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David Gustafsson, Kristina Isberg, Jörgen Rosberg, Berit Arheimer SMHI

Assessment of CCI Glacier and CCI Land cover data for hydrological modeling of the Arctic ocean drainage basin. David Gustafsson, Kristina Isberg, Jörgen Rosberg, Berit Arheimer SMHI CCI-CMUG Integration meeting 5, 26-28/5, 2015. WHY modelling the Arctic basin ?.

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David Gustafsson, Kristina Isberg, Jörgen Rosberg, Berit Arheimer SMHI

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  1. Assessment of CCI Glacier and CCI Land cover data for hydrological modeling of the Arctic ocean drainage basin David Gustafsson, Kristina Isberg, Jörgen Rosberg, Berit Arheimer SMHI CCI-CMUG Integration meeting 5, 26-28/5, 2015

  2. WHY modelling the Arctic basin? ~ 11% ofworld’s river-runoffflowsto the Arctic ocean (Gleick, 2000) > 50% offreshwaterto the Arctic Ocean is river runoff (Barry and Serreze, 2000) 30% is Ungauged Modified from: Shiklomanov and Lammers (2009), Environ. Res. Lett.

  3. WP3.9 Assessment of glacier, land cover and sea level data for hydrological modeling of the Arctic ocean drainage basin Objectives Assess the use of ESA CCI Glacier, Land cover (and Sea level) in hydrological modelling for the Arctic: • Compare CCI data with existing datasets: long term trends and seasonal variations? • Can use of CCI Glacier and Land cover improve simulated river runoff to the Arctic Ocean? • Is there a relation between changes in observed land cover and the simulated river runoff?

  4. WP3.9 Assessment of glacier, land cover and sea level data for hydrological modeling of the Arctic ocean drainage basin Hydrological models depend on observations of e.g. glacier area and land cover for setup, calibration and evaluation: Comparison with datasets used in the pan-arctic hydrological model Arctic-HYPE Models using CCI data (Glacier, LC) will be compared to previous model version CCI Glacier data will be used to improve the parameteri-zationof the sub-basin based glacier mass balance model. Use of CCI data

  5. Largescalemodellingusing a catchment approach The Arctic-HYPE model: 23 million km2 32 599 sub-basins average spatial resolution =715 km2 Model setup (short version): Sub-basindelineationbased on DEM (Hydro 1K), Lakes (GLWD), and River discharge stations (GRDC etc) Eachsub-basin is divided in sub-unitsrepresenting combinations ofsoiltype (HWSD) and land cover (GlobCover) Calibrationwithvarious data (snow, evaporation, galciermassbalance, discharge) HYdrologicalPredictions for the Environment (HYPE) (Lindström et al. (2010), Hydrology Research) HYPE source code, WIKI, manuals, etc: http://hype.sourceforge.net/

  6. Availableopen global databasesused

  7. Trends in water balance and storages Flow to Ocean - trends in annual mean Pan-Arctic Ob, Yenisei, Lena, Sernaja Dvina, Pechora, Kolyma Yukon, Mackenzie, Peel, Back Overall, similar trends to Shiklomaniv & Lammers (2009) – but overestimated flow in North America (and no trend / declining)

  8. Trends in water balance and storages Modelled water balance for the Arctic basin Trends in evaporation and precipitation < 1mm/year Increase in Prec and Runoff in last decade Storage change – 6 mm/year corresponding to glacier mass balance

  9. Trends in water balance and storages Modelled water storages in the Arctic basin • Negative trend in Glacier storage = - 6 mm/year for the entire basin: • Corresponds to -164 km3/yr in glacier volume • Probably too high – Glacier model need more attention! • Small changes in other storages Annual change in water storage:

  10. Assessment of CCI glacier, Land cover Progress (preliminary results): • CCI Glacier (RGI v4.0) and CCI Land Cover (v1.3-4) used to evaluate Arctic-HYPE (v3)glacier area and volume: • Glacier area: • Arctic-HYPE (v3) based on GlobCover 2004-2006 (v2.2) (“permanent snow and ice”) • CCI Land Cover (v1.3-4) gives more realistic snow and ice distribution in the Arctic: • >100% difference between CCI LC and GlobCover • However, CCI Land Cover (v1.3-4) gives ~30% larger area than CCI Glacier (RGI v4.0).

  11. Assessment of CCI glacier, Land cover Evaluation Glacier Area [km2] per RGI regions: • 95% of Region 1-10 (excl Greenland) is covered by Arctic HYPE • CCI clearlybetterthanGlobCover (still +30%) • Permanent snow and icelargelyoverestimate glacier area in Arctic North America and Arctic Russia/North Asia

  12. WP3.9 Assessment of glacier, land cover and sea level data for hydrological modeling of the Arctic ocean drainage basin Progress (preliminary results): • CCI Glacier (RGI v4.0) and CCI Land Cover (v1.3-4) used to evaluate Arctic-HYPE (v3)glacier area and volume: Glacier volume based on non-linear area-volume relationship (Bahr et al, 1997, Grindsted, 2003): • CCI Glacier outlines (RGIv4) was used to evaluate error when aggregating (or splitting) area from multiple glaciers in/between model sub-basins: • Volume overestimated by 28% • In combination with the area overestimation, current Arctic HYPE model overestimate Glacier volume with more than 200% compared to data derived from CCI Glacier!! Volume from RGI areas[km3] Volume from subbasin area [km3]

  13. Assessment of CCI glacier, Land cover Evaluation Glacier Volumeestimates per RGI regions: • Volume estimated from total area overestimatevolume from individual area by 28% • Variation depending on: • agreement glacier outlines and subbasins • numberof glaciers / subbasin • Combination of area and volumeestimationerrorsadduplargely in currentmodel! Eyafjallajökul, Iceland

  14. WP3.9 Assessment of glacier, land cover and sea level data for hydrological modeling of the Arctic ocean drainage basin Progress (preliminary results): • CCI Land cover used to evaluate and improve Arctic-HYPE surface water area: Example from the area around the lower Ob: • Globcover shows sparse vegetation • CCI 2005 shows water bodies; Shrub or herbaceous cover; flooded; fresh/saline/brakish water. On average 6-10% increase, depending on method for combining information from CCI and GLWD. • 3) CCI land cover time series 2000, 2005, 2010 show negative trend in Siberian deciduous needle-leaf vegetation: • Due to increase in soil moisture as response to increased precipitation? To be evaluated • 4) CCI Sea level - No results yet

  15. Conclusions Preliminary conclusions • CCI Glacier very useful for hydrological modelling: • setup and evaluation of glacier area and volume • Very high resolution and level of detail • Global coverage • Current limitations: • Time series missing in RGI dataset • needed for initialization, calibration, evaluation of long term modelling • Users may compile information from other data sets: • GLIMS/WGMS/literture/etc. • CCI Land cover: • Improved snow and ice area • Increased water surface area • Interesting trends in Arctic forest vegetation • Current limitations: • Static Surface water and Glacier information

  16. Thank you Q & A

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