jdc 22-jun-2007
METAR data can be obtained from http://www.noaa.org using ftp. This package can query data from the NOAA server and parse METAR data (obtained with this package or otherwise).
package provide tclmetarlib 0.1
package require ftp
namespace eval ::tclmetar {
variable ftpsock
variable metar_keys {abbrev raw year month day hour minute corrected winddir winddirstr windspeed windgust windvarfrom windvarfromstr windvarto windvartostr temperature dewpoint airpressure cloudstype cloudsheight toweringcumulus cumulonimbus weather visibility}
}
proc ::tclmetar::get_winddirstr { winddir } {
if { [string is integer -strict $winddir] } {
set wsi [expr {int(($winddir+11.25)/22.5)}]
return [lindex {N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW N} $wsi]
}
return $winddir
}
proc ::tclmetar::parse_wind { f wd winddirnm winddirstrnm ws windspeednm wg windgustnm wu } {
upvar $winddirnm winddir
upvar $winddirstrnm winddirstr
upvar $windspeednm windspeed
upvar $windgustnm windgust
set winddir [string trimleft $wd "0"]
if { [string length $winddir] == 0 } {
set winddir 0
}
set windspeed [string trimleft $ws "0"]
if { [string length $windspeed] == 0 } {
set windspeed 0
}
set windgust [string trimleft [string range $wg 1 end] "0"]
if { [string length $windgust] == 0 } {
set windgust 0
}
switch -exact -- $wu {
"KT" {
set windspeed [expr {round($windspeed * 1.852)}]
set windgust [expr {round($windgust * 1.852)}]
}
"MPS" {
set windspeed [expr {round($windspeed * 3.6)}]
set windgust [expr {round($windgust * 3.6)}]
}
"KMH" {
}
}
set winddirstr [get_winddirstr $winddir]
return
}
proc ::tclmetar::parse_wind_variability { wvf windvarfromnm windvarfromstrnm wvt windvartonm windvartostrnm } {
upvar $windvarfromnm windvarfrom
upvar $windvartonm windvarto
upvar $windvarfromstrnm windvarfromstr
upvar $windvartostrnm windvartostr
set windvarfrom [string trimleft $wvf "0"]
if { [string length $windvarfrom] == 0 } {
set windvarfrom 0
}
set windvarfromstr [get_winddirstr $windvarfrom]
set windvarto [string trimleft $wvt "0"]
if { [string length $windvarto] == 0 } {
set windvarto 0
}
set windvartostr [get_winddirstr $windvarto]
return
}
proc ::tclmetar::parse_temperature { f tempnm } {
upvar $tempnm temp
if { [string match "M*" $f] } {
set temp -[string trimleft [string range $f 1 end] "0"]
if { [string equal $temp "-"] } {
set temp "0"
}
} else {
set temp [string trimleft $f "0"]
if { [string length $temp] == 0 } {
set temp "0"
}
}
}
proc ::tclmetar::parse_air_pressure { pv airpressurenm pu } {
upvar $airpressurenm airpressure
switch -exact -- $pu {
"A" {
set airpressure [string trimleft [string range $pv 0 1] "0"].[string range $pv 2 3]
set airpressure [expr {$airpressure * 0.033864}]
}
"Q" {
set airpressure [expr {[string trimleft $pv "0"] / 1000.0}]
}
}
return
}
proc ::tclmetar::parse_clouds { ct cloudstypenm ch cloudsheightnm cbtcu toweringcumulusnm cumulonimbusnm } {
upvar $cloudstypenm cloudstype
upvar $cloudsheightnm cloudsheight
upvar $toweringcumulusnm toweringcumulus
upvar $cumulonimbusnm cumulonimbus
switch -exact -- $ct {
SKC -
CLR -
NSC {
if { [string equal $cloudstype "<unknown>"] } {
set cloudstype SKC
} else {
lappend cloudstype SKC
}
}
FEW -
SCT -
BKN -
OVC {
if { [string equal $cloudstype "<unknown>"] } {
set cloudstype $ct
} else {
lappend cloudstype $ct
}
}
}
set ch [string trimleft $ch "0"]
if { [string length $ch] == 0 } {
set ch "0"
}
if { [string equal $cloudsheight "<unknown>"] } {
set cloudsheight [expr {$ch * 30.48}]
} else {
lappend cloudsheight [expr {$ch * 30.48}]
}
switch -exact -- $cbtcu {
CB {
set toweringcumulus 0
set cumulonimbus 1
}
TCU {
set toweringcumulus 1
set cumulonimbus 0
}
default {
set toweringcumulus 0
set cumulonimbus 0
}
}
return
}
proc ::tclmetar::parse_weather { int vic desc wea weathernm } {
upvar $weathernm weather
set wl [list $int $vic $desc $wea]
if { [string equal $weather "<unknown>"] } {
set weather [list $wl]
} else {
lappend weather $wl
}
return
}
proc ::tclmetar::parse_international_visibility { m visibilitynm } {
upvar $visibilitynm visibility
set visibility [string trimleft $m "0"]
if { [string length $visibility] == 0 } {
set visibility 0
}
return
}
proc ::tclmetar::parse_american_visibility { v1 v2 prevf visibilitynm } {
upvar $visibilitynm visibility
if { ([string length $v2] == 0) || [string equal $v2 "0"] } {
set v2 1
}
append v2 ".0"
if { ![string is integer -strict $prevf] } {
set prevf 0
}
set visibility [expr {($prevf + $v1/$v2) * 1609.34}]
return
}
proc ::tclmetar::parse { metarl mi_abbrev } {
set ar(abbrev) $mi_abbrev
set ar(raw) $metarl
set ar(year) "<unknown>"
set ar(month) "<unknown>"
set ar(day) "<unknown>"
set ar(hour) "<unknown>"
set ar(minute) "<unknown>"
set ar(corrected) "<unknown>" ;# bool
set ar(winddir) "<unknown>" ;# 0 = north, 90 = east
set ar(winddirstr) "<unknown>"
set ar(windspeed) "<unknown>" ;# in km/h
set ar(windgust) "<unknown>" ;# in km/h
set ar(windvarfrom) "<unknown>" ;# 0 = north, 90 = east
set ar(windvarfromstr) "<unknown>" ;# 0 = north, 90 = east
set ar(windvarto) "<unknown>" ;# 0 = north, 90 = east
set ar(windvartostr) "<unknown>" ;# 0 = north, 90 = east
set ar(temperature) "<unknown>" ;# in degrees Celcius
set ar(dewpoint) "<unknown>" ;# in degrees Celcius
set ar(airpressure) "<unknown>" ;# in bar
set ar(cloudstype) "<unknown>" ;# list of SKC (sky clear) | FEW | SCT (scattered) | BKN (broken) | OVC (overcast) | CAVOK
set ar(cloudsheight) "<unknown>" ;# list of heights in meter | CAVOK
set ar(toweringcumulus) "<unknown>" ;# bool
set ar(cumulonimbus) "<unknown>" ;# bool
set ar(weather) "<unknown>" ;# in metar abbreviations
set ar(visibility) "<unknown>" ;# in meter
set prevf ""
set mi_abbrev_found 0
foreach f $metarl {
if { [string equal $mi_abbrev $f] } {
set mi_abbrev_found 1
continue
}
if { !$mi_abbrev_found && [regexp {([0-9]{4})/([0-9]{2})/([0-9]{2})} $f m y m d] } {
set ar(year) [string trimleft $y "0"]
set ar(month) [string trimleft $m "0"]
set ar(day) [string trimleft $d "0"]
} elseif { !$mi_abbrev_found && [regexp {([0-9]{2}):([0-9]{2})} $f ma h m] } {
set ar(hour) [string trimleft $h "0"]
if { [string length $ar(hour)] == 0 } {
set ar(hour) 0
}
set ar(minute) [string trimleft $m "0"]
if { [string length $ar(minute)] == 0 } {
set ar(minute) 0
}
} elseif { !$mi_abbrev_found } {
continue
} elseif { [string match "RMK*" $f] || [string match "TEMP*" $f] || [string match "NOSIG*" $f] } {
break
} elseif { [regexp {([0-9][0-9])([0-9][0-9])([0-9][0-9])Z} $f ma d h m] } {
# Date/time field
set ar(day) [string trimleft $d "0"]
set ar(hour) [string trimleft $h "0"]
if { [string length $ar(hour)] == 0 } {
set ar(hour) 0
}
set ar(minute) [string trimleft $m "0"]
if { [string length $ar(minute)] == 0 } {
set ar(minute) 0
}
} elseif { [string equal "COR" $f] } {
set ar(corrected) 1
} elseif { [string equal "AUT" $f] } {
set ar(corrected) 0
} elseif { [string match "R*" $f] } {
# Runway visibility still to be added
} elseif { [regexp {([0-9]{3}|VRB)([0-9]{2,3})(G[0-9]{2,3})?(KT|KMH|MPS)} $f m wd ws wg wu] } {
# Wind field
parse_wind $f $wd ar(winddir) ar(winddirstr) $ws ar(windspeed) $wg ar(windgust) $wu
} elseif { [regexp {([0-9]{3})V([0-9]{3})} $f m wvf wvt] } {
# Wind variability
parse_wind_variability $wvf ar(windvarfrom) ar(windvarfromstr) $wvt ar(windvarto) ar(windvartostr)
} elseif { [regexp {^(M?[0-9][0-9])/+(M?[0-9][0-9])$} $f m temp dewp] } {
# Temperature field
parse_temperature $temp ar(temperature)
parse_temperature $dewp ar(dewpoint)
} elseif { [regexp {(A|Q)([0-9]{4})} $f m pu pv] } {
# Altimeter settings field
parse_air_pressure $pv ar(airpressure) $pu
} elseif { [regexp {(SKC|FEW|SCT|BKN|OVC|CLR|NSC)([0-9]{3})?(CB|TCU)?} $f m ct ch cbtcu] } {
# Clouds field
parse_clouds $ct ar(cloudstype) $ch ar(cloudsheight) $cbtcu ar(toweringcumulus) ar(cumulonimbus)
} elseif { [string equal $f "CAVOK"] } {
set ar(cloudstype) "CAVOK"
set ar(cloudsheight) "CAVOK"
set ar(cumulonimbus) 0
set ar(toweringcumulus) 0
set ar(visibility) 9999
} elseif { [regexp {([\+\-]?)(VC)?(MI|BC|PR|TS|BL|SH|DR|FZ)?(DZ|RA|SN|SG|IC|PI|GR|GS|UP|BR|FG|FU|VA|SA|HZ|PY|DU|SQ|SS|DU|PO|FC|\+FC)} $f m int vic desc wea] } {
# Weather field
parse_weather $int $vic $desc $wea ar(weather)
} elseif { [regexp {[0-9]{4}} $f m ] } {
# International visibility field
parse_international_visibility $m ar(visibility)
} elseif { [regexp {^([0-9]{1,2})/?([0-9]{0,2})SM$} $f m v1 v2] } {
# American visibility field
parse_american_visibility $v1 $v2 $prevf ar(visibility)
}
# Visibility directions still to be added
set prevf $f
}
return [array get ar]
}
proc ::tclmetar::get_time { arnm } {
upvar $arnm ar
set y $ar(year)
while { [string length $y] < 4 } {
set y "0$y"
}
set M $ar(month)
while { [string length $M] < 2 } {
set M "0$M"
}
set d $ar(day)
while { [string length $d] < 2 } {
set d "0$d"
}
set h $ar(hour)
while { [string length $h] < 2 } {
set h "0$h"
}
set h "T$h"
set m $ar(minute)
while { [string length $m] < 2 } {
set m "0$m"
}
set s "00"
set mt [clock scan "$y$M$d$h$m$s" -gmt true]
return $mt
}
proc ::tclmetar::ftpopen { ftpserver ftpuser ftppassword ftpdir } {
variable ftpsock
set ftpsock [ftp::Open $ftpserver $ftpuser $ftppassword]
ftp::Cd $ftpsock $ftpdir
return
}
proc ::tclmetar::ftpget { mfile } {
variable ftpsock
set mdata ""
set rt [ftp::Get $ftpsock $mfile -variable mdata]
if { [string length $rt] && $rt } {
set mdata [string map {\n " " \r " " \t " "} [string trim $mdata]]
return [eval list [split $mdata]]
} else {
return -code error "Could not download file '$mfile'"
}
}
proc ::tclmetar::ftpclose { } {
variable ftpsock
ftp::Close $ftpsock
}
proc ::tclmetar::get_metar_data { mi_abbrev } {
set ftpserver tgftp.nws.noaa.gov
set ftpdir data/observations/metar/stations
set ftpuser anonymous
set ftppassword anonymous
set tVerbose $ftp::VERBOSE
set ::ftp::VERBOSE 0
::log::lvSuppress error
tclmetar::ftpopen $ftpserver $ftpuser $ftppassword $ftpdir
set rt [catch {tclmetar::ftpget $mi_abbrev.TXT} mi_data]
tclmetar::ftpclose
set ::ftp::VERBOSE $tVerbose
if { $rt } {
return -code error $mi_data
}
if { [catch {tclmetar::parse $mi_data $mi_abbrev} rl] } {
return -code error $rl
}
return $rl
}After a
package require tclmetarlib
the package is ready for use.
| abbrev | METAR station abbreviation |
| raw | Unparsed METAR data as obtained from the NOAA server |
| year | Year part of date on which METAR data was collected |
| month | Month part of date on which METAR data was collected |
| day | Day part of date on which METAR data was collected |
| hour | Hour part of date on which METAR data was collected |
| minute | Minute part of date on which METAR data was collected |
| corrected | Indication if METAR data was correct before upload to NOAA server by METAR Station of not |
| winddir | Wind direction, 0 = north, 90 = east, ... |
| winddirstr | String representation of wind direction (N, NNE, NE, ENE, E, ESE, SE, SSE, S, SSW, SW, WSW, W, WNW, NW, NNW, N) |
| windspeed | Wind speed, in km/h |
| windgust | Wind gusts, in km/h |
| windvarfrom | Variable wind direction from this direction, 0 = north, 90 = east, ... |
| windvarfromstr | String representation of wind variability from |
| windvarto | Variable wind direction to this direction, 0 = north, 90 = east, ... |
| windvartostr | String representation of wind variability to |
| temperature | Temperature, in degrees Celcius |
| dewpoint | Temperatur, in degrees Celcius |
| airpressure | Air-pressure, in bar |
| cloudstype | Clouds-type, list of SKC (sky clear), FEW (few), SCT (scattered), BKN (broken), OVC (overcast), CAVOK (ceiling and visibility OK) |
| cloudsheight | List of clouds-heights in meter or CAVOK |
| toweringcumulus | Boolean indicating if this type of clouds is present near the METAR station |
| cumulonimbus | Boolean indicating if this type of clouds is present near the METAR station |
| weather | Weather in METAR abbreviations |
| visibility | Horizontal visibility at ground level, in meter |
Command:
::tclmetar::get_metar_data metarStationCode