Tide Gauge Back Up

Some maintenance required, new battery installed.   It should be up and running again.

Do you need to measure Tides, or other water levels?

Shortly after starting this blog I was contacted by the folks at ioBridge.com.    If you've been reading this blog for a while (or care to go back through history), you'll see my design was based on the ioBridge sensor gateway.

Using their easy to use internet sensor interface, they built a tide gauge which they are considering turning into a product.   They asked me if I'd beta test it.   Here's a photo:

ioBridge.com Beta Test

We've been running the their tide gauge next to mine for a few weeks.    Their packaging is slick, includes temperature compensation (which is important as the speed of sound in air changes with temp), and is very much weather proof.   It uses a Zigbee radio to connect back to the ioBridge sensor gateway.

The temperature sensor is in the white PVC pipe (for sun shield), and the acoustic transducer is pointed down at the end of the arm reaching out from the piling.

They have also produced a beta quality web site to display the output:

www.iobridge.com/apps/GreenPondTide

The web site is still under construction, but it does display the tide level accurately, along with a couple of weeks of history.

I've been helping them with this.   If you think you might be interested in getting one of these, please let us know emailing sales@iobridge.com.    

Although we've focused on tides, other water level monitoring applications might be interesting, such as irrigation, river flood levels, reservoir levels, etc.

Still Running, total history to date

More Log Data

Here's a plot to date.

Full moon was late March, new moon was 4/14, we are approaching full moon again at the end of the month.   

Maximum negative declination was around 4/4, the moon was on the equator at about 4/12, and maximum positive declination was around 4/19.

Here's a potential simplified explanation of what's going on:

There was a big storm with NE winds late in March, along with the full moon.  Large tidal ranges resulted.

In early April, the large negative (below equator) lunar declination resulted in a larger diurnal component.   Smaller tidal range caused by lunar phase.

Around 4/12 the tide looks more semi-diurnal, presumably as the moon is at the equator.   I am surprised not to see more tidal range at the new moon around 4/14 (I cannot remember what the wind was doing).

Looks like the diurnal component increases again as we approach 4/19, and the lunar declination is at its maximum above the equator.

I am curious what is happening to the running average tide level.  It seems to bounce around a bit.   Some of this might be wind (for example the strong NE winds in late March), and maybe some is astronomical.   

Over 3 weeks of data

If you were expecting a regular sine wave, not here.

Tide Log to Date

Here's the tide log to date:

The Tide Log To date

The Tide Monitor has been up and running for nearly 2 weeks now.   Here's a plot of the data to date:

The full moon was around 4/1.   A coastal storm with strong easterlies occurred at the end of March.   Note that  in April, we seem to be measuring a mixed tide (with components of diurnal and semidiurnal).