synop_parser: Parse SYNOP messages into structured lists or a data frame

In climate: Interface to Download Meteorological (and Hydrological) Datasets

Parse SYNOP messages into structured lists or a data frame

Description

This function decodes SYNOP FM-12 meteorological messages which are commonly used for reporting weather observations under the regulations of the World Meteorological Organization (WMO). It parses one or more SYNOP messages and returns their structured representation as generated by the SYNOP R6 decoder.

Usage

synop_parser(message, country = NULL, simplify = TRUE, as_data_frame = FALSE)

Arguments

message	Character vector with SYNOP messages.
country	Optional; A single character value passed to the precipitation indicator decoder to adjust country-specific behaviour (e.g. "RU").
simplify	Logical. If TRUE (default) and a single message is provided, the function returns the decoded list directly instead of a length-one list. Ignored when as_data_frame = TRUE.
as_data_frame	Logical. If TRUE, return a data.frame with one row per message and commonly-used decoded fields as columns. Missing or unparsed fields are filled with NA. Default is FALSE.

Details

Currently, the decoder contains most of the core logic for parsing the main sections of SYNOP messages that are commonly used in atmospheric sciences. However, it does not yet cover all possible SYNOP groups and fields, and some fields may be missing or incomplete.

Value

When as_data_frame = FALSE (default): a list of decoded SYNOP messages, or the decoded list directly when simplify = TRUE and a single message is supplied. When as_data_frame = TRUE: a data.frame with one row per message and the following columns (all numeric/character as appropriate, NA when not present in the message): station_type, station_id, region, obs_day, obs_hour, wind_unit, wind_estimated, visibility, cloud_cover, wind_direction, wind_speed, air_temperature, dewpoint_temperature, station_pressure, sea_level_pressure, pressure_tendency, pressure_change, precipitation_amount, precipitation_time, cloud_base_min, cloud_base_max, low_cloud_type, middle_cloud_type, high_cloud_type, low_cloud_amount, maximum_temperature (Section 3 daily maximum, °C), minimum_temperature (Section 3 daily minimum, °C), gust (highest gust speed from Section 3 group 910ff/911ff, in the wind unit of the message), cloudiness_height (cloud cover in oktas of the highest cloud layer reported in Section 3, i.e. cirrus/cirrocumulus/cirrostratus; NA when absent), sunshine_duration (daily sunshine in hours, from Section 3 group 55SSS), snow_depth (total snow depth in cm; 0 for trace amounts, NA for non-continuous cover or unmeasurable depth), snow_depth_state (descriptive state of ground with snow/ice per WMO code table 0975, e.g. "Even layer of loose dry snow covering ground completely"), source (the original SYNOP message string). Row names are sequential integers.

Examples

synop_code = "AAXX 01004 88889 12782 61506 10094 20047 30111 40197 53007 60001 81541"
synop_parser(synop_code)
synop_parser(rep(synop_code, 2), simplify = FALSE)
synop_parser(synop_code, as_data_frame = TRUE)
synop_parser(rep(synop_code, 2), as_data_frame = TRUE)

climate documentation built on Sept. 18, 2026, 5:06 p.m.