McIDAS User's Guide
Version 2010.1
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PTCON
Converts
point data to grids; displays contours and plots.
Format
PTCON dataset1
. . datasetn [keywords]
Parameters
dataset1
. . n |
ADDE
dataset names and positions; specify one of the following formats for
each dataset: |
|
|
group/descriptor.position
alias.position |
|
a position greater
than zero represents an absolute position in the dataset; a position less
than or equal to zero represents a relative position in the dataset based
on date and time, for example, 0 is the most recent and -1 is the next
most recent; the position ALL represents all positions in the
dataset (no default for group/descriptor or alias; position default=ALL
if DAY is specified with the SELECT keyword, otherwise default=0) |
Keywords
OUT= |
|
CON |
contours
the gridded data (default) |
|
|
PLOT |
plots
grid points |
|
|
SAVE ddataset |
saves
the created grid to a destination dataset |
|
|
SCON ddataset |
contours
the gridded data and saves the created grid to a destination dataset |
|
|
SPLOT ddataset |
plots
grid points and saves the created grid to a destination dataset; see
the Remarks |
PARam= |
parameter
to contour; specify a native parameter, a computed parameter or one of
the four predefined parameters as listed below: |
|
|
native_parameter [unit] |
|
|
|
native
parameter to contour and its output units; native parameters are those
that are stored in the point file (no default for parameter; unit default=from dataset) |
|
|
'computed_parameter [unit]=expression' |
|
|
|
computed
parameter to contour, its output units, and the mathematical expression
used to compute it; computed parameters do not exist in the point file
but are derived with the specified mathematical expression containing
math operators (+ - * etc.) and the native parameters specified in the
Pn keywords, e.g., PAR='TDD[F]=P1-P2'; see the Remarks and the Pn keyword
description for more information (no default for parameter or expression; unit default=from dataset) |
|
|
MOVIE |
draws
streamlines with colored line segments that can be animated using the
CM command |
|
|
STREAML |
draws
streamlines using u- and v-component grids |
|
|
WINDB |
plots
wind barbs using u- and v-component grids |
|
|
WINDV |
plots
wind vectors using u- and v-component grids |
SELect= |
'clause1; clause2;
. . ; clausen'
finds only the data matching the values in the select clauses; single
quotes are mandatory; separate select clauses with semicolons; specify clause as
a range or a list using one of the following formats: |
|
|
range:
list: |
parameter [unit] bval
eval
parameter [unit] val1,val2,
. . ,valn |
|
|
parameter |
point
file parameter |
|
|
[unit] |
units
for the parameter values; units are optional but must be in square brackets
if specified; see the Remarks (default=from dataset) |
|
|
bval eval |
range
of parameter values; see the Remarks |
|
|
val1, . . ,valn |
list
of parameter values |
Mathematical Operations Keywords
Pn= |
parameter [unit]
'clause1; clause2; ..; clausen'
native parameters to use in the math expression specified in the PARAM
keyword; use a number between 1 and 99 in the keyword name (P1,P2,..,P99);
each keyword specifies a single native parameter and units to substitute
in matching Pn values in the math expression, where: |
|
|
parameter [unit]
is the native parameter name and units; unit defaults to those
for the parameter in the dataset; there is no default for parameter |
|
|
'clause1; clause2;
..; clausen'
are the clauses used to select data for this keyword; only data matching
their criteria is used; they are specified exactly as in the SELECT keyword;
the Pn keywords inherit the clauses specified in the SELECT keyword,
therefore, you should specify a Pn keyword clause only if a value differs
from that in the SELECT keyword or you need to add additional clauses;
for example, to set the values of P1 and P2 to the 850 and 1000 mb temperatures
in degrees Celsius at 0 UTC, respectively, specify the following keywords:
SEL='TIME 0; P 850' P1=T[C] P2=T[C] 'P 1000' |
GINFO= |
level
lunit day time src fhour
values to assign to the header of the computed parameter grid created
with the PARAM and Pn keywords, where: |
|
|
level |
grid
level |
|
|
lunit |
grid
level units; 2 character maximum |
|
|
day |
grid
day (default=value specified for DAY in the SELECT keyword; otherwise,
default=today) |
|
|
time |
grid
time (default=value specified for TIME in the SELECT keyword; otherwise,
default=22:22:22) |
|
|
src |
grid
source (default=MDX) |
|
|
fhour |
grid
forecast hour (default=0) |
Navigation Keywords
LAT= |
lat1
lat2 |
latitudes
of the points at the lower-right and upper-left corners of the map; you
cannot use LAT with the NAV or MAP keyword |
LON= |
lon1
lon2 |
longitudes
of the points at the lower-right and upper-left corners of the map; you
cannot use LON with the NAV or MAP keyword |
MAP= |
map
for the contour or plot; see the MAP command for a list of valid predefined
maps, for example, MID, USA, WORL; you cannot use MAP with the NAV, LAT
or LON keyword |
MCOlor= |
graphics
color level of the map (default=1) |
NAV= |
num |
frame
to use for navigation |
|
C |
use
the current frame's navigation |
|
the
plot is drawn using the navigation of the specified frame; no map is
drawn; you cannot use NAV with the MAP, LAT or LON keyword |
PRO= |
CONF |
polar
stereographic or Lambert conformal projection |
|
MERC |
Mercator
projection (default) |
SLAt= |
lat1
lat2 |
standard
latitudes for a CONF projection; two values for a general Lambert conformal
projection; one value for a polar stereographic projection (default=60
60 for northern hemisphere maps defined with the LAT and LON, or MAP
keywords; -60 -60 for southern hemisphere maps defined with the LAT and
LON, or MAP keywords) |
SLOn= |
standard
longitude for a CONF projection (default=computed) |
Contour and Plot Keywords
COLor= |
graphics
color level (default=2 for contour, 3 for plot) |
ELE= |
bele
eele |
beginning
and ending frame elements for output; specify MAX for maximum element
number (default=1 MAX when using the NAV keyword; default=20 MAX-20 when
using the MAP keyword) |
FORMAT= |
designator 'text'
output
format for the grid point values or contour labels, and associated text;
valid formats are I, F, or E; see the Remarks (designator default=from dataset;
no text default) |
GRA= |
graphics
frame for the display (default=current) |
LABel= |
'text' col
line ele size
text,
color, location and size for the contour or plot title |
|
|
'text' |
72
characters maximum; specify X without quotes for the default title (default=computed) |
|
|
col |
graphics
color level of the title (default=1 if PARAM=MOVIE, otherwise default=value
from the COLOR keyword) |
|
|
line |
beginning
TV line to write the title (default=below contour or plot) |
|
|
ele |
beginning
TV element to write the title (default=below contour or plot) |
|
|
size |
height
of the title text in pixels (default=8) |
LINE= |
blin
elin |
beginning
and ending frame lines for output; specify MAX for maximum line number
(default=1 MAX-57 when using the NAV keyword; default=20 MAX-57 when
using the MAP keyword) |
LSIze= |
height, in pixels, of the plot characters or contour labels; the range is 0-50 where 0 omits the labels (default=8) |
POWer= |
power
of 10 to multiply the grid point values by for display (default=0) |
TDAy= |
CAL |
display
calendar day on the default title; not valid if the ELE, LINE or PAN
keyword is used |
|
JUL |
display
the Julian day on the default title (default) |
Contour-Specific Keywords
CINt= |
num |
contour
interval; specify 0 to let PTCON compute a reasonable interval; specify
your own interval as an integer or decimal value greater than zero; see
the Remarks for the default value |
|
string |
contour
values; specify a string name that contains up to 64 values; e.g., CINT=SNOWDEPTH
will draw contours at the values specified in the string named SNOWDEPTH |
DASh= |
ALL |
dash
all contours |
|
NEG |
dash
negative contours only |
|
POS |
dash
positive contours only (default=solid contours) |
LINT= |
contour
label interval (default=1, meaning label every contour) |
MOVie= |
bcol
ecol bspd espd blen elen
change
the defaults for the PARAM=MOVIE output |
|
|
bcol |
beginning
graphics color level for line segments (default=2) |
|
|
ecol |
ending
graphics color level for line segments (default=maximum color level) |
|
|
bspd |
beginning
wind speed represented by blen, units are from the created grid
(default=computed) |
|
|
espd |
ending
wind speed represented by elen, units are from the created grid
(default=computed) |
|
|
blen |
beginning
length of line segments (default=2) |
|
|
elen |
ending
length of line segments (default=40) |
SMOoth= |
contour
smoothing factor; the range is 0 through 50; not valid with PARAM=MOVIE
or PARAM=STREAML; larger numbers produce smoother contours (default=20) |
Plot-Specific Keyword
PINt= |
row
col |
row
and column intervals of grid points to plot with OUT=PLOT, PARAM=WINDB
or PARAM=WINDV; for example, PINT=4 3 plots every fourth grid point in
the row direction and every third grid point in the column direction
(row default=1; col default=row) |
Grid Conversion Keywords
BPAr= |
smoothing
factor for the conversion of point data to grids; a larger number results
in a data point influencing a greater number of grid points, and the
generation of a smoother grid; BPAR is related to the Barnes parameter
used in the grid analysis; the suggested range is 5 to 500 (default=40) |
DISt= |
distance
in grid points to extrapolate into areas without data; the range is 1
to 25; grid points beyond the specified distance are assigned missing
value codes and therefore are not contoured; the results will vary for
a given value depending on data density, grid spacing and smoothing (default=10) |
LLInc= |
latinc
loninc |
latitudinal
and longitudinal incremements, in degrees, between the grid points in
the grid that PTCON creates; use this keyword to control the smoothing
and extents of the output contours (latinc default=1 if the
grid is 10° or more in the latitudinal and longitudinal directions, latinc default=computed
value <1 if the grid is less than 10° in either direction, loninc default=latinc) |
Grid Output Keywords
DEL= |
YES |
delete
the destination grid file before copying |
|
NO |
do
not delete the destination grid file (default) |
DGRid= |
beginning
grid number in the destination grid file to place the copied grids; this
keyword may overwrite existing grids; see the Remarks (default=append
after the last grid in the grid file) |
GLEV= |
level
unit |
grid
level to use in the grid header and on the display (default=value entered
for LEV, THA, or P in the SELECT keyword clause; otherwise,
no default) |
MAXgrd= |
maximum
number of grids the newly created destination grid file can store; see
the Remarks (default=1000) |
TITLE= |
'text' |
title
of the newly created destination grid file; 32 characters maximum |
Text Output Keyword
BYTecount= |
YES |
lists
the number of bytes received from the server |
|
NO |
does
not list the number of bytes (default) |
Remarks
PTCON gathers
data from one or more point files in one or more datasets. The SELECT keyword
defines which records to match and the PARAM keyword defines which parameters
in the matching records to use. The selected point data is used to produce
grid data.
The grid
data may be saved, displayed, or both. The grid is saved in a Mercator projection
with the native units or in the units specified with the PARAM keyword.
You must
specify a parameter using the PARAM keyword, and a type of navigation using
the NAV, MAP, or LAT and LON keywords. If the point file contains multiple
times and/or days, you should also specify the TIME and/or DAY parameter in
a SELECT keyword clause. Otherwise, all times and/or days will be used.
To file the
correct day information in the output grid header, you must specify the DAY
parameter in a SELECT keyword clause. If you don't specify a day,
the value stored in the grid header is today's Julian date.
If you specify
MOVIE, STREAML, WINDB, or WINDV with the PARAM keyword, grids of both the u-
and v-component of the wind are saved or contoured.
The default
contour interval for a grid is taken from the text file CONTOUR.DEF.
If no file entry matches the grid's parameter, units and level, the default
is calculated to produce a reasonable number of contours, usually between 10
and 20. To change, add or delete entries in CONTOUR.DEF,
first back up the current version, then modify it using the format described
near the top of the file.
If you specify
DEL=YES or a position number of a nonexistent grid file in the ddataset parameter,
the grids are copied into a newly created grid file with the attributes specified
in keywords MAXGRD and TITLE.
Using the
DGRID keyword may result in grids being overwritten in the destination grid
file. For example, if the destination grid file has 50 grids (in grids 1 to
50) and you specify NUM=10 DGRID=25, the new grids will overwrite grids 25
to 34 in the destination grid file.
Use the FORMAT
keyword options below to format output of the grid point values or contour
labels based on FORTRAN designators for data output. To add text to the labels,
follow the designator with a text in single quotes.
| Designator |
Description |
| I |
integer |
| F |
floating
point |
| E |
exponential |
To specify
a parameter's output format, use a designator followed by a number. For example,
I4 specifies an integer of up to four digits; F10.1 specifies a floating point
decimal of up to 10 digits (including the decimal point) with one digit to
the right of the decimal; E10.3 specifies an exponential number of up to 10
characters (including the decimal point and the four-character exponential
flag) with three digits to the right of the decimal. Specify an X to use the
parameter's default format. If the specified integer or floating point format
is too small for the parameter's values, a series of asterisks (***) is plotted.
When using
the SELECT and PARAM keywords, you can use the following units:
| Unit
type |
UNIT= |
Definition |
| Distance |
CM |
centimeters |
| DM |
decameters |
| FT |
feet |
| GPM |
geopotential
meters |
| IN |
inches |
| KM |
kilometers |
| M |
meters |
| MI |
miles |
| MM |
millimeters |
| NMI |
nautical
miles |
| YD |
yards |
| Pressure |
HPA |
hectopascals |
| INHG |
inches
of mercury |
| MB |
millibars |
| Speed |
KT
or KTS |
knots |
| MPH |
miles
per hour |
| MPS |
meters
per second |
| Temperature |
C |
Celsius |
| F |
Fahrenheit |
| K |
Kelvin |
The PARAM
keyword contains the parameter to contour. It can be a native parameter, a
computed parameter, or a predefined parameter (STREAML, WINDB, WINDV, or MOVIE).
Native parameters
are those stored in the point file. They are specified in the PARAM keyword
in the format parameter [unit], where parameter is
the parameter name in the file, and [unit] is the output units, which
are optional but must be in square brackets if specified.
Computed
parameters do not exist in the point file but are derived with a mathematical
expression. Computed parameters are specified in the PARAM keyword in the format
'parameter [unit]=expression', where parameter is
the user-defined parameter name; [unit] is the label units, which
are optional but must be in square brackets if specified; and expression is
the mathematical expression consisting of math operators and one or more native
parameters defined in the Pn keywords.
The table
below lists the math operators valid in the computed parameter expression in
the PARAM keyword.
| Math Operator |
Function |
| + |
addition |
| – |
subtraction |
| * |
multiplication |
| / |
division |
| ** |
power |
| SQRT |
square
root |
| EXP |
exponential
(the number e raised to a power) |
| LOG |
natural
logarithm |
| LOG10 |
base
10 logarithm |
| SIN |
sine |
| COS |
cosine |
| TAN |
tangent |
| ASIN |
arcsine |
| ACOS |
arccosine |
| ATAN |
arctangent |
| ABS |
absolute
value |
| MIN |
minimum
of two grids |
| MAX |
maximum
of two grids |
To compute
a power of ten, such as 102 or 10-3 in
the math expression of a computed parameter in the PARAM keyword, specify it
in either the 1epower or 10**(power) format. For example,
both 1e-5 and 10**(-5) represent 10-5. You must include
the parenthesis with 10**(-5) for it to be interpreted correctly.
The following
character limits exist for the PARAM keyword:
- 256 characters
maximum for the entire PARAM keyword list
- four characters
maximum for the computed parameter name
- four
characters maximum for the computed parameter units
When using
point/MD files with CYD (ccyyddd) date units (e.g., FO14, IRAB, ISEN, ISFC,
ISHP, PIRP and SYN schema MD files created with McIDAS-XCD 7.5 and later),
commands PTCON, PTCOPY, PTDISP and PTLIST default to the current year if you
don't specify a four-digit year and the nearest century if you specify only
the last two digits of the year. For example, if the file uses CYD units for
the DAY parameter and its value is 2004260, then you can specify the DAY in
the SELECT keyword as 2004260 or 04260. If the current year is 2004, you can
also specify it as 260. Use the PTLIST command with FORM=PARAM to list the
file's parameters and units.
The PTCON,
PTCOPY, PTDISP and PTLIST commands continue to work with point/MD files using
the old SYD (ssyyddd) date units (e.g., FO14, IRAB, ISEN, ISFC, ISHP,
PIRP and SYN schema MD files created with versions of McIDAS-XCD prior to 7.5),
with the following exception: If you want to specify DAY in the SELECT keyword
and the ss portion of the MD file's DAY value is nonzero, then you
must specify the units with DAY in the SELECT keyword. For example, if the
MD file uses SYD units for DAY and its value is 7197240, then it must appear
as SELECT='DAY[SYD] 7197240'. If the MD file uses SYD units for DAY but has
a zero (blank) ss value, you don't have to specify the units in the
SELECT keyword. For example, if the MD file uses SYD units for DAY and its
value is 97240 then it can appear as either SELECT='DAY 97240' or SELECT='DAY[SYD]
97240'.
Examples
PTCON SURFACE/HOURLY PARAM=T[F] SELECT='TIME 6' MAP=USA
This entry
draws a contour of today's 6:00 UTC surface temperature data (in degrees Fahrenheit)
over the United States. The data is taken from the most recent point file in
dataset SURFACE/HOURLY. The grid points used to draw the contour are not saved.
PTCON RTPTSRC/SFCHOURLY RTPTSRC/SYNOPTIC RTPTSRC/SHIP PARAM=TD[C]
SELECT='TIME 6; DAY 96311' LAT=0 70 LON=-20 120 PRO=CONF GRA=3 LABEL='DEW
POINT TEMPS' FORMAT=F6.1 'degrees C' DASH=NEG
This entry
draws a contour of the 6:00 UTC dew point temperature data (in degrees Celsius)
for day 96311. All data in datasets RTPTSRC/SFCHOURLY, RTPTSRC/SYNOPTIC, and
RTPTSRC/SHIP is searched. The contours are drawn on graphics frame 3 using
a map with a latitude range of 0° to 70° North and a longitude range
of 20° East to 120° West. The label on the image window is DEW
POINT TEMPS. The contour values are labeled with a floating point format
with degrees C after each value. Contours with negative values are
dashed. The grid points used to draw the contour are not saved.
PTCON SURFACE/SYNOPTIC.7 PARAM=PCP[IN] POW=2 BPAR=20 OUT=SCON TEST/GRIDS.2
MAP=MID SELECT='TIME 18; DAY 96317' DGRID=21 CINT=10 LINT=2
This entry
draws contours for the 18:00 UTC six-hour cumulative precipitation (in inches)
for day 96317. The data is taken from the point file in position 7 of the dataset
SURFACE/SYNOPTIC. The contour is drawn on a map of the Midwest. The values
are multiplied by one hundred times their original value. A contour interval
of 0.10" is used with labels on every other contour. The grid point conversion
is filtered using a smoothing factor of 20. The gridded analysis is saved as
grid number 21 of the grid file in position 2 of the dataset TEST/GRIDS.
PTCON SURFACE/HOURLY.5 SURFACE/SYNOPTIC.5 SURFACE/SHIP.5 PARAM=T[C]
SELECT='TIME 00; DAY 96315' LAT=-84 -68 LON=20 -171 SLAT=-75 SLON=160 PRO=CONF
OUT=SPLOT MYGRIDS.51 DGRID=13 COLOR=3 LLINC=1 4 DIST=6 PINT=2 5
This entry
plots surface temperature (in degrees Celsius) from 0:00 UTC for day 96315
using data from the point file in position 5 of datasets SURFACE/HOURLY, SURFACE/SYNOPTIC,
and SURFACE/SHIP. Grid point values are plotted on a map of West Antarctica
in graphics color level 3 with data from every second row and fifth column
displayed. The grid point increment is one degree of latitude and four degrees
of longitude. Data is extrapolated up to a distance of six grid points into
data void regions. The gridded analysis is saved in grid number 13 of the grid
file in position 51 of the dataset with the alias name MYGRIDS.
PTCON SURFACE/HOURLY SELECT='TIME 0; DAY #Y' PARAM=MOVIE MAP=USA MOVIE=2
8
TE MOVIECOLORS "GU MAKE !1 0 !2 0
REPEAT MOVIECOLORS 2 TO 8 BY 1 0 BY 40
CM 2 8 GO=YES
The PTCON
entry draws today's 00 UTC surface streamlines with colored line segments on
a map of the United States. The TE and REPEAT entries set graphics color levels
2 to 8 to increase linearly from black (level 2) to bright green (level 8).
The CM entry then circulates the graphics color levels to animate the wind
flow.
PTCON RTPTSRC/SFCHOURLY SEL='DAY #Y;TIME 12' PAR='DELT[F]=P1-P2' P1=T[F]
P2=T[F] 'TIME 0' MAP=USA
This entry
draws contours of today's 00 UTC to 12 UTC temperature change in degrees Fahrenheit
on a map of the United States. The data is taken from the most recent point
file in dataset RTPTSRC/SFCHOURLY.
PTCON RTPTSRC/SFCHOURLY SEL='DAY #Y;TIME 12' MAP=NA PARAM='THA[K]=P1/((P2/1000)**.286)'
P1=T[K] P2=PSL[MB]
This entry
contours potential temperature in degrees Kelvin at 12 UTC today on a map of
North America. The potential temperature values are calculated using the equation
in the PARAM keyword, known as Poisson's Equation.
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