Correcting Barometer in software

[Weather Display]

just a question:
the Davis VP uses temperature and humidity and entered elevation for the barometer value, yes?
and so for CWOP, reverse engineering needs to be done, using the values returned with the BARDATA command, to send the simpler altimeter value (elevation corrected value only) to CWOP?

[tinplate]

just a question:
the Davis VP uses temperature and humidity and entered elevation for the barometer value, yes?
and so for CWOP, reverse engineering needs to be done, using the values returned with the BARDATA command, to send the simpler altimeter value (elevation corrected value only) to CWOP?

Yes, and during the past two years most weather station programs have incorporated the changes necessary to do that.

[JOE]

Another question.

I have my elevation slightly different than CWOP.  6M (18 ft) higher

Is this worth changing? 

I am getting 100% MADIS ratings on Barometer and Humidity, and 98% or 99% on Temperature.

I can understand my temp being off a little (high) due to my immediate location.

Thank you.  This has been interesting.

[tinplate]

Ideally you would have your console elevation and CWOP elevation both be the true elevation. The CWOP elevation definitely should be true elevation. However, if you have calibrated your console with its elevation set as you have it, you should be ok. At a difference of about 30 ft, you would just begin to see a tiny drift introduced over the range of normal pressures, and beyond that, the bigger the difference, the bigger the resulting drift. What I mean by drift is that at some pressure (the pressure that you happened to be experiencing at the time you calibrated your console), your pressure would be right on. As you experienced varying weather systems, the farther the pressure got from that "golden" pressure, the more likely it would be that the console's displayed pressure would be different than the station to which you calibrated. But as I said, if the discrepancy is under 30 ft., the largest drift value you would see would be too small to actually detect on your equipment.

 

[JOE]

Thanks. 
I'm new to this.  When I was setting up my VP2, I just walked out to the driveway and got an elevation off my Handheld GPS.  Hindsight I should have know that wasn't accurate.  I'll change it someday.

[Scalphunter]

 Watch using those GPS units  as you can end up off. The common every days  handheld do not get a differencial signal for correction.. You migth want to get a chart of your area and  do a plot on there just to double check. I was able to use a nautical chart but areo chart would work also.

[NiceBill]

I have found Google Earth to be quite accurate.  For the most part, close enough for setting your barometer, if you wish to take that rout. It's on with what the NWS will tell you.

Bill.>>>>>>>>>>>>>>

[JOE]

I have about 300 quadrangle maps of southern Illinois. But they are at the office and I was at home when setting up.

I know how the hand helds are with regards to elevation.  It was just easy to do at the time.

Used to go to www.topozone.com until they sold out and now you have to pay to look.

I'm in engineering/surveying, so I should have known better.

[NiceBill]

Joe,

If you are really, really fussy, this is the best of the best that I know of.

Take your time and it will put you spot on.  These folks know where you are.


http://nmviewogc.cr.usgs.gov/viewer.htm

Bill.>>>>>>>>>>>>>>>

[JOE]

Joe,

If you are really, really fussy, this is the best of the best that I know of.

Take your time and it will put you spot on.  These folks know where you are.


http://nmviewogc.cr.usgs.gov/viewer.htm

Bill.>>>>>>>>>>>>>>>

I'm not that fussy and if I used the link you listed, I get the elevation CWOP used for my location.

However, my ISS is probably that 18 feet or whatever above ground.

Now what?  I guess if I'm getting 98-99%, I probably should just leave it be.

Too many neighborhood brat kids to leave equipment on ground, so I put station on roof.  No real choice.

[Scalphunter]

If your really really fussy forget the internet except for the time tick and get out sextant next clear day and do a sun/star shot and plot. little celestrical navigation anyone ????

[NiceBill]

18' will never make a never mind.

Personally, I don't  care what CWOP has to say.  It's in my computer, but I don't even look at it any more.
When they use stations that are so far out of wack, in conjunction with stations that are correctly set up, to evaluate mine,  and I can get a run of 100% for a long time.  Then out of the blue get evaluations of 64%, without changing anything, I don't need a program that is not run correctly.  You can't put 10 apples in a basket, four of them rotten to the core, charge 1$ ea. and expect to get 10$.

If it makes you happy, enjoy.

Bill.>>>>>>>>>>>

[blackjack52]

....little celestrical navigation anyone ????

When I flew the BUFFS, we had to maintain proficiency using the sextant.  There is a sextant port on the top of the fuselage and at altitude of 37k, the vacuum is quite strong.  Perfect for launching hard boiled eggs. Anyone ever experience mysterious falling eggs?  UFEs.

[Meteorologica]

Joe,

If you are really, really fussy, this is the best of the best that I know of.

Take your time and it will put you spot on.  These folks know where you are.


http://nmviewogc.cr.usgs.gov/viewer.htm

Bill.>>>>>>>>>>>>>>>

I'm not that fussy and if I used the link you listed, I get the elevation CWOP used for my location.

However, my ISS is probably that 18 feet or whatever above ground.

Now what?  I guess if I'm getting 98-99%, I probably should just leave it be.

Too many neighborhood brat kids to leave equipment on ground, so I put station on roof.  No real choice.

The barometer is in the console not the ISS

[JOE]

The barometer is in the console not the ISS

  That's right. Forgot that