UHI? What UHI Say GISS

By Paul Homewood

San Diego International Airport

San Diego International Airport, also known as Lindbergh Field, is the busiest single-runway commercial airport in the United States, and the second-busiest single-use runway in the world after London Gatwick with about 465 scheduled operations carrying 48,000 passengers each day; a total of 17,710,241 passengers in 2013.

It is also only 3 miles from downtown San Diego, and is now surrounded on three sides by the ever expanding city. In other words, just the sort of place where you would not want to monitor long term temperature trends.

Right? Well, not according to GISS and GHCN. The temperature record there is one of their prized long term sites, dating back to 1929, just after the airport was dedicated.

Station metadata shows there has been no change in location since 1929, which is now within yards of a large car parking area and jets taxiing. The main runway is about 100 yards away.

http://www.ncdc.noaa.gov/homr/#ncdcstnid=10001444&tab=LOCATIONS

Still, you say, surely GISS will have made allowance for the enormous UHI effect here.

And they sure have. The only trouble is their homogenisation adjustment has INCREASED the warming trend by, you’ve guessed it, cooling the past.

http://data.giss.nasa.gov/cgi-bin/gistemp/find_station.cgi?lat=32.73&lon=-117.17&dt=1&ds=14

The graph below shows the step changes made.

Apart from a small change made in 1954, the major changes took effect from 1992 onwards, and were staggered every year or so. As a result, 1990 annual temperatures, which at 17.99C were 0.44C higher than 2013, now show as 0.56C lower.

There is no question that the airport has expanded massively over the last few decades. For instance, the new East Terminal was opened in 1967 to address increased traffic, followed by the West Terminal 12 years later. This was then expanded in 1998.

In theory, GISS adjust urban sites so as to match the trends of rural stations. However, according to GISS, the only rural station within 250km of San Diego is Cuyamaca, which, as we mysteriously discovered yesterday, has had its actual temperature record, showing effectively no trend, turned into a fast warming one.

https://notalotofpeopleknowthat.wordpress.com/2015/01/14/cooling-the-past-in-california/

It is often claimed that these adjustments are just solitary examples, having next to no effect in the wider view of things. Yet, here we have an example where the temperature record of a large chunk of southern California is based around a massively adjusted rural site, which USHCN have already recognised as one of their highest quality sites, and an urban site, which, despite being heavily affected by UHI issues over the years, has inexplicably had its warming trend artificially increased.

If San Diego’s temperatures have been adjusted up because of a spurious warming trend at Cuyamaca, how many other nearby urban sites have been affected in the same way?

It is hard to escape the conclusion that what we have been told about the climate in this region bears no resemblance to what has actually been going on.