GC-Net Level 1 historical automated weather station data (ongoing)

The Greenland Climate Network (GC-Net) is a set of Automatic Weather Stations (AWS) set up and managed by the late Prof. Dr. Konrad (Koni) Steffen on the Greenland Ice Sheet (GrIS). This first station, "Swiss Camp" or the "ETH-CU" camp, was initiated in 1990 by A. Ohmura et al. (1991, 1992) with K. Steffen taking over the site from 1995 and expending the network from that year to 31 stations at 30 sites in Greenland (Steffen et al., 1996, 2001). The GC-Net was supported by multiple NASA, NOAA, and NSF grants throughout the years, and then supported by WSL in the later years. These data were previously hosted by the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado.

Provided in this dataset are the 25 two-level stations from 24 sites on the Greenland ice sheet and 3 experimental stations in Antarctica. The remaining 6 Greenland stations have a different design and will be added once quality checked. Although the GC-Net AWS transmitted their data near-real time through satellite communication, the present dataset was made from uncorrupted datalogger files, retrieved every 1-2 years during maintenance.

Full dataset description publication will be forthcoming. The Geological Survey of Denmark and Greenland (GEUS) has undertaken the continuation of multiple GC-Net sites through the Programme for Monitoring of the Greenland Ice Sheet (PROMICE.dk).

The level 1 data is provided in the newly described csv-compatible NEAD format, which is a csv file with added metadata header. The format is documented at https://doi.org/10.16904/envidat.187 and a python package is available to read and write NEAD files: https://github.com/GEUS-Glaciology-and-Climate/pyNEAD .

The GC-Net stations measure:

- Air temperature from four sensors at two heights above the surface
- Relative humidity at two heights above the surface
- Wind speed and direction at two heights above the surface
- Air pressure
- Surface height from two sonic sounders
- Incoming and outgoing shortwave radiation
- Net radiation (long- and short-wave)*
- Firn or ice temperatures at 10 levels below the surface

In the L1 dataset, these measurements are cleaned from sensor, station or logger malfunctions, adjusted and/or filtered when and where possible.

Additionally, the L1 dataset contains the following derived variables:

- Surface height (corrected from the shifts in sonic sounder height)
- Instrument heights (derived from sonic sounder height and station geometry)
- Inter- or extrapolated temperature, relative humidity and wind speed at respectively 2, 2, and 10 m above the surface
- Estimated depth of the subsurface temperature measurements (adjusted for snow accumulation, ice ablation and instrument replacement)
- Interpolated firn or ice temperature at 10 m below the surface
- Calculated solar an azimuth angles
- Sensible and latent heat fluxes calculated after Steffen and Demaria (1996)