Brisbane CO2 for 3 July 2023

With values slightly higher and winds more southerly, a simple test of the hypothesis of an association between Brisbane’s CO2 concentrations and wind direction seemed in order.  Step 1) Calculate the average wind direction from the BOM’s 9am and 3am reports as recorded at Archerfield for each of the last 25 days. Step 2) Calculate the absolute difference between 270 degrees and each of these values.  If zero, this number indicates winds from the west, if higher it indicates directions increasingly further away from the west.  Step 3), calculate the Pearson correlation between the daily average concentration across our three sensor sites and this value for those 25 days.  The result? r = 0.454, p= 0.02.  The tentative interpretation of this outcome – very unlikely to be due to chance? Winds from the west tend to bring air with lower carbon dioxide concentrations, winds from other directions tend to bring air across the city, with higher concentrations.  This isn’t just because two of our three sensors are towards the west – it’s also that the population distribution of Brisbane leaves a relatively less populated notch towards the west, meaning there is “less city” between even the CBD and the western urban edge than for other directions. A limitation of this analysis is that wind speed isn’t taken into account, and this could exert its own effect by simply pushing anthropogenic emissions out of the city and diluting the concentrations, irrespective of direction.  With more data, this factor can also be examined.

Daily Averages – Phase 2 (See explanation of differences between Phase 1 and Phase 2 data)

For reference, latest monthly average (May 2023) from CSIRO for Kennaook/Cape Grim in NW Tasmania was 415.7 ppm. (Note – these are provisional values, subject to revision folllowing sensor re-calibrations and other checks.)

DatePetrie TerraceChapel HillBellbird Park
3-Jul-2023428 ppm429 ppm412 ppm
2-Jul-2023424 ppm425 ppm414 ppm
1-Jul-2023419 ppm407 ppm405 ppm
30-Jun-2023414 ppm405 ppm402 ppm
29-Jun-2023415 ppm409 ppm405 ppm
28-Jun-2023435 ppm427 ppm428 ppm
27-Jun-2023426 ppm409 ppm415 ppm
26-Jun-2023412 ppm402 ppm412 ppm
25-Jun-2023447 ppm426 ppm429 ppm
24-Jun-2023427 ppm417 ppm423 ppm
23-Jun-2023434 ppm427 ppm435 ppm
22-Jun-2023442 ppm425 ppm436 ppm
21-Jun-2023443 ppm421 ppm437 ppm
20-Jun-2023421 ppm414 ppm417 ppm
19-Jun-2023430 ppm418 ppm419 ppm
18-Jun-2023436 ppm426 ppm434 ppm
17-Jun-2023440 ppm429 ppm437 ppm
16-Jun-2023438 ppm421 ppm433 ppm
15-Jun-2023433 ppm412 ppm428 ppm
14-Jun-2023435 ppm425 ppm438 ppm
13-Jun-2023441 ppm436 ppm442 ppm
12-Jun-2023442 ppm439 ppm448ppm
11-Jun-2023443 ppm441 ppm451 ppm
10-Jun-2023446 ppm432 ppm4444 ppm
9-Jun-2023441 ppm428 ppm440ppm
CO2 concentrations for Phase 2
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