Blending BUFR and TAC Marine in Situ data for ICOADS Near-Real-Time Release 3.0.2

In situ data used operationally in the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) Release 3.0.1 were from WMO Global Telecommunication Systems (GTS) transmissions in the Traditional Alphanumeric Codes (TAC) format. Many observing platforms have moved or are in the process of shifting to the Binary Universal Form for the Representation (BUFR) of meteorological data format. BUFR was in use officially since 2003 and the marine in situ GTS transition shift started around 2016. The switch to BUFR is necessary because of increased metadata and requirements to increase record length due to increasing instrumental accuracy and higher data precisions. In this paper, we describe the BUFR decoding process for observations from drifting buoys, moored buoys and ships, and the data quality control of the TAC and BUFR data streams. We also describe how the TAC and BUFR streams are merged into a new ICOADS Release 3.0.2 with duplicates removed. Finally, we compare the total number of reports and spatial coverage of essential climate variables (ECVs) between ICOADS R3.0.1 and ICOADS R3.0.2. Results show both quantitative and qualitative gains from the inclusion of BUFR reports. The observation totals in ICOADS R3.0.2 increased by nearly one million reports per month, and buoy and ship SST coverage increased 20% in 2°×2° degree grids. The number of reported EVCs also increased. For example, observations of sea surface temperature and sea level pressure increased around 30% and 20%, respectively, as compared to R3.0.1.

Key words: ICOADS R3.0.2, ICOADS R3.0.1, TAC, BUFR, marine, in situ, ship, drifting buoy, moored buoy, sea surface temperature, ocean