Cirrus Cloud Distribution During the 1997/98 El Nino

Click to play El Nino & Cirrus Cloud
Make a Smilebox slideshow

I made the slideshow above so that I could see if cirrus cloud distribution behaved signifcantly differently during the large El Nino of 1997/98.

Below is a graph showing the progression of the El Nino in the Pacific.

In the Pacific, it is apparent that there was (for the season) a strong cloud-free zone developing in the run up and very beginning of the SST rise.  During the middle of the rise, some problem with the collected data makes it difficult to see what the trend is, but it appears to be average.  During the end of the rise, the peak, and then the fall, there is an overwhelming amount of cirrus cloud distributed more South than would normally be seen during that season.  So, there may be evidence for a relationship between SST (sea surface temp) and cirrus cloud distribution, though the largest portion of of rise in SST occured with average cirrus cloud cover.  This would require a lag between changes in cloud cover and changes in SST, and this requires more work to determine if this is the case.  Also, I need to spend more time looking at years with no La Nina or El Nino in order to determine the extent to which cirrus cloud distribution fluctuates regardless of tropical warming/cooling events.  If the distribution remains extremely stable, except during El Nino/La Nina events, we would have more evidence to pursue the link between clouds and SST.  However, if distribution varies significantly on its own, it will be very hard to pursue to the possible connection.

Additionally, I will look at what cirrus cloud cover does during La Ninas. Unfortunately, the data starts in July 1983, and there have not been many strong La Ninas since then.


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