The code is open for all users with scientific purposes. Let's start using GRASP algorithm by your own!
GRASP algorithm has been applied to entire archive (~ 9 years) of French Space Agency’s PARASOL/POLDER instrument obtaining wide variety of aerosol and surface characteristics including Aerosol Optical Depth of extinction (AOT) and absorption (AAOD), Single Scattering Albedo (SSA), Angstrom Exponent (AE), Surface Albedo, NDVI vegetation index, etc..
The first processing was performed at LOA (Laboratoire d’Optique Atmosphérique). The video on the right shows a moving average of the parameter AOD 565nm obtained. The latest products are available at ICARE website: http://www.icare.univ-lille1.fr. Additionally the system allows the user to dive into the data using a web tool, which plots online the results.
The interested users can access the post-processed data by GRASP SAS using the following button.
Within the framework of projects supported by ESA, GRASP algorithm has been optimized and applied to the data of MERIS instrument. Two important results has been obtained from those studies:
The large amount of “optical depth only” measurements (AERONET – sun and moon photometers-, star-photometry, air-borne sun-photometers, GAW-PFR networks, etc.) has motivated the development of the so-called GRASP-AOD application. This application characterizes detailed properties of aerosols by making use of only spectral aerosol optical depth data.
The versatility of GRASP code allows to adequate the aerosol model to this scenario in which scattering information is not presented. Thus, the article by Torres et al., 2017 suggests to assume as known the refractive index and the sphericity parameter to retrieve the particle size distribution which is characterized as bimodal log-normal (defined by six independent parameters: volume median radius rVi[μm], geometric standard deviation σVi and particle volume concentration CVi[μm3/μm2] with i = f,c for the fine and coarse mode, respectively).
We developed a web tool that allows to play with the GRASP-AOD application in an interactive and educational way. Click the button below to try it!
Grasp algorithm provides the possibility state-of-the-art synergetic retrievals inverting simultaneously sun/sky radiometer and lidar ground-based observations. Specifically, the following of these synergetic retrievals can be outlined: