Sonja Murto, Michael Tjernström, Michail Karalis, John Prytherch
A weather station was deployed on the 7th top deck of the Swedish icebreaker Oden during the ARTofMELT (Atmospheric Rivers and the Onset of Arctic Melt) expedition in the Fram Strait pack ice during the spring transition, 8 May to 14 June of 2023.
The primary observed data include wind speed and direction, temperature, surface temperature and downwelling long- and shortwave radiation. Measurements ran continuously during the whole expedition. Additional data are added from other measuring systems due to some malfunctioning sensors and to help assess the radiation measurements.
An associated dataset, containing the raw data from the weather station alone, is available separately.
Download data
Citation
Sonja Murto, Michael Tjernström, Michail Karalis, John Prytherch (2024) Wind, temperature, relative humidity, surface temperature and radiation from expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-weather-station-1
References
Murto S, Tjernström T, Karalis M, Prytherch J (2024) Wind, temperature, relative humidity, surface temperature and radiation from expedition ARTofMELT, Arctic Ocean, 2023 — raw data. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-weather-station-raw-1
Data description
The dataset includes four NetCDF (.nc) files zipped into one zip-file. Total file size is about 145 MB (compressed to 50 MB).
The four NetCDF files have the following different time resolutions:
- native 5 s time resolution
- 1 minute time averaged data
- 10 minute time averaged data
- 20 minute time averaged data
A list of all variable names, with short explanations and units and definitions, can be found in an associated Readme_WX.txt file. The user is recommended to read this readme file as it provides further details of data problems and processing, and information on the several additional data provided.
Variables
Divided into:
- Primary variables
- ship's relative wind speed and direction.
- temperature, relative humidity, surface temperature (2, starboard and port sides) and downwelling short- and longwave radiation.
- Derived variables
- derived from other sensor systems to replace e.g. malfunctioning sensors and to help assess the radiation observations.
- e.g., true wind speed and direction, merged variables for relative humidity and air temperature and clear sky downwelling long- and shortwave radiation.
- Other variables
- e.g., time series from other sensors, such as for air temperature and relative humidity
- sensors as aid in investigating the need of shading for the shortwave radiation, such as total cloud cover and liquid water path.
- Quality control flag variables
- data flags to indicate corrections and for merged variables, which sensors are utilised.
Detailed lists:
- Primary variables
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]longitude Longitude from weather station (deg) [time]latitude Latitude from weather station (deg) [time]wind_direction_relative The measured wind direction (deg) relative to the ship. [time]wind_speed_relative Measured wind speed (m s⁻¹), corrected for flow distortion. [time]air_temperature_wx Temperature from WX Rotronic (K)., NaN after 2023-06-08T08:42:14 UTC due to sensor removal. [time]relative_humidity_wx Relative humidity from WX Rotronic (%). Corrected, NaN after 2023-06-08T08:42:14 UTC due to sensor removal. [time]relative_humidity_wx_original Relative humidity from WX Rotronic (%). Uncorrected, set to NaN after 2023-06-08T08:42:14 UTC due to sensor removal. [time]air_pressure Atmospheric pressure (hPa) at the station altitude. [time]downwelling_shortwave_flux_in_air Downwelling solar radiation (W m⁻²), corrected. [time]downwelling_shortwave_flux_in_air_original Downwelling solar radiation (W m⁻²), uncorrected but bad data set to NaN. [time]downwelling_longwave_flux_in_air Downwelling thermal radiation (W m⁻²), corrected. [time]downwelling_longwave_flux_in_air_original Downwelling thermal radiation (W m⁻²), uncorrected but bad data set to NaN. [time]net_downwelling_longwave_flux_in_air Net downwelling thermal radiation (W m⁻²), corrected. [time]net_downwelling_longwave_flux_in_air_original Net downwelling thermal radiation (W m⁻²), uncorrected but bad data set to NaN. [time]surface_temperature_portside Surface temperature (heated sensor) (K), /w sky reflection correction. [time]surface_temperature_portside_original Surface temperature (heated sensor) (K), w/o corrections. [time]surface_temperature_starboard Surface temperature (K), /w sky reflection correction. [time]surface_temperature_starboard_original Surface temperature (K), w/o correction. [time]
- Derived variables
wind_direction True wind direction (deg) from using ship's navigation data. [time]wind_speed True wind speed (m s⁻¹) from using ship's navigation data. [time]eastward_speed East-west wind component (m s⁻¹) from using ship's navigation data. [time]northward_speed South-north wind component (m s⁻¹) from using ship's navigation data. [time]air_temperature Air temperature (K). This it is the recommended merged data. [time]relative_humidity Relative humidity (%). This it is the recommended merged data. [time]downwelling_shortwave_flux_in_air_assuming_clear_sky Downwelling thermal radiation from RRTM assuming no clouds. [time]downwelling_longwave_flux_in_air_assuming_clear_sky Downwelling solar radiation from RRTM assuming no clouds. [time]
- Other variables
air_temperature_pwd Temperature from the PWD sensor (K). Used in the merged data set due to sensor removal. [time]air_temperature_mast Temperature from the foredeck mast Rotronic (K). Used in the merged data set due to sensor removal. [time]relative_humidity_ship Relative humidity from ship (%). Calibrated to the WX sensor and used in the merged data. [time]relative_humidity_mast Relative humidity from foredeck mast (%). Calibrated to the WX sensor and used in the merged data. [time]relative_humidity_mast_original Relative humidity from foredeck mast (%). Uncorrected. [time]ship_heading Ships heading, from navigation system (deg) [time]liquid_water_path Liquid water path estimation from HATPRO (g m⁻²) [time]total_cloud_cover Total cloud cover (octas) from CL31 celiometer. [time]
- Quality control flag variables
qc_flag_temperature Data quality flag for air temperature, indicating which sensors are used in the merged air_temperature variable. [time]qc_flag_relative_humidity Data quality flag for relative humidity, also indicating which sensors are used in the merged air_temperature variable. [time]qc_flag_surface_temperature_portside Data quality flag for the portside surface temperature sensor. [time]qc_flag_surface_temperature_starboard Data quality flag for the starboard surface temperature sensor. [time]qc_flag_flow_distortion Data quality flag for wind variables. [time]qc_flag_longwave_flux Data quality flag for downward (and net) longwave flux. [time]qc_flag_shortwave_flux Data quality flag for downward shortwave flux. [time]qc_flag_shortwave_shading Data quality flag for risk of shading on the PSP sensor, determined mainly from solar azimuth sectors relative to ship's heading (SZA). [time]qc_flag_shortwave_no_shading Data quality flag to determine if cloudy conditions mean that shading for the PSP sensor is not relevant. [time]
Comments
Measurement system
The data was obtained from a weather station with multiple sensors:
- Gill 2D sonic anemometer (wind direction and speed)
- Rotronic aspirated TRH for temperature and relative humidity
- Vaisala PTU pressure sensor (for air pressure)
- Eppley Precision Infrared Radiometer (PIR; downwelling and net longwave radiation)
- Eppley Precision Spectral Pyranometer (PSP; downwelling shortwave radiation)
- Two Heitronics KT15 infrared (IR) sensors mounted on the port side (heated) and starboard side (non-heated) of the rail (surface temperature)
These main instruments of the weather station are located at approximately 25 m above sea level, whereas additional sensors used in the corrections include measurements from the PWD22 present weather sensor (~27 m above sea level), CL31 ceilometer (~25 m above sea level), HATPRO radiometer (~20 m above sea level) and from an additional aspirated TRH sensor located on the foremast of Oden (~20 m above sea level).
Several specific conditions influence this data (see the Readme_WX.txt file):
- At the beginning of the expedition, the portside surface temperature sensor developed noise due to water creeping into the electronics. This was repaired 22 – 24 May. The published data has been cleaned up but some problematic data may remain.
- Towards the end of the expedition a fan malfunctioned on the Rotronic TRH sensor on the foredeck mast. The weather station is equipped with the same sensor, and this was moved to the foredeck mast on 8 June, hence the primary temperature and relative humidity measurement on the weather station is lacking from thereon. Merged (total) temperature and relative humidity time series were constructed using other from nearby sensors; these time series are also supplied for reference.
- Measuring downwelling radiation on ship is difficult, especially for solar radiation due to shading from the superstructure. A number of methods are applied to safeguard the quality of these observations. Shading risks are flagged, and liquid water path (from the HATPRO radiometer) and cloud fraction (from the CL31 ceilometer) are also included to facilitate judging when the solar radiation might have been dominated by diffuse radiation and hence shading is no problem. Finally, a calculated clear-sky radiation using RRTM and sounding profiles is supplied as a reference.
Associated raw data
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 users. The processing is a complex process involving different types of code and calculations, also including ingesting measurements from other instruments. The codes for this is therefore not available. Contact the data creators for more information.
Data creators' roles
The instrument system was continuously logging and was monitored by the Meteorology team onboard Oden:
- Sonja Murto (operator and dataset creator)
- Ian Brooks (WP lead)
- 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.