Summary
The aim of the DARDAR ( raDAR/liDAR ) project is to retrieve cloud properties by combining the CloudSat radar and the CALIPSO lidar measurments. This project originates from the collaboration between the LATMOS ( Laboratoire Atmosphères, Milieux, Observations Spatiales ) and the Cloud Group of the Department of Meteorology, University of READING.
We can infer the vertical distribution of detailed cloud properties since the radar and lidar backscatter are proportional to very different powers of particle size, so the combination provides accurate particle size with height and hence more accurate cloud properties than with just one instrument. Furthermore, the radar can penetrate deep ice cloud while lidar cannot but due to its higher sensitivity can identify very thin ice clouds. It is therefore possible to retrieve cloud properties seamlessly between regions of the cloud detected by both radar and lidar, and regions detected by just one of these two instruments. The radar-lidar combination is also very useful for distinguishing cloud phase, for instance the radar is mainly sensitive to ice (larger diameters) while the lidar is more sensitive to liquid water (higher concentration). This is very useful for identifying supercooled layer from ice clouds.
The main idea was to provide on the same grid CloudSat/CALIPSO/MODIS measurements and their associated errors and an optimized merge mask that any synergistic algorithm could use as inputs. The DARDAR project is not limited to colocated measurements since ice cloud properties such as extinction, ice water content, effective radii and related vertically integrated properties are retrieved using a synergistic varitional algorithm.
DARDAR project has 3 components:
- CALIPSO, CLOUDSAT and some A-Train colocated measurements.
- An atmospheric feature mask (derived from both radar and lidar).
- Ice cloud retrievals.
Each component can be considered as an indepedent project which infered the development of a specific software and an operational product. Each one is designed to be useful for a large number of users.
The sub-projects are:
CSXTRACT, developed by the Icare CGTD, CALIOP and CLOUDSAT profiles are colocated at 1.1km horizontal and 60m vertical resolution. The resulting product, including also MODIS, CALIPSO’s IIR, and ECMWF data, is known as CS-TRACK « CLOUDSAT-Track » product and is public access to any Icare registered users and can be downloaded here.
DARDAR_MASK represents the combined atmospheric feature mask. A full description of the product can be found here.
DARDAR_CLOUD refers to the ice cloud retrievals, all details are given here.