Description: Comparing helicopter-borne surface temperature maps in winter and optical orthomosaics in summer from the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate expedition, we find a strong geometric correlation between warm anomalies in winter and melt pond location the following summer. Warm anomalies are associated with thinner snow and ice, that is, surface depression and refrozen leads, that allow for water accumulation during melt. Warm surface temperature anomalies in January were 0.3–2.5 K warmer on sea ice that later formed melt ponds. A one-dimensional steady-state thermodynamic model shows that the observed surface temperature differences are in line with the observed ice thickness and snow depth. We demonstrate the potential of seasonal prediction of summer melt pond location and coverage from winter surface temperature observations. A threshold-based classification achieves a correct classification for 41% of the melt ponds.

Description: Oral presentation at the 2nd MOSAiC science conference showing the MOSAiC airborne laser scanner product overview and first results of seasonal surface roughness

Description: The Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition took place between October 2019 and September 2020 giving the rare opportunity to monitor sea-ice properties over a full annual cycle. Here we present 24 high-resolution orthomosaics and 14 photogrammetric digital elevation models of the sea-ice surface around the icebreaker RV Polarstern between March and September 2020. The dataset is based on 〉34.000 images acquired by a helicopter-borne optical camera system with survey flights covering areas between 1.8 and 96.5 km2 around the vessel. Depending on the flight pattern and altitude of the helicopter, ground resolutions of the orthomosaics range between 0.03 and 0.5 m. By combining the photogrammetric products with contemporaneously acquired airborne laser scanner reflectance measurements selected orthomosaics could be corrected for cloud shadows which facilitates their usage for sea-ice and melt pond classification algorithms. The presented dataset is a valuable data source for the interdisciplinary MOSAiC community building a temporal and spatially resolved baseline to accompany various remote sensing and in situ research projects.

Description: The hemispherical-directional reflectance factor (HDRF) of snow surfaces was measured in Antarctica during austral summer in 2013/14. The HDRF was retrieved from airborne measurements using a digital 180° fish-eye camera onboard the research aircraft Polar 6 operated by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven, Germany. -- The dataset contains the weighting functions for isotropic (f_iso), volumetric (f_vol), and geometric (f_geo) scattering obtained by inverting the kernel-driven, semi-empirical Ross-Thick-Li-Sparse-Reciprocal model for the bidirectional reflectance distribution function (BRDF). Along with the weighting functions f_iso, f_vol, and f_geo, the weights of determination (WoD) and root-mean-square errors (RMSE) are given as a criterion for the quality of the inversion for all 3 camera channels (Red: 602 nm central wavelength, Green: 538 nm, Blue: 470 nm). In addition, the footprint size of the camera observations is stated. -- The snow HDRF was measured over a variety of different solar zenith angles, optical-equivalent snow grain sizes, and surface roughness, which are given as parameters within the dataset. The optical-equivalent snow grain size was retrieved from spectral surface albedo measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART) mounted on Polar 6 using observations at 1280 and 1100 nm wavelength. The surface roughness was measured using the airborne laser scanner RIEGL VQ580 on Polar 6. -- Averaging was performed over time intervals of 30 s. The number of camera pictures, SSA measurements and laser scanner observations used for averaging over each 30s-interval are given. -- The dataset further includes basic flight parameters such as the second of day, longitude, latitude, flight altitude, surface elevation, aircraft velocity, and an attitude flag (0 = okay, 1 = do not use) corresponding to the times of measurement. -- Use of these data requires prior OK from the PIs.

Description: Data include area fractions of sea ice surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, bare ice) obtained from aerial imagery during 29 research flights that were performed within the scope of the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment from May 2020 until end of September 2020. The images were taken every four seconds by fisheye lens cameras (Canon EOS digital) installed on a helicopter or HELiPOD, a towed survey probe. The data set provides additional information about the attitude and geographic location of the helicopter/HELiPOD. Only images that passed the quality checks were included.

Description: Data include area fractions of sea ice surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, bare ice) obtained from aerial imagery during 29 research flights that were performed within the scope of the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment from May 2020 until end of September 2020. The images were taken every four seconds by fisheye lens cameras (Canon EOS digital) installed on a helicopter or HELiPOD, a towed survey probe. The data set provides additional information about the attitude and geographic location of the helicopter/HELiPOD. Only images that passed the quality checks were included.

Description: Data include area fractions of sea ice surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, bare ice) obtained from aerial imagery during 29 research flights that were performed within the scope of the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment from May 2020 until end of September 2020. The images were taken every four seconds by fisheye lens cameras (Canon EOS digital) installed on a helicopter or HELiPOD, a towed survey probe. The data set provides additional information about the attitude and geographic location of the helicopter/HELiPOD. Only images that passed the quality checks were included.

Description: Data include area fractions of sea ice surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, bare ice) obtained from aerial imagery during 29 research flights that were performed within the scope of the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment from May 2020 until end of September 2020. The images were taken every four seconds by fisheye lens cameras (Canon EOS digital) installed on a helicopter or HELiPOD, a towed survey probe. The data set provides additional information about the attitude and geographic location of the helicopter/HELiPOD. Only images that passed the quality checks were included.

Description: Data include area fractions of sea ice surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, bare ice) obtained from aerial imagery during 29 research flights that were performed within the scope of the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment from May 2020 until end of September 2020. The images were taken every four seconds by fisheye lens cameras (Canon EOS digital) installed on a helicopter or HELiPOD, a towed survey probe. The data set provides additional information about the attitude and geographic location of the helicopter/HELiPOD. Only images that passed the quality checks were included.