Synoptic Summaries of the Day (SSODs) are daily summaries provided with a short time delay from the thousands of network stations that transmit hourly and synoptic reports.
Daily climate summaries are computed from the hourly and synoptic reports provided in Global Hourly Climate Network hourly (GHCNh).
How do I access SSODv2 Data
Use the Dataset Search tool SSODv2 stations in a specific region or stations with a specific variable.
What kind of data does SSODv2 provide, and how is it different from GHCNh?
Daily climate summaries are computed from the hourly and synoptic reports provided in GHCNh. These daily summaries are based on hourly (e.g. METAR/FM15) or 6-hourly (SYNOP/FM16) reports for a calendar day that runs from 00 to 23 UTC. In this way, all daily climate summaries in SSOD conform to the same synchronous 24-hour period (the same “synoptic day") worldwide.
This contrasts with the daily summaries provided in the Global Historical Climatology Network daily (GHCNd) dataset. In GHCNd, daily climate summaries are provided by national Met Services and are compiled according to the observation time and conventions used in their country for daily climate reports (e.g., midnight local time for US Airports, 06 UTC in Canada, 9 am local in Australia etc.) CSV Data
SSODv2 Documentation
SSODs are daily summaries provided with a short time delay for the network of many thousands of stations that transmit hourly and synoptic reports. A complete list of data sources and parameter definitions is available in the SSOD documentation file.
What data types are included in a SSOD Report?
This ensures the SSOD summary day is consistent for all stations worldwide, making it easier to compare numerical weather prediction model outputs and remotely sensed data. One disadvantage of SSOD is that daily precipitation totals may be underreported in the synoptic messages. Additionally, maximum and minimum temperatures gleaned from the synoptic messages also may not correspond to the true daily extremes.
The daily summaries provided by National Met Services in GHCNd are therefore recommended when the most accurate reports are required for daily rainfall and maximum/minimum temperatures.
However, as noted above, the 24-hour periods represented in the daily summaries provided in GHCNd are not the same worldwide. This distinction between the consistent summary day in SSOD and the mix of summary days in GHCNd is the reason for the name change from Global Summary of the Day (GSOD) to Synoptic Summary of the Day (SSOD, version 2)