Last week we had quite a row about temperature and temperature adjustments in Wellington New Zealand. One of the stations cited was the Kelburn district of Wellington, NZ.
NIWA issued a response statement regarding the charges leveled by The NZ Climate Science Coalition here:
Warming over New Zealand through the past century is unequivocal.
NIWA’s analysis of measured temperatures uses internationally accepted techniques, including making adjustments for changes such as movement of measurement sites. For example, in Wellington, early temperature measurements were made near sea level, but in 1928 the measurement site was moved from Thorndon (3 metres above sea level) to Kelburn (125 m above sea level). The Kelburn site is on average 0.8°C cooler than Thorndon, because of the extra height above sea level.
The NZ Climate Science Coalition responded with a series of graphs that showed how the temperature record of stations in Wellington looks:
What’s interesting is that if you leave Kelburn out of the equation, Thorndon in 1910 is not far below Airport 2010. Perhaps that gave NIWA some confidence that the two locations were equivalent, but I’m betting Thorndon a hundred years ago was very different from an international airport now.
Of course we all know that airports tend to run hotter than surrounding areas due to the huge expanses of runway, tarmac, terminal buildings, and car parks they have become as aviation has grown in the last 100 years, so it is no surprise to see the airport hotter than Kelburn, which is higher in elevation and with a bit more greenery, owing to the nearby Botanical Gardens.
I had an interest in tracking down the Kelburn station, just to see how good it is. I was able to find it on Google Earth as an aerial view which you can see below. I was unsuccessful in my first attempts at finding a photograph to document the measurement environment of the Kelburn station. I picked up the hunt again a few days later, and found it hiding in plain site. Thank goodness for tourists.
You can see the Stevenson screen is surrounded by astronomical science, such as the historic Dominion Observatory and the Carter Observatory to the west (off screen). But from a climate science perspective, it is also surrounded by asphalt, with a car park to the east. According to the Google Earth measurement tool, vehicles are parked within 6 meters of the Stevenson Screen.
But I really really wanted to get a ground level view to absolute ascertain the placement of the Stevenson Screen. Lots of web searches turn up nothing. I found pictures of the observatories, pictures of the Krupp gun, pictures of the skyline, but no pictures of the nearby weather station. After all, other than myself and surfacestations.org volunteers, who takes pictures of weather stations while on vacation? Still I figured, this is a major tourist spot, within walking distance of the top of the famous Wellington cable car, surely somebody had snapped a photo?
Then I discovered something in Google Earth called “Panoramio”, which had a whole collection of tourist submitted shots around the observatories.
Here’s the full image from Panoramio, the Stevenson Screen is clearly visible. Thank you J. Baines, wherever you are.
The car park asphalt at 6 meters away puts the station rating at CRN4, based on NOAA’s site quality rating system used for their Climate Reference Network. I’ve found that the vast majority of historical stations in the USA have been affected this way:
One wonders how this area has changed over time, and how long the car park has been there, and how much it, and the tourist vehicles that park next to the fence have contributed to the Kelburn climate record. Someone familiar with the history of the observatory might be able to shed some light on this. Was the screen always in this location? When did the car park go in? How many tree have been cleared around the site over the years? How many new buildings (Like the Carter Observatory) have but put up nearby? These are all issues which affect the temperature record. Disentangling those influences is difficult without an historical context.
I don’t blame the scientists at the observatory for letting the climate measurement environment at Kelburn deteriorate, after all they are charged with looking upwards, not at the grounds around them.