ALTIM

Calculates sounding data at standard aviation heights or pressures.

Format

ALTIM ddataset time day [keywords]

Parameters

ddataset	destination ADDE point dataset name and absolute position; specify as group/descriptor.position or alias.position; only positive integers are valid for position
time	observation time (default=0 if current time is between 0 UTC and 11:59 UTC, otherwise default=12)
day	observation date; valid formats include YYYYDDD, YYYY/MM/DD and DD/MON/YYYY where YYYY, DDD, MM and DD are integers and MON is three or more letters, e.g., JAN or JANUARY (default=current)

Keywords

COuntry=	c1 . . cN		calculate and write data for soundings in these countries; specify up to six countries using their two-letter codes; use the CCODE command to list valid codes; see the Remarks (default=all countries)
DATaset=	mand sig		source ADDE point dataset names for mandatory- and significant-level data; specify as group/descriptor or alias; you must specify NONE in the sig parameter or SIG=NO keyword to use only mandatory data, i.e., ignore the significant data (mand default=RTPTSRC/UPPERMAND; sig default=RTPTSRC/UPPERSIG if mand=RTPTSRC/UPPERMAND, otherwise sig default=NONE)
DELete=	YES	delete the destination file before copying
	NO	do not delete the destination file before copying (default)
LAT=	slat nlat		calculate and write data for soundings in this latitude range, where slat and nlat are the southern and northern latitude limits, respectively; see the Remarks (default= –90 90)
LON=	elon wlon		calculate and write data for soundings in this longitude range, where elon and wlon are the eastern and western longitude limits, respectively; see the Remarks (default= –180 180)
OPTion=	H	calculate and write data at heights from 0 to 45,000 feet at 1,000 foot increments; see the Remarks (default)
	P	calculate and write data at standard pressures from 18,000 to 45,000 feet at 1,000 foot increments
SIG=	YES	include data from the significant-level dataset specified in the DATASET keyword (default)
	NO	do not include data from the significant-level dataset specified in the DATASET keyword; use only its mandatory-level dataset
STate=	s1 . . sN		calculate and write data for soundings in these states; specify up to six states using their two-letter state Post Office abbreviations; see the Remarks (default=all states)
TITLE=	'text'	title of the destination point file; must be 32 characters or less (default=Altimeter Interpolation: yyyyddd); yyyyddd in the default is the date of the source dataset

Remarks

ALTIM reads data from the source upper-air dataset and interpolates the values to standard aviation heights or pressures, then writes the data to the destination dataset (an IHGT schema MD file). The IHGT schema must be registered with command SCHE DCIHGT before you use this command. If the specified destination file already exists, you must delete it with DEL=YES since ALTIM cannot append data to an existing file.

Because of the large number of calculations performed for each sounding, ALTIM may take a long time to complete. You can minimize this time and the number of soundings by specifying only the needed data with the LAT and LON, COUNTRY or STATE keywords.

Standard pressures, as specified with OPT=P, are the pressures of the standard atmosphere from 18,000 feet to 45,000 in 1000 foot increments (i.e., 18000, 19000, 20000, etc.). Use OPT=P to calculate the data at these "standard atmosphere" pressures. Use OPT=H to calculate the data at heights from 0 to 45,000 feet at 1000 foot increments, using the heights in the source dataset (converted to thousands of feet), not the standard atmosphere pressure model.

Examples:

ALTIM LOCAL/AVIATION.10 0

This entry calculates upper-air data from 0 to 45,000 feet at 1000 foot increments using today's 0 UTC data in the default source datasets RTPTSRC/UPPERMAND and RTPTSRC/UPPERSIG. The data is written to position 10 of dataset LOCAL/AVIATION, an IHGT-schema point file.

ALTIM LOCAL/AVIATION.10 12 DEL=YES ST=FL TITLE='12 UTC IHGT data for Florida' OPT=H

This entry calculates upper-air data at standard pressures from 18,000 to 45,000 feet at 1000 foot increments for the state of Florida. It uses today's 12 UTC data in the default datasets RTPTSRC/UPPERMAND and RTPTSRC/UPPERSIG. The data is written to position 10 of dataset LOCAL/AVIATION, an IHGT-schema point file. The DEL=YES and TITLE keywords delete the existing destination point file and create a new one with the title 12 UTC IHGT data for Florida.