Tue, 19 Feb 2013 20:50:16 +0200
Added a basic FAQ (not checked for format, not added to index.rst)
binietoglou@23 | 1 | Frequently asked questions |
binietoglou@23 | 2 | ========================== |
binietoglou@23 | 3 | |
binietoglou@23 | 4 | Is it necessary to provide only measurment periods with cloud free conditions and |
binietoglou@23 | 5 | homogeneous atmosphere or is this part of ELDA or the pre processing of the data? |
binietoglou@23 | 6 | For example in cases with scattered low cumulus clouds. |
binietoglou@23 | 7 | |
binietoglou@23 | 8 | At moment you should provide cloud free data because the automatic cloud screening |
binietoglou@23 | 9 | is not yet implemented in the SCC. We are working on this issue and hopefully the new |
binietoglou@23 | 10 | module will be implemented at the end of ACTRIS project . |
binietoglou@23 | 11 | |
binietoglou@23 | 12 | What is the definition of low range, ultra near range and high range channels? |
binietoglou@23 | 13 | Are there any threshold values? |
binietoglou@23 | 14 | |
binietoglou@23 | 15 | There are no threshold values defined for the different range types. This information |
binietoglou@23 | 16 | is used only in the gluing procedures just to identify which channel should be taken |
binietoglou@23 | 17 | as low range and which one as far range. If no gluing is applied by the SCC the range |
binietoglou@23 | 18 | id flags are not taken into account. |
binietoglou@23 | 19 | |
binietoglou@23 | 20 | Due to changes in the settings of our lidarsystem, the depolarization factor can |
binietoglou@23 | 21 | change during the measurement. Is it necessary to provide one SCC-file for each settings |
binietoglou@23 | 22 | or is it possible to set the Depolarization_Factor variable time dependent? |
binietoglou@23 | 23 | |
binietoglou@23 | 24 | Unfortunately it is not possible to have time dependence on Depolarization_Factor variable. |
binietoglou@23 | 25 | So if this parameter changes you should provide different SCC files for each setting. |
binietoglou@23 | 26 | |
binietoglou@23 | 27 | Is it possible for documentation purposes to put own parameters in the SCC-NetCDF file? |
binietoglou@23 | 28 | For example who created the file.... Are there any reasons against this? |
binietoglou@23 | 29 | |
binietoglou@23 | 30 | Technically as long as you use not standard SCC variables for your own parameters there are |
binietoglou@23 | 31 | no problems for the SCC. It will just ignore these not standard variables. |
binietoglou@23 | 32 | |
binietoglou@23 | 33 | Which NetCDF version is to use? NetCDF3, NetCDF3 Classic, NetCDF4, NetCDF4 Classic? |
binietoglou@23 | 34 | |
binietoglou@23 | 35 | The NetCDF libraries 4.1.3 are used in all the SCC modules. So all the NetCDF formats you |
binietoglou@23 | 36 | have indicated should be compatible with the SCC (we have tested NetCDF3 and NetCDF4). |
binietoglou@23 | 37 | |
binietoglou@23 | 38 | What are the values for the lidar ratio used in the SCC_DB? |
binietoglou@23 | 39 | |
binietoglou@23 | 40 | The values of (fixed) lidar ratio used by the SCC in the elastic retrieval can be set by |
binietoglou@23 | 41 | the user using the SCC web interface. In particular you can define a lidar ratio value for |
binietoglou@23 | 42 | each elastic backscatter product: in the product page there is the section “Elastic Backscatter |
binietoglou@23 | 43 | options” in which there is the field “Fixed lr”. In case you want to use a lidar ratio profile |
binietoglou@23 | 44 | you should set LR_Input accordingly and provide an external LR profile NetCDF file |
binietoglou@23 | 45 | (see documentation on SCC file format). |
binietoglou@23 | 46 | |
binietoglou@23 | 47 | In cases of measurements where Raman channels are available, the SCC will calculate the Raman |
binietoglou@23 | 48 | backscatter profile. If I want to retrieve Klett-retrievals for this channel, too (e.g 532nm) |
binietoglou@23 | 49 | is it sufficient to set the value in LR_input(channels) to 1 or 0 plus a LR-profile to get |
binietoglou@23 | 50 | both retrievals? |
binietoglou@23 | 51 | |
binietoglou@23 | 52 | No. In general, for each lidar configuration you can define a set of optical products to be calculated |
binietoglou@23 | 53 | for that configuration using the SCC web interface. So suppose you have a system with 532nm and 607nm |
binietoglou@23 | 54 | channels. In this case you have 2 options: |
binietoglou@23 | 55 | #. Raman backscatter and extinction in the e532 file and Raman backscatter (full resolution) in the b532 |
binietoglou@23 | 56 | file. In this case you should associate to the configuration a product of type “lidar ratio and will |
binietoglou@23 | 57 | produce the e532 file and a product of type “Raman backscatter” which will produce the b532 file |
binietoglou@23 | 58 | #. Raman backscatter and extinction in the e532 file and elastic backscatter in the b532 file. |
binietoglou@23 | 59 | In this case you should associate to the configuration a product of type “lidar ratio and extinction” |
binietoglou@23 | 60 | which will produce the e532 file and a product of type “elastic backscatter” which will produce the b532 file |
binietoglou@23 | 61 | |
binietoglou@23 | 62 | Note: you cannot calculate a b532 file containing the Raman and elastic backscatters at the same time. |
binietoglou@23 | 63 | The reason is that the 2 products will produce an output file with the same name (according to the EARLINET rules). |
binietoglou@23 | 64 | Moreover in general, it makes no sense to calculate the elastic backscatter when you can calculate the Raman |
binietoglou@23 | 65 | one which usually is better. |
binietoglou@23 | 66 | |
binietoglou@23 | 67 | What are the conventions for the filnames for the various files that need to be uploaded? |
binietoglou@23 | 68 | |
binietoglou@23 | 69 | The following definitions apply: |
binietoglou@23 | 70 | - SCC raw lidar data file |
binietoglou@23 | 71 | |
binietoglou@23 | 72 | This file should be named as measID.nc. For example if your measurement had a measurementID of 20130101cc00 the corresponding NetCDF file should be named 20130101cc00.nc |
binietoglou@23 | 73 | |
binietoglou@23 | 74 | - Sounding file |
binietoglou@23 | 75 | |
binietoglou@23 | 76 | The file should be named as rs_measID.nc. Considering the above example the sounding file should be named rs_20130101cc00.nc |
binietoglou@23 | 77 | |
binietoglou@23 | 78 | In this case you should also set the global attribute Sounding_File_Name in the raw lidar data file as: |
binietoglou@23 | 79 | |
binietoglou@23 | 80 | Sounding_File_Name=rs_20130101cc00.nc |
binietoglou@23 | 81 | |
binietoglou@23 | 82 | - Lidarration file |
binietoglou@23 | 83 | |
binietoglou@23 | 84 | The file should be named as lr_measID.nc. Considering the above example the sounding file should be named lr_20130101cc00.nc |
binietoglou@23 | 85 | |
binietoglou@23 | 86 | In this case you should also set the global attribute LR_File_Name in the raw lidar data file as: |
binietoglou@23 | 87 | |
binietoglou@23 | 88 | LR_File_Name=lr_20130101cc00.nc |
binietoglou@23 | 89 | |
binietoglou@23 | 90 | - Overlap file |
binietoglou@23 | 91 | |
binietoglou@23 | 92 | The file should be named as ov_measID.nc. Considering the above example the sounding file should be named ov_20130101cc00.nc |
binietoglou@23 | 93 | |
binietoglou@23 | 94 | In this case you should also set the global attribute Overlap_File_Name in the raw lidar data file as: |
binietoglou@23 | 95 | |
binietoglou@23 | 96 | Overalp_File_Name=ov_20130101cc00.nc |
binietoglou@23 | 97 | |
binietoglou@23 | 98 | |
binietoglou@23 | 99 | |
binietoglou@23 | 100 |