Ice station micrometeorological data from expedition ARTofMELT, Arctic Ocean, 2023

Heather Guy, Ian Brooks, Sonja Murto, Michail Karalis, Michael Tjernström

Surface fluxes of momentum, and sensible and latent heat over the sea-ice, and other micrometeorological variables are derived from fast response (20 Hz) measurements of the 3-dimensional wind vector, temperature and humidity using eddy covariance. Some other meteorological measurements, supporting variables and quality checks are also included.

Measurements were obtained from the Met Mast instrument suite deployed on the sea ice near to 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. The installation was designed to fully characterise the surface energy budget over the sea-ice.

During ARTofMELT there were two Ice Stations: During Ice Station 1 measurements were collected on the sea ice continuously from 16 May to 22 May, and during Ice Station 2 measurements were collected on the sea ice continuously from 29 May to 12 June.

Citation

Heather Guy, Ian Brooks, Sonja Murto, Michail Karalis, Michael Tjernström (2024) Ice station micrometeorological data from expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-micrometeorology-ice-station-1

References

Guy H, Brooks I, Murto S, Karalis M, Tjernström M (2024) Ice station surface meteorology and radiation data from expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-surface-meteorology-ice-station-1

Data description

This dataset is provided in a zipped file containing 60 NetCDF (.nc) files, three files for each day during the two ice stations, containing Eddy Covariance calculations over 10, 20, and 30 minute averaging intervals. The zipped file also contains photographs of the instruments during each ice station, and the field log book (excel spreadsheet). The total file size is about 22 MB.

Each NetCDF file contains 34 variables with dimensions of time.

A detailed list of variables is included below.

Dimensions

• time Time (seconds since 1970-01-01 00:00:00)

Variables

Variables are divided into:

• Time variables
• General information about the observation site and run
• Surface turbulent fluxes
  • direct eddy covariance estimates of momentum, sensible and latent heat fluxes
• Quality control flag variables

Detailed lists:

• Time
  • year Year
  • month Month
  • day Day
  • hour Hour
  • minute Minute
  • second Second
  • day_of_year Time as decimal day of year
• General site information
  • latitude Latitude (degree_north)
  • longitude Longitude (degree_east)
  • start_of_run Start of run (seconds since 1970-01-01 00:00:00)
  • run_length Length of run (s)
  • height_above_surface Height of instrument platform above snow surface (m)
  • number_of_samples_in_run Number of samples in run
• Surface turbulent fluxes
  • buoyancy_flux Buoyancy Flux (J m-2 s-1)
  • kinematic_humidity_flux Kinematic Humidity Flux (kg kg-1 m s-1)
  • kinematic_heat_flux Kinematic Heat Flux ( K m s-1)
  • kinematic_sonic_temperature_flux Kinematic Sonic Temperature Flux (K m s-1)
  • upward_sensible_heat_flux_in_air Sensible heat flux (W m-2)
  • upward_latent_heat_flux_in_air Latent heat flux (W m-2)
  • momentum_flux_u Momentum flux (-rho. ; kg m-1 s-2)
  • momentum_flux_v Momentum flux (-rho. ; kg m-1 s-2)
  • bowen_ratio Bowen Ratio (sensible\latent)
• Data quality flags
  • qc_flag_skew_u Quality flag: Skew U
  • qc_flag_skew_q Quality flag: Skew Q
  • qc_flag_skew_v Quality flag: Skew V
  • qc_flag_skew_w Quality flag: Skew W
  • qc_flag_skew_ts Quality flag: Skew T
  • qc_flag_kurtosis_u Quality flag: Kurtosis U
  • qc_flag_kurtosis_q Quality flag: Kurtosis Q
  • qc_flag_kurtosis_v Quality flag: Kurtosis V
  • qc_flag_kurtosis_w Quality flag: Kurtosis W
  • qc_flag_kurtosis_ts Quality flag: Kurtosis Ts
  • qc_flag_quality_wu Quality flag: WU
  • qc_flag_quality_wq Quality flag: WQ
  • qc_flag_quality_wv Quality flag: WV
  • qc_flag_quality_wts Quality flag: WTs

Comments

Measurement system

The measurement system consisted of a Metek uSonic-3 sonic anemometer and Licor LI-7500 gas analyser mounted on a 2 m mast on the sea-ice alongside complementary meteorological instrumentation (see surface meteorology dataset). The installation was battery powered. Photographs of the measurement installations are included in the zipped datafile. A Raspberry Pi was used to log the 20 Hz data.

Quality control

During the measurement period, the installation was visited once per day when possible. During the visit, the data were downloaded, batteries were replaced, instrumentation were inspected, and any frost was removed from instrument windows. The daily visits were logged in the "icestation_logbook" which is included as an excel spreadsheet with this dataset.

The following corrections were additionally applied as part of the Eddy Covariance calculations:

• De-spiking: Replace outliers with and 11-data point median filter. Where outliers are defined as data that are greater than 3 standard deviations away from the median.
• Licor data are corrected for a known delay in data transmission of 200 ms.
• Cross wind temperature correction: Correct contamination of sonic temperature measurement for lengthening of sonic path by sidewind.
• Tilt correction: Correct tilt by alignment with horizontal streamline over a single averaging period.
• Sonic acoustic temperature water vapor correction. (T = Ts / (1 + 0.51 q))
• Linear interpolation over data gaps that are smaller than 60% of the averaging period.
• Absolute wind direction correction for ice floe rotation.

The following quality control tests were implemented, the results of which are stored in the NetCDF files:

• Basic instrumentation qc (unrealistic values and instrument errors).
• QC correction for licor window contamination
• Stationarity testing
• Calculations of skew and kurtosis
• Calculation of flux development

Quality control flags are included in the data file. Note that poor quality data has not been removed, therefore it is essential to filter the data using the appropriate quality control flags before use.

Associated raw data and code

The python code used to QC the raw data, compute the eddy covariance calculations, and generate the NetCDF files is available at GitHub.

The raw 20 Hz data and intermediate calculations are available upon request.

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.

Associated data from the expedition

1-minute averages of general meteorological data (including temperatures, winds, and radiation) from this ice station are published separately in the Ice station surface meteorology and radiation data from expedition ARTofMELT, Arctic Ocean, 2023 by Guy et al. (2024).

Data creators' roles

• Heather Guy (operator and dataset creator)
• Ian Brooks (operator and principal investigator)
• Sonja Murto (operator)
• Michail Karalis (operator)
• Michael Tjernström (chief scientist; operator)