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.TH create_startf

.SH NAME 

.B create_startf - 

create starting files for Lagranto

.SH SYNOPSIS 

.B create_startf 

.I date 

.I filename 

.I specifier 

[ 

.I optional arguments 

] 

.SH DESCRIPTION

Create starting files

for a Lagranto calculation. The staring positions are based on the P and S files for 

.I date

and are as specified in a 

.I specifier.

The starting coordinates (longitude, latitude, pressure [in hPa]) are written to the file 

.I filename.

.SH PARAMETERS

.TP 15

.I date        

date of input P and S file (e.g. 20100101_00). If the date is between two P and S files, 

linear interpolation is used between the two times.

.TP 15

.I filename    

output file with starting points (e.g. startf). Different formats are supported (see 

.B reformat

for details)

.TP 15

.I specifier   

detailed description of starting positions. The specifier has the following format:

.B 

.I <horizontal> 

@ 

.I <vertical> 

@ 

.I

<unit> 

@ 

.I <selection>.

The components of the specifier are described in greater detail in the following sections.

.SH HORIZONTAL

.TP 15

.B - file[filename] 

read lat/lon from file "filename"; each line contains one lat/lon pair.

.TP 15

.B - line[lon1,lon2,lat1,lat2,n] 

n points from (lon1,la1) to (lon2,lat2); the points are linearly interpolated in lat/lon space.

.TP 15

.B - box.eqd[lon1,lon2,lat1,lat2,ds] 

lat/lon box bounded with south-western point (lon1,lat1) and north-eastern point (lon2,lat2); the equdistant points within the box have a horizontal distance ds (in [km]).

.TP 15

.B - box.grid[lon1,lon2,lat1,lat2,] 

lat/lon box with south-western point (lon1,lat1) and north-eastern point (lon2,lat2 grid points; all grid points within this box are taken as staring points.

.TP 15

.B - point[lon,lat] 

single lon/lat point.

.TP 15

.B - shift[lon,lat,dlon,dlat] 

lon/at points and dlon/dlat shifhted ones, i.e. in total five points: central one and four shifted ones: (lon,lat), (lon+dlon,lat), (lon-dlon,lat), (lon,lat+dlat), (lon,lat-dlat).

.TP 15

.B - polygon.eqd[filename,ds] 

equidistant within arbirtrary polygon (ds in [km]). The file with the polygon points has the following format: 1st line a lon/lat point within the polygon; further lines lon/lat points of the vertices (max 500) of the polygon.

.TP 15

.B - polygon.grid[filename] 

grid points within arbirtrary polygon. The file with the polygon points has the following format: 1st line a lon/lat point within the polygon; further lines lon/lat points of the vertices (max 500) of the polygon.

.TP 15

.B - circle.eqd[lonc,latc,radius,ds] 

circle with centre at (lonc,latc) and radius "radius" (in km); the equdistant points within the circle have a horizontal distance ds (in [km]).

.TP 15

.B - circle.grid[lonc,latc,radius]

circle with centre at (lonc,latc) and radius "radius" (in km); all rid points within the circle are selected.

.TP 15

.B - region.eqd[id,ds] 

Read region specification from region file ("default regionf", to be changed with option "-regionf") and fill it equidistantly with starting points (ds in km). The region identification is "id", see below in section REGION FILE.

.TP 15

.B - region.grid[id]

Read region specification from region file ("default regionf", to be changed with option "-regionf") and fill it  with starting points on the input grid. The region identification is "id", see below in section REGION FILE.

.SH VERTICAL

.TP 15

.B - file[filename] 

read levels from file "filename"; each line in the file contains one level.

.TP 15

.B - level[lev]

a single level

.TP 15

.B - list[lev1,lev2,lev3,...] 

a list of levels; if many levels are needed they are better passed to "create_startf" with the option "file[filename]".

.TP 15

.B - profile[lev1,lev2,n]  

n equdistant levels between lev1 and lev2.

.SH UNIT

.TP 15

.B - hPa

pressure (in hPa).

.TP 15

.B - hPa,agl

pressure (in hPa) above ground level.

.TP 15

.B - K

potential temperature (in K).

.TP 15

.B - PVU

potential vorticty (in PVU). Note that potential vorticity (PV) might not be unique as a vertical coordinate; if several levels have a given PV value, the highest one is chosen.

.SH SELECTION

.TP 15

.B - criterion

Selection criteria based on meteorological fields applied to the starting position; The criteria follow the syntax of the program 

.B select.

.TP 15

.B - nil

If no selection criteria should be invoked, the argument "nil" should be given.

.SH REGION FILE

Several starting regions can be defined for every case in a region file (default filename is "regionf"; to be changed with optional parameter "-regionf filename"). There are two possible formats for specifying a region (they require either a line with 5 or 9 entries): 

.TP 5

.B "regnum lonw lone lats latn" 

a regular latitude-longitude square: regnum=integer region number; lonw=westernmost longitude of starting region; lone=easternmost longitude; lats=southernmost latitude; latnNorthernmost latitude. 

.TP 5

.B "regnum lon1 lat1 lon2 lat2 lon3 lat3 lon4 lat4" 

an irregular latitude-longitude square: regnum=integer region number; lon{x},lat{x} = longitude and latitude of the x-th corner. Note that the 4 corners must be arranged counterclockwise. For a triangle the 4th corner can be specified identically to the 3rd.

.TP 5

.B Note: (1) if a line starts with '#' it is regarded as comment and not further considered; (2) each line in the region file must start with '"!

.TP 5 

.B "101 -40. -24. 52. 60.": 

region in the central Atlantic from 40 W to 24 W and 52 N to 60 N; the region identifier is 101.

.TP 5

.B "250 -30. 43. -24. 36. -18. 50.2 -35.2 50.2": 

irregular square in the central Atlantic; the region identifier is 250.

.SH OPTIONAL

.br

.TP 15

.I -t tracefile 

tracing file with variables for selection criteria (see

.B trace

for format of the file). If no file is specified, the default 

"tracevars" is used. Further, if no selection criterion is invoked, no

tracing file is necessary.

.TP 15

.I -changet

flag whether the times of the P and S files should be changed or not before a calculation; the default is that the

times are not changed. 

.TP 15

.I -noclean

flag whether parameter and criterion files should be kept; this is particularly helpfuld for debugging.

.TP 15

.I -regionf filename

change the region file from its default value "regionf" to a new file name: the syntax is "-regionf filename".

.TP 15

.I -notimecheck

take the first time on the netCDF file - do no explicit test that the requested time is available on the file. This is particularly helpful if you have no write permission for the P files.

.SH EXAMPLES

.TP 5

.B [1] create_startf 19891020_00 startf 'point(-10,50) @ list(450,500,550) @ hPa' 

Starting points are (longitude, latitude, pressure in hPa): (-10,50,450); (-10,50,500); (-10,50,550). No selection criterion is applied; the positions are written to file "startf".

.TP 5

.B [2] create_startf 19891020_00 startf 'line(-10,-5,40,50,10) @ level(450) @ hPa,agl'

10 points are equidistantly specified between lon/lat point (-10,40) and (-5,50); all trajectories start at 450 hPa above ground level - the surface pressure is taken from the primary file P19891020_00. The positions are saved in "startf".

.TP 5

.B [3] create_startf 19891020_00 startf 'box.grid(-10,-5,40,50) @ list(300,320) @ K'

All grid points in the box with the south-eastern lon/lat point (-10,40) and the north-eastern one (-5,50) are taken - the horizontal grid spacing is specfified in the primary file P19891020_00. In the vertical, two isentropic levels are chosen: 300 K and 320 K. The potential temperature for the calculation is taken from the secondary file S19891020_00.

.TP 5

.B [4] create_startf 19891020_00 startf 'shift(-10,40,1,1) @ profile(1000,200,100) @ hPa'

A profile of 100 equidistant levels between 1000 hPa and 200 hPa; in the horizontal the central lon/lat point (-10,40) is taken and four horizontally displaced ones, the diplacement being 1 degree in zonal and meridional direction. 

.TP 5

.B [5] create_startf 19891020_00 startf.1 'shift(-10,40,1,1) @ profile(1000,200,100) @ hPa'

As in the previous example [4], but the starting positions are saved as a trajectory file instead of a (lon,lat,p)-list. 

.TP 5

.B [6] create_startf 19891020_00 startf.1 criterion

As in the previous example [5], but the criterion is saved on a file with filename "criterion". 

.TP 5

.B [7] create_startf 19891020_00 startf 'polygon.grid(polygon) @ level(500) @ hPa

A polygon is specified in the file "polygon"; the different lines in the file are:  -5. 45. / -10. 40. / 10. 40. / 10  50. / -10. 45. The first lon/lat point lies within the polygon, all other lon/lat points are the vertices of the polygon. All grid points within the polygon are taken as starting point, at level 500 hPa.

.TP 5

.B [8] create_startf 19891020_00 startf 'polygon.eqd(polygon,50) @ level(500) @ hPa

As in the previous example [7], except that the starting points are distributed equidistantly within the polygon. The horizontal distance between the starting points is 50 km in zonal and meridional direction.

.TP 5

.B [9] create_startf 19891020_00 startf 'shift(-10,40,1,1) @ profile(1000,200,100) @ hPa @ GT:TH:310'

As in example [4], but a selection criterion is additionally applied: only starting positions with potential temperature (TH) greater than (GT) 310 K are kept. Potential temperature must be available on the secondary file S19891020_00 and the file "tracevars" must have a line with "TH     1.  0   S". Further examples for selection criteria can be seen in 

.B

select.

.TP 5

.B [10] create_startf 19891020_00 START.1 'region.eqd(3,10) @ level(500) @ hPa'

get equidistant starting points (10 km distance) in the region with identifier 3, as listed in the region file "regionf" (the default).

.SH AUTHOR

Written by Michael Sprenger and Heini Wernli (January 2011)