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.
The dataset also includes several calculated variables, e.g. potential temperature, equivalent potential temperature, etc., that have been derived from the primary variables. The data here are quality controlled and interpolated to a common height grid. An associated dataset, containing the raw data, 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.
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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. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-radiosonde-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 — raw data. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-radiosonde-raw-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 one NetCDF (.nc) file provided in one zip file. File size is about 24 MB (compressed 18 MB).
A list of all variable names, with short explanations and units is provided below. There is also an associated Readme_radiosonde.txt file that provides further details of data and processing and explanations of quality control flags.
Variables
Divided into:
- Primary variables
- temperature, pressure, relative humidity
- winds measured by tracking the sonde using GPS
- some 1 D variables, e.g., date and time variables and maximum heights
- Derived variables
- e.g. potential temperature, relative humidity w.r.t. ice and saturation humidity, etc., derived from the interpolated data.
- derived 1D variable of integrated water vapour
Detailed lists:
- Primary variables
altitude height above mean sea level (m) [time/height]max_altitude real maximum height of each sonde (m) [time]elapsed_time time elapsed (in seconds) since radiosonde launch (s) [time/height]day_of_year day of year (in decimal days) for the radiosonde launch time, e.g., 129.48 [time] day_of_year_and_release_time day of year (as an integer value) and time of launch, given as "day H:M:S" [time]year year of aimed sonde launch time, e.g., a real launch at 31 May 23:33 UTC aims for a 1 June 00 UTC launch. [time]month month for the aimed launch time (see above for year) [time]day day for the aimed launch time (see above for year) [time]hour hour (in UTC) for the aimed launch time (see above for year) [time]longitude radiosonde longitude (degrees east; longitudes west of the Prime Meridian decrease from 0 to -180) [time/height]latitude radiosonde latitude (degrees north) [time/height]air_pressure (hPa) [time/height]air_temperature (K) [time/height]relative_humidity (%) [time/height]dew_point_temperature (K) [time/height]wind_speed (m s⁻¹) [time/height]eastward_wind west-east wind component (u) (m s⁻¹) [time/height]northward_wind south-north wind component (v) (m s⁻¹) [time/height]
- Derived variables
air_potential_temperature (K) [time/height]air_equivalent_potential_temperature (K) [time/height]air_virtual_potential_temperature (K) [time/height]relative_humidity_wrt_ice relative humidity with respect to ice (%) [time/height]specific_humidity (kg kg⁻¹) [time/height]humidity_mixing_ratio mixing ratio (kg kg⁻¹) [time/height]humidity_saturation_mixing_ratio saturation mixing ratio (kg kg⁻¹) [time/height]water_vapor_partial_pressure_in_air water vapour pressure (hPa) [time/height]saturation_water_vapor_partial_pressure_in_air saturation water vapour pressure (hPa) [time/height]integrated_water_vapor integrated water vapour (kg m⁻²) [time]wind_from_direction wind direction, recalculated for the interpolated u & v wind data (degree) [time/height]qc_flag_temperature Data quality flag for temperature and/or humidity profiles (corrected due to smoke plume or a suspect first level temperature) [time/height]
The majority of the derivations for thermodynamical variables are performed using the MetPy python library.
Dimensions
Dimensions for the fields are time (actual launch-times of each radiosonde; 151 launches) and the common vertical height axis (1890 vertical levels).
The data was extracted from the native format and interpolated to a common vertical axis. No time interpolation was performed.
The height levels are at:
- 13 m above sea level (the height of the helicopter deck)
- every 5 m, from 15 m to 5 km
- every 10 m, from 5 km to 10 km
- every 50 m, from 10 km up to 29550 m.
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
Variables in the lowest 50 m are advised to use with care, especially regarding winds and temperature closest to the surface because of interference from the ship and its superstructure. Some modifications were made on some temperature and humidity profiles below 75 m on 31 profiles (21 %) where it became obvious they were affected by ascending through the plume from the ships stack. Checking different surface sensors on ship at actual launch times also indicated a possible heat island problem, that was not corrected for practical reasons, finally, a few profiles suffered data dropouts for some variables and heights. A 2D Quality Control (QC) flag that indicates profiles and heights subjected to different QC procedures is provided (see the Readme_radiosonde.txt file for details).
Usefulness
These profiles by themselves provide important information on the state of the atmosphere, but can also be used in concert with other observations and also provide an important backbone for interpreting remote sensing instruments. The profiles are also important for numerical weather prediction and for reanalysis. Because of this, these sounding results were submitted to the WMO's Global Telecommunications System (GTS) in near-real time by Iridium file transfer, to be included in both real-time weather forecasting and reanalysis.
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 computer code, in Python, written by Murto and Prytherch (2024), used to derive this processed dataset from the raw data is also available.
Additional data
The sondes ascend at about 5 m/s borne by a Helium-filled balloon, until the balloon bursts at an altitude of ~10 – 30 km. Local conditions and balloon quality determines actual ascent velocity and burst height. The sonde continues to transmit data also after the balloon has burst and package is falling. While the decent is less controlled, happens at a higher vertical velocity, and signal is lost when the instrument falls below the horizon, the data during the descent is less accurate. Never the less, the data is stored, but is not included in this dataset. Contact the PI in case there is an interest also in this data.
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.