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Evaluating a tiled land-surface model with multi-site energy flux observations

Evaluating a tiled land-surface model with multi-site energy flux observations. A. Nordbo 1 , A. Manrique-Sunen 2 , G. Balsamo 2 , I. Mammarella 1 , and A. Beljaars 2. 1 University of Helsinki, Finland 2 European Centre for Medium-Range Weather Forecasts.

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Evaluating a tiled land-surface model with multi-site energy flux observations

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  1. Evaluating a tiled land-surface model with multi-site energy flux observations A. Nordbo1, A. Manrique-Sunen2, G. Balsamo2, I. Mammarella1, and A. Beljaars2 1 University of Helsinki, Finland 2European Centre for Medium-Range Weather Forecasts Acknowledgements: Leena Järvi, Pasi Kolari, Samuli Launiainen, Jussi Huotari, Anne Ojala, Timo Vesala Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  2. 1. Background • Resolution of NWPs not sufficient for resolving smaller scale surface heterogeneities • → represented by coupling tiles (different surfaces) with one atmospheric column • research on the pros and cons of this type of coupling is scarce • current loading of the ECMWF surface scheme is 1.7% of computational power • AIM: To run ECMWF surface scheme offline with ERA-Interim forcing and compare results with measurements from 3 distinct sites • → is tiling worthwhile? Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  3. 2. Methods Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  4. 2.1 Models • Hydrology Tiled ECMWF Scheme for Surface Exchanges over Land HTESSEL (cycle 37R1 ) • currently 6 tiles over land; lakes considered only if fraction >50% • estimates surface water and energy fluxes, soil temperature and water content • LAKEHTESSEL (Dutra et al. 2010) includes lake model Flake (Mironov 2008) • no urban scheme • year 2006 (each run iterated 3 times) Balsamo et al. 2011

  5. 2.2. Measurement sites SMEAR II, Hyytiälä • 49-year-old Scots pine stand Launiainen et al. 2010 Lake Valkea-Kotinen • extinction coefficient 3.0 m-1 • depth 4 m, area 0.041 km2 Nordbo et al. 2011 SMEAR III, Helsinki Eddy-covariance technique for flux measurements Järvi et al. 2009

  6. 2.3 Forcing & run details • Forcing: ERA-Interim reanalysis • T255, 80 km grid • 10m height • Forest: geographical information: • Integrated Forecast System • T1279, 16km grid • 75% tall vegetation, 8% bare ground, 17% lakes (not considered) • Lake: run with 100% lake fraction • Urban: no runs Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  7. Comparison of forcing data from ERAI and observations10-day running means 31m lake lower in spring higher in fall 1.5m 16.8m ERAI 20 Wm-2 higher Lake higher Forest lower 1kPa

  8. 2.4. Surface energy balance Turbulent fluxes (eddy-covariance) Rn H LE Mixed layer G Thermocline depth Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  9. 3. Results Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  10. 3.1 Water temperature ice melting 8 dayslate Measured Modeled Inversestratification Thermoclinedeepenstowardsfall Isothermalunder ice

  11. 3.2 Energy fluxes Net radiation, averagediurnalcourses per month Forest: modeledRnsmaller Lake: modeledRnlarger

  12. Heat storage change , average diurnal courses per month Forest: fluxestiny Lake: modeledamplitudelarger Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi

  13. Measurementsincludeonlyheatstorage in ground Modelice-out8 dayslate Ice/snow Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi

  14. Sensibleheatflux , averagediurnalcourses per month Urban: largest Lake: tiny, differentphase

  15. Forest: modeledsmaller in spring heat to the water -> ice-out

  16. Latentheatflux , averagediurnalcourses per month Forest: moreevaporation in spring and less in summer Lake: hugeevaporation in modelall the time -> hugevaporpressuredeficit Lake: nocturnalevaporation 50 Wm-2

  17. Forest: modeledlarger in spring Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi

  18. 4. Summary and discussion • FLake gives an isothermal temperature profile under ice though water really inversely stratified → reason for late ice melting? • Does tiling work with very different surfaces (lake-vegetation)?

  19. 5. Future • run for lake using closer ERAI forcing • runs with higher level forcing (30m & 60m) • → how does tiling work now? • runs using real measurements • → how much of the error is attributed to ERAI forcing? Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

  20. Annika Nordbo Department of physics P.O.Box 48 FI – 00014 University of Helsinki annika.nordbo@helsinki.fi +358 50 415 4830 Danke! Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi www.tinyurl.com/HelsinkiMicromet

  21. References • Balsamo G., S. Boussetta, E. Dutra, A. Beljaars, P. Viterbo, B. Van den Hurk (2011) Evolution of land-surface processes in the IFS. ECMWF Newsletter No. 127. • Dutra E., Stepanenko V.M., Balsamo G., Viterbo P., Miranda P.M.A., Mironov D., Schär S. (2010) An offline study of the impact of lakes on the performance of the ECMWF surface scheme. Bor. Env. Res. 15: 100-112. • Järvi, L., Hannuniemi, H., Hussein, T., Junninen, H., Aalto, P.P., Hillamo, R., Mäkelä, T., Keronen, P., Siivola, E., Vesala, T. and Kulmala, M. (2009). The urban measurement station SMEAR III: Continuous monitoring of air pollution and surface-atmosphere interactions in Helsinki, Finland. Boreal Environ. Res., 14, 86-109. • Launiainen (2010) Seasonal and inter-annual variability of energy exchange above a boreal Scots pine forest. Biogeosciences, 7, 1–20. • Mironov D. (2008) Parameterization of Lakes in Numerical Weather Prediction, Description of Lake Model. Technical Report No. 11. Deutsche Wetterdienst. • Nordbo A., S. Launiainen, I. Mammarella, M. Leppäranta, J. Huotari, A. Ojala, T. Vesala (2011) Long-term energy flux measurements and energy balance over a small boreal lake using eddy covariance technique. J. Geophys. res. 116:1-17. doi:10.1029/2010JD014542 Lake Valkea-Kotinen also in the Lake intercomparison project (LakeMIP) www.unige.ch/climate/lakemip/index.html Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

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