The Directional Polarimetric Camera (DPC), made by a research team from the Anhui Institute of Optics and Fine Mechanics (AIOFM) of the Hefei Institutes of Physical Science (HFIPS), passed test recently. It will be loaded on CM-1, a carbon dioxide monitoring satellite.

As the first satellite serving the forestry industry in China, CM-1 can not only catch the forest height information but also retrieve forest volume and biomass, which is a novel technical means to monitor China's forest resources.

DPC can obtain remote sensing data products of global atmospheric aerosol and cloud optical and physical parameters, including aerosol optical thickness, particle size distribution, etc.

Besides, this novel instrument boasts a new feature "on-orbit cloud identification function" basing on optimization of the indicators of previous similar products.

The researchers analyzed the multi angle and multi spectral radiation information provided by polarization imager as the data source of on-orbit cloud identification and focused on the research of fast Cloud Identification Algorithm and software development. After being loaded in the information processing box of DPC, the software would conduct the calculation of the orbit cloud judgment data and send the result to the satellite data management subsystem as the basis for controlling the on-off of lidar and other optical payloads.

As the life of lidar is related to the number of working times, this technology can greatly reduce the amount of cloud polluted data and extend lidar on-orbit service life.

"We have been working on this project for 5 years," said JIN Jie, a member of the team, "We made all efforts to overcome the difficulties of tight time cycle and limited on-board computing resources to ensure the smooth delivery of the flight products."

DPC has realized high-precision atmospheric correction with other optical loads of satellite platform and would provide aerosol intensity observational data of atmospheric parameters needed for the study of forced radiation effect to support the study of global climate change.

Directional Polarimetric Camera boasts new feature "on orbit cloud identification function" (Image by JIN Jie)