We released updated versions of HadISD, and this time two versions have been released at the same time. As described in this post, we noted that the buddy/neighbour checks had not been running since 2018. We have released a version of HadISD which correctly implements these checks as intended (v3.4.0.2023f), but for those who may wish to do their own comparison or use a version where these checks are absent as per the last few years of updates, then v3.3.1.202312p is also made available.
As we noted in our earlier post, the missing buddy checks also affect some of the other QC checks - predominantly those where a comparison with neighbouring stations can lead to flags set being removed. The Odd Cluster (Fig 1) and Climatological (Fig 2) checks show clear increases in the fractions of observations flagged by these checks across most stations.
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| Fig 1: Odd cluster checks for Dewpoint. Top - v3.3.1.202312p, Bottom - v3.4.0.2023f |
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| Fig 2: Climatological Outlier checks for Tempeature. Top - v3.3.1.202312p, Bottom - v3.4.0.2023f |
Although there is a general increase in the amount of observations flagged, most of these are in the lowest categories of fractions of the total record (to be expected). We also expected changes in the flagging rates for the Distributional Gap check, but saw only very slight differences.
The other test with a clear impact is that of Dewpoint Depression (Fig 3).
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| Fig 1: Dewpoint Depression checks. Top - v3.3.1.202312p, Bottom - v3.4.0.2023f |
Future Look
As noted in another earlier post, the ISD will be pausing updates during 2024. The timeline for this is now looking like end March 2024 rather than being December 2023, and we'll post on here when we get further details. In the meantime, we will continue HadISD updates (under v3.4.1.2024XXp) until ISD updates cease.
