

Show HN: PressureNet – The Weather's Future - cryptoz
http://pressurenet.io/?newsitehn

======
mturmon
From the top of the about page
([http://pressurenet.io/about/](http://pressurenet.io/about/)) -- "Our mission
is to dramatically improve weather and climate forecasting."

How does this have to do with climate? It seems like your time scale doesn't
overlap with typical climate models. I guess it feels like a speculative claim
(better pressure measurements -> fine-grained model improvements at small
temporal scales -> better climate model outcomes).

Also, I wonder if you have a link to a paper or presentation that details how
these measurements could fit in with the assimilation models that are used in
weather forecasting? I see a link to Cliff Mass' blog (as a whole), but I'm
more interested in a specific reference. In particular, I wonder if it's
possible to quantify how much a perfectly-accurate ground-level pressure field
could constrain upper atmosphere dynamics. Has there been a session at AGU
([http://fallmeeting.agu.org/2014/](http://fallmeeting.agu.org/2014/)), for
example, examining how this could work? Or is it too new for this yet?

~~~
cryptoz
Excellent questions. Regarding climate: there are many indications that
measurements of atmospheric pressure are useful in forecasting longer-range
trends. For example, the pressure over the Tibetan plateau can have a large
affect on El Niño. Additionally, we've collected atmosphere data over a period
of years, and we expect to find interesting climactic trends as well as
shorter-term weather trends.

Here's a paper by Cliff and Luke regarding dense surface-level pressure
observations:
[http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-13-00269.1...](http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-13-00269.1?af=R)

> I wonder if it's possible to quantify how much a perfectly-accurate ground-
> level pressure field could constrain upper atmosphere dynamics

Yes it is possible and we're working on this currently. There are some neat
math techniques that we can use to estimate what kind of forecast accuracy
increase we'll get with a dense network - but the only way to actually know is
to scale up and start running experiments to find all the thresholds for
improvements and diminishing returns.

~~~
mturmon
Thanks for the _MWR_ reference. It's really great you've got people within
that community so interested.

"...we've collected atmosphere data over a period of years, and we expect to
find interesting climactic trends..."

Hmm, multi-year-scale trends in pressure data, as seen through a temporally-
evolving sensor network subject to many kinds of extraneous variations
(hardware changes, spatial sampling changes)? Color me skeptical on that one.

But that's typical HN "yes, but" skepticism. What you're doing sounds great
and the case for weather is clear. Best wishes!

------
smoyer
I've gotten into the habit of not installing applications that ask for access
to my Google accounts. I'm also curious as to why this application needs to
prevent my phone from sleeping ... wouldn't waking up every 15 minutes and
taking a sample be enough?

~~~
cryptoz
We don't ask for permission for your accounts at all actually - we just ask
permission to use Google Maps, which Google unfortunately lumps together. The
app is open source on GitHub so you can verify that we don't do anything
weird. For example, here's our AndroidManifest.xml file that shows the
permissions we list in code:
[https://github.com/Cbsoftware/pressureNET/blob/master/Androi...](https://github.com/Cbsoftware/pressureNET/blob/master/AndroidManifest.xml)

READ_GSERVICES is the permission in question and is required for Google Maps.
I'd like to switch to an open mapping tool but it's not a top priority right
now.

As for the sleeping mechanism: you're correct, an in fact we do only wake the
phone up every x minutes. It's off ~99% percent of the time. We require the
wakelock to ensure that the phone stays on long enough for us to measure the
barometer and store/transmit the data. We don't keep the device on for any
longer than absolutely required.

~~~
smoyer
READ_GSERVICES being so "wide" was one of my major complaints about Android
... and while I'm sure you guys are ethical, there are a lot of applications
I'd like to have that insist on having this permission.

Once you've granted the permission, any future version of even an app you've
verified can expand its use of that permission into data I'm not willing to
share. I know it's not your fault but you still end up being the victim (of my
effort not to be a victim).

~~~
criley2
Google's permission model is fundamentally flawed.

Google in it's insanity has required an "all or nothing" approach to
permissions. Because of this, the vast majority of all users must accept all
permission requests up front, and developers are highly motivated to ask for
more than they need up front to prevent asking for more later.

The far, far superior model for permissions is for basic permissions to be
granted at install, and each new permission to be requested at run time.

But, how can the majority* of your apps download personal information, hijack
your contact list, and spy on your location if you have to explicitly give
them the permission to do so when they begin the function...

* I'm being hyperbolic, but we have very few ways of actually knowing how many apps abuse their permissions. Generally, one or two popular ones get "called out" for doing what everyone is doing, and everyone descends back into feigned ignorance at permission abuse.

------
danparsonson
Love the idea; naive, noobie question: since your sensor density presumably
depends very much on population density, how does this affect your model? I
was under the impression that regularly-spaced measurements were important but
presumably not so much? Or is this still better (or will be eventually) than
the national network?

~~~
cryptoz
Population density is indeed a problem for us. Some of the most severe weather
like tornados and supercell thunderstorms (and hurricanes for that matter)
don't happen in high smartphone density areas. What we're finding is that in
cities we are already reaching the density required for useful weather
forecasts, so we're fine for now in terms of density....for now.

However, as we grow and expand it will eventually become important to start
building drones and buoys to help us collect this high-res data without
smartphones. The end vision is a high-density network of sensors all over the
globe to continuously feed live data to models. We'll solve this however we
have to, and I think the solution is eventually a roaming drone network. We'll
see.

~~~
darkmighty
How is a roaming drone network better than simple low cost sensors powered by
sun/wind? (ie what's already in use)

Another question: how do you intend to tackle sensor inaccuracy? What about
manufacturer biases that cannot be averaged out?

~~~
cryptoz
Well, I'm not sure that a drone network would be better - it's just a hunch.
We have so much growth left inside the smartphone world that our focus is
exclusively on smartphone sensor acquisition right now (through our SDK
platform approach). Stationary sensors are in our horizons too, definitely.

In terms of sensor accuracy: luckily, one of the most valuable metrics we're
watching is actually pressure tendency over time and not necessarily absolute
pressure values. This means that even offsets of 2-3mbar are okay as long as
the trends are visible (which they are).

Absolute pressure is valuable too, so we're developing some techniques to deal
with corrections for altitude noise as well as manufacturer bias - none of
this is live yet, though.

------
cmpb
I enjoyed looking through your blog
([http://pressurenet.io/blog/](http://pressurenet.io/blog/)). Do you perhaps
have a rss/atom feed for the blog or plan to have one at some point?

------
beardicus
404 on the "Read the full documentation" link under "API" on the API page.
(Edit: I see you already found the broken link and the file is yonder
[http://apps.cumulonimbus.ca/PressureNetDataAPI-v2.pdf](http://apps.cumulonimbus.ca/PressureNetDataAPI-v2.pdf)
)

Do you have any examples/links to research being done with the data currently?
I poked through the blog quickly and didn't see anything in depth.

~~~
cryptoz
Here's a recent paper being published by Cliff Mass and his students and
colleagues:
[http://journals.ametsoc.org/doi/pdf/10.1175/MWR-D-13-00269.1](http://journals.ametsoc.org/doi/pdf/10.1175/MWR-D-13-00269.1)
That's a good comment though: we should have more details and visualizations
of the active research. Thanks for the heads up.

------
eutropia
Is there any concern about people spending most of their time inside, which
might have a higher pressure than outside because of climate control?

~~~
cryptoz
Inside vs outside isn't really a problem actually, the pressure is effectively
the same. The bigger issue is altitude changes, which even small amounts can
cause noise...but there are ways to filter that out.

------
torstesu
Any chance the Netatmo weatherstation will be able to supply data in the
future? Quite alot of them out there [1], and I would love to contribute.

[1] [http://www.netatmo.com/en-
US/product/community/station#view2](http://www.netatmo.com/en-
US/product/community/station#view2)

------
dandelany
Game Oven Studios posted this Vine yesterday about why it's so hard to develop
on the fragmented Android platform:
[https://vine.co/v/MgWLMmmwUQQ](https://vine.co/v/MgWLMmmwUQQ) Do you guys not
run into this same problem with pressure sensors?

~~~
yellowbkpk
The Vine you link to isn't necessarily a problem with Android itself. Sure,
Android runs on several different devices from lots of different vendors that
all use different hardware (which is a good thing), but the compass sensor
shown here is notoriously finicky. Simply having the devices near other metal
(like other phones) will cause completely erroneous data.

------
cryptoz
Oops, the API page has a link to documentation that's 404ing right now, we'll
fix that ASAP. Here's the file:
[http://apps.cumulonimbus.ca/PressureNetDataAPI-v2.pdf](http://apps.cumulonimbus.ca/PressureNetDataAPI-v2.pdf)

------
LamaOfRuin
Is there information anywhere about what, if any, license (CC or otherwise)
the data is/would be under? All I saw was that the SDK is MIT.

------
lazyant
isn't this similar to weathersignal.com ?

~~~
cryptoz
Well, it's more like weathersignal is similar to this - we launched our
project a year or two before theirs.

