Topic: Weatherlink Data

[ocala]

Looking at the browse screen on WL software there is an  item I am not familiar with.
 Inside Air Density which is .0730. Under the Index in the help screen there is no listing for this.
Does anyone know what this is? Even Googling it I'm still not sure.
The software also measures something called EMC which is the moisture density in wood.
Who knew?
 

[davidg_nz]

Air density is discussed in AppNote 14. According to my notes the formula in that doc matches the values WeatherLink produces.

EMC is covered by AppNote 22. According to my notes the values in the supplied table don't match the values produced by WeatherLink (for a Vantage Pro2 at least), and that the formula in this doc give much closer (but not identical) results. My implementation of the formula was 0.05-0.07 below the values from WeatherLink in three random tests. Never got around to figuring out why - EMC wasn't very interesting and I got distracted trying to implement the THSW formula

[TraderGary]

Looking at the browse screen on WL software there is an  item I am not familiar with.
 Inside Air Density which is .0730. Under the Index in the help screen there is no listing for this.
Does anyone know what this is? Even Googling it I'm still not sure.
The software also measures something called EMC which is the moisture density in wood.
Who knew?

The new Davis WLL (WeatherLink Live) doesn't report either item. I'm using the current Davis WLL Internet browser app in Microsoft Edge on Windows 10 and the latest Davis WLL Android app on a Google Pixel 3XL. Can anyone report if they see either item with the Apple iOS Davis WLL app?

[johnd]

I haven't explicitly checked, but I wouldn't necessarily expect either EMC or air density to be there. Both are obviously derived values and the whole thrust of wl.com via eg WLL seems to be not to provide many such values, at least not beyond a basic set like Dew Point, wind chill etc. The philosophy of wl.com looks like being a focus on actual sensor readings rather than derived ones. The extra values are easy enough for the user to calculate if the local need is there. In 20+ years of dealing with Davis stations I can't remember anyone, not even once, asking about EMC. Air density was of marginally more interest in the car tuning fraternity, but with the demise - to a large extent - of carburettors and the presence of more sensors actually on the engines that interest has mostly lapsed too.

[PaulMy]

Hi Dave,
I had noticed those in WLPC data but never thought about what/why?


Checking the WLPC Browse station data and comparing to the WL.com data there are some differences.
WLPC has Wind Run, Solar Energy, the EMC and In Air Density, along with some stats like Wind Samp, Wind TX, ISS Recept, Arc. Int.
WL.com has Wet Bulb, and several High and Low Hum, Dew Point, Wind Chill, Heat Index,
etc.


Enjoy,
Paul

[davidg_nz]

Solar Energy is just Solar Radiation converted to langleys (1Ly == 11.622Wh/m^2). Not sure what this is useful for or why you wouldn't just use Wh/m^2.

Wind Samp, Wind TX and Arc Int are useful for calculating ISS Recept - the percentage of received Wind packets (Arc Int & Wind TX give you the approx. number of expected packets, Wind Samp is the number of received packets)

I'd be a little surprised if ISS Recept wasn't available in some form - seems like an useful stat to have. Looking at the 2018 data for one of my old stations I clearly needed to put the console somewhere better:

[johnd]

Solar Energy is just Solar Radiation converted to langleys (1Ly == 11.622Wh/m^2). Not sure what this is useful for or why you wouldn't just use Wh/m^2.

Agreed. Langleys has always been rather an obscure unit, but I imagine it's baked into the WL way of doing things. Personally, I've always used MJ/sqm for daily TSE.

Wind Samp, Wind TX and Arc Int are useful for calculating ISS Recept - the percentage of received Wind packets (Arc Int & Wind TX give you the approx. number of expected packets, Wind Samp is the number of received packets)

It's a shame that RSSI never made it into the data reported by old WL, though it is there in the WLL data.

I'd be a little surprised if ISS Recept wasn't available in some form - seems like an useful stat to have. Looking at the 2018 data for one of my old stations I clearly needed to put the console somewhere better:

All the relevant transmitter and WLL Health data (including RSSI  and much else) is contained in the data structures returned from wl.com by the v2 API.