an average agreement of 0.925. Agreement of Landsat 7/8 and Sentinel 2 was found to be acceptable, with <span class="inline-formula"><i>R</i><sup>2</sup></span> values 0.96, 0.92 and 0.95, respectively, and in agreement with other studies. By applying daily data merging from Terra and Aqua and a temporal aggregation of 7&thinsp;d, unclassified pixels were reduced from 75&thinsp;% to 14&thinsp;%. The remaining unclassified pixels after daily merging and temporal aggregation were removed with classification learners trained with classified data, pixel location, aspect and elevation. Various snow cover characteristic metrics were derived for each pixel such as snow cover duration, first and last snow-free dates, deviation and dynamics of snow cover and trends during the study period. On average the first snow-free date in Iceland is 27 June, with a standard deviation of 19.9&thinsp;d. For the study period a trend of increasing snow cover duration was observed for all months except October and November. However, statistical testing of the trends indicated that there was only a significant trend in June.</p>https://www.hydrol-earth-syst-sci.net/23/3021/2019/hess-23-3021-2019.pdf
spellingShingle A. Gunnarsson
A. Gunnarsson
S. M. Garðarsson
Ó. G. B. Sveinsson
Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product
Hydrology and Earth System Sciences
title Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product
title_full Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product
title_fullStr Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product
title_full_unstemmed Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product
title_short Icelandic snow cover characteristics derived from a gap-filled MODIS daily snow cover product
title_sort icelandic snow cover characteristics derived from a gap filled modis daily snow cover product
url https://www.hydrol-earth-syst-sci.net/23/3021/2019/hess-23-3021-2019.pdf
work_keys_str_mv AT agunnarsson icelandicsnowcovercharacteristicsderivedfromagapfilledmodisdailysnowcoverproduct
AT agunnarsson icelandicsnowcovercharacteristicsderivedfromagapfilledmodisdailysnowcoverproduct
AT smgarðarsson icelandicsnowcovercharacteristicsderivedfromagapfilledmodisdailysnowcoverproduct
AT ogbsveinsson icelandicsnowcovercharacteristicsderivedfromagapfilledmodisdailysnowcoverproduct