Variables and dimensions in attenuated backscatter files - DA10

DA10 User Guide

Document code
M212895EN
Revision
D
ft:locale
en-US
Product
DA10
Document type
User guide

The following tables list the DA10 netCDF dimensions and variables in the attenuated backscatter (ABS) files. For the full list of attributes, types, and dimensions associated with each variable, see the example file in the appendix.

The dimensions and variables are listed in alphabetical order. The order in output files depends on the software used.
Table 1. NetCDF dimensions in attenuated backscatter files
Dimension Description
layer 1 Vector that gives the number of the observed cloud layer, ordered from lowest to highest with length 5.
module Vector for the 2 measurement units ordered from the near-range measurement unit to the far-range measurement unit, with length 2.
range

Range grid vector with a resolution of 4.8 m (15 ft 9 in) and a length of 3741.

Starts at 48 m (157 feet) and ends at 18 000 m (59 000 ft).

time Temporal grid of the measurements, length unlimited.
Table 2. Variables in attenuated backscatter files
Variable Attribute Value/Description
airplane_filter_max_range 2 airplane_filter_max_range:units

m, ft

airplane_filter_max_range:long_name

Airplane filter max. range.

airplane_filter_max_range:comment

Maximum range where airplane echoes are filtered to prevent false cloud detection.

azimuth_angle 2 azimuth_angle:units

Degrees

azimuth_angle:long_name

Measurement azimuth angle

azimuth_angle:standard_name sensor_azimuth_angle
azimuth_angle:comment

Azimuth direction of tilted beam for each optics unit, clockwise positive from north.

beta_att

beta_att:units

1/(m*sr)

beta_att:long_name

Attenuated volume backscatter coefficient

beta_att:coordinates Time range longitude latitude
beta_att:averaging_time_in_seconds 5
beta_att_noise_level 2 beta_att_noise_level:long_name

Noise level of the attenuated volume backscatter coefficient.

beta_att_noise_level:comment Unitless number describing the noise level.
beta_att_sum 2 beta_att_sum:units

1/(10^4*sr)

beta_att_sum:long_name

Scaled integral of the attenuated volume backscatter coefficient

cloud_base_heights 2 cloud_base_heights:units

m, ft

cloud_base_heights:long_name

Heights (range) of the detected cloud bases

cloud_base_heights:coordinates Time layer longitude latitude
cloud_base_heights:comment Reported in vertical, or in the instrument beam direction, depending on tilt_correction setting
cloud_calibration_factor 2 cloud_calibration_factor:long_name

Factory cloud calibration value.

cloud_calibration_factor:comment

Instrument-specific beta_att calibration value measured at the factory.

cloud_calibration_factor_user 2 cloud_calibration_factor_user:long_name

User set cloud calibration value.

cloud_calibration_factor_user:comment

Instrument-specific beta_att calibration value set by the user, same as the factory value by default.

cloud_penetration_depth2 cloud_penetration_depth:units

m, ft

cloud_penetration_depth:long_name

Cloud penetration depth in the direction of the instrument beam

cloud_penetration_depth:coordinates Time layer longitude latitude
cloud_penetration_depth:comment Reported in the instrument beam direction
cloud_thickness2 cloud_thickness:units

m, ft

cloud_thickness:long_name

Cloud thickness in the direction of the instrument beam

cloud_thickness:coordinates Time layer longitude latitude
cloud_thickness:comment Reported in the instrument beam direction

elevation

elevation:units

m

Always in meters

elevation:long_name

Ground-level altitude

elevation:standard_name ground_level_altitude
elevation:comment

Measurement site height above or below a fixed reference point, most commonly mean sea level

fog_detection 2 fog_detection:long_name

Detection of fog

fog_detection:coordinates Time longitude latitude
fog_detection:comment
  • 1 = detected
  • 0 = not detected

height_offset

height_offset:units

m

Always in meters

height_offset:positive Up
height_offset:long_name

Instrument height offset to ground level.

height_offset:comment

Instrument height offset relative to ground level, for example, when the instrument is placed on a roof of a building or below the ground level; the offset is added to the cloud base height results

latitude

latitude:units

Degrees north

latitude:long_name

Latitude

latitude:standard_name latitude
layer 2 layer:units

Layer

layer:long_name

Cloud layer

layer:comment 1 ... 5: observed cloud layer or cloud base

longitude

longitude:units

Degrees east

longitude:long_name

Longitude

longitude:standard_name longitude

merging_region

merging_region:units

m, ft

merging_region:long_name

Merging region from near range to far range.

merging_region:comment

Region where transition from near-range measurement to far-range measurement occurs.

module

module:long_name

Measurement unit

module:comment
  • 1 = near-range measurement unit
  • 2 = far-range measurement unit
overlap_function 2 overlap_function:long_name

Instrument-specific overlap function.

overlap_function:comment

The part of the transmitted power that hits the receiver detector, as a function of distance, normalized to be unity at the distance of the best focus.

precipitation_detection 2 precipitation_detection:long_name

Detection of ground reaching precipitation

precipitation_detection:coordinates Time longitude latitude
precipitation_detection:comment
  • 1 = detected
  • 0 = not detected

range

range:units

m, ft

range:long_name

Measurement range

range:axis Z
range:positive Up
range:comment Measurement distance from the instrument in the direction of the transmitted laser beam

range_resolution

range_resolution:units

m, ft

range_resolution:long_name

Range resolution.

range_resolution:comment

Distance between consecutive profile elements in the direction of the transmitted laser beam.

receiver_gain receiver_gain:long_name

Receiver gain status

receiver_gain:comment

Value 1 corresponds to nominal gain

sky_condition_cloud_layer_covers2 sky_condition_cloud_layer_covers:units

Oktas

sky_condition_cloud_layer_covers:long_name

Cloud cover per cloud layer

sky_condition_cloud_layer_covers:coordinates Time layer longitude latitude
sky_condition_cloud_layer_covers:averaging_time_in_seconds 1800
sky_condition_cloud_layer_covers:comment

Amount of cloud cover for different cloud layers for up to 5 layers

sky_condition_cloud_layer_heights2 sky_condition_cloud_layer_heights:units

m, ft

sky_condition_cloud_layer_heights:long_name

Cloud layer heights

sky_condition_cloud_layer_heights:coordinates Time layer longitude latitude
sky_condition_cloud_layer_heights:averaging_time_in_seconds 1800
sky_condition_cloud_layer_heights:comment

Heights for different cloud layers for up to 5 layers, reported in vertical, or in the instrument beam direction, depending on tilt_correction setting

sky_condition_total_cloud_cover2 sky_condition_total_cloud_cover:units

Oktas

sky_condition_total_cloud_cover:long_name

Total cloud cover

sky_condition_total_cloud_cover:comment

Total amount of cloud cover aggregated across cloud layers.

sky_condition_total_cloud_cover:coordinates Time longitude latitude
sky_condition_total_cloud_cover:averaging_time_in_seconds 1800
tilt_angle 2 tilt_angle:units

Degrees

tilt_angle:long_name

Optics unit tilt angle from the vertical

tilt_angle:standard_name zenith_angle
tilt_correction 2 tilt_correction:long_name

Tilt correction

tilt_correction:comment

When correction is on, cloud bases are reported in vertical direction; when correction is off, in beam direction.

  • 1 = on
  • 0 = off

time

time:units

Seconds since 1970-01-01 00:00:00.000

time:long_name

UTC time

time:axis T
time:standard_name time
time:cf_role profile_id
time:comment

End of the averaging period

vertical_visibility2 vertical_visibility:units

m, ft

vertical_visibility:long_name

Vertical visibility

vertical_visibility:coordinates Time longitude latitude
vertical_visibility:comment Reported in the instrument beam direction
Table 3. Variables, group monitoring
Variable Attribute Description
laser_power_percent laser_power_percent:units

Percent

Point measurement of the laser output power, with a PIN photodiode at CLL board.

laser_power_percent:comment Laser output power relative to the laser power measured at factory.
laser_power_percent:long_name Laser power percent
time time:units

Seconds since 1970-01-01 00:00:00.000

The timestamp of the monitoring values. Common reporting frequency with profiles.

time:long_name Time
time:axis T
time:standard_time time
window_condition window_condition:units Percent
window_condition:long_name Window condition (near-range measurement unit)
window_condition:comment

0–100 %

  • 100 = Clean window
  • 0 = Dirty window
1 The value for this dimension is not reported in software release 2.0.
2 The value for this variable is not reported in software release 2.0. The netCDF shows value -99 for the following variables: cloud_base_heights, cloud_penetration_depth, cloud_thickness, sky_condition_cloud_layer_covers, sky_condition_cloud_layer_heights, sky_condition_total_cloud_cover, and vertical_visibility. The netCDF shows value -999 for the following variables: airplane_filter_max_range, fog_detection, layer, precipitation_detection, and tilt_correction. The netCDF shows value -999.0 for the following variables: azimuth_angle, beta_att_noise_level, beta_att_sum, cloud_calibration_factor, cloud_calibration_factor_user, and overlap_function, and tilt_angle.