htcp

Properties of water suspended in clouds
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htcp.5 (3603B)


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      2 .\" Copyright (C) 2018 Centre National de la Recherche Scientifique
      3 .\" Copyright (C) 2018 Université Paul Sabatier
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     17 .Dd November 17, 2023
     18 .Dt HTCP 5
     19 .Os
     20 .Sh NAME
     21 .Nm htcp
     22 .Nd High-Tune: Cloud Properties
     23 .Sh DESCRIPTION
     24 .Nm
     25 is a binary file format for storing the properties of liquid water content
     26 suspended in clouds.
     27 Cloud properties are double-precision spatio-temporal floating-point values,
     28 structured in a 4D grid whose definition and origin are stored in the
     29 .Va definition
     30 and
     31 .Va lower-pos
     32 fields.
     33 The size of a grid cell along the X and Y axes is constant, whereas the size
     34 along the Z axis may be irregular.
     35 In this case, the
     36 .Va is-Z-irregular
     37 flag is set to 1 and the Z cell size is explicitly indicated in
     38 .Va voxel-size
     39 .Pq in meters .
     40 .Pp
     41 For each property, the list of its data is enumerated linearly along the X, Y,
     42 Z and time dimensions, in that order.
     43 The address where its first data is stored is aligned with the value defined by
     44 the
     45 .Va pagesize
     46 field; several padding bytes can therefore be added before a property to ensure
     47 data alignment.
     48 Padding bytes are also added at the end of the file to align its overall size
     49 with the size of a page.
     50 .Pp
     51 The stored cloud properties are as follows:
     52 .Bl -dash -offset indent -compact
     53 .It
     54 .Va RVT :
     55 water vapor mixing ratio in kg of water per m^3 of dry air.
     56 .It
     57 .Va RCT :
     58 liquid water in suspension mixing ratio in kg of water per m^3 of dry air.
     59 .It
     60 .Va PABST :
     61 pressure in Pascal.
     62 .It
     63 .Va T :
     64 temperature in Kelvin.
     65 .El
     66 .Pp
     67 Data are encoded with respect to the little endian bytes ordering, i.e. least
     68 significant bytes are stored first.
     69 .Pp
     70 The file format is as follows:
     71 .Bl -column (is-Z-irregular) (::=) ()
     72 .It Ao Va htcp Ac Ta ::= Ta Ao Va pagesize Ac Ao Va is-Z-irregular Ac
     73 .It Ta Ta Aq Va definition
     74 .It Ta Ta Aq Va lower-pos
     75 .It Ta Ta Aq Va voxel-size
     76 .It Ta Ta Aq Va padding
     77 .It Ta Ta Aq Va RVT
     78 .It Ta Ta Aq Va padding
     79 .It Ta Ta Aq Va RCT
     80 .It Ta Ta Aq Va padding
     81 .It Ta Ta Aq Va PABST
     82 .It Ta Ta Aq Va padding
     83 .It Ta Ta Aq Va T
     84 .It Ta Ta Aq Va padding
     85 .It \  Ta Ta
     86 .It Ao Va pagesize Ac Ta ::= Ta Vt uint64_t
     87 .It Ao Va is-Z-irregular Ac Ta ::= Ta Vt int8_t
     88 .It \  Ta Ta
     89 .It Ao Va definition Ac Ta ::= Ta Ao Va X Ac Ao Va Y Ac Ao Va Z Ac Ao Va time Ac
     90 .It Ao Va lower-pos Ac Ta ::= Ta Vt double double double
     91 # In m
     92 .It Ao Va voxel-size Ac Ta ::= Ta Vt double double double ...
     93 # In m
     94 .It Ao Va X Ac Ta ::= Ta Vt uint32_t
     95 .It Ao Va Y Ac Ta ::= Ta Vt uint32_t
     96 .It Ao Va Z Ac Ta ::= Ta Vt uint32_t
     97 .It Ao Va time Ac Ta ::= Ta Vt uint32_t
     98 .It \  Ta Ta
     99 .It Ao Va RVT Ac Ta ::= Ta Vt double ...
    100 .It Ao Va RCT Ac Ta ::= Ta Vt double ...
    101 .It Ao Va PABST Ac Ta ::= Ta Vt double ...
    102 .It Ao Va T Ac Ta ::= Ta Vt double ...
    103 .It Ao Va padding Ac Ta ::= Ta Op Vt int8_t ...
    104 .El
    105 .Sh SEE ALSO
    106 .Xr htrdr 1 ,
    107 .Xr les2htcp 1
    108 .Sh HISTORY
    109 The
    110 .Nm
    111 format was first developed for the
    112 .Xr htrdr 1
    113 program.