1. The Cabauw Experimental Site for Atmospheric Research (CESAR): New developments Fred C. Bosveld (KNMI)
Content
CESAR and its research themes
Long term boundary layer observations
New or improved observations
Fog observations
New Soil heat flux observation
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2. Consortium of 8 institutes:
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3. Energy fluxes, evaporation
CESAR Research Themes
Ice clouds
radiation
Mixed phase clouds
Water clouds
Aerosols
Water vapour
Air Quality
drizzle
GHG budgets
rainfall
Water balance
Energy fluxes, evaporation
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4. Cabauw 26 year Evaporation time series Energy budget residual method (Beljaars and Bosveld, 1997)
Yearly mean observed evaporation (OBS).
Compared with Makkink reference evaporation (REF)
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5. New/improved instruments since 2008
Flux levels
Drizzle Radar at top of the 200 m tower
Raman Lidar (not continuous)
Improved Relative Humidity (heated polymere sensors)
Improved Ceilometer (Lufft CMK15k)(Better cirrus and BLH detection)
Regional scale fluxes – Scintillometer over a 10 km path – Turbulent fluxes in the main tower (60, 100 and 180m)
Here we present:
Fog observations
Improved soil observations
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6. Fog observational programme (Inspired by Meteo France)
Incoming long and short wave radiation at 213 m
7 Visibility sensors (forward scattering) in 200 m profile.
Pyrometer for surface radiation temperature
Visibility sensor in calibration mode
Together with surface radiation gives transmissivity of fog layer in visible and infrared
Sees 1 ha, including the surface flux field
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7. Visibility from 200m tower. 48+ hr fog period 20-21 Nov 2011
10 km
1 km
100 m
10 m
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8. Profiles from 200m tower. 48+ hr fog period 20-21 Nov 2011
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9. Fog event 20-21 Nov 2011 Radiative temperature of the top of fog layer
is lower than bulk of the fog layer
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10. Sonic anemometers in tower kept working during fog episode
Downward convection from top of fog-layer observed at 100 and 60 m level
σW m/s
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11. Improved soil heat observations
Combination of:
3 sets of self-calibrating heat flux plates at 5 and 10 cm depth
Two soil temperature profiles
High accurate and high resolution (0.01oC) for soil heat budget
At timesteps of 10 minutes
Profiles of soil water content for soil heat capacity.
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12. Soil temperature and an unexpected guest
Midday 01 July 2013
Midday 01 July 2014
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13. How to …! Wait for summer 2016 Apr - 2016 May - 2015 Jun - 2016
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14. Conclusions
25+ year long time series are available for the most relevant parameters characterizing the atmospheric boundary layer at Cabauw and the interaction with the land-surface.
Important improvements have been implemented the last few years.
To show the potential for process studies and model evaluation an example is given of a fog case.
Issues with the new soil heat observation show that reality often comes with surprises.
Looking for Cabauw data? Consult
or contact me at:
12-Sep-2016 EMS Trieste