http://bolin.su.se/data/oden-ryder-2019-misu-weather-1 John Prytherch, Michael Tjernström Bolin Centre Database 2021 Datafile Atmosphere Weather observations Weather station Meteorology Arctic boundary layer Arctic clouds Arctic Ocean Northern Greenland Northwest Passage Ryder 2019 expedition Icebreaker Oden ACAS Earth science > Atmosphere John Prytherch 2021-04-29T14:12:27+00:00 English 1 None Separate data files from the MISU weather station, the MISU Vaisala CL31 ceilometer and the MISU Vaisala PWD22 present weather sensor. Each system has data files averaged over either 1 or 30-minute intervals. Two data formats are provided: Matlab (.mat) and NetCDF (.nc), with accompanying readme (.rtf) files for each system. The main components of the MISU weather station (Gill 2D sonic anemometer, Vaisala PTU pressure sensor, Eppley PIR and PSP downwelling radiation sensors) were mounted mid-ship on the 7th deck forward railing. An additional Rotronic aspirated TRH sensor was mounted at the top of Oden’s foremast. Two Heitronics KT15.IIp infrared sensors for measurement of surface temperature were mounted separately on the 7th deck, to enable measurement of the sea/ice surface to beam of the ship. 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 110° of bow on. Due to the significant distortion at the site of the weather station, weather station winds should be treated with caution for wind directions more than 60° from bow on. The ship-relative winds and navigation data are also used to derive ‘true’ wind speed and direction. Downwelling radiation sensors were subject to icing during the expedition. Ice was removed with regular cleaning. A flag is provided to indicate when solar radiation may be affected by shading from the ship superstructure. The height to the lowest cloud base, and up to two additional cloud bases when the lowest cloud layer does not cover the whole sky, was measured by a Vaisala CL31 ceilometer, located above Oden’s bridge on the 7th deck. The system uses a proprietary Sky Condition algorithm to determine cloud fraction at up to five levels, converting single-point time-series measurements to time-averaged area coverage. The system additionally recorded the backscatter profile, and hence serves as a so-called poor-man’s LiDAR. When the attenuation of the laser beam reaches a threshold, like in a dense fog, it switches to reporting vertical visibility, rather than cloud-base height. Visibility, up to a maximum range of 20km, air temperature and precipitation type and intensity determined by the Vaisala PWD22 present weather sensor installed above Oden’s bridge on the 7th deck, at a height of 27 m above sea level. The system additionally reports instantaneous, 15-minute and 60-minute WMO present weather codes. Data from each system are combined into cruise-length files. The data are time-averaged to both 1-minute and 30-minute intervals. Data were collected during the NorthWest Passage 2019 expedition and the [Ryder 2019 expedition](https://polarforskningsportalen.se/en/arctic/expeditions/ryder-2019) on board the Swedish icebreaker (I/B) Oden, which was organized by the Swedish Polar Research Secretariat.