Gabarró, Carolina; Fabregat, Pau; Hernández-Macià, Ferran; Martínez, Justino; Jove, Roger; Salvador, Joaquin; Spreen, Gunnar; Thielke, Linda; von Albedyll, Luisa (2022): Brightness temperature measured by ARIEL radiometer at 1.4GHz from July to September 2020 during the MOSAiC expedition [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.943755
Always quote citation above when using data! You can download the citation in several formats below.
Abstract:
The data contains brightness temperature data measured by ARIEL at 1.4GHz, during the MOSAIC expedition, in particular from July to September 2022 (LEG4 and LEG5).
The ARIEL radiometer is a dual polarization (H & V) total power radiometer with internal calibration. The central frequency is 1.41 GHz, with a bandwidth of 20 MHz. The system has a 2x1 patch antenna, with a beam width of 36 ◦ at 3 dB at the azimuth direction and 70 ◦ at 3 dB at the elevation angle. The radiometric accuracy of ARIEL is 1.06 K at 1 Hz sampling frequency, with the capability to measure at higher sampling rates (up to 10 Hz) at the expenses of the radiometric accuracy. A co-located thermal infrared photodiode to measure the surface temperature and a GPS receiver complete the sensor equipment. Calibration is performed with a hot load and a cold load. To adapt the ARIEL instrument to the harsh and cold conditions of the Arctic,
two adaptions were required to increase the internal thermal resistance by adding isolating material and to apply conformal coating to protect the electronics against humidity. The ARIEL accuracy was 2.3 K (instead of 1 K, due to a software error on the sampling rate).
This light (7 kg) and small radiometer (40 cm x 60 cm x 20 cm) is ideal for frequent manoeuvres. The radiometer was mounted on a wooden sledge to measure microwave emission at 40 ◦ incidence angle with respect to nadir.
A calibration procedure for the radiometers is needed to convert the measured voltages to brightness temperatures. The calibration of the ARIEL was done pointing the radiometer to cold and hot targets. The cold target is the cold sky (approx. temperature of 6 K (from Le Vine and Skou (2006)), while the hot target was absorber material at the instrument frequency stored into a big box (which represent an emissivity of 1). The calibration routines were performed every few days (3-5 days).
After filtering the outliers, the data was smoothed to further reduce the noise. A sliding window of 20 samples was applied, which has proven to work better with ARIEL data, reducing standard deviation and therefore the noise of the measurements (Fabregat (2021)). Moreover, since the radiometer was over a moving ice cap, the position with respect to the Polarstern is computed, in addition to the GPS position, to simplify the collocation with other instrument measurements. We used a Python code provided by Dr. Stefan Hendricks (AWI) to compute this relative position (Gitlab reference: https://gitlab.awi.de/floenavi-crs).
Further details:
Fabregat, Pau (2021): L-band radiometry: data processing and emissivity models for Arctic sea-ice. Degree Thesis, Escola Tècnica Superior d'Enginyeria de Telecomunicació de Barcelona, hdl:2117/357248
Hendricks, Stefan: FloeNavi - Coordinate Reference System. GitLab, https://gitlab.awi.de/groups/floenavi-crs
Project(s):
Funding:
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven (AWI), grant/award no. AFMOSAiC-1_00: Multidisciplinary drifting Observatory for the Study of Arctic Climate
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven (AWI), grant/award no. AWI_PS122_00: Multidisciplinary drifting Observatory for the Study of Arctic Climate / MOSAiC
Coverage:
Median Latitude: 86.677966 * Median Longitude: 82.936666 * South-bound Latitude: 79.745166 * West-bound Longitude: -1.974803 * North-bound Latitude: 89.154490 * East-bound Longitude: 120.766727
Date/Time Start: 2020-07-13T08:09:00 * Date/Time End: 2020-09-30T09:31:00
Minimum Elevation: -4322.6 m * Maximum Elevation: -2111.0 m
Event(s):
PS122/4_47-4 * Latitude Start: 81.424090 * Longitude Start: 0.318862 * Latitude End: 81.420826 * Longitude End: 0.318054 * Date/Time Start: 2020-07-13T08:09:00 * Date/Time End: 2020-07-13T09:33:00 * Elevation Start: -2111.0 m * Elevation End: -2126.3 m * O2A Registry URI: sensor.awi.de * Location: Arctic Ocean * Campaign: PS122/4 (MOSAiC20192020) * Basis: Polarstern * Method/Device: L-Band Microwave Radiometer (L-MRA) * Comment: "second half with transect group (GEM, Magna Probe); Calibration in Log Area"
PS122/4_47-147 * Latitude Start: 80.861555 * Longitude Start: -0.315752 * Latitude End: 80.851194 * Longitude End: -0.338051 * Date/Time Start: 2020-07-19T17:13:00 * Date/Time End: 2020-07-19T18:47:00 * Elevation Start: -3130.9 m * Elevation End: -3135.8 m * O2A Registry URI: sensor.awi.de * Location: Arctic Ocean * Campaign: PS122/4 (MOSAiC20192020) * Basis: Polarstern * Method/Device: L-Band Microwave Radiometer (L-MRA) * Comment: PS122/4_47-140: gem2-556 data
PS122/4_47-148 * Latitude Start: 81.057066 * Longitude Start: 0.436592 * Latitude End: 81.028166 * Longitude End: 0.410947 * Date/Time Start: 2020-07-18T09:54:00 * Date/Time End: 2020-07-18T13:42:00 * Elevation Start: -2364.1 m * Elevation End: -2417.0 m * O2A Registry URI: sensor.awi.de * Location: Arctic Ocean * Campaign: PS122/4 (MOSAiC20192020) * Basis: Polarstern * Method/Device: L-Band Microwave Radiometer (L-MRA) * Comment: stationary at remote sensing site
Comment:
The files contain:
• Date of acquisition
• Number of samples per load
• Processed Horizontal Brightness Temperature (K) - TB H
• Processed Vertical Brightness Temperature (K) - TB H
• Latitude
• Longitude
• X coordinate of in situ with respect Polarstern position (m) - X coord
• Y coordinate of in situ with respect Polarstern position (m) - Y coord
• Ice temperature (K)
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | Gabarró, Carolina | |||
| 2 | DATE/TIME | Date/Time | Gabarró, Carolina | Geocode | ||
| 3 | Action | action | Gabarró, Carolina | |||
| 4 | Comment | Comment | Gabarró, Carolina | |||
| 5 | Binary Object | Binary | Gabarró, Carolina | L-Band Microwave Radiometer (L-MRA) | ||
| 6 | Binary Object (File Size) | Binary (Size) | Bytes | Gabarró, Carolina | L-Band Microwave Radiometer (L-MRA) |
Change history:
2022-10-18T08:39:12 – The authorship was extended to include Martínez, J, Jove, R and Salvador, J
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0)
Status:
Curation Level: Basic curation (CurationLevelB) * Processing Level: PANGAEA data processing level 3 (ProcLevel3)
Size:
179 data points