Results from One-Year Continuous Operation of a Large Aperture Scintillometer over a Heterogeneous Land Surface

Beyrich, Frank; Bruin, H.A.R. de; Meijninger, W.M.L.; Schipper, Janus Willem; Lohse, H.

doi:10.1023/a:1019640014027

Cited by 84 publications

(59 citation statements)

References 21 publications

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“…Furthermore Fig. 3 Figure 3, thus, corroborates the performance of the WagLAS and K&ZLAS09 found in the literature: the WagLAS has been shown to give accurate flux estimates (De Bruin et al 1995;Green 2001;Beyrich et al 2002;Meijninger et al 2002Meijninger et al , 2006, whereas the K&ZLAS has been shown to have systematic errors of up to 20% (Kleissl et al 2008(Kleissl et al , 2009). In the following we therefore use the WagLAS as the reference scintillometer.…”

Section: Comparison Of H Ec With H W Agl As and H K Andz L As09supporting

confidence: 86%

Analysis of the Systematic Errors Found in the Kipp & Zonen Large-Aperture Scintillometer

Kesteren

Hartogensis

2010

Boundary-Layer Meteorol

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Studies have shown a systematic error in the Kipp & Zonen large-aperture scintillometer (K&ZLAS) measurements of the sensible heat flux, H . We improved on these studies and compared four K&ZLASs with a Wageningen large-aperture scintillometer at the Chilbolton Observatory. The scintillometers were installed such that their footprints were the same and independent flux measurements were made along the measurement path. This allowed us to compare H and the direct scintillometer output, the refractive index structure parameter, C 2 n . Furthermore, spectral analysis was performed on the raw scintillometer signal to investigate the characteristics of the error. Firstly, correlation coefficients ≥0.99 confirm the robustness of the scintillometer method, and secondly we discovered two systematic errors: the low-C 2 n error and the high-C 2 n error. The low-C 2 n error is a non-linear error that is caused by high-frequency noise, and we suspect the error to be caused by the calibration circuit in the receiver. It varies between each K&ZLAS, is significant for H ≤ 50 W m −2 , and we propose a solution to remove this error using the demodulated signal. The high-C 2 n error identified by us is the systematic error found in previous studies. We suspect this error to be caused by poor focal alignment of the receiver detector and the transmitter light-emitting diode that causes ineffective use of the Fresnel lens in the current Kipp & Zonen design. It varies between each K&ZLAS (35% up to 240%) and can only be removed by comparing with a reference scintillometer in the field.

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Section: Comparison Of H Ec With H W Agl As and H K Andz L As09supporting

confidence: 86%

Analysis of the Systematic Errors Found in the Kipp & Zonen Large-Aperture Scintillometer

Kesteren

Hartogensis

2010

Boundary-Layer Meteorol

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“…(2) and (3)], surface homogeneity over the footprint area is required and horizontal flux transport and storage fluxes should be zero. However, Meijninger et al (2002) and Beyrich et al (2002) demonstrated that a LAS sensible heat flux over a chessboard pattern of crop matched the weighted average of the individual crop H measured by EC. They argued that the LAS beam should be located above the blending height (Bou-Zeid et al 2004) of individual heterogeneities for similarity theory to hold.…”

Section: Scintillometrymentioning

confidence: 95%

“…Thus, the validation and data assimilation of sensible and latent heat fluxes into hydrologic and meteorological models is complicated by the scale gap between footprints of existing surface flux measurement and the pixel or gridcell area of these models. Meijninger et al (2002) and Beyrich et al (2002) recently demonstrated that scintillometry allows the measurements of sensible heat fluxes H at footprint dimensions from 500 to 10,000 m or areas comparable with several pixels of a satellite image (tens of Landsat thermal pixels or a few MODIS thermal pixels). The objective of this paper is to present "lessons learned" from our first-of-itskind network of seven scintillometers in semiarid New Mexico (Table 1).…”

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confidence: 99%

New Mexico Scintillometer Network: Supporting Remote Sensing and Hydrologic and Meteorological Models

Kleissl¹,

Hong²,

Hendrickx³

2009

Bull. Amer. Meteor. Soc.

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Large-aperture scintillometers have been successfully used in a variety of ecosystems in New Mexico to measure sensible heat fluxes at the kilometer scale. Sustainable management of water resources in arid and semiarid watersheds requires accurate information on consumptive water use over a range of space and time scales. Consumptive water use by grasses and shrubs, irrigated crops, and riparian vegetation in desert regions is highly variable in space and time. The spatial variability is caused by the heterogeneous nature of vegetation cover, hydraulic soil properties, groundwater table depths, and differences in water availability caused by hydrological

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“…The reliability of scintillometers to provide accurate estimates on surface fluxes has been proven in many different natural or semi-natural areas (e.g. Thiermann and Grassl 1992;Green et al 1994;De Bruin et al 1995;Beyrich et al 2002Beyrich et al , 2012Meijninger et al 2006;Ezzachar et al 2007;Evans et al 2012;Samain et al 2012).…”

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confidence: 99%

Long-term Turbulent Sensible-Heat-Flux Measurements with a Large-Aperture Scintillometer in the Centre of Łódź, Central Poland

Zieliński

Fortuniak

Pawlak

et al. 2018

Boundary-Layer Meteorol

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We investigate the area-averaged sensible heat flux (Q H ) obtained with a scintillometer along a 3.1-km path length over the city centre of Łódź, Central Poland. The annual cycle of Q H peaks in June but is lower by the middle of summer. In winter, due to a large amount of anthropogenic heat input, Q H remains positive all day long, with positive nighttime fluxes also found during months with frequent cold advection, e.g., June 2010. In the diurnal cycle of this flux, several features specific to urban areas are seen: the peak shifts 1-2 h after noon, the heat flux turns from positive to negative 1-2 h after sunset. In Łódź Q H was observed during inflow from the north and north-west, i.e. from the city centre. As this area is mostly covered with impervious materials, most of the heat exchanged between the ground and the overlying air is in the form of sensible heat flux. Under the conditions of inflow from the east and south-east, the maximum heat flux is approximately 100 W m −2 lower than during the inflow from the city centre, since more vegetation exists to the east and south-east of the scintillometer path. Cold and warm advection are found to be a vital factor in the observed heat-flux variability in the centre of Łódź.

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Results from One-Year Continuous Operation of a Large Aperture Scintillometer over a Heterogeneous Land Surface

Cited by 84 publications

References 21 publications

Analysis of the Systematic Errors Found in the Kipp & Zonen Large-Aperture Scintillometer

Analysis of the Systematic Errors Found in the Kipp & Zonen Large-Aperture Scintillometer

New Mexico Scintillometer Network: Supporting Remote Sensing and Hydrologic and Meteorological Models

Long-term Turbulent Sensible-Heat-Flux Measurements with a Large-Aperture Scintillometer in the Centre of Łódź, Central Poland

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