Details
| Original language | English |
|---|---|
| Pages (from-to) | 83-112 |
| Number of pages | 30 |
| Journal | Boundary-Layer Meteorology |
| Volume | 144 |
| Issue number | 1 |
| Publication status | Published - 28 Mar 2012 |
Abstract
Scintillometry has been increasingly used over the last decade for the experimental determination of area-averaged turbulent fluxes at a horizontal scale of a few kilometres. Nevertheless, a number of assumptions in the scintillometer data processing and interpretation still call for a thorough evaluation, in particular over heterogeneous terrain. Moreover, a validation of the path-averaged structure parameters derived from scintillometer data (and forming the basis for the flux calculations) by independent measurements is still missing. To achieve this, the LITFASS-2009 field campaign has been performed around the Meteorological Observatory Lindenberg - Richard-Aßmann-Observatory of the German Meteorological Service (DWD) in July 2009. The experiment combined tower-based in-situ turbulence measurements, field-scale laser scintillometers, long-range optical (large-aperture) and microwave scintillometers, and airborne turbulence measurements using an automatically operating unmanned aircraft. The paper describes the project design and strategy, and discusses first results. Daytime near-surface values of the temperature structure parameter, CT2, over different types of farmland differ by more than one order of magnitude in their dependence on the type and status of the vegetation. Considerable spatial variability in CT2 was also found along the flight legs at heights between 50 and 100 m. However, it appeared difficult to separate the effects of heterogeneity from the temporal variability of the turbulence fields. Aircraft measurements and scintillometer data agreed in magnitude with respect to the temporal variation of the path-averaged CT2 values during the diurnal cycle. The decrease of CT2 with height found from the scintillometer measurements close to the surface and at 43 m under daytime convective conditions corresponds to free-convection scaling, whereas the aircraft measurements at 54 and 83 m suggest a different behaviour.
Keywords
- Heterogeneous terrain, LITFASS, Scintillometer, Temperature structure parameter, Turbulence, Unmanned aircraft
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Atmospheric Science
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In: Boundary-Layer Meteorology, Vol. 144, No. 1, 28.03.2012, p. 83-112.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Towards a Validation of Scintillometer Measurements
T2 - The LITFASS-2009 Experiment
AU - Beyrich, Frank
AU - Bange, Jens
AU - Hartogensis, Oscar K.
AU - Raasch, Siegfried
AU - Braam, Miranda
AU - van Dinther, Daniëlle
AU - Gräf, Doreen
AU - van Kesteren, Bram
AU - van den Kroonenberg, Aline C.
AU - Maronga, Björn
AU - Martin, Sabrina
AU - Moene, Arnold F.
N1 - Funding Information: Acknowledgements The LITFASS-2009 experiment was performed as part of the research project “Turbulent structure parameters over heterogeneous terrain—implications for the interpretation of scintillometer data”. This project is funded by the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG) through grants BA1988/9-1, BE2044/3-1, RA617/20-1, and by the Dutch Science Foundation (Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO) through grant DN76-274. The DBSAS operated in the maize field has been provided by the Meteorological Institute of the University of Leipzig in co-operation with the Institute for Tropospheric Research Leipzig, thanks go to A. Raabe and T. Conrath. The MWRAL system was provided by the Centre for Ecology and Hydrology Wallingford, UK, the authors are thankful to J. Evans and H. Ward. Significant support in performing the measurements and preparing the data came from the MOL-RAO staff members P. Dereszynski, C. Heret, G. Hollaz, J. Janiak, K. Jantze, S. Niesche, S.H. Copyright: Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2012/3/28
Y1 - 2012/3/28
N2 - Scintillometry has been increasingly used over the last decade for the experimental determination of area-averaged turbulent fluxes at a horizontal scale of a few kilometres. Nevertheless, a number of assumptions in the scintillometer data processing and interpretation still call for a thorough evaluation, in particular over heterogeneous terrain. Moreover, a validation of the path-averaged structure parameters derived from scintillometer data (and forming the basis for the flux calculations) by independent measurements is still missing. To achieve this, the LITFASS-2009 field campaign has been performed around the Meteorological Observatory Lindenberg - Richard-Aßmann-Observatory of the German Meteorological Service (DWD) in July 2009. The experiment combined tower-based in-situ turbulence measurements, field-scale laser scintillometers, long-range optical (large-aperture) and microwave scintillometers, and airborne turbulence measurements using an automatically operating unmanned aircraft. The paper describes the project design and strategy, and discusses first results. Daytime near-surface values of the temperature structure parameter, CT2, over different types of farmland differ by more than one order of magnitude in their dependence on the type and status of the vegetation. Considerable spatial variability in CT2 was also found along the flight legs at heights between 50 and 100 m. However, it appeared difficult to separate the effects of heterogeneity from the temporal variability of the turbulence fields. Aircraft measurements and scintillometer data agreed in magnitude with respect to the temporal variation of the path-averaged CT2 values during the diurnal cycle. The decrease of CT2 with height found from the scintillometer measurements close to the surface and at 43 m under daytime convective conditions corresponds to free-convection scaling, whereas the aircraft measurements at 54 and 83 m suggest a different behaviour.
AB - Scintillometry has been increasingly used over the last decade for the experimental determination of area-averaged turbulent fluxes at a horizontal scale of a few kilometres. Nevertheless, a number of assumptions in the scintillometer data processing and interpretation still call for a thorough evaluation, in particular over heterogeneous terrain. Moreover, a validation of the path-averaged structure parameters derived from scintillometer data (and forming the basis for the flux calculations) by independent measurements is still missing. To achieve this, the LITFASS-2009 field campaign has been performed around the Meteorological Observatory Lindenberg - Richard-Aßmann-Observatory of the German Meteorological Service (DWD) in July 2009. The experiment combined tower-based in-situ turbulence measurements, field-scale laser scintillometers, long-range optical (large-aperture) and microwave scintillometers, and airborne turbulence measurements using an automatically operating unmanned aircraft. The paper describes the project design and strategy, and discusses first results. Daytime near-surface values of the temperature structure parameter, CT2, over different types of farmland differ by more than one order of magnitude in their dependence on the type and status of the vegetation. Considerable spatial variability in CT2 was also found along the flight legs at heights between 50 and 100 m. However, it appeared difficult to separate the effects of heterogeneity from the temporal variability of the turbulence fields. Aircraft measurements and scintillometer data agreed in magnitude with respect to the temporal variation of the path-averaged CT2 values during the diurnal cycle. The decrease of CT2 with height found from the scintillometer measurements close to the surface and at 43 m under daytime convective conditions corresponds to free-convection scaling, whereas the aircraft measurements at 54 and 83 m suggest a different behaviour.
KW - Heterogeneous terrain
KW - LITFASS
KW - Scintillometer
KW - Temperature structure parameter
KW - Turbulence
KW - Unmanned aircraft
UR - http://www.scopus.com/inward/record.url?scp=84861923401&partnerID=8YFLogxK
U2 - 10.1007/s10546-012-9715-8
DO - 10.1007/s10546-012-9715-8
M3 - Article
AN - SCOPUS:84861923401
VL - 144
SP - 83
EP - 112
JO - Boundary-Layer Meteorology
JF - Boundary-Layer Meteorology
SN - 0006-8314
IS - 1
ER -