I have been plotting a global temperature index based on daily NCEP/NCAR reanalysis. A big spike to unpresedented levels in October has attracted comment. The daily record is characterised by sharp spikes and dips, but bthis was exceptional. I've long been curious about the local temperature changes that might cause such a spike, so I analysed this one.
I calculated trends for each of the 10512 cells of the lat/lon grid over a period of 10 days, from 27 September, to 6 October. In this time, the index rose from 0.271°C to 0.865. The trend of global average was .0634°C/day.
I plotted them with WebGL, with the usual trackball sphere you can see below the fold. You can also click to see the trend at any point.
As people suspected, and I blogged here, Antarctica had been cold in September, and there was a reversal which explains much of the rise. Local trends are very high - up to 3°C per day, which is 30°C over 10 days. But there was also a broad swathe of also very large rises through China and central Asia, continuing through Iran. Further north, there was a cold patch on each side of the Urals, extending to Scandinavia. The US also cooled.
As a sanity check, I note that it says southern Australia also warmed rapidly. Melbourne is in the centre of that, and it shows various trends, as high as 1.264 °C/day. We did indeed have a rapid run-up. Late September was quite cool, which means a daily average of about 13°C, but 5-6 October were very warm, averaging about 27°C, following other warm days. The implied rise of 12.64C in trend is not unreasonable.
Anyway, the WebGL is below the jump. Remember, you can click any shading for a numeric trend to show.
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