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Re: "homebrew radiation shield"

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  • chronarch33
    Jeff & Others, I have a question for you and a few comments. I was reading through CWOP s manual and believe I noticed that errors can be as much as 6 degrees
    Message 1 of 5 , Aug 28, 2007
      Jeff & Others,

      I have a question for you and a few comments. I was reading through
      CWOP's manual and believe I noticed that errors can be as much as 6
      degrees before your data gets flagged by MADIS as being strange. Have
      you compared your values with a nearby NWS station throughout the day
      as a sanity check? I only ask this because I have a 2308 station as
      well and have been struggling for months trying to get "quality"
      data. I finally signed up for CWOP last week so I should start
      getting my QC data this week. For my modifications I started off by
      drilling holes in the cover for the 2308 so rain could not get in but
      air would be able to pass through. This did not do much. I have
      always kept it in the shade though because the temp spike were 10-15
      degrees when sunlight touched it. I then proceeded to purchase one of
      those manufatured gill plate/plastic dish radiation shields from
      AMbient Weather and moved the sensor so it was in the sun. I only
      get morning to early afternoon sun though because I live on a green
      belt so the sun dissapears behind the trees after lunch time. This
      helped a bunch but I would still get around a 5 degree spike when the
      sun hit and then it would flatten out. So I made another
      modification by cutting a hole in the 2nd to top plate and added a
      8mm 75 CFM DC computer fan that pulls the air up thus making it an
      aspirated shield. Now my temps read within exact to no more than 3
      degrees off at times from the NWS station at the airport. I
      originally had a 5 watt solar panel to run the fan but then I thought
      it would be a great idea to get a tractor/lawn mower battery to make
      it 24 hour aspiration. Well with the green belt issues the battery
      would croak after about 3 days. HAHA. SO I bought a 1.5 Amp small
      battery charger that trickle charges and acts as a DC power supply.
      Seems to be working so far. I have done all this over the past few
      weeks. Pretty fun modification. It cost me just around $120 for all
      the various goodies. So add that to the $79 for the station I now
      have a pretty decent setup for around $200.

      Here is my station data

      http://www.wunderground.com/weatherstation/WXDailyHistory.asp?
      ID=KWAARLIN6


      --- In wuhu_software_group@yahoogroups.com, "Jeffrey C. Le Doux"
      <jefcled@...> wrote:
      >
      > WUHU,
      >
      > I did not want to say anything until I had several sunny days on
      record.
      > That has now occurred. I have a small shelter (will photograph
      tomorrow)
      > and the aluminum foil wrapped perforated cover that came with my ws
      2308
      > weather station (La Crosse). Despite my connectivity problems the
      following
      > is what I have been getting for weather quality reports from CWOP.
      >
      > DATE UTC * ALT * POT TEMP * DEW PNT * DD *
      FF
      >
      > * (MB) * (DEG F) * (DEG F) * (DEG) *
      (KNT)
      >
      > 28-AUG-2007 Errs * 0/35 * 0/35 * 2/35 * 0/35 *
      0/35
      >
      > DATE UTC * ALT * POT TEMP * DEW PNT * DD *
      FF
      >
      > * (MB) * (DEG F) * (DEG F) * (DEG) *
      (KNT)
      >
      > 27-AUG-2007 Errs * 0/46 * 0/46 * 1/46 * 0/46 *
      0/46
      >
      > DATE UTC * ALT * POT TEMP * DEW PNT * DD *
      FF
      >
      > * (MB) * (DEG F) * (DEG F) * (DEG) *
      (KNT)
      >
      > 26-AUG-2007 Week *-0.5(0.48)* 1.5(3.74)*0.82(3.47)*-6.7( 94)*0.05
      (1.53)
      >
      >
      >
      > Note that times are in UTC. The values displayed are 'Observed
      (error)'
      >
      > The error value is 'analysis - observed'. I.e. if your observed
      value is
      > higher than the computed value, then the error will be negative.
      You have to
      > pick out the reading that is in error. The row with the time
      of 'Smry' is a
      > daily summary and the data is 'mean(standard deviation)' for each
      > observation during that day.
      >
      > The 'Week' row is the summary for the preceding 7 days.
      >
      >
      >
      > As you can see, no temperature errors at all, and we have had
      plenty of sun
      > for the last couple days. The ones before these two are equally
      impressive.
      >
      >
      > Jeff L.
      >
      > The WiltonWeatherGuy
      >
      > KMEWILTO1
      >
      > CW5246
      >
    • Rich Brunnworth
      In my case...... it does no good to compare to the NWS station at the airport because the airport is twenty miles away and doesn t match the data we get here
      Message 2 of 5 , Aug 28, 2007
        In my case...... it does no good to compare to the NWS station at the
        airport because the airport is twenty miles away and doesn't match the
        data we get here in the metro area.

        What I do compare myself to is the various stations within a couple of
        miles of my station. As long as I am close, I figure that my data is
        correct. You never know exactly how the other persons station is
        mounted, or how the actual weather over their location really is. This
        is really true when a rainstorm moves through and rainfall is heavier
        over you than it is over them.

        I do is compare my station temp to that of a calibrated thermometer. So
        far I've not seen more than a couple of degrees difference between the
        two, and they are in different locations on my property, and I double
        check my station rainfall against another rain gauge. Again they are
        located in different places on the property.

        Personally I consider the "quality" of my data to be 99% accurate for my
        location. Any comparison to a station that isn't within an eighth to a
        quarter mile of me is an exercise in futility as conditions may be
        different beyond those boundaries just enough to create vast differences.

        As long as the equipment being used is accurate then a persons station
        quality is 100%.

        chronarch33 wrote:
        >
        > Jeff & Others,
        >
        > I have a question for you {snip} Have
        > you compared your values with a nearby NWS station throughout the day
        > as a sanity check? I only ask this because I have a 2308 station as
        > well and have been struggling for months trying to get "quality"
        > data.
        >
      • Jeffrey C. Le Doux
        Chronarch33, et.al., Before I sent my note I checked the 4 closest stations as well as the NWS analysis graphs. There is one station that is way out, but
        Message 3 of 5 , Aug 29, 2007

          Chronarch33, et.al.,

          Before I sent my note I checked the 4 closest stations as well as the NWS “analysis” graphs.  There is one station that is way out, but the rest are within a degree of mine, and mine lays right on the analysis graph.  There is very little time when the sun has the opportunity to shine on the thermo/hygro sensor, and that was even before my modifications.  The most important modification, apparently was the addition of the aluminum foil on the cover to reflect the heat.  The holes merely provide a way to circulate the air.  Later this morning I will photograph the setup, and submit those photos.  (The holes will probably not be visible, but we will see. 

          Jeff L.

          The WiltonWeatherGuy

          KMEWILTO1

          CW5246

           


          From: wuhu_software_group@yahoogroups.com [mailto: wuhu_software_group@yahoogroups.com ] On Behalf Of chronarch33
          Sent: Wednesday, August 29, 2007 1:38 AM
          To: wuhu_software_group@yahoogroups.com
          Subject: [wuhu_software_group] Re: "homebrew radiation shield"

           

          Jeff & Others,

          I have a question for you and a few comments. I was reading through
          CWOP's manual and believe I noticed that errors can be as much as 6
          degrees before your data gets flagged by MADIS as being strange. Have
          you compared your values with a nearby NWS station throughout the day
          as a sanity check? I only ask this because I have a 2308 station as
          well and have been struggling for months trying to get "quality"
          data. I finally signed up for CWOP last week so I should start
          getting my QC data this week. For my modifications I started off by
          drilling holes in the cover for the 2308 so rain could not get in but
          air would be able to pass through. This did not do much. I have
          always kept it in the shade though because the temp spike were 10-15
          degrees when sunlight touched it. I then proceeded to purchase one of
          those manufatured gill plate/plastic dish radiation shields from
          AMbient Weather and moved the sensor so it was in the sun. I only
          get morning to early afternoon sun though because I live on a green
          belt so the sun dissapears behind the trees after lunch time. This
          helped a bunch but I would still get around a 5 degree spike when the
          sun hit and then it would flatten out. So I made another
          modification by cutting a hole in the 2nd to top plate and added a
          8mm 75 CFM DC computer fan that pulls the air up thus making it an
          aspirated shield. Now my temps read within exact to no more than 3
          degrees off at times from the NWS station at the airport. I
          originally had a 5 watt solar panel to run the fan but then I thought
          it would be a great idea to get a tractor/lawn mower battery to make
          it 24 hour aspiration. Well with the green belt issues the battery
          would croak after about 3 days. HAHA. SO I bought a 1.5 Amp small
          battery charger that trickle charges and acts as a DC power supply.
          Seems to be working so far. I have done all this over the past few
          weeks. Pretty fun modification. It cost me just around $120 for all
          the various goodies. So add that to the $79 for the station I now
          have a pretty decent setup for around $200.

          Here is my station data

          http://www.wundergr ound.com/ weatherstation/ WXDailyHistory. asp?
          ID=KWAARLIN6

          --- In wuhu_software_ group@yahoogroup s.com, "Jeffrey C. Le Doux"
          <jefcled@... > wrote:

          >
          > WUHU ,
          >
          > I did not want to say anything until I had several sunny days on
          record.
          > That has now occurred. I have a small shelter (will photograph
          tomorrow)
          > and the aluminum foil wrapped perforated cover that came with my ws
          2308
          > weather station ( La Crosse ).
          Despite my connectivity problems the
          following
          > is what I have been getting for weather quality reports from CWOP.
          >
          > DATE UTC * ALT * POT TEMP * DEW PNT * DD *
          FF
          >
          > * (MB) * (DEG F) * (DEG F) * (DEG) *
          (KNT)
          >
          > 28-AUG-2007 Errs * 0/35 * 0/35 * 2/35 * 0/35 *
          0/35
          >
          > DATE UTC * ALT * POT TEMP * DEW PNT * DD *
          FF
          >
          > * (MB) * (DEG F) * (DEG F) * (DEG) *
          (KNT)
          >
          > 27-AUG-2007 Errs * 0/46 * 0/46 * 1/46 * 0/46 *
          0/46
          >
          > DATE UTC * ALT * POT TEMP * DEW PNT * DD *
          FF
          >
          > * (MB) * (DEG F) * (DEG F) * (DEG) *
          (KNT)
          >
          > 26-AUG-2007 Week *-0.5(0.48)* 1.5(3.74)*0. 82(3.47)* -6.7(
          94)*0.05
          (1.53)
          >
          >
          >
          > Note that times are in UTC. The values displayed are 'Observed
          (error)'
          >
          > The error value is 'analysis - observed'. I.e. if your observed
          value is
          > higher than the computed value, then the error will be negative.
          You have to
          > pick out the reading that is in error. The row with the time
          of 'Smry' is a
          > daily summary and the data is 'mean(standard deviation)' for each
          > observation during that day.
          >
          > The 'Week' row is the summary for the preceding 7 days.
          >
          >
          >
          > As you can see, no temperature errors at all, and we have had
          plenty of sun
          > for the last couple days. The ones before these two are equally
          impressive.
          >
          >
          > Jeff L.
          >
          > The WiltonWeatherGuy
          >
          > KMEWILTO1
          >
          > CW5246
          >

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