- -

The SCC netCDF file format¶

Rationale¶

The Single Calculus Chain (SCC) is composed by two different modules:

pre-processing module ( scc_preprocessing)
optical processing module ( ELDA)

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 the -present the SCC can handle four different types of input files:

Raw Lidar Data
Sounding Data
Overlap
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 explanation 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. -Every comments or suggestions regarding this document can be sent to -Giuseppe D’Amico by e-mail at damico@imaa.cnr.it

This document is available for downloading at www.earlinetasos.org

In table tab:rawdata is reported 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.

In table tab:sounding, tab:overlap and tab:lr are reported 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	\(30^{th}\) 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 -

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 -

607 \(N_2\) 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:math:^mathrmth January 2009.

Dimensions¶

Looking at table tab:rawdata 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	\(\rightarrow\) is the time-series of 1064 nm
Raw_Lidar_Data(time,1,points	\(\rightarrow\) is the time-series of 532 cross
Raw_Lidar_Data(time,2,points	\(\rightarrow\) is the time-series of 532 parallel
Raw_Lidar_Data(time,3,points	\(\rightarrow\) 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	\(\rightarrow\) dark time-series at 1064 nm
Background_Profile(time_bck,1,points	\(\rightarrow\) dark time-series at 532 cross
Background_Profile(time_bck,2,points	\(\rightarrow\) dark time-series at 532 parallel
Background_Profile(time_bck,3,points	\(\rightarrow\) 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	\(\rightarrow\) channel ID=7
532 cross	\(\rightarrow\) channel ID=5
532 parallel	\(\rightarrow\) channel ID=6
607 nm	\(\rightarrow\) 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 \(\alpha\) is the scan angle used -and \(\Delta z\) is the range resolution the vertical -resolution is calculated as \(\Delta -z'=\Delta z \cos\alpha\). This array has to be filled with -\(\Delta z\) and not with \(\Delta z'\). 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 ;
-

-

ID_Range(channels)

This optional array defines if a particular channel is configured as -high, low or ultranear range channel. In particular a value 0 -indicates a low range channel, a value 1 a high range channel and a -value of 2 an ultranear range channel. If for a particular channel -you don’t separate between high and low range channel, please set the -corresponding value to 1. This information can be also taken from -SCC_DB. In our case we have to set:

ID_Range = 1, 1, 1, 1 ;
-

-

Scattering_Mechanism(channels)

This optional array defines the scattering mechanism involved in -each lidar channel. In particular the following values are adopted:

- ---- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

0	\(\rightarrow\) Total elastic backscatter
1	\(\rightarrow\) \(N_2\) vibrational Raman backscatter
2	\(\rightarrow\) Cross polarization elastic backscatter
3	\(\rightarrow\) Parallel polarization elastic backscatter
4	\(\rightarrow\) \(H_2O\) vibrational Raman backscatter
5	\(\rightarrow\) Rotational Raman Stokes line close to elastic line
6	\(\rightarrow\) Rotational Raman Stokes line far from elastic line
7	\(\rightarrow\) Rotational Raman anti-Stokes line close to elastic line
8	\(\rightarrow\) Rotational Raman anti-Stokes line far from elastic line
9	\(\rightarrow\) Rotational Raman Stokes and anti-Stokes lines close to elastic line
10	\(\rightarrow\) Rotational Raman Stokes and anti-Stokes lines far from elastic line

This information can be also taken from SCC_DB. In our example we have:

Scattering_Mechanism = 0, 2, 3, 1 ;
-

-

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 tab:sounding). 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 ;
-

-

Depolarization_Factor(channels)

This array is required only for lidar systems that use the two -depolarization channels for the backscatter retrieval. It represents -the factor \(f\) to calculate the total backscatter signal -\(S_t\) combining its cross \(S_c\) and parallel -\(S_p\) components: \(S_t=S_p+fS_c\). This factor is -mandatory only for systems acquiring \(S_c\) and \(S_p\) -and not \(S_t\). For systems acquiring \(S_c\), -\(S_p\) and \(S_t\) this factor is optional and it will -be used only for depolarizaton ratio calculation. Moreover only the -values of the array corresponding to cross polarization channels will -be considered; all other values will be not taken into account and -should be set to undefined value. In our example for the wavelength -532nm we have only the cross and the parallel components and not the -total one. So we have to give the value of this factor only in -correspondence of the 532nm cross polarization channel that -corresponds to the channel index 1. Suppose that this factor is 0.88. -Moreover, because we don’t have any other depolarization channels we -have also to set all other values of the array to undefined value.

Depolarization_Factor = _,0.88,_,_ ;
-

-

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 tab:lr). 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 ID_Range(channels) ;
-        int Scattering_Mechanism(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 ;
-
- ID_Range = 1, 1, 1, 1 ;
-
- Scattering_Mechanism = 0, 2, 3, 1 ;
-
- 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 = ...

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 tab:sounding.
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 tab:overlap.
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 tab:lr.

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" ;
-

-

- - -

The SCC netCDF file format
- Rationale
- Example
  - Dimensions
  - Variables
  - Global attributes
  -
- Example of file (CDL format)
-

- -

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- - - -

Emission wavelength=532nm -	Detection wavelength=607nm -
Time resolution=60s -	Number of laser shots=3000 -
Number of bins=5000 -	Detection mode=photoncounting -
Range resolution=15m -

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