Michael Tjernström, Sonja Murto, Michail Karalis, John Prytherch
Profiles of temperature and humidity are obtained from an RPG HATPRO5 microwave radiometer deployed on the roof of a container on the 4th deck of Oden during the expedition ARTofMELT (Atmospheric Rivers and the Onset of Arctic Melt) in the Fram Strait, operating continuously from 7 May, 2023, until 14 June, 2023.
The data include observations from different measurement modes, with different accuracy and resolution, as well as a set of corrected data where the radiosoundings were used as ground truth.
An associated dataset, containing the raw data from the microwave profiler, is available separately.
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Citation
Michael Tjernström, Sonja Murto, Michail Karalis, John Prytherch (2024) Temperature and humidity profiles from microwave radiometer during expedition ARTofMELT, Arctic Ocean, 2023. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-microwave-profiles-1
References
Tjernström M, Murto S, Karalis M, Prytherch J (2024) Temperature and humidity profiles from microwave radiometer during expedition ARTofMELT, Arctic Ocean, 2023 — raw data. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-artofmelt-2023-microwave-profiles-raw-1
Tjernström M, Murto S (2024) Scripts for concatenating, processing NetCDF native output files and creating final netCDF files from HATPRO microwave-profiler 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-microwave-profiles-1.0.0
Data description
This dataset includes two NetCDF (.nc) files zipped into one zip-file. Total file size is about ~140 MB (compressed 103 MB).
The observations stem from microwave irradiances but is converted to temperature and humidity profiles in different observation modes. Therefore, there are two separate NetCDF files with data at different temporal resolution. For each there is also a derived set of data where radiosonde data was used to correct the data.
A list of all variable names, with short explanations and units is provided below. There is also an associated Readme_Hatpro_profiles.txt file that provides further details of the data and how it was processed.
Variables — higher resolution data
The variables below refers to the larger data subset, and include temperature and humidity profiles at high temporal resolution (~1 minute).
- Primary variables high res
day_of_year Decimal day of year (in UTC) [time]year Year - constant [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]altitude altitudes, instrument height (15 m) added (m) [height]air_temperature Best estimate temperature from instrument (recommended) (K) [time/height]air_temperature_deep Temperature profiles, vertical stare only (K) [time/height]absolute_humidity Absolute humidity profiles from vertical stare (g m⁻³) [time/height]relative humidity Relative humidity profiles from vertical stare (%) [time/height]
- Derived variables high res
air_temperature_corrected Corrected best estimate temperature profiles (K) [time/height]air_temperature_deep_corrected Corrected temperature profiles from vertical stare (K) [time/height]absolute_humidity_corrected Corrected absolute humidity profiles (g m⁻³) [time/height]relative_humidity_corrected Corrected relative humidity profiles (%) [time/height]
Variables — lower resolution data
The variables below refers to the smaller data set using the scan mode optimized for the lowest 1 km atmosphere and include temperature profiles at lower temporal resolution (~15 minutes).
- Primary variables low res
day_of_year Decimal day of year (in UTC) [time]year Year - constant [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]altitude Altitudes, instrument height (15 m) added (m) [height] air_temperature Best estimate temperature from instrument, scan only (recommended) (K) [time/height]
- Derived variables low res
air_temperature_corrected Corrected best estimate temperature profiles (K) [time/height]
Dimensions
Dimensions for the fields are time and height.
The two NetCDF files have the following different time resolutions:
- 1 minute average data from vertical stare, interrupted every 15 minute for vertical scan
- 15 minute averaged data from vertical scan every 15 minutes
The data was concatenated from the native format and is based on neural network retrieval algorithm and inherently based on averaged irradiances.
Comments
Measurement system
The data is obtained from an RPG HATPRO5 microwave radiometer. This is a passive instrument detecting microwave radiation emitted by the atmosphere in a number of wavelengths. Profiles of temperature and humidity are retrieved from the microwave irradiances using a proprietary neural network, trained on reanalysis of Arctic profiles (ERA5).
The instrument has two modes of observing: vertical stare and scanning in the vertical. For the vertical-stare mode, well-defined weighting functions are utilized by scanning over several nearby frequencies. When the instrument is scanning in the vertical, the atmospheric path is progressively increased as the zenith angle increases and the maxima of the weighting functions are thereby shifted lower, hence increasing the resolution in the lower parts of the atmosphere. The latter is sometimes referred to as a "boundary-layer mode".
The normal continuous mode for the instrument is the vertical stare. Every 15 minutes, this is briefly interrupted by the vertical-scan mode; however, this is only relevant for temperature profiles. Hence, all high-temporal resolution data are summarized in one file along with a "best estimate" temperature and the humidity profiles. while a separate datafile at lower temporal resolution contains the vertical scan data.
Quality control
In additional derived data, the radiometer profiles were corrected by comparisons to radiosounding data. No other data quality control is applied, except for adding the instrument height to the altitude variable.
Associated raw data and code
The raw data, from which this dataset is derived, was created by Tjernström et al. (2024) and is available separately. The current dataset is the concatenation of the original NetCDF files from the instrument system. Computer codes, in Matlab and Python, written by Tjernström and Murto (2024), used to derive this dataset in NetCDF format from the instrument 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:
- Michael Tjernström (chief scientist and dataset creator)
- Sonja Murto (operator)
- Michail Karalis (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.