Wednesday 31 July 2019

Quick update

Just a very quick update on this.  We have now received all the data we were expecting to receive - and so can start adjusting some of the processing criteria. 

However, to give an indication of the number of stations and rough coverage for trend analysis, I thought I'd put the latest plots here.  Once the processing criteria are settled on my intention is to put a draft document together.
Fig 1 - Stations in the Rx1day grids
Fig 2 - Stations in the TXx grids
As you can see, we have stations now covering the majority of the globe.  However, we want to ensure that the hard work from colleagues who have submitted data is recognised, and include as many stations as makes sense.  Currently, we're requiring that stations report relatively continuously during the period when they do - so can only have a maximum of 2 missing years, and I think that this is reducing the final numbers from over Brazil, India and elsewhere. 
Fig 3 - Rx1day trends (only from grid boxes with 66% completeness)
Fig 4 -TXx trends (only from grid boxes with 66% completeness)
And from these trend plots, the coverage is much reduced.  This arises from knock on effects, fewer stations being currently selected because of the completeness criterion.  Those that do may result in a too sparse network to ensure grids are calculated (which is more likely for indices which have a short spatial correlation).  And when they are, they may not be for sufficient years to calculate the trends. 

Fig 5 - Timeseries of Rx1day, compared to GHCNDEX and HadEX2

Fig 6 - Timeseries of TXx, compared to GHCNDEX and HadEX2
What is interesting is that, despite the limitations of the spatial coverage, the long term trends in quasi-global averages match very well with the other ETCCDI datasets available (GHCNDEX and HadEX2).

We're seeing what can be done to improve the spatial coverage without impacting the integrity of the dataset, so watch this space.