diff -r c782e3130fbc -r c6855e46c311 docs/file_formats/netcdf_file.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/file_formats/netcdf_file.rst Mon Feb 06 14:02:20 2017 +0200 @@ -0,0 +1,1250 @@ +.. _netcdf_file: + +The SCC input netCDF file format +================================ + +A more detailed version of this document can be found in this :download:`pdf file <../files/NetCDF_input_file_v3.pdf>`. + +.. note:: + + You can check the format of the files you create using the linked `script `_ . + + +Rationale +--------- + +The Single Calculus Chain (SCC) is composed by three different modules: + +- pre-processing module (*ELPP*) + +- optical processing module (*ELDA*) + +- depolarization calibrator module (*ELDEC*) + +To perfom aerosol optical retrievals the SCC needs not only the raw +lidar data but also a certain number of parameters to use in both +pre-processing and optical processing stages. The SCC gets these +parameters looking at two different locations: + +- Single Calculus Chain relational database (SCC\_DB) + +- Input files + +There are some paramenters that can be found only in the input files +(those ones changing from measurement to measurement), others that can +be found only in the SCC\_DB and other ones that can be found in both +these locations. In the last case, if a particular parameter is needed, +the SCC will search first in the input files and then in SCC\_DB. If the +parameter is found in the input files, the SCC will keep it without +looking into SCC\_DB. + +The input files have to be submitted to the SCC in NetCDF format. At +present the SCC can handle four different types of input files: + +1. Raw Lidar Data + +2. Sounding Data + +3. Overlap + +4. Lidar Ratio + +As already mentioned, the *Raw lidar data* file contains not only the +raw lidar data but also other parameters to use to perform the +pre-processing and optical processing. The *Sounding Data* file contains +the data coming from a correlative radiosounding and it is used by the +SCC for molecular density calculation. The *Overlap* file contains the +measured overlap function. The *Lidar Ratio* file contains a lidar ratio +profile to use in elastic backscatter retrievals. The *Raw Lidar Data* +file is of course mandatory and the *Sounding Data*, *Overlap* and +*Lidar Ratio* files are optional. If *Sounding Data* file is not +submitted by the user, the molecular density will be calculated by the +SCC using the "US Standard Atmosphere 1976". If the *Overlap* file is +not submitted by the user, the SCC will get the full overlap height from +SCC\_DB and it will produce optical results starting from this height. +If *Lidar Ratio* file is not submitted by the user, the SCC will +consider a fixed value for lidar ratio got from SCC\_DB. + +The user can decide to submit all these files or any number of them (of +course the file *Raw Lidar Data* is mandatory). For example the user can +submit together with the *Raw Lidar Data* file only the *Sounding Data* +file or only the *Overlap* file. + +This document provides a detailed example about the structure of +the NetCDF input files to use for SCC data submission. All Earlinet +groups should read it carefully because they have to produce such kind +of input files if they want to use the SCC for their standard lidar +retrievals. + +Additionaly, the linked :download:`pdf file <../files/NetCDF_input_file_v3.pdf>` contains +tables with all mandatory and optional variables for the netcdf files +accepted by the SCC. Table 1 contains a list of dimensions, variables and +global attributes that can be used in the NetCDF *Raw Lidar Data* +input file. For each of them it is indicated: + +- The name. For the multidimensional variables also the corresponding + dimensions are reported + +- A description explaining the meaning + +- The type + +- If it is mandatory or optional + +As already mentioned, the SCC can get some parameters looking first in +the *Raw Lidar Data* input file and then into SCC\_DB. This means that +to use the parameters stored in SCC\_DB the optional variables or +optional global attributes must not appear within *Raw Lidar Data* file. +This is the suggested and recommended way to use the SCC. Please include +optional parameters in the *Raw Lidar Data* only as an exception. + +Tables 2, 3, and 4 report all the +information about the structure of *Sounding Data*, *Overlap* and *Lidar +Ratio* input files respectively. + + +Example +------- + +Let's now consider an example of *Raw Lidar Data* input file. Suppose +we want to generate NetCDF input file corresponding to a measurement +with the following properties: + ++----------------------+-------------------------------------------+ +| Start Date | 30\ :sup:`th` January 2009 | ++----------------------+-------------------------------------------+ +| Start Time UT | 00:00:01 | ++----------------------+-------------------------------------------+ +| Stop Time UT | 00:05:01 | ++----------------------+-------------------------------------------+ +| Station Name | Dummy station | ++----------------------+-------------------------------------------+ +| Earlinet call-sign | cc | ++----------------------+-------------------------------------------+ +| Pointing angle | 5 degrees with respect to the zenith | ++----------------------+-------------------------------------------+ + + +Moreover suppose that this measurement is composed by the following +lidar channels: + +#. 1064 lidar channel + + +------------------------------+-------------------------------+ + | Emission wavelength=1064nm | Detection wavelength=1064nm | + +------------------------------+-------------------------------+ + | Time resolution=30s | Number of laser shots=1500 | + +------------------------------+-------------------------------+ + | Number of bins=3000 | Detection mode=analog | + +------------------------------+-------------------------------+ + | Range resolution=7.5m | Polarization state=total | + +------------------------------+-------------------------------+ + +#. 532 cross lidar channel + + +-----------------------------+------------------------------------------+ + | Emission wavelength=532nm | Detection wavelength=532nm | + +-----------------------------+------------------------------------------+ + | Time resolution=60s | Number of laser shots=3000 | + +-----------------------------+------------------------------------------+ + | Number of bins=5000 | Detection mode=photoncounting | + +-----------------------------+------------------------------------------+ + | Range resolution=15m | Polarization state=cross (transmitted) | + +-----------------------------+------------------------------------------+ + +#. 532 parallel lidar channel + + +-----------------------------+-------------------------------------------+ + | Emission wavelength=532nm | Detection wavelength=532nm | + +-----------------------------+-------------------------------------------+ + | Time resolution=60s | Number of laser shots=3000 | + +-----------------------------+-------------------------------------------+ + | Number of bins=5000 | Detection mode=photoncounting | + +-----------------------------+-------------------------------------------+ + | Range resolution=15m | Polarization state=parallel (reflected) | + +-----------------------------+-------------------------------------------+ + +#. | 607 :math:`N_2` vibrational Raman channel + + +-----------------------------+---------------------------------+ + | Emission wavelength=532nm | Detection wavelength=607nm | + +-----------------------------+---------------------------------+ + | Time resolution=60s | Number of laser shots=3000 | + +-----------------------------+---------------------------------+ + | Number of bins=5000 | Detection mode=photoncounting | + +-----------------------------+---------------------------------+ + | Range resolution=15m | | + +-----------------------------+---------------------------------+ + +Finally let's assume we have also performed dark measurements before the +lidar measurements from the 23:50:01 UT up to 23:53:01 UT of +29\ :sup:`th` January 2009. + + +Dimensions +~~~~~~~~~~ + +Looking at table 1 of the pdf file we have to fix the following dimensions: + +:: + + points + channels + time + nb_of_time_scales + scan_angles + time_bck + +The dimension ``time`` is unlimited so we don’t have to fix it. +We have 4 lidar channels so: + +:: + + channels=4 + +Regarding the dimension ``points`` we have only one channel with a +number of vertical bins equal to 3000 (the 1064nm) and all other +channels with 5000 vertical bins. In cases like this the dimension +``points`` has to be fixed to the maximum number of vertical bins so: + +:: + + points=5000 + +Moreover only one channel (1064nm) is acquired with a time resolution of +30 seconds, all the other channels have a time resolution of 60 seconds. +This means that we have to define two different time scales. We have to +set: + +:: + + nb_of_time_scales=2 + +The measurement is performed only at one scan angle (5 degrees with +respect to the zenith) so: + +:: + + scan_angles=1 + +We have 3 minutes of dark measurements and two different time scales one +with 60 seconds time resolution and the other one with 30 seconds time +resolution. So we will have 3 different dark profiles for the channels +acquired with the first time scale and 6 for the lidar channels acquired +with the second time scale. We have to fix the dimension ``time_bck`` as +the maximum between these values: + +:: + + time_bck=6 + + +Variables +~~~~~~~~~ + +In this section it will be explained how to fill all the possible +variables either mandatory or optional of *Raw Lidar Data* input file. + +- | ``Raw_Data_Start_Time(time, nb_of_time_scales)`` + | This 2 dimensional mandatory array has to contain the acquisition + start time (in seconds from the time given by the global attribute + ``RawData_Start_Time_UT``) of each lidar profile. In this example + we have two different time scales: one is characterized by steps of + 30 seconds (the 1064nm is acquired with this time scale) the other + by steps of 60 seconds (532cross, 532parallel and 607nm). Moreover + the measurement start time is 00:00:01 UT and the measurement stop + time is 00:05:01 UT. In this case we have to define: + + :: + + Raw_Data_Start_Time = + 0, 0, + 60, 30, + 120, 60, + 180, 90, + 240, 120, + _, 150, + _, 180, + _, 210, + _, 240, + _, 270 ; + + The order used to fill this array defines the correspondence between + the different time scales and the time scale index. In this example + we have a time scale index of 0 for the time scale with steps of 60 + seconds and a time scale index of 1 for the other one. + +- | ``Raw_Data_Stop_Time(time, nb_of_time_scales)`` + | The same as previous item but for the data acquisition stop time. + Following a similar procedure we have to define: + + :: + + Raw_Data_Stop_Time = + 60, 30, + 120, 60, + 180, 90, + 240, 120, + 300, 150, + _, 180, + _, 210, + _, 240, + _, 270, + _, 300 ; + +- | ``Raw_Lidar_Data(time, channels, points)`` + | This 3 dimensional mandatory array has to be filled with the + time-series of raw lidar data. The photoncounting profiles have to + submitted in counts (so as integers) while the analog ones in mV. + The order the user chooses to fill this array defines the + correspondence between channel index and lidar data. + | For example if we fill this array in such way that: + + +-------------------------------------+---------------------------------------+ + | ``Raw_Lidar_Data(time,0,points)`` | is the time-series of 1064 nm | + +-------------------------------------+---------------------------------------+ + | ``Raw_Lidar_Data(time,1,points)`` | is the time-series of 532 cross | + +-------------------------------------+---------------------------------------+ + | ``Raw_Lidar_Data(time,2,points)`` | is the time-series of 532 parallel | + +-------------------------------------+---------------------------------------+ + | ``Raw_Lidar_Data(time,3,points)`` | is the time-series of 607 nm | + +-------------------------------------+---------------------------------------+ + + | + | from now on the channel index 0 is associated to the 1064 channel, + 1 to the 532 cross, 2 to the 532 parallel and 3 to the 607nm. + +- | ``Raw_Bck_Start_Time(time_bck, nb_of_time_scales)`` + | This 2 dimensional optional array has to contain the acquisition + start time (in seconds from the time given by the global attribute + ``RawBck_Start_Time_UT``) of each dark measurements profile. + Following the same procedure used for the variable + ``Raw_Data_Start_Time`` we have to define: + + :: + + Raw_Bck_Start_Time = + 0, 0, + 60, 30, + 120, 60, + _, 90, + _, 120, + _, 150; + +- | ``Raw_Bck_Stop_Time(time_bck, nb_of_time_scales)`` + | The same as previous item but for the dark acquisition stop time. + Following a similar procedure we have to define: + + :: + + Raw_Bck_Stop_Time = + 60, 30, + 120, 60, + 180, 90, + _, 120, + _, 150, + _, 180 ; + +- | ``Background_Profile(time_bck, channels, points)`` + | This 3 dimensional optional array has to be filled with the + time-series of the dark measurements data. The photoncounting + profiles have to submitted in counts (so as integers) while the + analog ones in mV. The user has to fill this array following the + same order used in filling the array ``Raw_Lidar_Data``: + + +---------------------------------------------+-------------------------------------+ + | ``Background_Profile(time_bck,0,points)`` | dark time-series at 1064 nm | + +---------------------------------------------+-------------------------------------+ + | ``Background_Profile(time_bck,1,points)`` | dark time-series at 532 cross | + +---------------------------------------------+-------------------------------------+ + | ``Background_Profile(time_bck,2,points)`` | dark time-series at 532 parallel | + +---------------------------------------------+-------------------------------------+ + | ``Background_Profile(time_bck,3,points)`` | dark time-series at 607 nm | + +---------------------------------------------+-------------------------------------+ + + | + +- | ``channel_ID(channels)`` + | This mandatory array provides the link between the channel index + within the *Raw Lidar Data* input file and the channel ID in + SCC\_DB. To fill this variable the user has to know which channel + IDs in SCC\_DB correspond to his lidar channels. For this purpose + the SCC, in its final version will provide to the user a special + tool to get these channel IDs through a Web interface. At the + moment this interface is not yet available and these channel IDs + will be communicated directly to the user by the NA5 people. + | Anyway to continue the example let’s suppose that the four lidar + channels taken into account are mapped into SCC\_DB with the + following channel IDs: + + +----------------+-----------------+ + | 1064 nm | channel ID=7 | + +----------------+-----------------+ + | 532 cross | channel ID=5 | + +----------------+-----------------+ + | 532 parallel | channel ID=6 | + +----------------+-----------------+ + | 607 nm | channel ID=8 | + +----------------+-----------------+ + + | + | In this case we have to define: + + :: + + channel_ID = 7, 5, 6, 8 ; + +- | ``id_timescale(channels)`` + | This mandatory array is introduced to determine which time scale is + used for the acquisition of each lidar channel. In particular this + array defines the link between the channel index and the time scale + index. In our example we have two different time scales. Filling + the arrays ``Raw_Data_Start_Time`` and ``Raw_Data_Stop_Time`` we + have defined a time scale index of 0 for the time scale with steps + of 60 seconds and a time scale index of 1 for the other one with + steps of 30 seconds. In this way this array has to be set as: + + :: + + id_timescale = 1, 0, 0, 0 ; + +- | ``Laser_Pointing_Angle(scan_angles)`` + | This mandatory array contains all the scan angles used in the + measurement. In our example we have only one scan angle of 5 + degrees with respect to the zenith, so we have to define: + + :: + + Laser_Pointing_Angle = 5 ; + +- | ``Laser_Pointing_Angle_of_Profiles(time, nb_of_time_scales)`` + | This mandatory array is introduced to determine which scan angle is + used for the acquisition of each lidar profile. In particular this + array defines the link between the time and time scales indexes and + the scan angle index. In our example we have a single scan angle + that has to correspond to the scan angle index 0. So this array has + to be defined as: + + :: + + Laser_Pointing_Angle_of_Profiles = + 0, 0, + 0, 0, + 0, 0, + 0, 0, + 0, 0, + _, 0, + _, 0, + _, 0, + _, 0, + _, 0 ; + +- | ``Laser_Shots(time, channels)`` + | This mandatory array stores the laser shots accumulated at each + time for each channel. In our example the number of laser shots + accumulated is 1500 for the 1064nm channels and 3000 for all the + other channels. Moreover the laser shots do not change with the + time. So we have to define this array as: + + :: + + Laser_Shots = + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _ ; + +- | ``Emitted_Wavelength(channels)`` + | This optional array defines the link between the channel index and + the emission wavelength for each lidar channel. The wavelength has + to be expressed in nm. This information can be also taken from + SCC\_DB. In our example we have: + + :: + + Emitted_Wavelength = 1064, 532, 532, 532 ; + +- | ``Detected_Wavelength(channels)`` + | This optional array defines the link between the channel index and + the detected wavelength for each lidar channel. Here detected + wavelength means the value of center of interferential filter + expressed in nm. This information can be also taken from SCC\_DB. + In our example we have: + + :: + + Detected_Wavelength = 1064, 532, 532, 607 ; + +- | ``Raw_Data_Range_Resolution(channels)`` + | This optional array defines the link between the channel index and + the raw range resolution for each channel. If the scan angle is + different from zero this quantity is different from the vertical + resolution. More precisely if :math:`\alpha` is the scan angle used + and :math:`\Delta z` is the range resolution the vertical + resolution is calculated as :math:`\Delta + z'=\Delta z \cos\alpha`. This array has to be filled with + :math:`\Delta z` and not with :math:`\Delta z'`. The unit is + meters. This information can be also taken from SCC\_DB. In our + example we have: + + :: + + Raw_Data_Range_Resolution = 7.5, 15.0, 15.0, 15.0 ; + +- | ``Scattering_Mechanism(channels)`` + | This optional array defines the scattering mechanism involved in + each lidar channel. In particular the following values are adopted: + + +-----+---------------------------------------------------+ + | 0 | Total elastic backscatter | + +-----+---------------------------------------------------+ + | 1 | N\ :math:`_2` vibrational Raman backscatter | + +-----+---------------------------------------------------+ + | 2 | Cross polarization elastic backscatter | + +-----+---------------------------------------------------+ + | 3 | Parallel polarization elastic backscatter | + +-----+---------------------------------------------------+ + | 4 | H\ :math:`_2`\ O vibrational Raman backscatter | + +-----+---------------------------------------------------+ + | 5 | Rotational Raman low quantum number | + +-----+---------------------------------------------------+ + | 6 | Rotational Raman high quantum number | + +-----+---------------------------------------------------+ + + | + | This information can be also taken from SCC\_DB. In our example we + have: + + :: + + Scattering_Mechanism = 0, 2, 3, 1 ; + +- | ``Signal_Type(channels)`` + | This optional array defines the type of signal involved in each + lidar channel. In particular the following values are adopted: + + +------+--------------------------------------------------------------+ + | 0 | Total elastic | + +------+--------------------------------------------------------------+ + | 1 | Total elastic near range | + +------+--------------------------------------------------------------+ + | 2 | Total elastic far range | + +------+--------------------------------------------------------------+ + | 3 | N\ :math:`_2` vibrational Raman | + +------+--------------------------------------------------------------+ + | 4 | N\ :math:`_2` vibrational Raman near range | + +------+--------------------------------------------------------------+ + | 5 | N\ :math:`_2` vibrational Raman far range | + +------+--------------------------------------------------------------+ + | 6 | Elastic polarization reflected | + +------+--------------------------------------------------------------+ + | 7 | Elastic polarization transmitted | + +------+--------------------------------------------------------------+ + | 8 | Rotational Raman line close to elastic line | + +------+--------------------------------------------------------------+ + | 9 | Rotational Raman line far from elastic line | + +------+--------------------------------------------------------------+ + | 10 | Elastic polarization reflected near range | + +------+--------------------------------------------------------------+ + | 11 | Elastic polarization reflected far range | + +------+--------------------------------------------------------------+ + | 12 | Elastic polarization transmitted near range | + +------+--------------------------------------------------------------+ + | 13 | Elastic polarization transmitted far range | + +------+--------------------------------------------------------------+ + | 14 | H\ :math:`_2`\ O vibrational Raman backscatter | + +------+--------------------------------------------------------------+ + | 15 | Rotational Raman line far from elastic line near range | + +------+--------------------------------------------------------------+ + | 16 | Rotational Raman line far from elastic line far range | + +------+--------------------------------------------------------------+ + | 17 | Rotational Raman line close to elastic line near range | + +------+--------------------------------------------------------------+ + | 18 | Rotational Raman line close to elastic line far range | + +------+--------------------------------------------------------------+ + | 19 | H\ :math:`_2`\ O vibrational Raman backscatter near range | + +------+--------------------------------------------------------------+ + | 20 | H\ :math:`_2`\ O vibrational Raman backscatter far range | + +------+--------------------------------------------------------------+ + | 21 | Total elastic ultra near range | + +------+--------------------------------------------------------------+ + | 22 | +45 rotated elastic polarization transmitted | + +------+--------------------------------------------------------------+ + | 23 | +45 rotated elastic polarization reflected | + +------+--------------------------------------------------------------+ + | 24 | -45 rotated elastic polarization transmitted | + +------+--------------------------------------------------------------+ + | 25 | -45 rotated elastic polarization reflected | + +------+--------------------------------------------------------------+ + | 26 | +45 rotated elastic polarization transmitted near range | + +------+--------------------------------------------------------------+ + | 27 | +45 rotated elastic polarization transmitted far range | + +------+--------------------------------------------------------------+ + | 28 | +45 rotated elastic polarization reflected near range | + +------+--------------------------------------------------------------+ + | 29 | +45 rotated elastic polarization reflected far range | + +------+--------------------------------------------------------------+ + | 30 | -45 rotated elastic polarization transmitted near range | + +------+--------------------------------------------------------------+ + | 31 | -45 rotated elastic polarization transmitted far range | + +------+--------------------------------------------------------------+ + | 32 | -45 rotated elastic polarization reflected near range | + +------+--------------------------------------------------------------+ + | 33 | -45 rotated elastic polarization reflected far range | + +------+--------------------------------------------------------------+ + + | + | This information can be also taken from SCC\_DB. In our example we + have: + + :: + + Signal_Type = 0, 7, 6, 3 ; + +- | ``Acquisition_Mode(channels)`` + | This optional array defines the acquisition mode (analog or + photoncounting) involved in each lidar channel. In particular a + value of 0 means analog mode and 1 photoncounting mode. This + information can be also taken from SCC\_DB. In our example we have: + + :: + + Acquisition_Mode = 0, 1, 1, 1 ; + +- | ``Laser_Repetition_Rate(channels)`` + | This optional array defines the repetition rate in Hz used to + acquire each lidar channel. This information can be also taken from + SCC\_DB. In our example we are supposing we have only one laser + with a repetition rate of 50 Hz so we have to set: + + :: + + Laser_Repetition_Rate = 50, 50, 50, 50 ; + +- | ``Dead_Time(channels)`` + | This optional array defines the dead time in ns associated to each + lidar channel. The SCC will use the values given by this array to + correct the photoncounting signals for dead time. Of course for + analog signals no dead time correction will be applied (for analog + channels the corresponding dead time values have to be set to + undefined value). This information can be also taken from SCC\_DB. + In our example the 1064 nm channel is acquired in analog mode so + the corresponding dead time value has to be undefined. If we + suppose a dead time of 10 ns for all other channels we have to set: + + :: + + Dead_Time = _, 10, 10, 10 ; + +- | ``Dead_Time_Corr_Type(channels)`` + | This optional array defines which kind of dead time correction has + to be applied on each photoncounting channel. The SCC will correct + the data supposing a not-paralyzable channel if a value of 0 is + found while a paralyzable channel is supposed if a value of 1 is + found. Of course for analog signals no dead time correction will be + applied and so the corresponding values have to be set to undefined + value. This information can be also taken from SCC\_DB. In our + example the 1064 nm channel is acquired in analog mode so the + corresponding has to be undefined. If we want to consider all the + photoncounting signals as not-paralyzable ones: we have to set: + + :: + + Dead_Time_Corr_Type = _, 0, 0, 0 ; + +- | ``Trigger_Delay(channels)`` + | This optional array defines the delay (in ns) of the middle of the + first rangebin with respect to the output laser pulse for each + lidar channel. The SCC will use the values given by this array to + correct for trigger delay. This information can be also taken from + SCC\_DB. Let’s suppose that in our example all the photoncounting + channels are not affected by this delay and only the analog channel + at 1064nm is acquired with a delay of 50ns. In this case we have to + set: + + :: + + Trigger_Delay = 50, 0, 0, 0 ; + +- | ``Background_Mode(channels)`` + | This optional array defines how the atmospheric background has to + be subtracted from the lidar channel. Two options are available for + the calculation of atmospheric background: + + #. Average in the far field of lidar channel. In this case the value + of this variable has to be 1 + + #. Average within pre-trigger bins. In this case the value of this + variable has to be 0 + + This information can be also taken from SCC\_DB. Let’s suppose in our + example we use the pre-trigger for the 1064nm channel and the far + field for all other channels. In this case we have to set: + + :: + + Background_Mode = 0, 1, 1, 1 ; + +- | ``Background_Low(channels)`` + | This mandatory array defines the minimum altitude (in meters) to + consider in calculating the atmospheric background for each + channel. In case pre-trigger mode is used the corresponding value + has to be set to the rangebin to be used as lower limit (within + pre-trigger region) for background calculation. In our example, if + we want to calculate the background between 30000 and 50000 meters + for all photoncounting channels and we want to use the first 500 + pre-trigger bins for the background calculation for the 1064nm + channel we have to set: + + :: + + Background_Low= 0, 30000, 30000, 30000 ; + +- | ``Background_High(channels)`` + | This mandatory array defines the maximum altitude (in meters) to + consider in calculating the atmospheric background for each + channel. In case pre-trigger mode is used the corresponding value + has to be set to the rangebin to be used as upper limit (within + pre-trigger region) for background calculation. In our example, if + we want to calculate the background between 30000 and 50000 meters + for all photoncounting channels and we want to use the first 500 + pre-trigger bins for the background calculation for the 1064nm + channel we have to set: + + :: + + Background_High = 500, 50000, 50000, 50000 ; + +- | ``Molecular_Calc`` + | This mandatory variable defines the way used by SCC to calculate + the molecular density profile. At the moment two options are + available: + + #. US Standard Atmosphere 1976. In this case the value of this + variable has to be 0 + + #. Radiosounding. In this case the value of this variable has to be 1 + + If we decide to use the option 1. we have to provide also the + measured pressure and temperature at lidar station level. Indeed if + we decide to use the option 2. a radiosounding file has to be + submitted separately in NetCDF format (the structure of this file is + summarized in table 2 of the pdf file). Let’s suppose we want to use the + option 1. so: + + :: + + Molecular_Calc = 0 ; + +- | ``Pressure_at_Lidar_Station`` + | Because we have chosen the US Standard Atmosphere for calculation + of the molecular density profile we have to give the pressure in + hPa at lidar station level: + + :: + + Pressure_at_Lidar_Station = 1010 ; + +- | ``Temperature_at_Lidar_Station`` + | Because we have chosen the US Standard Atmosphere for calculation + of the molecular density profile we have to give the temperature in + C at lidar station level: + + :: + + Temperature_at_Lidar_Station = 19.8 ; + +- | ``LR_Input(channels)`` + | This array is required only for lidar channels for which elastic + backscatter retrieval has to be performed. It defines the lidar + ratio to be used within this retrieval. Two options are available: + + #. The user can submit a lidar ratio profile. In this case the value + of this variable has to be 0. + + #. A fixed value of lidar ratio can be used. In this case the value + of this variable has to be 1. + + If we decide to use the option 1. a lidar ratio file has to be + submitted separately in NetCDF format (the structure of this file is + summarized in table ). If we decide to use the option 2. the + fixed value of lidar ratio will be taken from SCC\_DB. In our example + we have to give a value of this array only for the 1064nm lidar + channel because for the 532nm we will be able to retrieve a Raman + backscatter coefficient. In case we want to use the fixed value + stored in SCC\_DB we have to set: + + :: + + LR_Input = 1,_,_,_ ; + +- | ``DAQ_Range(channels)`` + | This array is required only if one or more lidar signals are + acquired in analog mode. It gives the analog scale in mV used to + acquire the analog signals. In our example we have only the 1064nm + channel acquired in analog mode. If we have used a 100mV analog + scale to acquire this channel we have to set: + + :: + + DAQ_Range = 100,_,_,_ ; + + +Global attributes +~~~~~~~~~~~~~~~~~ + +- | ``Measurement_ID`` + | This mandatory global attribute defines the measurement ID + corresponding to the actual lidar measurement. It is a string + composed by 12 characters. The first 8 characters give the start + date of measurement in the format YYYYMMDD. The next 2 characters + give the Earlinet call-sign of the station. The last 2 characters + are used to distinguish between different time-series within the + same date. In our example we have to set: + + :: + + Measurement_ID= "20090130cc00" ; + +- | ``RawData_Start_Date`` + | This mandatory global attribute defines the start date of lidar + measurements in the format YYYYMMDD. In our case we have: + + :: + + RawData_Start_Date = "20090130" ; + +- | ``RawData_Start_Time_UT`` + | This mandatory global attribute defines the UT start time of lidar + measurements in the format HHMMSS. In our case we have: + + :: + + RawData_Start_Time_UT = "000001" ; + +- | ``RawData_Stop_Time_UT`` + | This mandatory global attribute defines the UT stop time of lidar + measurements in the format HHMMSS. In our case we have: + + :: + + RawData_Stop_Time_UT = "000501" ; + +- | ``RawBck_Start_Date`` + | This optional global attribute defines the start date of dark + measurements in the format YYYYMMDD. In our case we have: + + :: + + RawBck_Start_Date = "20090129" ; + +- | ``RawBck_Start_Time_UT`` + | This optional global attribute defines the UT start time of dark + measurements in the format HHMMSS. In our case we have: + + :: + + RawBck_Start_Time_UT = "235001" ; + +- | ``RawBck_Stop_Time_UT`` + | This optional global attribute defines the UT stop time of dark + measurements in the format HHMMSS. In our case we have: + + :: + + RawBck_Stop_Time_UT = "235301" ; + + +Example of file (CDL format) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +To summarize we have the following NetCDF *Raw Lidar Data* file (in CDL +format): + +:: + + dimensions: + points = 5000 ; + channels = 4 ; + time = UNLIMITED ; // (10 currently) + nb_of_time_scales = 2 ; + scan_angles = 1 ; + time_bck = 6 ; + variables: + int channel_ID(channels) ; + int Laser_Repetition_Rate(channels) ; + double Laser_Pointing_Angle(scan_angles) ; + int Signal_Type(channels); + double Emitted_Wavelength(channels) ; + double Detected_Wavelength(channels) ; + double Raw_Data_Range_Resolution(channels) ; + int Background_Mode(channels) ; + double Background_Low(channels) ; + double Background_High(channels) ; + int Molecular_Calc ; + double Pressure_at_Lidar_Station ; + double Temperature_at_Lidar_Station ; + int id_timescale(channels) ; + double Dead_Time(channels) ; + int Dead_Time_Corr_Type(channels) ; + int Acquisition_Mode(channels) ; + double Trigger_Delay(channels) ; + int LR_Input(channels) ; + int Laser_Pointing_Angle_of_Profiles(time, nb_of_time_scales) ; + int Raw_Data_Start_Time(time, nb_of_time_scales) ; + int Raw_Data_Stop_Time(time, nb_of_time_scales) ; + int Raw_Bck_Start_Time(time_bck, nb_of_time_scales) ; + int Raw_Bck_Stop_Time(time_bck, nb_of_time_scales) ; + int Laser_Shots(time, channels) ; + double Raw_Lidar_Data(time, channels, points) ; + double Background_Profile(time_bck, channels, points) ; + double DAQ_Range(channels) ; + + // global attributes: + :Measurement_ID = "20090130cc00" ; + :RawData_Start_Date = "20090130" ; + :RawData_Start_Time_UT = "000001" ; + :RawData_Stop_Time_UT = "000501" ; + :RawBck_Start_Date = "20090129" ; + :RawBck_Start_Time_UT = "235001" ; + :RawBck_Stop_Time_UT = "235301" ; + + data: + + channel_ID = 7, 5, 6, 8 ; + + Laser_Repetition_Rate = 50, 50, 50, 50 ; + + Laser_Pointing_Angle = 5 ; + + Signal_Type = 0, 7, 6, 3 ; + + Emitted_Wavelength = 1064, 532, 532, 532 ; + + Detected_Wavelength = 1064, 532, 532, 607 ; + + Raw_Data_Range_Resolution = 7.5, 15, 15, 15 ; + + Background_Mode = 0, 1, 1, 1 ; + + Background_Low = 0, 30000, 30000, 30000 ; + + Background_High = 500, 50000, 50000, 50000 ; + + Molecular_Calc = 0 ; + + Pressure_at_Lidar_Station = 1010 ; + + Temperature_at_Lidar_Station = 19.8 ; + + id_timescale = 1, 0, 0, 0 ; + + Dead_Time = _, 10, 10, 10 ; + + Dead_Time_Corr_Type = _, 0, 0, 0 ; + + Acquisition_Mode = 0, 1, 1, 1 ; + + Trigger_Delay = 50, 0, 0, 0 ; + + LR_Input = 1,_,_,_ ; + + DAQ_Range = 100,_,_,_ ; + + Laser_Pointing_Angle_of_Profiles = + 0, 0, + 0, 0, + 0, 0, + 0, 0, + 0, 0, + _, 0, + _, 0, + _, 0, + _, 0, + _, 0 ; + + + Raw_Data_Start_Time = + 0, 0, + 60, 30, + 120, 60, + 180, 90, + 240, 120, + _, 150, + _, 180, + _, 210, + _, 240, + _, 270 ; + + Raw_Data_Stop_Time = + 60, 30, + 120, 60, + 180, 90, + 240, 120, + 300, 150, + _, 180, + _, 210, + _, 240, + _, 270, + _, 300 ; + + + Raw_Bck_Start_Time = + 0, 0, + 60, 30, + 120, 60, + _, 90, + _, 120, + _, 150; + + + Raw_Bck_Stop_Time = + 60, 30, + 120, 60, + 180, 90, + _, 120, + _, 150, + _, 180 ; + + + Laser_Shots = + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _ ; + + + Raw_Lidar_Data = ... + + Background_Profile = ... + +The name of the input file should have the following format: + +:: + + Measurement_ID.nc + +| so in the example the filename should be 20090130cc00.nc. +   +Please keep in mind that in case you submit a file like the previous +one all the parameters present in it will be used by the SCC even if +you have different values for the same parameters within the SCC\_DB. +If you want to use the values already stored in SCC\_DB (this should +be the usual way to use SCC) the *Raw Lidar Data* input file has to be +modified as follows: + +:: + + dimensions: + points = 5000 ; + channels = 4 ; + time = UNLIMITED ; // (10 currently) + nb_of_time_scales = 2 ; + scan_angles = 1 ; + time_bck = 6 ; + variables: + int channel_ID(channels) ; + double Laser_Pointing_Angle(scan_angles) ; + double Background_Low(channels) ; + double Background_High(channels) ; + int Molecular_Calc ; + double Pressure_at_Lidar_Station ; + double Temperature_at_Lidar_Station ; + int id_timescale(channels) ; + int Laser_Pointing_Angle_of_Profiles(time, nb_of_time_scales) ; + int Raw_Data_Start_Time(time, nb_of_time_scales) ; + int Raw_Data_Stop_Time(time, nb_of_time_scales) ; + int Raw_Bck_Start_Time(time_bck, nb_of_time_scales) ; + int Raw_Bck_Stop_Time(time_bck, nb_of_time_scales) ; + int LR_Input(channels) ; + int Laser_Shots(time, channels) ; + double Raw_Lidar_Data(time, channels, points) ; + double Background_Profile(time_bck, channels, points) ; + double DAQ_Range(channels) ; + + // global attributes: + :Measurement_ID = "20090130cc00" ; + :RawData_Start_Date = "20090130" ; + :RawData_Start_Time_UT = "000001" ; + :RawData_Stop_Time_UT = "000501" ; + :RawBck_Start_Date = "20090129" ; + :RawBck_Start_Time_UT = "235001" ; + :RawBck_Stop_Time_UT = "235301" ; + + data: + + channel_ID = 7, 5, 6, 8 ; + + Laser_Pointing_Angle = 5 ; + + Background_Low = 0, 30000, 30000, 30000 ; + + Background_High = 500, 50000, 50000, 50000 ; + + Molecular_Calc = 0 ; + + Pressure_at_Lidar_Station = 1010 ; + + Temperature_at_Lidar_Station = 19.8 ; + + id_timescale = 1, 0, 0, 0 ; + + LR_Input = 1,_,_,_ ; + + DAQ_Range = 100,_,_,_ ; + + Laser_Pointing_Angle_of_Profiles = + 0, 0, + 0, 0, + 0, 0, + 0, 0, + 0, 0, + _, 0, + _, 0, + _, 0, + _, 0, + _, 0 ; + + + Raw_Data_Start_Time = + 0, 0, + 60, 30, + 120, 60, + 180, 90, + 240, 120, + _, 150, + _, 180, + _, 210, + _, 240, + _, 270 ; + + Raw_Data_Stop_Time = + 60, 30, + 120, 60, + 180, 90, + 240, 120, + 300, 150, + _, 180, + _, 210, + _, 240, + _, 270, + _, 300 ; + + + Raw_Bck_Start_Time = + 0, 0, + 60, 30, + 120, 60, + _, 90, + _, 120, + _, 150; + + + Raw_Bck_Stop_Time = + 60, 30, + 120, 60, + 180, 90, + _, 120, + _, 150, + _, 180 ; + + + Laser_Shots = + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, 3000, 3000, 3000, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _, + 1500, _, _, _ ; + + + Raw_Lidar_Data = ... + + Background_Profile = ... + +This example file contains the minimum collection of mandatory +information that has to be found within the *Raw Lidar Data* input file. +If it is really necessary, the user can decide to add to these mandatory +parameters any number of additional parameters considered in the +previous example. + +Finally, suppose we want to make the following changes with respect to +the previous example: + +#. use a sounding file for molecular density calculation instead of “US + Standar Atmosphere 1976” + +#. supply a lidar ratio profile to use in elastic backscatter retrieval + instead of a fixed value + +#. provide a overlap function for overlap correction + +In this case we have to generate the following NetCDF additional files: + +- | ``rs_20090130cc00.nc`` + | The name of *Sounding Data* file has to be computed as follows: + | ``"rs_"``\ +\ ``Measurement_ID`` + | The structure of this file is summarized in table 2 of the pdf. + +- | ``ov_20090130cc00.nc`` + | The name of *Overlap* file has to be computed as follows: + | ``"ov_"``\ +\ ``Measurement_ID`` + | The structure of this file is summarized in table 3 of the pdf. + +- | ``lr_20090130cc00.nc`` + | The name of *Lidar Ratio* file has to be computed as follows: + | ``"lr_"``\ +\ ``Measurement_ID`` + | The structure of this file is summarized in table 4 of the pdf. + +Moreover we need to apply the following changes to the *Raw Lidar Data* +input file: + +#. Change the value of the variable ``Molecular_Calc`` as follows: + + :: + + Molecular_Calc = 1 ; + + Of course the variables ``Pressure_at_Lidar_Station`` and + ``Temperature_at_Lidar_Station`` are not necessary anymore. + +#. Change the values of the array ``LR_Input`` as follows: + + :: + + LR_Input = 0,_,_,_ ; + +#. Add the global attribute ``Sounding_File_Name`` + + :: + + Sounding_File_Name = "rs_20090130cc00.nc" ; + +#. Add the global attribute ``LR_File_Name`` + + :: + + LR_File_Name = "lr_20090130cc00.nc" ; + +#. Add the global attribute ``Overlap_File_Name`` + + :: + + Overlap_File_Name = "ov_20090130cc00.nc" ; +