Fast Decoding of SYNOP (Surface Synoptic Observations) Meteorological Messages.

synopR

Overview

The goal of synopR is to provide a simple and fast tool for decoding FM 12 SYNOP (Report of surface observation from a fixed land station) messages, following the WMO standards (World Meteorological Organization (WMO). Manual on Codes (WMO-No. 306), Volume I.1. Geneva, 2019.). It focuses on extracting data from Sections 0, 1 and 3.

synopR is dependency-free! Only R (>= 4.1.0) is needed.

Installation

Install from CRAN:

install.packages("synopR")

Or install the development version from GitHub with:

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

Features

• More than 50 meteorological parameters can be obtained in just seconds. A detailed guide of data extracted by show_synop_data() is available in the vignette "Extracted_data_reference".

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

library(synopR)

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="))

• Download raw SYNOP messages from Ogimet with download_from_ogimet(), or download, check and decode all at once with direct_download_from_ogimet().

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

library(synopR)

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()

print(decoded)

Performance

show_synop_data(), the core function, is completely vectorized. It means it's super fast!

45k SYNOP messages decoded in just 13 seconds.

Constraints & Assumptions

• Sections: The package does not support sections 222 (maritime data), 444 (data for clouds with base below station level) and 555 (data for national use, which is quietly discarded).
• Time of observation: Observations are assumed to occur at the time indicated in Section 0 (Group 9 from Section 1 is currently ignored).
• Humidity: Group 2 (Section 1) contains dew point, not relative humidity.
• Geopotential height: Only pressure levels 850, 700 and 500 hPa are supported.
• Trace Precipitation: They are converted to 0.01 (mm).
• Groups not supported: Groups starting with 54 and 9 from Section 3 are currently ignored.

Issues

Feel free to report any issue you may find: Github

• "NA introduced by coercion" are generally associated with a specific part of the SYNOP message incorrectly codified.

Documentation

The complete documentation, including function references and tutorials is available at: https://ezequiel1593.github.io/synopR/

Citation

Elias E (2026). synopR: Fast Decoding of SYNOP (Surface Synoptic Observations) Meteorological Messages. R package version 1.0.0, https://ezequiel1593.github.io/synopR/.