10.1594/PANGAEA.996472Bühler, LinnuLinnuBühlerUniversity of CologneWalbröl, AndreasAndreasWalbröl0000-0003-2603-2724University of CologneKrobot, PavelPavelKrobotUniversity of CologneMech, MarioMarioMech0000-0001-6229-9616University of ColognePANGAEA2026ArcticAtmospherecloudsPolarsternPS149PS150DATE/TIMEImage, skyImage, sky (File Size)Total sky imager, visual and infraredPS149PS150PolarsternArctic Amplification (AC3)2025-07-04T00:00:00/2025-10-17T23:59:00Dataset10.1594/PANGAEA.99049710.1594/PANGAEA.98783310.1594/PANGAEA.98783210.1594/PANGAEA.98713210.1594/PANGAEA.987133104 data pointstext/tab-separated-valuesCreative Commons Attribution 4.0 InternationalA Total Sky Imager (TSI) camera recorded cloud cover in the visual and infrared during Polarstern cruises PS149 and PS150 from July to October 2025 in the Arctic Ocean. The TSI was mounted on the bow-facing reling of the Observation Deck, where it recorded an image every minute. The setup consists of the Mobotix visual fish-eye sensor Mx-O-SMA-S-6D016-X with 180° angles in both directions, 3072 x 2048 pixels, focal length of 1.6 mm and an aperture of f/2.0, as well as the infrared sensor Mx-O-SMA-TS-R079. The infrared sensor operates in the IR range of 7.5 to 13.5 𝜇m, with angles of 45° and 35° and 336 x 252 pixels. For temperatures below −40 °C, i.e., in clear sky conditions, the TSI did not take pictures continuously after 250912. The ship's crow's nest covers a large section of the fish-eye camera's field of view, and one of the ship's antenna is partially in the infrared camera's field of view over the whole time period. For the infrared images, only colored plots set on a fixed color scale from 310 to 400 with no physical meaning or unit could be saved. The pictures can be downloaded as daily zip files. Data are available from 25-07-04 08:07 to 25-10-17 08:13, with gaps at 2507090404 - 2507121651, 2508191151 - 2508201022, and 2508301547 - 2508301702.For usage of the infrared images, a mask needs to be applied for 2508251713 - 2508251816. After 250912, a time offset between the TSI internal and the external computer develops and gradually increases up to 50 minutes from 251016. Only infrared and occasional color-distorted visual images were taken on 2509130930-2509131110, 2509131738-2509131930, 2509170754-2509170907, 2509210353-2509210502, 2509210552-2509210707, 2509211237-2509211342, 2509211443-2509211659, 2509221604-2509221720, 2509231834-2509231935, 2509240347-2509240457, 2509240704-2509240808, 2509240920-2509241055, 2509241845-2509242012, 2509242131-2509242242, 2509250726-2509251141, 509251453-2509251831, 2509280152-2509280305, 2509281313-2509281417, 2509281558-2509281751, 2510101403-2510101542, 2510101655-2510101806, 2510101831-2510102011, 2510102252-2510110036, 2510110605-2510110747, 2510110925-2510111028, 2510111335-2510111513, 2510120056-2510120206, 2510120606-2510120717, 2510120911-2510121014, 2510140615-2510140741, 2510140741-2510141034, 2510141349-2510141659, 2510141817-2510142034, 2510142234-2510150157, 2510150429-2510150546, 2510151534-2510151638, 2510151650-2510152004, 2510160228-2510160345, 2510160724-2510160935, 2510161155-2510161419, 2510161719-2510161839, 2510161841-2510162021, 2510162200-2510162311.4.56833824.08529277.40127583.987198Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhavenhttps://doi.org/10.13039/501100003207AWI_PS149_07VAMPIRE-2German Research Foundationhttps://doi.org/10.13039/501100001659268020496TRR 172: ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms