MOSAiC-ACA and AFLUX - Arctic airborne campaigns characterizing the exit area of MOSAiC

Two airborne field campaigns focusing on observations of Arctic mixed-phase clouds and boundary layer processes and their role with respect to Arctic amplification have been carried out in spring 2019 and late summer 2020 over the Fram Strait northwest of Svalbard. The latter campaign was closely connected to the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. Comprehensive data sets of the cloudy Arctic atmosphere have been collected by operating remote sensing instruments, insitu probes, instruments for the measurement of turbulent fluxes of energy and momentum, and dropsondes on board the AWI research aircraft Polar 5. In total, 24 flights with 111 flight hours have been performed over open ocean, the marginal sea ice zone, and sea ice. The data sets follow documented methods and quality assurance and are suited for studies on Arctic mixed-phase clouds and their transformation processes, for studies with a focus on Arctic boundary layer processes, and for satellite validation application

Water vapour mixing ratio over Ny-Alesund from LiDAR measurements 2015-2018

Using the Raman channels of the Koldeway Aerosol Raman Lidar (KARL) a water vapour mixing ratio is derived. Data is availiable for all measurements during the dark season since 2015. Calibration in the winters 2015/2016 and 2016/2017 was performed using the GRUAN radiosounding product. For comparison those winters where recalculated with radiosounding measurements processed by the Vaisala Algorithm. The winter 2017/2018 is calibrated using radiosounding measurement from the RS41processed by the Vaisala Algrithm. The details of the calibration of this water vapour product are explained in Kulla & Ritter 2019

Water Vapor Calibration: Using a Raman Lidar and Radiosoundings to Obtain Highly Resolved Water Vapor Profiles

We revised the calibration of a water vapor Raman lidar by co-located radiosoundings for a site in the high European Arctic. For this purpose, we defined robust criteria for a valid calibration. One of these criteria is the logarithm of the water vapor mixing ratio between the sonde and the lidar. With an error analysis, we showed that for our site correlations smaller than 0.95 could be explained neither by noise in the lidar nor by wrong assumptions concerning the aerosol or Rayleigh extinction. However, highly variable correlation coefficients between sonde and consecutive lidar profiles were found, suggesting that small scale variability of the humidity was our largest source of error. Therefore, not all co-located radiosoundings are useful for lidar calibration. As we assumed these changes to be non-systematic, averaging over several independent measurements increased the calibration’s quality. The calibration of the water vapor measurements from the lidar for individual profiles varied by less than ±5%. The seasonal median, used for calibration in this study, was stable and reliable (confidence ±1% for the season with most calibration profiles). Thus, the water vapor mixing ratio profiles from the Koldewey Aerosol Raman Lidar (KARL) are very accurate. They show high temporal variability up to 4 km altitude and, therefore, provide additional, independent information to the radiosonde

Cloud top altitude retrieved from Lidar measurements during ACLOUD at 1 second resolution

During the ACLOUD aircraft campaign (23.5.2017 - 26.6.2017) the AMALi Lidar was installed mostly nadir pointing. This dataset contains the cloud top altitude from those measurements (altitudes with a strong signal increase) as well as a cloud mask, derived from the optical depth of the column at 1 second resolution. The majority of the data was collected northwest of the Svalbard archipelago. More details on the campaign can be found in Wendisch 2018 and Ehrlich 2019 and here (https://home.uni-leipzig.de/~ehrlich/ACLOUD_wiki_doku). Please check the data documentation (https://download.pangaea.de/reference/108729/attachments/readme_documentation_AMALi_cloudtop.pdf) before using this dataset

Cloud top altitude retrieved from Lidar measurements during MOSAiC-ACA at 1 second resolution

During the MOSAiC-ACA aircraft campaign (31.8.2020 - 13.9.2020) the AMALi Lidar was installed nadir pointing. This dataset contains the cloud top altitudes below the aircraft (altitudes with strong signal increase), as well as a cloud mask, derived from the optical depth of the column. The majority of the data was collected northwest of the Svalbard archipelago. More details on the campaign can be found here (https://home.uni-leipzig.de/~ehrlich/MOSAiC_ACA_wiki_doku). Please check the data documentation before using this dataset