Sir Peter Blake Trust Ambassador Mitchell Chandler - in the field


Mitchell Chandler is the recipient of the Sir Peter Blake Trust Climate/Atmospheric Research Award. In his role as a Sir Peter Blake Trust Ambassador, Mitchell is currently based at NIWA's campus in Wellington working alongside NIWA Scientists to conduct field measurements of climate and atmospheric variables.

During my time here at NIWA I am associated with the TROPAC group (TROpospheric Physics and Chemistry) which looks at many different details of our troposphere. This means that I have the opportunity to be involved in a variety of different projects.

This past week I have been based in Wellington. My favourite aspect of being here so far has been the field work.  I have been able to get out in the field twice this week. The first of these field trips was through the inner city, while the second was out to Baring Head.

Measuring nitrogen dioxide in Wellington city

The purpose of the first field trip was to replace small glass cylinders around the inner city. These cylinders contain filter paper that chemically reacts with NO2 (nitrogen dioxide). The filters can then be analysed to see how much NO2 is present in the surrounding air. NO2 is a pollutant aerosol that is produced through combustion (such as in engines) and negatively affects air quality. Most of the glass cylinders are located along major bus routes (with some in less used streets), with the purpose of measuring how much NO2 is produced along major bus routes, compared to the city's background levels. This project is mostly driven by the talk of Wellington phasing out their electric trolley-buses in favour of diesel buses. If this does happen the difference in NO2 pollution before and after the change can be quantified by comparing datasets. 

Baring Head

Baring Head. [Mitchell Chandler]

My second field trip was to Baring Head, a NIWA air monitoring station near Wellington. We were there to replace some old monitoring equipment. This ‘change-over’ has to happen every few years as equipment gets corroded by salt (and weathered by wind and rain etc.). On top of this we also carried out some of the usual weekly tasks. I was charged with 'cleaning' out the water traps and taking a manual air sample for Scripps Oceanographic Institute. The water trap is a super-cooled system (surrounded by ethanol at approximately –80 C) with glass beads inside a metal cylinder. As air passes through the glass beads the water in the air freezes out. The water is removed from the air as this gives more accurate readings of gases such as CO2 and CH4. Cleaning the water trap is essentially just removing the cylinder and pulling it apart, then heating each component with a heat gun to evaporate off the water. The system is then put back together and can continue functioning to remove water out of the air for another week. If the water trap is not cleaned, ice can accumulate stopping the air from passing through the system. 

Taking the air samples for Scripps Institution of Oceanography. The method through which these samples are taken has not changed since the first samples were taken at Hawaii in the 1950's. Samples can only be taken at Baring Head during southerly wind conditions to prevent the air from being altered by land processes.

In the lab

I have also enjoyed being in the lab and during the past week have helped out in the gas lab with data analysis, as well as building gas traps for a methane project in Fiji. These gas traps will be sent over to Fiji (along with a tank of methane gas that I helped calibrate) and installed around a landfill near Suva. This will enable the amount of methane coming out of the ground and landfill to be measured. Methane is a significant greenhouse gas, however can also be burnt to produce heat and energy. Therefore gas is measured to see if it is feasible for a system that will capture the methane gas and burn it for energy.

One of the finished gas traps.