### 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 |