DARDAR CLOUD - Brown and Francis mass-size relationship

DARDAR CLOUD products (raDAR/liDAR cloud parameter retrievals) CALIPSO/CALIOP-CloudSat/CPR Radar-Lidar Cloud Level 2 Product This synergetic ice cloud retrieval product is derived from the combination of the CloudSat radar, the CALIPSO lidar and MODIS measurements. The algorithm used to retrieve ice cloud properties, within a variational framework, is referred to as Varcloud. It was developed at the University of Reading by Julien Delanoë and Robin Hogan, Delanoë and Hogan (2008, 2010). Ice cloud retrievals are available at CloudSat horizontal resolution (1.4km) and CALIPSO vertical resolution (60m). This algorithm uses a variational method for retrieving profiles of visible extinction coefficient, ice water content and effective radius in ice clouds using the combination of radar reflectivity, lidar attenuated backscatter. The forward model includes effects such as non-Rayleigh scattering by the radar and molecular and multiple scattering by the lidar. By rigorous treatment of errors, and a careful choice of state variables and associated a priori estimates, a seamless retrieval is possible between regions of the cloud detected by both radar and lidar, and regions detected by just one of these two instruments. Thus, when the lidar signal is unavailable (such as due to strong attenuation), the retrieval tends towards an empirical relationship using radar reflectivity factor and temperature, and when the radar signal is unavailable (such as in optically thin cirrus), the a priori information is used to support lidar measurement. <b>Important note: this declination uses the Brown and Francis modified mass/size relationship.</b> This is the one used in previous versions of the product. An another declination based on the Heymsfield's composite one (Delanoë et al. 2013, https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013JD020700) is also available. As shown in Cazenave et al. 2019 (https://amt.copernicus.org/articles/12/2819/2019/) one of the major hypotheses in the retrieval is the mass-size relationship. Therefore you might use both products in order to assess the impact of this choice on your study. You could refer to Listowski et al. 2020 for a comparison between the two products (https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL088785).