Solar atmospheric tides?

[Nick James]

I have a weather station in the garden which has been recording barometric pressure since 2010. For fun I have just folded the pressure recordings to 24 hours using 1/2 hour bins. Each bin is an average of around 45000 readings. The folded version shows a nice semi-diurnal period which I assume is the effect of Solar atmospheric tides. The peaks seem to be in an odd place though (10h and 22h UTC). I’d be interested if anyone else has tried this. It is easy to bin the data with a folding period of 24h. I need to write a script now to bin it phased with the Moon to see if I can pick up lunar tides.

Attachments:

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   pressure_long.png
   

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   pressure_binned.png
   

[Mr Wiliam Graeme Waddington]

Nick

   A similar graph can be found in a short paper in Weather (2011), online at https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/wea.857

Graeme

Graeme

[Dr Andrew Smith]

Two things one the equation if time so that meridian crossing of the sun is not exactly at noon or midnight UTC and sea tides lag the moon position. Not sure what impact they have though.

Regards  Andrew 

[Peter Meadows]

Nick,

This http://www.met.reading.ac.uk/~williams/publications/10.1002_wea.1890.pdf will be of interest suggesting analysis during the year will also be useful.

Peter

[Nick James]

Thanks for all the links and references. I hadn’t realised that the Solar atmospheric “tides” were actually thermal rather than gravitational unlike the lunar one which is definitely gravitational or that the solar tides lead to small (mm) deformations in the solid body of the earth. Yet another small cause of the increase in day length. Anyway, I have a big dataset and will write some code to do a proper analysis of this for the sun and moon and see what I can find.

[Author]

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