ALCFbeta

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 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 in atmosphere layer time, level %
cli mass fraction of cloud ice in air time, level 1
clw mass fraction of cloud liquid water in air time, level 1
lat latitude time degrees north
lon longitude time degrees east
orog surface altitude time m
pfull air pressure time, level Pa
ps surface air pressure time Pa
ta air temperature time, level K
time time time days since -4712-01-01 12:00
zfull height above reference ellipsoid 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 backscatter coefficient time, level, column m-1.sr-1
backscatter_mol total attenuated molecular backscatter 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 days since -4712-01-01 12:00
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 backscatter coefficient time, range m-1.sr-1
backscatter_sd total attenuated backscatter 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 -4712-01-01 12:00
zfull height above reference ellipsoid 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 backscatter coefficient average zfull m-1.sr-1
backscatter_full total attenuated backscatter coefficient backscatter_full m-1.sr-1
backscatter_hist backscatter histogram backscatter_full, zfull %
backscatter_mol_avg total attenuated molecular backscatter coefficient average zfull m-1.sr-1
backscatter_sd_full total attenuated backscatter coefficient standard deviation backscatter_sd_full m-1.sr-1
backscatter_sd_hist total attenuated backscatter coefficient standard deviation histogram backscatter_sd_full %
backscatter_sd_z total attenuated backscatter coefficient standard deviation height above reference ellipsoid m  
cl cloud area fraction in atmosphere layer zfull %
clt cloud area fraction   %
n number of profiles   1
zfull height above reference ellipsoid zfull m