ALCF

Automatic Lidar and Ceilometer
Framework

Documentation

ALCF output

The ALCF output is stored in NetCDF files. Below is a description of variables contained in the data files. Variable names follow the CMIP5 standard output. Time is stored as Julian date (fractional number of days since -4712-01-01 12:00 UTC, or -4713-11-24 12:00 UTC in the proleptic Gregorian calendar) and can be converted to Unix time (the number of non-leap seconds since 1970-01-01 00:00 UTC) with the formula (time - 2440587.5)*86400.

model

alcf model output is a 2-dimensional “curtain” of model data at a given location over a length of time or along a ship track.

Variable Description Dimensions Units
cl cloud area fraction time, level %
cli mass fraction of cloud ice time, level 1
clw mass fraction of cloud liquid water time, level 1
lat latitude time degrees north
lon longitude time degrees east
orog surface altitude time m
pfull pressure at model full-levels time, level Pa
ps surface air pressure time Pa
ta air temperature time, level K
time time time days since -4713-11-24 12:00 UTC (proleptic_gregorian calendar)
zfull altitude of model full-levels time, level m

cosp

alcf simulate output is a 2-dimensional “curtain” of simulated backscatter at a given location over a length of time or along a ship track.

Variable Description Dimensions Units
backscatter total attenuated volume backscattering coefficient time, level, column m-1.sr-1
backscatter_mol total attenuated molecular volume backscattering coefficient time, level m-1.sr-1
lat latitude time degrees north
lon longitude time degrees east
pfull air pressure time, level Pa
time time time -4713-11-24 12:00 UTC (proleptic_gregorian calendar)
zfull height above reference ellipsoid time, level m

lidar

alcf lidar output is a 2-dimensional “curtain” of observed or simulated backscatter at a given location over a length of time or along a ship track.

Variable Description Dimensions Units
backscatter total attenuated volume backscattering coefficient time, range m-1.sr-1
backscatter_sd total attenuated volume backscattering coefficient standard deviation time, range m-1.sr-1
cbh cloud base height time m
cloud_mask cloud mask time, range 1
lr lidar ratio time sr
time time time days since -4713-11-24 12:00 UTC (proleptic_gregorian calendar)
zfull altitude of full-levels time, level m

stats

alcf stats output contains histograms and summary statistics calculated from a 2-dimensional “curtain” of observed or simulated backscatter.

Variable Description Dimensions Units
backscatter_avg total attenuated volume backscattering coefficient average zfull m-1.sr-1
backscatter_full total attenuated volume backscattering coefficient backscatter_full m-1.sr-1
backscatter_hist total attenuated volume backscattering coefficinet histogram backscatter_full, zfull %
backscatter_mol_avg total attenuated molecular volume backscattering coefficient average zfull m-1.sr-1
backscatter_sd_full total attenuated volume backscattering coefficient standard deviation backscatter_sd_full m-1.sr-1
backscatter_sd_hist total attenuated volume backscattering coefficient standard deviation histogram backscatter_sd_full %
backscatter_sd_z total attenuated volume backscattering coefficient standard deviation height above reference ellipsoid m  
cl cloud area fraction zfull %
clt total cloud fraction   %
n number of profiles   1
zfull altitude of model full-levels zfull m