Kipp & Zonen LAS, Instruction Manual

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3.2 STEP BY STEP INSTALLATION PROCEDURE
3.2.1 Site selection
For the installation of the
LAS -system it is important that the following aspects are taken into account
in order to have a reliable operational system:
The scintillometer (see also
LAS instruction manual):
•
Orientation optical path:
1)
it is advised to install the scintillometer such that the
orientation of the path is north-south to prevent direct sunlight into the
transmitter/receiver unit;
2)
Install the LAS in a way that the path is (near) horizontal
along the surface and that it is measuring within the constant flux layer and within the
saturation free region;
3)
The optical path must be free from obstacles, such as trees or
high buildings.
•
Minimum height: depending on the surface conditions and the planned path length. First, the
effective height of the scintillometer should be high enough to avoid saturation of the signal .
For example high buildings, robust towers or surface topography can be used to mount the
scintillometer (see e.g. Figure 3). Second, for reliable flux derivations the
LAS / XLAS must
measure within the so-called Constant Flux Layer of the Surface Layer (above the Roughness
Sublayer), where MOST is applicable. For further instructions the reader is referred to section
3.3 of the
LAS instruction manual!
•
Availability of net AC power (in case no solar-battery power is used).
The weather station:
•
A spot that is representative for the area of interest, away from forest edges or other rough
surface elements.
•
A spot, which is preferably near the centre of the path of the scintillometer (as the LAS / XLAS
is most sensitive in the centre of its path).
•
Availability of net AC power (in case no solar-battery power is used).
•
In case a RF telemetry link is used (based on RF modems and antennas) the installation
requirements of RF communication devices must be considered also. For detailed information
the reader is referred to APPENDIX 3 – MOUNTING ANTENNAS.
The site selection of the
LAS / XLAS and weather station involves an iterative procedure:
1. Select a proper site for the LAS / XLAS (Transmitter and Receiver), such that the
observations of the instrument are representative for the area of interest, thereby taking into
account the installation requirements of the
LAS / XLAS .
2. Select a representative site for the weather station, also taking into account the installation
requirements of the station (see above and section 3.2.4.1 Site selection).
3. Check the RF telemetry link (see APPENDIX 1 – TESTING RF TELEMETRY LINK)
a. Communication established
→
continue with step 4
b. Communication fails
→
go back to step 1 and/or 2
c. If one uses no RF telemetry link
→
skip step 3 and continue with step 4
4. Check scintillometer path for saturation and MOST applicability (see section 3.3 of LAS
instruction manual)
a. No saturation and in compliance with MOST
→
continue with step 4
b. Saturation is highly possible
→
go back to step 1
5. Install the weather station and the LAS / XLAS (and RF telemetry link)
→
go to next paragraph for further instructions