Role of land surface processes and diffuse/direct radiation partitioning in simulating the European climate

Abstract. The influence of land processes and in particular of diffuse/direct radiation partitioning on surface fluxes and associated regional-scale climate feedbacks is investigated using ERA-40 driven simulations over Europe performed with the COSMO-CLM2 Regional Climate Model (RCM). Two alternative Land Surface Models (LSMs), a 2nd generation LSM (TERRA_ML) and a more advanced 3rd generation LSM (Community Land Model version 3.5), and two versions of the atmospheric component are tested, as well as a revised coupling procedure allowing for variations in diffuse/direct light partitioning at the surface, and their accounting by the land surface component. Overall, the RCM performance for various variables (e.g., surface fluxes, temperature and precipitation) is improved when using the more advanced 3rd generation LSM. These improvements are of the same order of magnitude as those arising from a new version of the atmospheric component, demonstrating the benefit of using a realistic representation of land surface processes for regional climate simulations. Taking into account the variability in diffuse/direct light partitioning at the surface further improves the model performance in terms of summer temperature variability at the monthly and daily time scales. Comparisons with observations show that the RCM realistically captures temporal variations in diffuse/direct light partitioning as well as the evapotranspiration sensitivity to these variations. Our results suggest that a modest but consistent fraction (up to 3 %) of the overall variability in summer temperature can be explained by variations in the diffuse to direct ratio.

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Role of land surface processes and diffuse/direct radiation partitioning in simulating the European climate

Biogeosciences Discussions ◽

10.5194/bgd-8-11601-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 11601-11630 ◽

Cited By ~ 3

Author(s):

E. L. Davin ◽

S. I. Seneviratne

Keyword(s):

Land Surface ◽

Regional Climate ◽

Summer Temperature ◽

Surface Fluxes ◽

Surface Processes ◽

Land Surface Processes ◽

Direct Radiation ◽

Atmospheric Component ◽

Direct Light ◽

Light Partitioning

Abstract. The influence of land processes and in particular of diffuse/direct radiation partitioning on surface fluxes and associated regional-scale climate feedbacks is investigated. ERA-40 driven simulations over Europe are performed using the COSMO-CLM2 Regional Climate Model (RCM). Two alternative Land Surface Models (LSMs), a 2nd generation LSM (TERRA_ML) and a more advanced 3rd generation LSM (Community Land Model version 3.5), and two versions of the atmospheric component are tested, as well as a revised coupling procedure allowing for variations in diffuse/direct light partitioning at the surface, and their accounting by the land surface component. Overall, the RCM performance for various variables (e.g., surface fluxes, temperature and precipitation) is improved when using the more advanced 3rd generation LSM. These improvements are of the same order of magnitude as those arising from a new version of the atmospheric component, demonstrating the benefit of using a realistic representation of land surface processes for regional climate simulations. Taking into account variability in diffuse/direct light partitioning at the surface further improves the model performance in terms of summer temperature variability at the monthly and daily time scales. Comparisons with observations show that the RCM realistically captures temporal variations in diffuse/direct light partitioning as well as the evapotranspiration sensitivity to these variations. Our results suggest that a modest but consistent fraction (up to 3 %) of the overall variability in summer temperature can be explained by variations in the diffuse to direct ratio.

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2-way coupling the hydrological land surface model PROMET with the regional climate model MM5

Hydrology and Earth System Sciences ◽

10.5194/hess-17-1705-2013 ◽

2013 ◽

Vol 17 (5) ◽

pp. 1705-1714 ◽

Cited By ~ 21

Author(s):

F. Zabel ◽

W. Mauser

Keyword(s):

Heat Flux ◽

Land Surface ◽

Regional Climate ◽

Surface Processes ◽

Surface Model ◽

Land Surface Processes ◽

Near Surface ◽

Danube Catchment ◽

Simulated Precipitation ◽

The Impact

Abstract. Most land surface hydrological models (LSHMs) consider land surface processes (e.g. soil–plant–atmosphere interactions, lateral water flows, snow and ice) in a spatially detailed manner. The atmosphere is considered as exogenous driver, neglecting feedbacks between the land surface and the atmosphere. On the other hand, regional climate models (RCMs) generally simulate land surface processes through coarse descriptions and spatial scales but include land–atmosphere interactions. What is the impact of the differently applied model physics and spatial resolution of LSHMs on the performance of RCMs? What feedback effects are induced by different land surface models? This study analyses the impact of replacing the land surface module (LSM) within an RCM with a high resolution LSHM. A 2-way coupling approach was applied using the LSHM PROMET (1 × 1 km2) and the atmospheric part of the RCM MM5 (45 × 45 km2). The scaling interface SCALMET is used for down- and upscaling the linear and non-linear fluxes between the model scales. The change in the atmospheric response by MM5 using the LSHM is analysed, and its quality is compared to observations of temperature and precipitation for a 4 yr period from 1996 to 1999 for the Upper Danube catchment. By substituting the Noah-LSM with PROMET, simulated non-bias-corrected near-surface air temperature improves for annual, monthly and daily courses when compared to measurements from 277 meteorological weather stations within the Upper Danube catchment. The mean annual bias was improved from −0.85 to −0.13 K. In particular, the improved afternoon heating from May to September is caused by increased sensible heat flux and decreased latent heat flux as well as more incoming solar radiation in the fully coupled PROMET/MM5 in comparison to the NOAH/MM5 simulation. Triggered by the LSM replacement, precipitation overall is reduced; however simulated precipitation amounts are still of high uncertainty, both spatially and temporally. The distribution of precipitation follows the coarse topography representation in MM5, resulting in a spatial shift of maximum precipitation northwards of the Alps. Consequently, simulation of river runoff inherits precipitation biases from MM5. However, by comparing the water balance, the bias of annual average runoff was improved from 21.2% (NOAH/MM5) to 4.4% (PROMET/MM5) when compared to measurements at the outlet gauge of the Upper Danube watershed in Achleiten.

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Sensitivity of high-resolution Arctic regional climate model projections to different implementations of land surface processes

Climatic Change ◽

10.1007/s10584-011-0138-1 ◽

2011 ◽

Vol 111 (2) ◽

pp. 197-214 ◽

Cited By ~ 14

Author(s):

Heidrun Matthes ◽

Annette Rinke ◽

Paul A. Miller ◽

Peter Kuhry ◽

Klaus Dethloff ◽

...

Keyword(s):

High Resolution ◽

Regional Climate Model ◽

Land Surface ◽

Climate Model ◽

Regional Climate ◽

Surface Processes ◽

Land Surface Processes

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A Study on the Influence of the Land Surface Processes on the Southwest Monsoon Simulations using a Regional Climate Model

Pure and Applied Geophysics ◽

10.1007/s00024-014-0905-9 ◽

2014 ◽

Vol 172 (10) ◽

pp. 2791-2811 ◽

Cited By ~ 10

Author(s):

C. V. Srinivas ◽

D. V. Bhaskar Rao ◽

D. Hari Prasad ◽

K. B. R. R. Hari Prasad ◽

R. Baskaran ◽

...

Keyword(s):

Regional Climate Model ◽

Land Surface ◽

Climate Model ◽

Regional Climate ◽

Southwest Monsoon ◽

Surface Processes ◽

Land Surface Processes

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Analysis of feedback effects and atmosphere responses when 2-way coupling a hydrological land surface model with a regional climate model – a case study for the Upper-Danube catchment

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-9-7543-2012 ◽

2012 ◽

Vol 9 (6) ◽

pp. 7543-7570

Author(s):

F. Zabel ◽

W. Mauser

Keyword(s):

Heat Flux ◽

Land Surface ◽

Regional Climate ◽

Land Surface Model ◽

The Other ◽

Surface Processes ◽

Surface Model ◽

Land Surface Processes ◽

Danube Catchment ◽

The Impact

Abstract. Most land surface hydrological models (LSHMs) take land surface processes (e.g. soil-plant-atmosphere interactions, lateral water flows, snow and ice) into detailed spatial account. On the other hand, they usually consider the atmosphere as exogenous driver only, thereby neglecting feedbacks between the land surface and the atmosphere. Regional climate models (RCMs), on the other hand, generally describe land surface processes much coarser but naturally include land-atmosphere interactions. What is the impact on RCMs performance of the differently applied model physics and spatial resolution of LSHMs? In order to investigate this question, this study analyses the impact of replacing the land surface model (LSM) within a RCM by a LSHM. Therefore, a 2-way coupling approach was applied for a full integration of the LSHM PROMET (1×1 km2) and the atmospheric part of the RCM MM5 (45×45 km2). The scaling interface SCALMET is used for down- and upscaling the linear and non-linear fluxes between the model scales. The response of the MM5 atmosphere to the replacement is investigated and validated for temperature and precipitation for a 4 yr period from 1996 to 1999 for the Upper-Danube catchment. By substituting the NOAH-LSM with PROMET, simulated non-bias-corrected near surface air temperature significantly improves for annual, monthly and daily courses, when compared to measurements from 277 meteorological weather stations within the Upper-Danube catchment. The mean annual bias was improved from −0.85 K to −0.13 K. In particular, the improved afternoon heating from May to September is caused by increased sensible heat flux and decreased latent heat flux as well as more incoming solar radiation in the fully coupled PROMET/MM5 in comparison to the NOAH/MM5 simulation. Triggered by the LSM replacement, precipitation overall is reduced, however simulated precipitation amounts are still of high uncertainty, both spatially and temporally. The distribution of precipitation follows the coarse topography representation in MM5, resulting in a spatial shift of maximum precipitation northwards the Alps. Consequently, simulation of river runoff inherits precipitation biases from MM5. However, by comparing the water balance, the bias of annual average runoff was improved from 21.2% (NOAH/MM5) to 4.4% (PROMET/MM5) when compared to measurements at the outlet gauge of the Upper-Danube watershed in Achleiten.

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