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) |
| time_bnds | time bounds | time, bnds | days since -4713-11-24 12:00 UTC (proleptic_gregorian calendar) |
| zfull | altitude of model full-levels | time, level | m |
simulate
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) |
| time_bnds | time bounds | time, bnds | days since -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.
Simulated lidar output contains an additional dimension column.
| Variable | Description | Dimensions | Units |
|---|---|---|---|
| backscatter | total attenuated volume backscattering coefficient | time, level, [column] | m-1.sr-1 |
| backscatter_sd | total attenuated volume backscattering coefficient standard deviation | time, level | m-1.sr-1 |
| cbh | cloud base height | time, [column] | m |
| cloud_mask | cloud mask | time, level, [column] | 1 |
| lr | lidar ratio | time, [column] | sr |
| time | time | time | days since -4713-11-24 12:00 UTC (proleptic_gregorian calendar) |
| time_bnds | time bounds | time, bnds | days since -4713-11-24 12:00 UTC (proleptic_gregorian calendar) |
| zfull | altitude of full-levels | level | m |
stats
alcf stats output contains histograms and summary statistics calculated
from a 2-dimensional “curtain” of observed or simulated backscatter.
Simulated lidar statistics contain an additional dimension column.
| Variable | Description | Dimensions | Units |
|---|---|---|---|
| backscatter_avg | total attenuated volume backscattering coefficient average | zfull, [column] | 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, [column] | 1 |
| backscatter_mol_avg | total attenuated molecular volume backscattering coefficient average | zfull, [column] | 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, [column] | 1 |
| backscatter_sd_z | total attenuated volume backscattering coefficient standard deviation height above reference ellipsoid | m | |
| cbh | cloud base height | zfull, [column] | % |
| cl | cloud area fraction | zfull, [column] | % |
| clt | total cloud fraction | [column] | % |
| n | number of profiles | [column] | 1 |
| time_total | total time | [column] | s |
| zfull | altitude of model full-levels | zfull | m |