Confronting the WRF and RAMS mesoscale models with innovative observations in the Netherlands: Evaluating the boundary layer heat budget

• Published in: Journal of Geophysical Research: Atmospheres Vol. 116; no. D23
• Main Authors: Steeneveld, G. J., Tolk, L. F., Moene, A. F., Hartogensis, O. K., Peters, W., Holtslag, A. A. M.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 16-12-2011; American Geophysical Union
• Subjects: Air quality; Atmospheric boundary layer; Atmospheric sciences; boundary layer; Boundary layers; Cabauw; co2 mixing ratios; contrasting nights; diurnal cycles; Earth sciences; Earth, ocean, space; energy budget; Exact sciences and technology; Fluctuations; Geophysics; Heat budget; land-surface; large-eddy simulations; Mesoclimatology; mesoscale modelling; RAMS; regional-scale; Sensible heat; transport models; vertical diffusion; weather forecasts; WRF; Netherlands; Europe; Western Europe; Netherlands, Utrecht, Cabauw; Divergence; Entrainment (atmosphere, ocean); sensitivity analysis; heat balance; boundary layer; thermodynamics; focus; BASIC; refining; currents; Eddy covariance method; Height; scale models; Scintillation counter; heat flux; sensible heat; Long wave; Regional scope; Air quality; climate; Mesoscale; radiation; Atmospheric boundary layer; heat transfer; errors
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2011JD016303

The Weather Research and Forecasting Model (WRF) and the Regional Atmospheric Mesoscale Model System (RAMS) are frequently used for (regional) weather, climate and air quality studies. This paper covers an evaluation of these models for a windy and calm episode against Cabauw tower observations (Netherlands), with a special focus on the representation of the physical processes in the atmospheric boundary layer (ABL). In addition, area averaged sensible heat flux observations by scintillometry are utilized which enables evaluation of grid scale model fluxes and flux observations at the same horizontal scale. Also, novel ABL height observations by ceilometry and of the near surface longwave radiation divergence are utilized. It appears that WRF in its basic set‐up shows satisfactory model results for nearly all atmospheric near surface variables compared to field observations, while RAMS needed refining of its ABL scheme. An important inconsistency was found regarding the ABL daytime heat budget: Both model versions are only able to correctly forecast the ABL thermodynamic structure when the modeled surface sensible heat flux is much larger than both the eddy‐covariance and scintillometer observations indicate. In order to clarify this discrepancy, model results for each term of the heat budget equation is evaluated against field observations. Sensitivity studies and evaluation of radiative tendencies and entrainment reveal that possible errors in these variables cannot explain the overestimation of the sensible heat flux within the current model infrastructure.
Key Points
PBL schemes in WRF and RAMS are evaluated
New techniques are used for model validation (ceilometry and scintillometry)
Models need larger sensible heat flux than observed for correct PBL temperature