CONA - Community Observation Networks for Air

In air quality lingo  we normally refer to small areas of increased pollutant concentrations as hot spots  but since this story is about the temperature  field I needed to use something else ... warm spots  will do. As part of the measurement campaign we deployed in Rangiora we not only used ODINs but also four weather stations (like the one on the picture) scattered around the town to explore small scale wind flows and how uniform or otherwise the temperature field is in the area. Before we dive too deep in the analysis, let's pause and look at the two kind of temperature sensors used here. First is the meteorological sites that have thoroughly calibrated and well housed thermometers, protected from the sunshine while the ODIN thermometers were ... well ... not perfectly housed (see image of the inside of an ODIN) and then put in plain sunlight attached to lamp posts (see image of ODIN attached to a lamp post). Now, don't despair! There is a reason why the ODIN tem...

The main reason we asked for some volunteers to accept temperature sensors in the home was to track when people were using their woodburners and how that might change from day to day. But the data from these sensors reveal a whole lot more information if you care to look and we’re just starting to look now. The sensors themselves were thermocouples provided on loan by BRANZ  the building research institute. They consist of a probe which was attached to the top of the firebox and a logger placed nearby. So far I have looked through data from 9 of the 14 homes we surveyed. In a moment, a taste of some of the things we can work out from the indoor temperature data. But first, a quick look at the outdoor temperatures. Below is a 'box plot'. All of the data from every days is combined and sorted into hours. The middle 50 % of all data lies within the box (the short horizontal line is the average). The top and bottom 25% are represented by the dashed lines. This chart shows that, o...

Hopefully something more substantial than the fox! ... ( that song is still in my head after I let my kids get their hands on the radio!) [EDIT: Added missing link to full analysis script] Let's talk ODIN then ... Now that we have more data from the ODINs we can start to build answers to the questions: How uniform is the air pollution field in Rangiora? Is the plume of emissions recirculated under certain conditions? But there is a big caveat. The ODINs do not give us $PM_{10}$ and it cannot be directly compared to the measurements done by ECan. So ... let's dive in ... carefully. First, let's review where we installed the ODINs. Our original intention was to locate them in two west-to-east lines, one to the north of the town and another one to the south. We were fortunate to be able to use lamp posts for our deployments and Sally and Sam managed to get them pretty close to where we wanted them. This map shows the location of ECan's air quality stati...

Actually we were ... we got lots of data and that's what we wanted (sorry for the clickbait title ... a scientist has to have some fun right? ) Now in all seriousness, we were very pleased with the data from the first two weeks of PACMAN deployment in Rangiora. They allow us to test the units in a real world  setup outside of the researchers' control and evaluate whether the data we get from them can tell us something useful about the exposure of the people inside to particulate matter. Let's look at data from one unit PACMAN_17 and what it can tell us about the home it was living it. Temperature The PACMAN has an internal temperature sensor within its real time clock to keep it accurate. This is not quite room temperature  but it approximates it pretty well. See a comparison below between the temperature closest to the wood burner stack (BRANZ logger) and the internal PACMAN temperature. Not bad right! However, the same issue that I mentioned before remains ... it is not...

If you thought that we've gone away ... you're partly right, we've been away  but not in a bad way! About a week ago we got our first full set of data from a few of the participants in Rangiora and just to give you an idea ... for every home  we have about one million records with between 5 and 10 parameters each ... that's a lot of numbers! So, yes, we've been away but it has been trying to get our heads around this large dataset ... with various levels of success... as a German general said in the 1800s:  "No plan survives contact with the enemy" . At the beginning of this campaign we thought that the temperature data obtained through the iButtons  and BRANZ's loggers was going to be simple to interpret. High temperature = heater on, low temperature = heater off. The next level in complexity would be ECan's temperature and $PM_{10}$ data as it is standard compliant and we have a long time series for that location that would give us some context ...

A place to keep cows, but that's not important right now (if you need help with the reference ... see here ) By Worldview999 (Own work) [CC BY-SA 3.0], via Wikimedia Commons In atmospheric science we're always looking to have information about the vertical structure of the atmosphere. We can deploy weather stations to measure the wind speed and direction but we're always missing what's going on in the air above us. Of course there are ways to get information from higher in the air and we'll be using one of those in this project (helikite) which we'll cover when it's operating in Rangiora but now I'd like to talk about another piece of kit that we have deployed in the town. A Ceilometer . Ceilometers are intended to measure the ceiling , which means the height of the lowest cloud. These sensors send a light pulse and measure its reflection from clouds and aerosol layers to obtain this height. Ceilometer installed near the AWS site in Rangiora. Photo by Sa...

If you remember , we had some troubles with our outdoor sensors last week and one of them is still in pieces in our bench and the sledgehammer looks very tempting at this stage! I think that the rest of the units heard the message and are now behaving better . However, we're not entirely happy as a large peak in $PM_{10}$ concentrations observed on the night of the 11th of August was not captured by any of our units. Unfortunately we didn't get good weather (too warm) last week to test for another large peak in concentrations so we deployed the ODINs to their target locations last Friday and I'll be very busy looking at the data when we have the first download this coming Friday... stay tuned.

On Tuesday I told you about the tests of our PACMAN units before they were being deployed in our volunteers' homes. Now is the turn of ODIN (Outdoor Dust Information Node). A little bit of history ... After the first PACMAN deployments we realised that we needed to have information from the outside of the home as well as the inside so we developed a stripped down version of PACMAN focusing solely on the dust measurements. Here you can see a presentation we gave about the ODIN after the very first tests.   Now, we have six ODINs to be deployed in Rangiora but before we go ahead and distribute them across the town we need to know that they are working fine so we set all of them up at ECan's air quality station in Rangiora. For this test we're looking for indications that the units are recording all the data, that the temperature looks plausible and that the dust sensors respond to something other than temperature. In simple terms, we're looking for plots t...

Here is PACMAN in its native environment One of the key pieces of hardware we're deploying in this campaign is our PACMAN ( Particles, Activity and Context Measurement Autonomous Node ) ... not this pac-man . This little unit is capable of logging air quality parameters (dust concentrations, $CO_2$, $CO$), activity information (motion, distance to closest object) and context (time, temperature) every second. We expect to use this information to estimate what drives the indoor concentrations of dust in homes. All the participants that want to have instruments in their home will have one of these units installed but before we can do that we need to test if they are working as expected. So, we set them up in a bench facing a wall for a few days and as it is normal with experimental technology, not all of them worked perfectly but most of them did so we are go for PACMAN deployment. If you're curious as to what the data looks like ... here is a link to the test results of one of...

That's a trick question, I haven't told you what ODINs are! Well, ODIN stands for O utdoor D ust I nformation N ode and it is the name of our low-cost outdoor dust sensor. You may ask why not calling it "low-cost outdoor sensor" to which I would respond: for the same reason that Apple doesn't call their phones "high-cost shiny communication devices". A lot goes in a name and I believe that for a project to be successful it needs a good name. So, as strange as it sounds, we have a Norse god gathering data for us. The sensors themselves are rather simple. At the heart of the ODIN is an optical dust sensor that, together with a temperature and relative humidity sensor and a clock send data to a microcontroller which saves it on a micro-SD card. The ODIN is battery operated and it can run unattended for two months on a full 6Ah LiPo battery. Simplified schematics of ODIN (left) and an actual ODIN (right) with its internal components visible. A more in depth...