Radiosonde profiles from expedition ARTofMELT, Arctic Ocean, 2023 — raw data

Sonja Murto, Michael Tjernström, Ian Brooks, Heather Guy, Michail Karalis, Timo Vihma, Gabin Urbancic, John Prytherch

Atmospheric profile measurements of temperature, humidity, pressure and wind speed are obtained from radiosonde weather balloons, launched from 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. Radiosondes were routinely released, typically every 6 hours.

This dataset contains the raw native data. A few additional variables, e.g., height, dew-point temperature and balloon ascent rate, calculated from the primary variables are also included. An associated user friendly dataset, interpolated to a common height grid and with more derived variables, is available separately.

The data enable analysis of the atmospheric vertical structure in the Arctic. Data were incorporated into the GTS global forecast system immediately following the completion of each profile, and are hence included in ERA5 the reanalysis.

Citation

Sonja Murto, Michael Tjernström, Ian Brooks, Heather Guy, Michail Karalis, Timo Vihma, Gabin Urbancic, John Prytherch (2024) Radiosonde profiles from expedition ARTofMELT, Arctic Ocean, 2023 — raw data. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-radiosonde-raw-1

References

Sonja Murto, Michael Tjernström, Ian Brooks, Heather Guy, Michail Karalis, Timo Vihma, Gabin Urbancic, John Prytherch (2024) Radiosonde profiles from expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-radiosonde-1

Sonja Murto, John Prytherch (2024) Scripts for quality control and creating a single netCDF file from radiosonde profiles from the expedition ARTofMELT, Arctic Ocean, 2023. Software version 1.0.0. Bolin Centre Code Repository. https://doi.org/10.57669/oden-artofmelt-2023-radiosonde-1.0.0

Data description

The dataset is provided in 151 ascii txt files; one file for each sounding, provided in one zip file. Total file size is about 94 MB (compressed 30 MB).

An explanation of the file naming rule and a list of all variable names, with short explanations and units, can be found in an associated Readme.txt file. Each txt data file starts with 18 header rows, also explained in the readme. The content below the header rows is like a csv file with semicolon as value separator. The data are sampled at 1 Hz.

Variables

Divided into:

• Primary variables
  • temperature, pressure, relative humidity.
  • position of the balloon using GPS.
• Derived variables
  • e.g. different heights, dew-point temperature.
  • winds measured by tracking the sonde using GPS.

Detailed lists:

• Primary variables
  • time_stamp actual date and UTC time of the sample
  • gph_gnss geopotential height from GPS (m); always NaN for technical reasons
  • gph_press geopotential height from pressure sensor (m)
  • press_gnss pressure from GPS height and temperature (hPa)
  • press_sens pressure from sensor (hPa)
  • temp_air air temperature (°C)
  • rh relative humidity (%)
  • lat latitude (degrees north)
  • lon longitude (degrees east)
• Derived variables
  • dew_point dew point temperature (°C) (calculated from relative humidity and temperature)
  • wind_speed wind speed (m/s)
  • wind_dir wind direction (degrees)
  • alt height of sonde (m) (offset by station altitude; do not use)
  • height_amsl height of sonde above sea level (m)
  • ascent_speed ascent velocity of sonde (m/s)

Dimensions

Dimensions for the fields are time (actual launch-times of each radiosonde; 151 launches) and the actual vertical height, different in each sounding, depending on the ascent velocity and the balloon burst height.

The data is in the native format directly from the sounding station. The first height level is at 13 m above sea level (the height of the helicopter deck). Then, height distances are determined by the sampling rate and the ascent velocity of the balloon.

Comments

Radiosounding system

The data are obtained from radiosoundings, launched with the Vaisala Digicora 5.4.0 radiosounding system with RS41 sondes.

Launching schedule

A total of 151 radiosondes were launched from the helicopter deck on the Swedish icebreaker Oden (13 m above sea level). Radiosondes were launched between 2023-05-09 12 UTC and 2023-06-13 12 UTC every 6-hour, except for a 2-day period every 3-hour (2023-06-10 15 UTC – ⁠2023-06-12 21 UTC).

Quality control

No quality control is applied and missing values occur. Missing data is represented by NaN.

Usefulness

This dataset contains the raw native data.

Associated processed data and code

An associated user friendly dataset, in NetCDF format, created by Murto et al. (2024), interpolated to a common height grid and with more derived variables, is available. The computer code, in Python, written by Murto and Prytherch (2024), used to derive the processed data from the raw data is also available.

Data creators' roles

The sondes were launched by the meteorology team onboard Oden:

• Stockholm University
  • Sonja Murto (operator and dataset creator)
  • Michail Karalis (operator)
  • Michael Tjernström (chief scientist; operator, only a few launches)
• Leeds University
  • Ian Brooks (work package leader)
  • Heather Guy (operator)
• Finnish Meteorological Institute, Helsinki
  • Timo Vihma (operator)
  • Gabin Urbancic (operator)

John Prytherch (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.