Skip to contents

synopR

Overview

The goal of synopR is to provide a simple and robust tool for decoding FM 12 SYNOP (Report of surface observation from a fixed land station) messages, specifically optimized for data retrieved from Ogimet or standard WMO formats. It focuses on extracting Sections 0, 1 and 3 into a tidy, analysis-ready format.

Installation

Install from CRAN:

Or install the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("ezequiel1593/synopR", build_vignettes = TRUE)

Features

This package extracts the following meteorological parameters:

Section 1

  • Clouds: Lower cloud base height (h), total coverage (N), low or medium cloud amount (Nh), and types (Cl, Cm, Ch).
  • Visibility: Horizontal visibility (VV).
  • Wind: Direction (dd) in tens of degree and speed (ff) with its unit.
  • Temperature and humidity: Air temperature (TTT) and dew point (TdTdTd) in °C. Relative humidity is derived from both.
  • Pressure: Mean sea level pressure (PPPP) and surface pressure (PPPP1) in hPa. Also, geopotential height (hhh) in gpm.
  • Precipitation: Amount (RRR1) in mm and time window (tR1) in hours.
  • Weather: Present (ww) and past weather (W1, W2).

Section 3

  • Temperature extremes: Maximum (Tx) and Minimum (Tn) temperature in °C.
  • Ground and snow: State of the ground (E, E'), snow depth (sss) in cm and ground minimum temperature (TgTg) in °C.
  • Section 3 Precipitation: Amount (RRR3) in mm and time window (tR3) in hours.

Note: Parameters like h, VV,dd,ff, N, Nh, ww, W1, W2, E, E', Cl, Cm, and Ch are extracted in their original coded format from the WMO tables. For N and Nh, the values 0-8 directly represent coverage in oktas. Vectors with some WMO Code Tables are available here.

Usage

Decoding Ogimet Data

The package includes a parser specifically designed for the comma-separated format used by Ogimet:

library(synopR)

# Example Ogimet string
# Downloaded from: https://www.ogimet.com/cgi-bin/getsynop?block=87736&begin=202601011800&end=202601011800
raw_data <- "87736,2026,01,01,18,00,AAXX 01183 87736 11463 41813 10330 20148 39982 40072 5//// 60001 70700 83105 333 56600 83818="

# Parse and decode
decoded <- parse_ogimet(raw_data) |>
  show_synop_data(wmo_identifier = "87736")

print(decoded)

Constraints & Assumptions

To ensure accurate decoding, the package assumes:

  • Sections: The package does not support sections 222 (Maritime data) or 444 (Cloud data).
  • Format: The package automatically discards national data sections (Section 555).
  • Timing: Observations are assumed to occur at the time indicated in Section 0 (Group 9 from Section 1 is currently ignored).
  • Wind: Speed (ff) is reported in m/s or knots and its value does not exceed 99.
  • Humidity: Group 2 (Section 1) contains dew point, not relative humidity.
  • Geopotential height: Only pressure levels 850, 700 and 500 hPa are supported.
  • Snow: Group 4 from Section 3 contains a snow depth value between 1 cm and 996 cm.
  • Precipitation (Trace): They are converted to 0.01 (mm).
  • Ground temperature: Group 3 from Section 3 is interpreted as ground minimum temperature.
  • Groups not supported: Groups starting with 5, 7, 8 and 9 from Section 3 are currently not supported.

Validation

You can check the structural integrity of your SYNOP messages before decoding:

check_synop(c("AAXX 01183 87736 11463 41813 10330 20148 39982 40072 5//// 60001 70700 83105 333 56600 83818=",
              "AAXX 01183 87736 11463 41813 10330 20148 39982 4007 5//// 60001 70700 83105 333 56600 83818="))

Documentation

The complete documentation, including function references and tutorials in both English and Español, is available at:

👉 https://ezequiel1593.github.io/synopR/

Future versions

As far, this package has been tested with an ingest of ~4000 SYNOP messages from Argentina. There are plans to include more groups in the future, like sunshine hours. Also, it would be great to perform massive tests with SYNOP from other regions, to improve performance.