Pmetar is an R package that allows to download and parse current or historical METAR (Meteorological Terminal Aviation Routine Weather Report) reports, mainly for airports.
It has to be underlined that the package pmetar is not intended for flight planning or navigation.
For downloading a METAR report we need to know an airport four letters ICAO code, International Civil Aviation Organization, or three letters IATA code, International Air Transport Association.
Let’s download a current METAR weather report for Warsaw Okecie Airport. Its ICAO, International Civil Aviation Organization, code is EPWA. A report can be got from Aviation Weather Center https://www.aviationweather.gov/metar
library(pmetar)
metar_get("EPWA")
#> Getting airport informaiton from the file downloaded from
#> http://ourairports.com/data/airports.csv
#> Getting information from Aviation Weather Center www.aviationweather.gov/metar
#> Don't use for flight planning or navigation!
#> [1] "EPWA 012030Z 07006KT 040V100 9999 BKN007 14/13 Q1011 NOSIG"Now let’s take a look at Newark Liberty International Airport, EWR IATA code. This type of code you find on your airplane tickets.
metar_get("EWR")
#> Getting airport informaiton from the file downloaded from
#> http://ourairports.com/data/airports.csv
#> Getting information from Aviation Weather Center www.aviationweather.gov/metar
#> Don't use for flight planning or navigation!
#> [1] "KEWR 012051Z 12008KT 080V150 10SM FEW032 SCT040 SCT080 BKN250 26/17 A3008 RMK AO2 SLP186 T02610167 55009"The above message is intended for professionals like pilots or air traffic controllers. The first purpose of preparing the pmetar package was the need of extracting wind speed and air pressure values from METAR reports for some airports in Poland. Later the package functionality was extended. We will go through the main functions with a historical METAR report from John F. Kennedy International Airport.
The function metar_get_historical allows to download METAR weather reports for a defined period of time. The default online source of METAR reports, from = “iastate” is the Iowa Environmental Mesonet web page of Iowa State University ASOS-AWOS-METAR http://mesonet.agron.iastate.edu/AWOS/.
dm <- metar_get_historical("JFK", start_date = "2020-06-25", end_date = "2020-06-29", from = "iastate")
#> Getting airport informaiton from the file downloaded from
#> http://ourairports.com/data/airports.csv
#> Iowa Environmental Mesonet web page of Iowa State University
#> ASOS-AWOS-METAR http://mesonet.agron.iastate.edu/AWOS/
#> Don't use for flight planning or navigation!
head(dm)
#> [1] "202006250000 METAR KJFK 250000Z AUTO 27015KT 10SM CLR 28/12 A2978 RMK T02800120 MADISHF"
#> [2] "202006250005 METAR KJFK 250005Z AUTO 26014KT 10SM CLR 28/11 A2978 RMK T02800110 MADISHF"
#> [3] "202006250010 METAR KJFK 250010Z AUTO 27016KT 10SM CLR 28/12 A2979 RMK T02800120 MADISHF"
#> [4] "202006250015 METAR KJFK 250015Z AUTO 26014KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF"
#> [5] "202006250020 METAR KJFK 250020Z AUTO 27013KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF"
#> [6] "202006250025 METAR KJFK 250025Z AUTO 27014KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF"The second backup source, from = “ogimet” is Weather Information Service provided by Ogimet http://www.ogimet.com/. Please take into consideration that Ogimet usually blocks too frequent requests for data due to the server overload, the requested period is limited to 31 days and for the most of airports METAR reports are available from the beginning of the year 2005.
We will parse the last report from the above dm. In historical reports dates and hours are placed at the beginning of texts. Normally it’s extracted and parsed, but for now let’s remove it
(dm[length(dm)])
#> [1] "202006292355 METAR KJFK 292355Z AUTO 07007KT 10SM FEW079 24/18 A2986 RMK T02400180 LTG DSNT S! MADISHF"
my_report <- substr(dm[length(dm)], 14, nchar(dm[length(dm)]))
my_report
#> [1] "METAR KJFK 292355Z AUTO 07007KT 10SM FEW079 24/18 A2986 RMK T02400180 LTG DSNT S! MADISHF"It has to be noted that the report part after the RMK, remarks, is not analyzed, except the temperature information, which is provide more precisely in remarks.
The first element METAR indicates the text consist of a METAR weather report. If a report was issued under special circumstances, a text SPECI replaces METAR.
The second four letters element, KJFK identifies an airport from which a METAR issued. We can extract it
and find the KJFK geographical coordinates, elevation, airport IATA code, airport name and source of information.
metar_location(metar_airport(my_report))
#> Getting airport informaiton from the file downloaded from
#> https://ourairports.com/data/airports.csv
#> created by David Megginson
#> # A tibble: 1 x 7
#> ICAO_Code IATA_Code Airport_Name Longitude Latitude Elevation Source
#> <chr> <chr> <chr> <dbl> <dbl> <dbl> <chr>
#> 1 KJFK JFK John F Kennedy I… -73.8 40.6 3.96 http://our…The third element 282355Z includes a day of a month, a time and a time zone.
metar_day(my_report)
#> [1] 29
metar_hour(my_report)
#> [1] "23:55"
metar_time_zone(my_report)
#> [1] "Z"The fourth element, in our case AUTO informs that a report was generated automatically. If a report was manually corrected it is COR. This element is not taken into consideration by the package pmetar.
Next, there is the text 07007KT where three first digits informs about a wind direction in degrees. Two next digits are a wind speed and the letters the end define units, here KT, hence a wind speed is in knots.
metar_dir(my_report)
#> [1] "70"
metar_speed(my_report, metric = TRUE)
#> [1] 3.601113
metar_speed(my_report, metric = FALSE)
#> [1] 7The function metar_speed reports a wind speed in m/s with the default value of the parameter metric = TRUE, or in knots when metric = FALSE.
When a wind direction varies, a METAR report has additional component, like 140V200, which informs that a wind direction fluctuates from 140 to 200 degrees.
variable_direction_METAR <- "EPWA 281830Z 18009KT 140V200 9999 SCT037 03/M01 Q1008 NOSIG"
metar_dir(variable_direction_METAR)
#> [1] "180, variable from 140 to 200"In this case an output is character what can be useless for statistical calculations. If only main direction in the numeric format is needed, it is possible to set the parameter numeric_only = TRUE.
The part 10SM is the visibility. In this case it’s 10 statue miles. With the default value of the paremeter metric= TRUE we get output in meters. For metric = FALSE in statute miles.
The function metar_wx_codes extracts and parses the below weather conditions codes:
metarWXcodes
#> Type Abbreviation Meaning
#> 1 Descriptor MI Shallow (French: Mince)
#> 2 Descriptor BC Patches (French: Bancs)
#> 3 Descriptor BL Blowing
#> 4 Descriptor TS Thunderstorm
#> 5 Descriptor PR Partial
#> 6 Descriptor DR Low drifting
#> 7 Descriptor SH Showers
#> 8 Descriptor FZ Freezing
#> 9 Intensity - Light intensity
#> 10 Intensity + Heavy intensity
#> 11 Intensity blank Moderate intensity
#> 12 Intensity VC In the vicinity
#> 13 Obscuration FG Fog
#> 14 Obscuration BR Mist (French: Brume)
#> 15 Obscuration DU Widespread Dust
#> 16 Obscuration SA Sand
#> 17 Obscuration VA Volcanic Ash
#> 18 Obscuration HZ Haze
#> 19 Obscuration FU Smoke (French: Fumee)
#> 20 Obscuration PY Spray
#> 21 Other SQ Squall
#> 22 Other DS Duststorm
#> 23 Other FC Funnel Cloud
#> 24 Other PO Dust or Sand Whirls
#> 25 Other SS Sandstorm
#> 26 Precipitation RA Rain
#> 27 Precipitation SN Snow
#> 28 Precipitation IC Ice Crystals
#> 29 Precipitation GR Hail (French: Grele)
#> 30 Precipitation UP Unknown Precipitation
#> 31 Precipitation DZ Drizzle
#> 32 Precipitation SG Snow Grains
#> 33 Precipitation PL Ice Pellets
#> 34 Precipitation GS Small Hail and/or Snow Pellets (French: Gresil)
#> 35 Precipitation
#> 36 Time B Began At Time
#> 37 Time 2 digits Minutes of current hour
#> 38 Time E Ended At Time
#> 39 Time 4 digits Hour/Minutes Zulu TimeIn our METAR examples part -RA informs about weather conditions.
This part of a METAR can be quite complex, like in the below example:
Next part, SCT028 SCT035 BKN079, informs about a cloud coverage
The temperature and the dew point can be extracted from two elements of a METAR report, before the RMK remarks marker 23/20 which can be found in the most reports. Or from the part after the RMK remarks marker T02300200, more precise but not always available.
The temperature is coded in Celsius degrees, here 23/20, or more detailed in T02300200.
If there is a letter M in the front of two digits, M23/00, or there is a digit one after T, T1230, the temperature is below zero Celsius degrees.
The dew point can be decoded from the last two digits 23/20, or more detailed from T02300200. Dew points below zero Celsius degrees are decoded in the same method as above. For example 04/M03 or T00391033 mean that the dew point temperature is -3 Celsius degrees or more precisely -3.3 Celsius degrees.
Here there is a report with the more precise temperature information in the RMK remarks part.
In our example a pressure value is coded in the A2972 as inHg (inch of mercury). With the default parameter altimeter = FALSE, the function metar_pressure returns a pressure in hPa.
The pressure value can be also presented in a METAR report as Q1008, already in hPa.
If a pressure is needed in inHg (inch of mercury), the parameter altimeter has to be set to TRUE.
Let’s come back to our dm list with historical METAR reports downloaded at the top of this document. Please notice that in all rows there are dates and hours in the front of METAR reports. It will be parsed and placed in the column METAR_Date below.
head(dm)
#> [1] "202006250000 METAR KJFK 250000Z AUTO 27015KT 10SM CLR 28/12 A2978 RMK T02800120 MADISHF"
#> [2] "202006250005 METAR KJFK 250005Z AUTO 26014KT 10SM CLR 28/11 A2978 RMK T02800110 MADISHF"
#> [3] "202006250010 METAR KJFK 250010Z AUTO 27016KT 10SM CLR 28/12 A2979 RMK T02800120 MADISHF"
#> [4] "202006250015 METAR KJFK 250015Z AUTO 26014KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF"
#> [5] "202006250020 METAR KJFK 250020Z AUTO 27013KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF"
#> [6] "202006250025 METAR KJFK 250025Z AUTO 27014KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF"Now we can decode all elements and place them in the tibble.
decoded_metars <- metar_decode(dm)
#> Getting airport informaiton from the file downloaded from
#> https://ourairports.com/data/airports.csv
#> created by David MegginsonThe following columns were created:
names(decoded_metars)
#> [1] "Remark" "Airport_ICAO" "METAR_Date"
#> [4] "Day_of_Month" "Hour" "Time_zone"
#> [7] "Wind_speed" "Wind_speed_unit" "Gust"
#> [10] "Gust_unit" "Wind_shear" "Wind_direction"
#> [13] "Temperature" "Dew_point" "Pressure"
#> [16] "Visibility" "Visibility_unit" "Cloud_coverage"
#> [19] "Weather_information" "Airport_Name" "Airport_IATA"
#> [22] "Longitude" "Latitude" "Elevation"
#> [25] "Decode_Date" "Original_METAR"First rows of the tibble with decoded METAR reports:
print.data.frame(head(decoded_metars))
#> Remark Airport_ICAO METAR_Date
#> 1 Don't use for flight planning or navigation! KJFK 2020-06-25 00:00:00
#> 2 Don't use for flight planning or navigation! KJFK 2020-06-25 00:05:00
#> 3 Don't use for flight planning or navigation! KJFK 2020-06-25 00:10:00
#> 4 Don't use for flight planning or navigation! KJFK 2020-06-25 00:15:00
#> 5 Don't use for flight planning or navigation! KJFK 2020-06-25 00:20:00
#> 6 Don't use for flight planning or navigation! KJFK 2020-06-25 00:25:00
#> Day_of_Month Hour Time_zone Wind_speed Wind_speed_unit Gust Gust_unit
#> 1 25 00:00 Z 7.716670 m/s NA m/s
#> 2 25 00:05 Z 7.202226 m/s NA m/s
#> 3 25 00:10 Z 8.231115 m/s NA m/s
#> 4 25 00:15 Z 7.202226 m/s NA m/s
#> 5 25 00:20 Z 6.687781 m/s NA m/s
#> 6 25 00:25 Z 7.202226 m/s NA m/s
#> Wind_shear Wind_direction Temperature Dew_point Pressure Visibility
#> 1 <NA> 270 28 12 1008.47 16093.44
#> 2 <NA> 260 28 11 1008.47 16093.44
#> 3 <NA> 270 28 12 1008.81 16093.44
#> 4 <NA> 260 27 12 1008.81 16093.44
#> 5 <NA> 270 27 12 1008.81 16093.44
#> 6 <NA> 270 27 12 1008.81 16093.44
#> Visibility_unit
#> 1 m
#> 2 m
#> 3 m
#> 4 m
#> 5 m
#> 6 m
#> Cloud_coverage
#> 1 No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)
#> 2 No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)
#> 3 No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)
#> 4 No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)
#> 5 No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)
#> 6 No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)
#> Weather_information Airport_Name Airport_IATA
#> 1 John F Kennedy International Airport JFK
#> 2 John F Kennedy International Airport JFK
#> 3 John F Kennedy International Airport JFK
#> 4 John F Kennedy International Airport JFK
#> 5 John F Kennedy International Airport JFK
#> 6 John F Kennedy International Airport JFK
#> Longitude Latitude Elevation Decode_Date
#> 1 -73.7789 40.6398 3.9624 2020-09-01 22:56:07
#> 2 -73.7789 40.6398 3.9624 2020-09-01 22:56:07
#> 3 -73.7789 40.6398 3.9624 2020-09-01 22:56:07
#> 4 -73.7789 40.6398 3.9624 2020-09-01 22:56:07
#> 5 -73.7789 40.6398 3.9624 2020-09-01 22:56:07
#> 6 -73.7789 40.6398 3.9624 2020-09-01 22:56:07
#> Original_METAR
#> 1 202006250000 METAR KJFK 250000Z AUTO 27015KT 10SM CLR 28/12 A2978 RMK T02800120 MADISHF
#> 2 202006250005 METAR KJFK 250005Z AUTO 26014KT 10SM CLR 28/11 A2978 RMK T02800110 MADISHF
#> 3 202006250010 METAR KJFK 250010Z AUTO 27016KT 10SM CLR 28/12 A2979 RMK T02800120 MADISHF
#> 4 202006250015 METAR KJFK 250015Z AUTO 26014KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF
#> 5 202006250020 METAR KJFK 250020Z AUTO 27013KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF
#> 6 202006250025 METAR KJFK 250025Z AUTO 27014KT 10SM CLR 27/12 A2979 RMK T02700120 MADISHF