Micrometeorological data from icebreaker Oden’s foremast during the Arctic Ocean 2016 expedition

John Prytherch, Michael Tjernström, Ian Brooks

Air-sea fluxes and other micrometeorological variables derived from fast response (20 Hz) measurements of the 3-dimensional wind vector, temperature and humidity, and mean meteorological measurements using eddy covariance.

These are rare, direct measurements of the air sea exchange of momentum, sensible and latent heat from open water and sea-ice regions of the Arctic Ocean. They are key parameters in numerous processes, for example, determination of the surface energy balance.

The measurements are from instrumentation mounted on icebreaker Oden’s foremast at approximately 20 m above sea level during the Arctic Ocean 2016 (AO2016) expedition to the central Arctic Ocean in August and September 2016. Eddy covariance fluxes are determined on 30-minute intervals.

Citation

John Prytherch, Michael Tjernström, Ian Brooks (2020) Micrometeorological data from icebreaker Oden’s foremast during the Arctic Ocean 2016 expedition. Dataset version 3. Bolin Centre Database. https://doi.org/10.17043/oden-ao-2016-micromet-oden-3

Data description

Micrometeorology data from icebreaker Oden’s foremast, averaged over either 1 or 30-minute intervals. Flux data are not included in the 1-minute files. System operated by Ian Brooks (University of Leeds) and John Prytherch. Three data formats are available: Matlab (.mat), NetCDF (.nc) and comma separated value (.csv) text, with an accompanying readme (.rtf) file.

Comments

The instrumentation on the foremast consisted of a Gill R3 sonic anemometer, a LI-COR 7500 infrared gas analyser, an aspirated TRH sensor, an XSENS MTiG 3-axis inertial motion unit (managed by ICAS, University of Leeds). Other instrumentation included an LGR fast response greenhouse gas analyser installed at the base of the mast with an inlet drawing air at the top of the mast (managed by Department of Geological Sciences, Stockholm University).

Wind measurements were corrected for platform motion following Edson et al. (1998; Direct covariance flux estimates from mobile platforms at sea. J. Atmos. Ocean. Tech, 15, 547-562) and Prytherch et al. (2015: Motion-correlated flow distortion and wave-induced biases in air-sea flux measurements from ships. Atmos. Chem. Phys., 15, 10619–10629).

Winds are measured relative to the ship. The ship acts to distort the wind speed and direction, increasingly so for winds away from bow-on. A computational fluid dynamics (CFD) model of airflow over Oden is used to correct the measured winds for wind directions within 150° of bow on (Yelland et al. (2002) CFD model estimates of the airflow distortion over research ships and the impact on momentum flux measurements, J. Atmos. Ocean. Technol., 19, 1477–1499; Moat et al. (2015) Airflow distortion at instrument sites on the ODEN during the ACSE project, National Oceanography Centre, Southampton, UK, 114 pp., National Oceanography Centre Internal Document, 17). Winds are then adjusted to Earth frame using GPS measurements.

The majority of the fast-response instrumentation is measured at 20 Hz. Atmosphere-surface fluxes were determined from the fast-response measurements using eddy covariance.

CO₂ and CH₄ flux and atmospheric concentrations will be published in separate data sets and are not included here.

Quality control flagging follows Foken et al. (2012): Chapter 4 in Eddy Covariance: A practical guide to measurement and data analysis (eds. M. Aubinet, T. Vesala, D. Papale), Springer Atmospheric Sciences, and references therein: Foken and Wichura (1996) and Vickers and Mahrt (1997). Some of the code implementing these was adapted from the Eddycalc suite.

Data from the foremast are combined into a cruise-length file. The data are time-averaged to both 1-minute and 30-minute intervals. Flux data are not included in the 1-minute files.

Coordinates (lat, lon) for the observations are not included in this dataset, but they are the same as in the Weather data from MISU weather station during the Arctic Ocean 2016 expedition.

More information about the Canadian-Swedish Arctic Ocean 2016 expedition is available from the Swedish Polar Research Secretariat.

Version history

Version 3

All wind speeds and directions in processing and final data are now strict vector averages.

Version 2

Initial release.

Version 1

Not published.