Longwave downwelling irradiance (LWD)

The 2017 report mentions that the station has a CGR4, whereas the 2014 report mentions a CGR3.
- [ ] Check the server and binder with datasheets to see if we have ever had a CGR3.

It is uncertain whether the LWD parameter represents net or downwelling irradiance:
- [ ] Look into LabView code to see what is being logged.
- [ ] Check with the BSRN QC limits
- [ ] Recheck the low values in late 2017

The body temperature of the pyrgeometer is RTD3 (which is not documented in any of the reports). It is generally favorable to use this measurement to determine when the sensor has been disconnected.

## After QC
The LWD and LWD_temperature (RTD3) after QC (95% availability after start):

## Before QC
The before QC plot is resample to hourly data to speed up the plotting.


Start by checking the server and binder against the CGR3/CGR4 datasheets, then inspect the LabView logging code and BSRN QC limits. Recheck the late-2017 low values and determine whether LWD is net or downwelling irradiance, how RTD3 should identify disconnection, and document the conclusions.

Written by the indexing model from the issue text.