WU Wind graphs

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Praveen Chandrasekaran

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Jul 26, 2019, 1:15:52 AM7/26/19
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Hi,

I am seeing that on stations with rapdifire, WU is not differentiating wind speed and wind gust in graph correctly. However in stations without rapidfire it is fine.

Example my station with rapidfire:


Another station without rapidfire:


Is this issue arising from weewx by any chance?

Regards,
Praveen

Praveen Chandrasekaran

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Jul 26, 2019, 1:26:49 AM7/26/19
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Andrew Milner

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Jul 26, 2019, 1:59:47 AM7/26/19
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I would suspect WU ignore windgust on rapidfire because you need a sustained period of I think 3 seconds for the gust to count as a gust in metereological definitions - and the rf interval is probably too short - so gust will always equal speed in rf situations.  

Praveen Chandrasekaran

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Jul 26, 2019, 2:01:30 AM7/26/19
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The table somehow has it right. The graph alone is wrong.

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Andrew Milner

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Jul 26, 2019, 2:27:50 AM7/26/19
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if from rf it has no gusts it cannot graph them.  non rf sites will provide a gust value per archive interval.  who knows what wu do when they receive both rf and archive record data!!  The tables may well create an artificial gust value from rf speeds, but again who knows what wu use to create the graphs!!



On Friday, 26 July 2019 09:01:30 UTC+3, Praveen Chandrasekaran wrote:
The table somehow has it right. The graph alone is wrong.

On Fri, 26 Jul 2019 at 11:29, Andrew Milner <andrew....@gmail.com> wrote:
I would suspect WU ignore windgust on rapidfire because you need a sustained period of I think 3 seconds for the gust to count as a gust in metereological definitions - and the rf interval is probably too short - so gust will always equal speed in rf situations.  

On Friday, 26 July 2019 08:26:49 UTC+3, Praveen Chandrasekaran wrote:
Related wxforum post:



On Friday, 26 July 2019 10:45:52 UTC+5:30, Praveen Chandrasekaran wrote:
Hi,

I am seeing that on stations with rapdifire, WU is not differentiating wind speed and wind gust in graph correctly. However in stations without rapidfire it is fine.

Example my station with rapidfire:


Another station without rapidfire:


Is this issue arising from weewx by any chance?

Regards,
Praveen

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Praveen Chandrasekaran

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Jul 26, 2019, 3:42:14 AM7/26/19
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If I set rtfreq to a higher value like 5 seconds, should that resolve the issue? 

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Andrew Milner

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Jul 26, 2019, 5:32:51 AM7/26/19
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i doubt it very much.  what weather station do you have?
changing the rf frequency changes the upload to wu interval but the station will still be being polled as before.  Does the station provide the gust value in the LOOP data?  If not then the gust value is an artificial one created by weewx from loop records wind speeds received.  If your station provides partial packets as LOOP data you could always try and set the wu flag that set specifies windGust must be present before rf is uploaded

On Friday, 26 July 2019 10:42:14 UTC+3, Praveen Chandrasekaran wrote:
If I set rtfreq to a higher value like 5 seconds, should that resolve the issue? 

Praveen Chandrasekaran

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Jul 29, 2019, 2:24:19 AM7/29/19
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My weather station is Davis Vantage Vue. I believe it never emits partial packets.

Andrew Milner

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Jul 29, 2019, 2:59:51 AM7/29/19
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I really do not see how you can have a meaningful gust value from readings submitted every few seconds!!  I see from the Davis comms protocol the gust values are in LOOP2 packets and the smallest appears to be a 2 minute gust value.

Setting debug=1 may shed more light on what is actually being sent to WU

Praveen Chandrasekaran

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Jul 29, 2019, 5:40:27 AM7/29/19
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Hmm. Will try. Before the WU overhaul it was showing them separately on the graph though. The gust value from LOOP2 seems to be 10 min wind gust while the wind speed sent out is the instantaneous wind speed from LOOP packet I believe? This may explain why wind speed and wind gust are same in graph. But then how does the table have different values. U never know with WU! :)  

As you mentioned will set debug=1 and observe sometime.  

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Praveen Chandrasekaran

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Jul 29, 2019, 5:54:52 AM7/29/19
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Looking at below:


WU expects wind speed average over 2 min average and 10 min gusts and instantaneous speed. Did something change in this recently? Looking at weewx code from restx.py I am not sure if weewx uploads all these? 


winddir - [0-360 instantaneous wind direction]
windspeedmph - [mph instantaneous wind speed]
windgustmph - [mph current wind gust, using software specific time period]
windgustdir - [0-360 using software specific time period]
windspdmph_avg2m  - [mph 2 minute average wind speed mph]
winddir_avg2m - [0-360 2 minute average wind direction]
windgustmph_10m - [mph past 10 minutes wind gust mph ]
windgustdir_10m - [0-360 past 10 minutes wind gust direction]

Andrew Milner

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Jul 29, 2019, 6:18:22 AM7/29/19
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I do not think weewx reads LOOP2 packets - so none of the LOOP2 data is available.



On Monday, 29 July 2019 12:54:52 UTC+3, Praveen Chandrasekaran wrote:
Looking at below:


WU expects wind speed average over 2 min average and 10 min gusts and instantaneous speed. Did something change in this recently? Looking at weewx code from restx.py I am not sure if weewx uploads all these? 


winddir - [0-360 instantaneous wind direction]
windspeedmph - [mph instantaneous wind speed]
windgustmph - [mph current wind gust, using software specific time period]
windgustdir - [0-360 using software specific time period]
windspdmph_avg2m  - [mph 2 minute average wind speed mph]
winddir_avg2m - [0-360 2 minute average wind direction]
windgustmph_10m - [mph past 10 minutes wind gust mph ]
windgustdir_10m - [0-360 past 10 minutes wind gust direction]

On Mon, 29 Jul 2019 at 15:10, Praveen Chandrasekaran <prave...@gmail.com> wrote:
Hmm. Will try. Before the WU overhaul it was showing them separately on the graph though. The gust value from LOOP2 seems to be 10 min wind gust while the wind speed sent out is the instantaneous wind speed from LOOP packet I believe? This may explain why wind speed and wind gust are same in graph. But then how does the table have different values. U never know with WU! :)  

As you mentioned will set debug=1 and observe sometime.  

Andrew Milner

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Jul 29, 2019, 6:19:43 AM7/29/19
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slight correction - the LOOP2 data is more than likely software generated by weewx

Praveen Chandrasekaran

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Jul 29, 2019, 6:24:00 AM7/29/19
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Understand that weewx does not read LOOP2 packets. Did not get the part about " LOOP2 data is more than likely software generated by weewx"

The LOOP2 packet format is specified in Davis protocol and it seems to be containing some data that WU is expecting. Shouldnt weewx be reading it then? Not sure if something changed in WU upload protocol as well. The earlier wiki link with upload protocol no longer works! So I am not sure what the protocol was before. 

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Andrew Milner

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Jul 29, 2019, 6:41:41 AM7/29/19
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I suspect there is some history involved.  As far as I can make out, if LOOP2 data were to be read then the packets are alternated with LOOP - which would result in LOOP packets being received every 5 seconds instead of every 2.5 seconds - perhaps that is why they are not being read!!!  As to whether they should or should not be why not make a posting on the development group!!

What I mean was that dewpoint and heatindex and other items which are actually in LOOP2 packets I believe are software generated in weewx, and not read from the station.


On Monday, 29 July 2019 13:24:00 UTC+3, Praveen Chandrasekaran wrote:
Understand that weewx does not read LOOP2 packets. Did not get the part about " LOOP2 data is more than likely software generated by weewx"

The LOOP2 packet format is specified in Davis protocol and it seems to be containing some data that WU is expecting. Shouldnt weewx be reading it then? Not sure if something changed in WU upload protocol as well. The earlier wiki link with upload protocol no longer works! So I am not sure what the protocol was before. 

Praveen Chandrasekaran

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Jul 29, 2019, 8:12:30 AM7/29/19
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Thanks. Posted in weewx-development group also.

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