Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis
<p>This study introduces and evaluates a comprehensive, model-generated dataset of Northern Hemisphere permafrost conditions at 81 km<span class="inline-formula"><sup>2</sup></span> resolution. Surface meteorological forcing fields from the Modern-E...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-08-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/13/2087/2019/tc-13-2087-2019.pdf |
| _version_ | 1798043771767619584 |
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| author | J. Tao J. Tao J. Tao J. Tao R. D. Koster R. H. Reichle B. A. Forman Y. Xue Y. Xue R. H. Chen M. Moghaddam |
| author_facet | J. Tao J. Tao J. Tao J. Tao R. D. Koster R. H. Reichle B. A. Forman Y. Xue Y. Xue R. H. Chen M. Moghaddam |
| author_sort | J. Tao |
| collection | DOAJ |
| description | <p>This study introduces and evaluates a comprehensive,
model-generated dataset of Northern Hemisphere permafrost conditions at
81 km<span class="inline-formula"><sup>2</sup></span> resolution. Surface meteorological forcing fields from the
Modern-Era Retrospective Analysis for Research and Applications 2 (MERRA-2)
reanalysis were used to drive an improved version of the land component of
MERRA-2 in middle-to-high northern latitudes from 1980 to 2017. The
resulting simulated permafrost distribution across the Northern Hemisphere
mostly captures the observed extent of continuous and discontinuous
permafrost but misses the ecosystem-protected permafrost zones in western
Siberia. Noticeable discrepancies also appear along the southern edge of the
permafrost regions where sporadic and isolated permafrost types dominate.
The evaluation of the simulated active layer thickness (ALT) against remote
sensing retrievals and in situ measurements demonstrates reasonable skill
except in Mongolia. The RMSE (bias) of climatological ALT is 1.22 m (<span class="inline-formula">−0.48</span> m) across all sites and 0.33 m (<span class="inline-formula">−0.04</span> m) without the Mongolia sites. In
northern Alaska, both ALT retrievals from airborne remote sensing for 2015
and the corresponding simulated ALT exhibit limited skill versus in situ
measurements at the model scale. In addition, the simulated ALT has larger spatial variability than the remotely sensed ALT, although it agrees well with the retrievals when considering measurement uncertainty. Controls on
the spatial variability of ALT are examined with idealized numerical
experiments focusing on northern Alaska; meteorological forcing and soil
types are found to have dominant impacts on the spatial variability of ALT,
with vegetation also playing a role through its modulation of snow
accumulation. A correlation analysis further reveals that accumulated
above-freezing air temperature and maximum snow water equivalent explain
most of the year-to-year variability of ALT nearly everywhere over the
model-simulated permafrost regions.</p> |
| first_indexed | 2024-04-11T22:53:44Z |
| format | Article |
| id | doaj.art-91a22d0b6c484fafb45470353d8c83c3 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-04-11T22:53:44Z |
| publishDate | 2019-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-91a22d0b6c484fafb45470353d8c83c32022-12-22T03:58:30ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242019-08-01132087211010.5194/tc-13-2087-2019Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysisJ. Tao0J. Tao1J. Tao2J. Tao3R. D. Koster4R. H. Reichle5B. A. Forman6Y. Xue7Y. Xue8R. H. Chen9M. Moghaddam10Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USAGlobal Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USAnow at: Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USAnow at: Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USAGlobal Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USAGlobal Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USADepartment of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USADepartment of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USAnow at: Department of Geography and GeoInformation Science, George Mason University, Fairfax, Virginia, USADepartment of Electrical Engineering, University of Southern California, Los Angeles, California, USADepartment of Electrical Engineering, University of Southern California, Los Angeles, California, USA<p>This study introduces and evaluates a comprehensive, model-generated dataset of Northern Hemisphere permafrost conditions at 81 km<span class="inline-formula"><sup>2</sup></span> resolution. Surface meteorological forcing fields from the Modern-Era Retrospective Analysis for Research and Applications 2 (MERRA-2) reanalysis were used to drive an improved version of the land component of MERRA-2 in middle-to-high northern latitudes from 1980 to 2017. The resulting simulated permafrost distribution across the Northern Hemisphere mostly captures the observed extent of continuous and discontinuous permafrost but misses the ecosystem-protected permafrost zones in western Siberia. Noticeable discrepancies also appear along the southern edge of the permafrost regions where sporadic and isolated permafrost types dominate. The evaluation of the simulated active layer thickness (ALT) against remote sensing retrievals and in situ measurements demonstrates reasonable skill except in Mongolia. The RMSE (bias) of climatological ALT is 1.22 m (<span class="inline-formula">−0.48</span> m) across all sites and 0.33 m (<span class="inline-formula">−0.04</span> m) without the Mongolia sites. In northern Alaska, both ALT retrievals from airborne remote sensing for 2015 and the corresponding simulated ALT exhibit limited skill versus in situ measurements at the model scale. In addition, the simulated ALT has larger spatial variability than the remotely sensed ALT, although it agrees well with the retrievals when considering measurement uncertainty. Controls on the spatial variability of ALT are examined with idealized numerical experiments focusing on northern Alaska; meteorological forcing and soil types are found to have dominant impacts on the spatial variability of ALT, with vegetation also playing a role through its modulation of snow accumulation. A correlation analysis further reveals that accumulated above-freezing air temperature and maximum snow water equivalent explain most of the year-to-year variability of ALT nearly everywhere over the model-simulated permafrost regions.</p>https://www.the-cryosphere.net/13/2087/2019/tc-13-2087-2019.pdf |
| spellingShingle | J. Tao J. Tao J. Tao J. Tao R. D. Koster R. H. Reichle B. A. Forman Y. Xue Y. Xue R. H. Chen M. Moghaddam Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis The Cryosphere |
| title | Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis |
| title_full | Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis |
| title_fullStr | Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis |
| title_full_unstemmed | Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis |
| title_short | Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis |
| title_sort | permafrost variability over the northern hemisphere based on the merra 2 reanalysis |
| url | https://www.the-cryosphere.net/13/2087/2019/tc-13-2087-2019.pdf |
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