3.14.3. LASMKII

3.14.3.1. Introduction

The LAS MKII is a large aperture scintillometer, manufactured by Kipp and Zonen. A scintillometer measures turbulence over a path, which can then be used to calculate heat flux, cross wind and evapotranspiration. The LAS MKII consists of two main parts for observations: a transmitter and a receiver. These are placed between 100m and 4500m apart. The transmitter transmits visible light towards the receiver, which uses the principle of modulation of light by atmospheric refractive index fluctuations in air, known as scintillation, to determine atmospheric turbulence over the path. The main benefit of scintillometry is the greater spatial representation achieved compared to point sensors.

3.14.3.2. Manufacturer and Model

Model	Brand	Type
MkII	Kipp & Zonen	Large Aperture Scintillometer

3.14.3.3. Output definitions

Ouput definition ID	File Identifier	Level Number	QAQC notes	File time resolution
LASMkII	LASMkII_Fast_%SITE	0	No_QC	1min
LASMkII	LASMkII_Fast_%SITE	0	No_QC	15min
LASMkII	LASMkII_Fast_%SITE	0	No_QC	30min
LASMkII	LASMkII_Fast_%SITE	1	Thresholds	1min
LASMkII	LASMkII_Fast_%SITE	1	Thresholds	15min
LASMkII	LASMkII_Fast_%SITE	1	Thresholds	30min

3.14.3.4. Processing code

Code used to process raw data: https://github.com/Urban-Meteorology-Reading/Operations-LAS

3.14.3.5. Variables measured by instrument

Table 3.13 Variables measured - sorted alphabetically

Variable ID	Full Name	Unit	Lower Threshold	Upper Threshold	Files present (Output definition ID,Level No,Time resolution)
Cn2	refractive_index_structure_parameter	m-2/3			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
Cn2_SigUCn2	refractive_index_structure_parameter_UCn2Sig_method	m-2/3			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
Cn2Sig	refractive_index_structure_parameter	m-2/3			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
CT2	temperature_structure_parameter	K-2m^2/3			LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
Demod	demodulated_signal	mV			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
DemodSig	demodulated_signal_sig	mV			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
FLAG	Status flag	N/A			LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
nSamples	nSamples	samples/interval			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
Q_H	upward_turbulent_sensible_heat_flux	W.m-2			LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
Q_H_db	upward_turbulent_sensible_heat_flux_de_bruin_method	W.m-2			LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
Q_H_fc	upward_turbulent_sensible_heat_flux_free_convection_method	W.m-2			LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
SatCorrFactor	Saturation_Correction_Factor	dimensionless			LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
UCn2	UCn2	m-2/3			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min
UCn2Sig	standard_deviation_UCn2	m-2/3			LASMkII,0,1min LASMkII,0,15min LASMkII,0,30min LASMkII,1,1min LASMkII,1,15min LASMkII,1,30min

3.14.3.6. Serials

Serial	Suffix
120029	A
120028	B

3.14.3.7. Deployments

3.14.3.7.1. Serial number: 120029

Site ID	Start date	End date
NTT	2012-02-01 00:00	2013-02-26 00:00
IMU	2014-04-09 00:00	2018-10-31 00:00

3.14.3.7.2. Serial number: 120028

Site ID	Start date	End date
NGT	2012-02-22 00:00	2012-09-21 00:00
NDT	2012-09-21 00:00	2013-02-26 00:00
BCT	2014-04-01 00:00	2017-03-16 00:00
SWT	2017-08-25 00:00	2021-04-09 00:00

3.14.3.8. Photos

Fig. 3.36 LAS MKII (right) at NTT 25/10/2012

Fig. 3.37 LAS receiver (centre) and transmitter (right) at BCT 09/04/2014

Fig. 3.38 Receiver at IMU 03/10/2015

3.14.3.9. Supplementary information

Link	Title	Description
https://www.kippzonen.com/Download/598/LAS-MkII-Scintillometer-Manual?ShowInfo=true	LAS MKII manual	Manual from Kipp and Zonen. If link has expired please raise a GitHub Issues.

3.14.3.10. Data acquisition

Data can be requested from Prof. Sue Grimmond (c.s.grimmond@reading.ac.uk).

3.14.3.11. References

1. Crawford, B., Grimmond, S. B., Gabey, A., Marconcini, M., Ward, H. C. and Kent, C. W. (2018) Variability of urban surface temperatures and implications for aerodynamic energy exchange in unstable conditions. Quarterly Journal of the Royal Meteorological Society, 144 (715). pp. 1719-1741. ISSN 1477-870X doi: https://doi.org/10.1002/qj.3325

2. Ward, H. C., Evans, J. G. and Grimmond, C. S. B. (2014) Multi-scale sensible heat fluxes in the urban environment from large aperture scintillometry and eddy covariance. Boundary-Layer Meteorology, 152 (1). pp. 65-89. ISSN 0006-8314 doi: https://doi.org/10.1007/s10546-014-9916-4

Tip

1. Stuck? the user guide is a useful place to start.

2. Please report issues at GitHub Issues. Go from the page with the problem - an automatic link will be inserted. Thanks.