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Weather Software => Other Weather Software => Topic started by: ginahoy on August 31, 2021, 03:12:34 PM

Title: effect of wind on rainfall measurement
Post by: ginahoy on August 31, 2021, 03:12:34 PM

Hello, I know from past experience that identical, ideally placed rain gauges can still end up with different readings due to wind effects. Where I live (SE Arizona), the majority of our annual rainfall occurs during July-Aug monsoon season and is typically associated with thunderstorms and stout wind. I'm curious how official NWS reporting stations overcome wind effects.

Title: Re: effect of wind on rainfall measurement
Post by: miraculon on August 31, 2021, 04:42:30 PM

Probably one or more of these, I have seen them surrounding the NWS rain gauges at the local (KAPX) site. They have several concentric rings of them.

https://www.campbellsci.com/windscreen260-953 (https://www.campbellsci.com/windscreen260-953)

(https://campbellsci-res.cloudinary.com/image/upload/c_limit,f_auto,w_500,h_500/6040.png)

Here is the NWS rain gauge installation at DFW:

(https://dmn-dallas-news-prod.cdn.arcpublishing.com/resizer/9hN69U_g6EOU8K7u9NvUJVR7xw8=/1660x934/smart/filters:no_upscale()/arc-anglerfish-arc2-prod-dmn.s3.amazonaws.com/public/7QJ6R7LYQ3MMQ55CBSJAHINMNE.jpg)

Greg H.

Title: Re: effect of wind on rainfall measurement
Post by: miraculon on August 31, 2021, 04:50:23 PM

perhaps "Other Weather Software" is not the ideal location for this thread...

not sure what the subject has to do with weather software.

Greg H.

Title: Re: effect of wind on rainfall measurement
Post by: ginahoy on August 31, 2021, 05:20:03 PM

Thanks, Greg. Sorry, I meant to post in "Other Weather Station Hardware"... perhaps the moderator will move...

Title: Re: effect of wind on rainfall measurement
Post by: the beteljuice on August 31, 2021, 07:27:19 PM

Re. miraculon pics ....

The first is an 'Alter' windscreen.

The NWS installation is an odd mix of an inner 'Nipher' screen and an outer 'Alter' screen.

Explanations can be found here https://www.fs.fed.us/t-d/pubs/pdfpubs/pdf02252325/pdf02252325dpi72.pdf together with comparisons. Generally the 'Nipher' is used in snow locations.

... but you can do the same thing with one or two picket fences (the tops should be level with the top of the gauge)

Going back to 'old school' I have seen a few circular 'turf wall screens' (https://cumulus.hosiene.co.uk/viewtopic.php?p=84226#p84226) in the UK at old Met Office sites.

You can even put them in a ground level 'pit' (http://www.ecn.ac.uk/measurements/technical-notes/ground-level-rain-gauge) !