Sonja Murto, Michael Tjernström, Michail Karalis, John Prytherch
Horisontal visibility, precipitation rate and air temperature data are obtained from a Present Weather observation station deployed on the 7th top deck of the Swedish icebreaker Oden during the expedition ARTofMELT (Atmospheric Rivers and the Onset of Arctic Melt) in the Fram Strait pack ice during the spring transition, 8 May to 14 June of 2023. Measurements ran continuously during the whole expedition.
The dataset also includes the World Meteorological Organization (WMO) synop code 'present weather', which is derived from the primary variables, and a few other derived variables showing accumulated precipitation.
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Citation
Sonja Murto, Michael Tjernström, Michail Karalis, John Prytherch (2024) Visibility, precipitation and present weather observations from expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-present-weather-1
References
Sonja Murto, Michael Tjernström, Michail Karalis, John Prytherch (2024) Visibility, precipitation and present weather observations from expedition ARTofMELT, Arctic Ocean, 2023 — raw data. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-present-weather-raw-1
Sonja Murto, John Prytherch (2024) Scripts for quality control and creating netCDF files from present weather sensor observations from the expedition ARTofMELT, Arctic Ocean, 2023. Software version 1.0.0. Bolin Centre Code Repository. https://doi.org/10.57669/oden-artofmelt-2023-present-weather-1.0.0
Data description
The dataset includes four NetCDF (.nc) files zipped into one zip-file. Total file size is about 16 MB (compressed 2.1 MB).
A list of all variable names, with short explanations and units is provided below. There is also an associated Readme_PWD.txt file that provides WMO code definitions and further details of data and processing.
Variables
Primary variables are visibility range, precipitation rate and temperature. Based on this established weather codes and accumulated precipitation are generated.
- Primary variables
air_temperature Air temperature (K) [time]day_of_year Decimal day of year (in UTC) [time]year Year [time]month Month of the year [time]day Day of the month [time]hour Hour of the day (in UTC) [time]minute Minutes of the hour [time]second Seconds of the minute [time]visibility_in_air_1min Visibility range averaged over one minute (m) [time]visibility_in_air_10min Visibility range averaged over ten minute (m) [time]precipitating_water_intensity Intensity of precipitation (mm h⁻¹) [time]
- Derived variables
cumulative_water Accumulated precipitation (mm) [time]cumulative_snow Accumulated snow fall (mm) [time]NWS_present_weather_code_inst Instaneous US National Weather Service 'present weather' code [time]WMO_present_weather_code_inst Instaneous World Meteorological Organization 'present weather' code [time]WMO_present_weather_code_15min World Meteorological Organization 'present weather' code averaged over 15 minutes [time]WMO_present_weather_code_60min World Meteorological Organization 'present weather' code averaged over one hour [time]
Dimensions
Dimensions for the fields are time.
The four NetCDF files have the following different time resolutions:
- native 30 s time resolution
- 1 minute time averaged data
- 10 minute time averaged data
- 20 minute time averaged data
The data was concatenated from the native format and averaged when necessary.
Comments
Measurement system
The data was obtained from a Present Weather Detector sensor from Vaisala (Vaisala PWD22). Visibility is measured with a laser using forward scattering as the WMO standard, the greatest distance at which it would be just possible to see and identify a prominent dark object against the sky at the horizon with the unaided eye. The precipitation comes from a Vaisala RAINCAP sensor, an acoustic sensor that measures the impact of individual raindrops on a smooth stainless steel surface using a piezoelectric detector. Weather codes are determined from this information and the temperature, measured with a platinum-resistance sensor in an unventilated radiation shield.
Quality control
Some data quality control is applied:
- remove unnecessary variables
- remove visibility values above 20 km
- remove present weather code above 100
- correct for errors in the accumulated variables (water and snow)
- remove bad temperature values.
Associated raw data and code
The raw data, from which this dataset is derived, was created by Murto et al. (2024) and is available separately. The current dataset is the concatenation of the original raw files on the native time scale and also averaged into 1 min, 10 min and 20 min averaging periods to accommodate the user. The computer codes, in Matlab and Python, written by Murto and Prytherch (2024), used to derive this dataset in NetCDF format from the raw data files are also available.
Data creators' roles
The instrument system was continuously logging and was monitored by the Stockholm University Meteorology team onboard Oden:
- Sonja Murto (operator and dataset creator)
- Michail Karalis (operator)
- Michael Tjernström (chief scientist; operator)
John Prytherch (also Stockholm University) is responsible for the instrument system.
The expedition
Data were collected during the ARTofMELT 2023 expedition on board the Swedish icebreaker Oden, which was organized by the Swedish Polar Research Secretariat from 8 May through 14 June, 2023.