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 University of Helsinki, Finland 2 European 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

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? 1. Background Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

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

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) 2.1 Models Balsamo et al. 2011

Measurement sites SMEAR II, Hyytiälä Lake Valkea-Kotinen SMEAR III, Helsinki Eddy-covariance technique for flux measurements ‒ 49-year-old Scots pine stand ‒ extinction coefficient 3.0 m -1 ‒ depth 4 m, area km 2 Järvi et al Nordbo et al Launiainen et al. 2010

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 2.3 Forcing & run details Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

Comparison of forcing data from ERAI and observations 10-day running means 31m 1.5m 16.8m 1kPa Lake higher Forest lower ERAI 20 Wm -2 higher lake lower in spring higher in fall

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

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

3.1 Water temperature Thermocline deepens towards fall Isothermal under ice ice melting 8 days late MeasuredModeled Inverse stratification

3.2 Energy fluxes Net radiation, average diurnal courses per month Lake: modeled R n larger Forest: modeled R n smaller

Heat storage change, average diurnal courses per month Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi Lake: modeled amplitude larger Forest: fluxes tiny

Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi Model ice-out 8 days late Ice/snow Measurements include only heat storage in ground

Sensible heat flux, average diurnal courses per month Urban: largest Lake: tiny, different phase

heat to the water -> ice-out Forest: modeled smaller in spring

Latent heat flux, average diurnal courses per month Forest: more evaporation in spring and less in summer Lake: huge evaporation in model all the time -> huge vapor pressure deficit Lake: nocturnal evaporation 50 Wm -2

Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi Forest: modeled larger in spring

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)? 4. Summary and discussion FluxesForestLakeUrban RnRn ERAI SW down larger, LW down smaller (less clouds), different albedos important GA lot smaller than at lakeLarge seasonal heat storage change, time of ice-out important! - LETranspiration, modeled energy partitioning different in spring Night-time evaporation important, large ERAI water vapor deficit induces too much evaporation Impervious surfaces HSame order of magnitude and in phase with LE Tiny and out of phase with LEAnthropogenic heat flux

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? Future Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations

Matemaattis-luonnontieteellinen tiedekunta / Henkilön nimi / Esityksen nimi Annika Nordbo Department of physics P.O.Box 48 FI – University of Helsinki Danke!

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 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: 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, 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: doi: /2010JD References Lake Valkea-Kotinen also in the Lake intercomparison project (LakeMIP) Department of Physics / Annika Nordbo / Evaluating a tiled land-surface model with multi-site energy flux observations