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It is important that there should be one report containing all data from the ascent, although there can be earlier partial reports (particularly up to 100 hPa) for timeliness reasons.
Ideally there should be an overlap of 2-6 months between good quality BUFR made available over the GTS and the withdrawal of TAC reports - with notification of these changes via https://community.wmo.int/news/operational-newsletter .
Following approval of the plans for the Global Basic Observing Network (GBON) in October 2021, radiosonde data should be reported at high vertical resolution from January 2023 and details of the horizontal/time sampling required. See https://public.wmo.int/en/events/constituent-bodies/cg-ext2021 and https://meetings.wmo.int/Cg-Ext-2021/SitePages/Session%20Information.aspx .
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