A weeks worth of data from my new MMTS unit

Last week you may recall that I posted about my new self contained MMTS unit that I’m experimenting with as a possible replacement of as a check system for NOAA’s existing MMTS. Below you can see my test setup in my back yard.

new-mmts-backyard-view.jpg
This is a custom wireless MMTS with internal data logger that I built, view from my backyard.

The most valuable thing about my version of MMTS is that it is cable free, can be placed anywhere, and can log data automatically for days, weeks of even months, depending on the interval. It also logs relative humidity, and dewpoint.

Here is what the internal sensor package/datalogger unit looks like when not installed in the infrared radiation shield:

new-mmts-labeled520.jpg

When you are ready to download the data for analysis, all you have to do is unscrew the head, connect the USB cable to the datalogger and to your laptop as I did shown below. This easy ability to plug into a laptop to download data and start a new data logging run in under 5 minutes makes the design very suitable for field work away from networking and AC power.

new_mmts_connected.jpg

Data transfer for the one week of data I recorded only took about two seconds.

I have plotted all three measurements from the sensor below:

jan20-2008
Click for a larger image:

And here is the raw data file, with data logged every minute, in comma delimited format if you wish to plot it, a key to the values is on line1 of the file. jan20-2008.txt

For comparison, I have logs online from the Davis Vantage Pro2 weather station shown in the background

Jan 13th http://www.bidwellranchcam.com/data/011308hd.txt
Jan 14th http://www.bidwellranchcam.com/data/011408hd.txt
Jan 15th http://www.bidwellranchcam.com/data/011508hd.txt
Jan 16th http://www.bidwellranchcam.com/data/011608hd.txt
Jan 17th http://www.bidwellranchcam.com/data/011708hd.txt
Jan 18th http://www.bidwellranchcam.com/data/011808hd.txt
Jan 19th http://www.bidwellranchcam.com/data/011908hd.txt
Jan 20th http://www.bidwellranchcam.com/data/012008hd.txt

I also prepared a comparison file showing how the New MMTS and the nearby Davis Weather Station max/min readings compare. There is good agreement, with some slight differences that could be related to observation height differences between the two sensor sets.

See the comparison file: newmmts_hi-lo_compare.txt

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11 Responses to A weeks worth of data from my new MMTS unit

  1. Jeff in Seattle says:

    I get a “file not found” error when I click on the graph.

  2. Jeff in Seattle says:

    OT: But History Channel is re-airing their “10 Greatest Threats to Humanity” show. And of course they have “Climate Change” at the top of the list, with token appearances by Al Gore saying “The debate is over”, and another “scientist” directly comparing holocaust deniers with those who are skeptical of AGW.

    I’m officially renaming them the Hysteria Channel, from their previous appellation The Holy Channel.

  3. Russ says:

    Anthony,

    When I click on the graphic for a larger image, I get a 404 file error. The link must be broken and with my old eyes the graphic has to be LARGE for me to read the details.

    Russ

    REPLY: Thanks to both Russ and Jeff for pointing that out, fixed. Try it now

  4. John Andrews says:

    The graph works from Google reader image and it works from your site image, but on your site when you mouse over it, a WordPress 404 missage is displayed.

    Sorry for the bad news.

    John Andrews, Knoxville, Tennessee

    REPLY it will resolve itself eventually, no big deal, it was broken its fixed, cache.

  5. Jackson says:

    In an earlier entry, you said this MMTS unit is accurate to plus or minus 5 degrees. How does this compare to the MMTS units NOAA uses now? And how accurate should the unit be to replace current models?

    REPLY: “you said this MMTS unit is accurate to plus or minus 5 degrees”

    I never said any such thing. That level of accuracy would be useless.

  6. Evan Jones says:

    Jackson: POINT 5 degrees C!

    No, it’s not as accurate as the NOAA MMTS, but the siting of most NOAA stations introduces warming biases that like so totally dwarf the MoE that it ain’t funny. (I lied. it is funny, actually. “Lights=0, Har, Har!” Though I really shouldn’t be laughing.)

    Considering that T-Max, T-Min, and TOBS data is rounded off to the whole degree (0.5′s rounded up, therefore an average 0.3C spurious warm bias, BTW), the Rev’s setup is minimally acceptable to be going along with, assuming the MoE is roughly evenly distributed and the skew is not too bad.

    Roughly the same MoE as a CRN-2 rating, though A CRN-2 would probably indicate a warming skew.

    He’s working on fining it down.

  7. Stan Needham says:

    Jeff,

    The History Channel folks must not have attended any of Bjorn Lomborg’s economic conferences a few years ago. Whether presented to audiences of Nobel Laureates in Economics or College Students, the results were pretty much the same: When it comes down to “bang for the buck”, GW comes in at or near the bottom.

    Some of the world’s top economists – including three Nobel Laureates – answered this question at the Copenhagen Consensus last May, prioritising all the major requirements for improving the world. They found that dealing with HIV/Aids, hunger, free trade and malaria were the world’s top priorities. This was where we could do the most good for our dollar. Equally, the experts rated urgent responses to climate change at the bottom. In fact, the panel called these ventures – including Kyoto – “bad projects”, simply because they cost more than the good they do. (emphasis added)

    He’s working on fining it down.

    Evan has confidence in you, Anthony. (and so do I.) How close do you think you’ll be able to get to the performance of a hard-wired MMTS with this device?

  8. jbleth says:

    Is that a heat pump at the left edge of the picture?

    REPLY: No its a garden hose reel box.

    http://www.hosereelstore.com/ProductDetails.asp?ProductCode=STB200B

    Do ya think I’m stupid? ;-)

  9. JoeH says:

    Anthony,

    For what it’s worth, I was curious as to the difference in daily average temperatures when you averaged all readings vs averaging the high/low points. Here’s a table of the daily readings and the results. If you need it the spread sheet with the calculations, let me know and will send them to you. I was a bit surprised at the difference but also understand this is a very limited data set so no conclusions or inferences are implied or can be drawn. Just interesting.

    Readings Start @00:01 13-Jan 14-Jan 15-Jan 16-Jan 17-Jan 18-Jan 19-Jan
    Avg all rdgs. 43.3 43.3 43.0 40.1 43.3 45.1 44.2
    Min 34.0 35.0 32.0 28.0 30.0 33.0 33.0
    Max 55.0 56.0 60.0 57.0 63.0 67.0 59.0
    Avg. of MM 44.5 45.5 46.0 42.5 46.5 50.0 46.0

    Delta: Avg MM vs All -1.2 -2.2 -3.0 -2.4 -3.2 -4.9 -1.8

    Delta, Min-Max 21.0 21.0 28.0 29.0 33.0 34.0 26.0

  10. jerry bono says:

    To JoeH…. on the 14th I posted the following comments concerning the same issue you mention above. This was in “A Typical Day In The Stevenson Screen Test” on the 14th.

    “I digitized the Chico points and took the average of 24 measures, 78.14F. If we average the Tmax and Tmin we get, 76.0F. That is 2.14 degrees lower than the integrated value and that is a lot . That is about 1.9C difference between the two methods. When was the B91 form put in place? If it was decades ago like in the 30’s then I can see why this was done, GW was not an issue then. If it is a recent invention then shame shame shame.”

    “Looking at the zoomed Tmax, if we take the average Tmax for the three boxes and compare to the air temp, the boxes are 2.69F hotter than the air. Similarly, for Tmin, the boxes are an average 0.78F hotter. If this holds for these stations in general, then the daytime Tmax has 3 times the error than an early morning Tmin. It bothers me that the Tmax difference is so large.”

    “Is there any accounting for this?”

    JoeH, what you show in your post indicates that averaging MM compared to integrating the data results in a hotter value. I wonder how prevalent this is?

  11. wattsupwiththat says:

    Stan the resolution of the current solid state sensor is not likely to exceed 0.5°, no matter what I do. Thermal noise precludes that. However, since I only plan to check against MMTS and Mercury MAX-MIN thermometers rounded to the nearest degree, this may be acceptable.

    I could also opt for a different design that uses a thermocouple. But that presents other problems.

Comments are closed.