cloudgrid - Cloud retrieval for image segments

SYNOPSIS

cloudgrid [ parameter=value ] [inputfile outputfile ]
cloudgrid [ parameter=value ] [inputfile ... directory ]
 
Parameters are:   ir_prefix,   cloudmaskfile,    cloudmaskname,     swap_size,    climatology,    radiation_model,   temprof_set,
                              geoprof_set,   temprof_var,    geoprof_var,     pressprof_var,    out_prefix.
 

DESCRIPTION
   cloudgrid generates cloud grids for image data segments  and  produces  output dataset variables consisting of a cloudmask and cloud amounts for various cloud levels.  Input  datasets  must contain histogram and statistics variables generated by the histograms procedure. Cloud retrieval  is  performed  utilizing  infrared  segment  statistics  data,  and  climatology,  forecast  or radiation   model geopotential/temperature profiles. Tests are performed   utilizing  segment  histograms,  comparing  these with model  temperature profiles, with model thresholds providing cutoff  values  distinguishing  altitude levels associated with temperatures. Output   variables    are    named    according    to    the   out_prefix=outprefix  name specified, which serves as a prefix, with suffixes appended as: <outprefix>_<suffix> .     Output  variable  name  suffixes  are  cloud,  cloudamount0,     cloudamount1,...  cloudamount4, thus  generating the output     variable names: <outprefix>_cloud,  <outprefix>_cloudamount,     <outprefix>_cloudamount0, <outprefix>_cloudamount1,   ...  <outprefix>_cloudamount4. The results of cloudgrid's algorithm  applied  to  the  full  range  of data segments comprises a cloudmask which is saved as variable <outprefix>_cloud . The range of values for this  cloudmask are   UNDECIDED=<badvalue>,  CLEAR=0,  CLOUDY=1. cloudgrid also produces total cloud amount  data  and  cloud  amount  data  for five levels of clouds, in terms of percent cloudiness, for each segment,  at  specified  levels.  Cloud  amounts      are      written     to     variables     named <outprefix>_cloudamount,      <outprefix>_cloudamount0,   outprefix>_cloudamount1,...    <outprefix>_cloudamount4. Cloudiness percentages are compiled from segment  histograms     by  identifying  the  temperatures  at  relevent atmospheric levels delimiting cloud  types,  and  integrating  histogram   values  between  those temperatures; the ratio of counts per temperature  interval  to  the  integrated  total  histogram   counts  provides  a  ratio which is the fraction of coverage for that temperature interval/cloud-level type. The association  of  temperatures  with  atmospheric pressure levels is implemented with a climatology, forecast, or radiation_model     dataset providing temperature, pressure and height profiles.
 

PARAMETERS

 ir_prefix Prefix for input infrared segment  statistics  variable   names. Segment  statistics  data is distributed across   several dataset variables, and a dataset  usually  contains  segment  statistics for several image data channels. The prefix name serves to identify the subset  of   segment statistics variables associated with a specific   image data channel, in this case the infrared (temperature)  data.   Relevent dataset variable names targeted by this prefix are named <prefix>_<suffix>. No default.

cloudmaskfile OPTIONAL. Name of dataset  containing  cloud  mask  for   data segments. The default is cloudmaskfile="".

cloudmaskname OPTIONAL. This parameter is irrelevent when  cloudmaskfile="" (default) was specified. Name of variable containing cloud mask in dataset defined by cloudmaskfile. The default is cloudmaskname="".
swap_size Number of data lines defining the output/input swapping   stride.   Larger  swap_size values require more memory, but less swapping  (faster).   This  parameter  permits   handling  large  input histograms for large grids. The   default is swap_size=10 .
climatology Parameter to  enable  using  climatology  profiles  for  cloud  top height determination.  The default climatology dataset (provided by TeraScan in $REFDATA/climate/geopclim.tdf, tempclim.tdf) contains 12 months of monthly averaged  profiles. These profiles were derived from the NCEP/NCAR Reanalysis.          -NCAR website:    http://www.scd.ucar.edu/dss/pub/reanalysis/index.html
                      -Bull. Am. Met. Soc. 1996, (77) 437-471, "NCEP/NCAR 40 year Reanalysis Project",  Kolmay et. al. The  alternative  is to use (a) time specific forecast or radiation model profile dataset(s). The default is climatology="no"

radiation_model Parameter to enable/disable use of radiation model temperature  profile dataset.  The alternative is to use a   forecast  model. This  parameter  is   irrelevent   if   climatology=yes   was   specified. The   default   is   radiation_model="no" .

temprof_set Name of dataset containing  temperature  profile  variable.  This  parameter  is irrelevent if climatology=yes   was specified. The default is temprof_set="" .
geoprof_set Name of dataset containing geopotential  profile  variable.     This  parameter     is    irrelevent    if   climatology=yes  was  specified. The  default  is   geoprof_set="" .
temprof_var Name of temperature profile variable. This parameter is   irrelevent   if   climatology=yes  was  specified. The   default is temprof_var="" .

pressprof_var Name of pressure profile variable. This parameter is   irrelevent   if   climatology=yes  was  specified. The   default is pressprof_var="" .
geoprof_var Name of geopotential profile variable.  This  parameter   is  irrelevent  if  climatology=yes  was specified. The default is temprof_var="" .

out_prefix OPTIONAL.  Specifies  prefix  out_prefix=outprefix  for   output  cloudmask and cloudamount variable names designated for the output  dataset. The  output  dataset(s)   will  contain  variables  with names <outprefix>_cloud,   <outprefix>_cloudamount,  outprefix>_cloudamount1, <outprefix>_cloudamount2,      ...,   <outprefix>_cloudamount4. The default is out_prefix=""    .
 
 

EXAMPLES

This  example  processes  input  statistics  prefixed   with     "gvar_ch4"  for infrared channels respectively, contained in
input dataset histest.tdf.  Notice that the output dataset     clouds.tdf  contains  variables  whose names have the prefix
specified by the parameter out_prefix   (default = "").
  
     % cloudgrid
     in/out files   : char(255) ? histest.tdf clouds.tdf
     ir_prefix      : char(255) ? gvar_ch4
     swap_size      : int       ? [10]
     climatology    : char(  3) ? [no] yes
     out_prefix     : char(255) ? [] segment
     % contents clouds.tdf
     printout       : char(  3) ? [no]
     Dimension         Size    Coord         Scale      Offset    Variable
      line                50    y                1           0
      sample              80    x                1           0
     Attribute       Type            Units           Value
      minlat          double                          25
      maxlat          double                          50
      minlon          double                          -140
      maxlon          double                          -100
      projection      long            std_projection  rectangular
      et_affine       double                          -0.0183284 0 0 0.0229496 25.5 40.5
      center_lat      double          std_latitude    37 30.92 N
      center_lon      double          std_longitude   119 59.92 W
      map_angle       double          radians         0
      proj_param      double          std_latitude     0  0.00 N
      equator_radius  double          km              6378.14
      flattening      double                          0.00335281
      history         byte
     Variable        Type            Units
      segment_cloud long
      segment_cldamount double
      segment_cldamount0 double
      segment_cldamount1 double
      segment_cldamount2 double
      segment_cldamount3 double
      segment_cldamount4 double
     Variable        Dimension       Size
      segment_cloud line              50
      segment_cloud sample            80
      segment_cldamount line              50
      segment_cldamount sample            80
      segment_cldamount0 line              50
      segment_cldamount0 sample            80
      segment_cldamount1 line              50
      segment_cldamount1 sample            80
      segment_cldamount2 line              50
      segment_cldamount2 sample            80
      segment_cldamount3 line              50
      segment_cldamount3 sample            80
      segment_cldamount4 line              50
      segment_cldamount4 sample            80
     Variable            BadValue    ValidMin    ValidMax       Scale      Offset
      segment_cloud -2.1475e+09 -2.1475e+09  2.1475e+09           1           0
      segment_cldamount -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
      segment_cldamount0 -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
      segment_cldamount1 -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
      segment_cldamount2 -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
      segment_cldamount3 -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
      segment_cldamount4 -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
     %
SEE ALSO
     histograms,  cloudprod,  cloudprodsegs

Last Update: $Date: 2000/11/20 19:00:55 $