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I am working on a case from a paper talking about a decomposition method to quantitatively differentiate wind and non-wind effect on HK air pollution.

One case in the paper need to draw wind rose and pollution rose to analyze the wind influencing pollution concentration.

I used openair package in R to draw the figures, but I was not sure the difference between function pollutionRose and polarPlot in that package.

In addition, I feel like knowing if I can get the difference between two polarPlots or pollutionRoses using this package.

This is my first time asking questions. I will be very thankful for any help!

Vladimir Vagaytsev
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Zhong Chen
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  • I feel like you could easily find this yourself in the documentation. But I could be wrong. – Rich Scriven Jul 10 '16 at 18:06
  • Thanks for your reply! I did download the 'openair' manual by myself and was working on it these days. But it seems not clear when demonstrating the function pollutionRose in the manual. – Zhong Chen Jul 12 '16 at 02:32

1 Answers1

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The differences between those two plotting functions is the informational function behind each one.

The pollutionRose is a wrapper around the windRose functions and its MAIN intent is to elucidate the effect of wind DIRECTION on the dispersion of a specific pollutant. It has the features of both the radiating 'blades' length and the evolving color to show the contribution of pollution due to wind from a given direction.

The polarPlot is bivariate. It is designed to illuminate the effect of both wind SPEED and wind DIRECTION on the movement of air pollution. This plot shows a continuous series of tones that reflect the mean concentrations by changing hue. The color and intensity at a given location on the plot reflects the concentration. This type of plot can also accomodate other features such a temperature or pressure.

In a super simple summary:

pollutionRose illustrates the proportion of contribution based on wind direction (how much of the pollution comes from a given wind direction)

polarPlot illustrates the localized concentration mean based on wind direction and speed (how much is present at a specific regions of the plot based on the wind direction and speed and other factors)

So you should pick based on what you are trying to show.

sconfluentus
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  • Thx a lot for your detailed answer. I have a further question. Given that pollutionRose did nothing with ws, I deleted the wind speed in 'mydata'. In this way the pollutionRose function do not work anymore. But why? – Zhong Chen Jul 10 '16 at 17:20
  • It does look at the speed to estimate how pollution moves (the speed effects diffusion) but it is more concerned with looking at the contribution that each direction brings. I have yet to see a wind or wave model for pollution that does not use both speed and direction, even if it's predominant function is to estimate the influence of just one. You should add it back in if you still have the data. – sconfluentus Jul 10 '16 at 18:02
  • Thank you very much again!!! You are quite professional on this question. And I'm wondering if you can give me a hand on a related question, which is "Can I get the spatial product (the difference spatially) from two polarPlots?" Or to move a small step forward, "Can I get the difference spatially between one windRose and one pollutionRose?" – Zhong Chen Jul 12 '16 at 02:46