Overview

STRAT (STRucture of the ATmosphere) is designed to retreive the vertical distribution of cloud and aerosol layers in the boundary layer and through the free troposhere, to identify particle-free regions of the verticale profile and the range at which the lidar signal to becomes too attenuated for exploitation.

This program was initially developed by Yohann Morille at Laboratoire de Métrologie Dynamique.

ICARE streamlined the original code to facilitate processing in the frame of the AEROCLUB project.

Algorithm

Product

ICARE provides STRAT data retrievals for 5 lidar platforms belonging to the ORAURE network namely:

For each platform, these data are available as a Level-2 daily file, formatted in the NetCDF standard format.

File Naming Convention

STRAT-L2_<YYYY>-<MM>-<DD>T00-00-00_<PLATFORM-NAME>_V<X-XX>.nc

with<YYYY>the year of the acquistion (4 digits)<MM>the month of the acquistion (2 digits)<DD>the day of the acquisition (2 digits)<PLATFORM-NAME>the name of the lidar platform, where each underscode character "_"has been replaced by a minus character "-"<X-XX>the product version

By example for the platform named SIRTA_Palaiseau with lidar data measured the March 20th, 2012, and with 1-00 as product version, the name of the generated file will be:

STRAT-L2_2012-03-20T00-00-00_SIRTA-Palaiseau_V1-00.nc

NetCDF Output

STRAT run produces one NetCDF file as output, that contains miscellaneous variables. See the product information page of STRAT for more information.

CF-Conventions

Since version 1.5.0 the NetCDF file produced as output has also been updated to follow the CF-Conventions (Conventions=CF-1.6). It has been designed as a Profile Data (featureType=profile). And recommended attributes as been added in variables if necessary, namely:

  • standard_name
  • long_name
  • units
  • _FillValue
  • valid_range

File Description

Then the STRAT product generates a daily NetCDF file for each platform.

The flag variable streamlines the layer distribution results. It provides a classification of the layers along the lidar profile namely:

Flag ValueDescription
0Noise
1Molecular Layers
2MLD
3Aerosol Layers
4Cloud Layers
10Unknown Layers
Example: The layer distribution retreived by STRAT above Villeneuve d’Ascq (FRANCE), the 20th March 2012 
STRAT.

The cbh variable contains the altitude of Cloud Base Height along the LIDAR signal.

Example: Cloud Base Height retreived by STRAT above Villeneuve d’Ascq (FRANCE), the 20th March 2012
 STRAT.

The mld variable contains the altitude of the Mixing Layer Depth (best estimated) along the LIDAR signal.

Example: Mixing Layer Depth (best estimated) retreived by STRAT above Villeneuve d’Ascq (FRANCE), the 20th March 2012
 STRAT.