From 4 June to 15 September 2019, the MAPM team has conducted a field campaign in Christchurch to collect a wide variety of data to test and validate the MAPM method. 50 ODIN (Outdoor Dust Information Node) instruments and 17 ES-642 sensors have been distributed around the city, measuring pollution levels in the air every minute. Furthermore, we set up three automatic weather stations that measured temperature, humidity and wind speed/direction at several locations around Christchurch. These meteorological measurements are an essential input required by the inverse model. A micropulse lidar and a ceilometer provided vertical profiles of air pollution while the other instruments measured the pollution levels on the ground.

The distribution of instruments during the MAPM field campaign. Additionally, data from privately owned weather stations were used (not shown here).

The purpose of this campaign is not to be the ‘air quality police’ but rather to collect the air quality data that the MAPM inverse model requires as input. We have been relying on the generosity of many members of the public who have kindly offered to host different instruments and would like to thank all of those involved for their support for this campaign. We have collected a rich data set which we are using to test different aspects of the MAPM method. Key questions we will be looking to answer from the analysis of the data collected through the field campaign include:

• How do uncertainties in the meteorological data fields affect the quality of the emissions maps we extract from our inverse model; after all we can’t measure the meteorological data everywhere. If you have a meteorological station in your back yard and are willing to share those measurements with us, please contact us (see below).

• How does the spatial and temporal resolution of the air pollution concentration measurements affect the uncertainties in the retrieved pollution emissions maps?

• Where would investment in additional meteorological or air pollution measurements best reduce uncertainties in the retrieved pollution emissions maps for a given city?

Specific instruments that were deployed during the 3-month field campaign include:

  • A miniMPL that we rented from the University of Canterbury.
  • 50 ODIN instruments that we purchased from NIWA.
  • 10 ES-642 instruments that we rented from Mote.
  • 3 ES-642 instruments that were provided by Environment Canterbury.
  • 4 ES-642 instruments that were provided by the University of Canterbury.
  • 3 temporary weather stations, measuring temperature, pressure, wind, and humidity that we rented from NIWA.
  • 12 GRAW radiosondes were launched during two 24-hour periods in July and August 2019. The vertical profiling allowed us to measure the conditions in the boundary layer and above at high temporal resolution over the course of a night. The radiosonde measurements took place during two nights that exhibited quite distinct meteorological conditions, one night was foggy and the other night was cold and clear. During both of these nights, a temperature inversion formed, which typically leads to especially bad air pollution in Christchurch. Given the lack of regular radiosonde observations from Christchurch, this data set will be invaluable for MAPM. The GRAW radiosonde ground station was kindly provided by the Otago University.

We would like to express our gratitude to ECan, University of Otago, Nariefa Abrahim (PhD student based at Otago University), Jan-Niklas Schmidt (DAAD intern), and Jonathan Barte (intern). Thank you very much for all the efforts and continuous support during the MAPM field campaign. We really appreciated your help.