DOI: 10.5285/05c9124b-7119-4d99-8e17-ab754eb3f51c
title: Dataset from iWS 18 in Cabinet Inlet, Larsen C Ice Shelf, Antarctica, 2014-2017

description: The data consists of 30 minute observations recorded by an automatic weather station (iWS 18) in Cabinet Inlet on Larsen C Ice Shelf on the Antarctic Peninsula. The iWS consists of a custom-built weather station unit, assembled at the Institute of Marine and Atmospheric research Utrecht (IMAU). There are sensors for air temperature, surface air pressure, relative humidity, as well as a gps, an acoustic snow height sensor, an ARGOS communication antenna, and three Lithium batteries that fuel the unit when solar radiation is absent. The unit is complemented by a propeller-vane Young anemometer measuring wind direction and speed. Additionally, all radiation fluxes are measured with a Kipp and Zonen CNR4 radiometer. This dataset runs from November 2014 to January 2017.
description: A number of corrections and adjustments to the raw data were applied for this dataset. 1) The temperature sensor is not artificially ventilated. This leads to a positive bias in temperature measurements under conditions of high insolation and low wind speed. Simultaneous observations from a thin-wire thermocouple provided a correction procedure, detailed in Smeets et al. (2017). 2) The relative humidity sensor is placed within the unit and experiences elevated temperature under sunny conditions. Internally-observed temperature of the sensor allows the calculation of a dew point, which gives a relative humidity for the observed air temperature. Next, relative humidity is corrected for observations over ice rather than over water. And finally, a well-known underestimation of RH-observations at low temperatures is corrected for by fitting a polynomial through the upper percentile of data and define that polynomial as a RH of 100%. 3) Longwave radiation observations are corrected for the internal instrument temperature, and for window heating under high insolation conditions. 4) Acoustic snow height observations are corrected for the dependency of sound propagation on air temperature. 5) A few small data 30- to 60-minute data gaps were filled by linearly interpolation.
description: The format of the datafiles is described below: Date ; dd-mmm-yyyy hh:mm:ss Year; - Hour ; hhmm Time; decimal day of year Air temperature; degrees Celsius; instantaneous Relative humidity; %; instantaneous Surface air pressure; hPa; instantaneous Horizontal wind speed; m/s; 30-minute average Wind direction; degrees; 30-minute average Incoming shortwave; W/m2; 30-minute average Reflected shortwave; W/m2; 30-minute average Downwelling longwave; W/m2; 30-minute average Upwelling longwave ; W/m2; 30-minute average Instrument height; m; instantaneous Snow depth; m; instantaneous The date represents the end of a 30-minute interval. So observations reported for 12:30 are instantaneous values of air temperature, relative humidity, surface air pressure, and instrument height/snow depth, and the average value of the other parameters between 12:00 and 12:30. Instrument height is the height between the weather station unit and the snow surface, as measured with an acoustic snow height ranger. Instrument height represents the height above the surface of the temperature, humidity, pressure, and radiation sensors. For the wind sensor, add +0.40 m. Snow depth is a virtual quantity (no initial snow depth is known) that varies proportional to the observed instrument height.