Australian Politics Forum - Why satellites cannot measure sea level..??

muso

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Re: Why satellites cannot measure sea level..??
Reply #105 - Sep 27^th, 2013 at 12:18pm

Ajax wrote on Sep 27^th, 2013 at 11:59am:

muso wrote on Sep 27^th, 2013 at 11:39am:

Ajax wrote on Sep 27^th, 2013 at 10:37am:

muso wrote on Sep 27^th, 2013 at 10:12am:

With an altimeter reading having an accuracy of +/- 25mm and a precision of better than +/- 1mm, what is the drift in the reading?

Like I keep saying, thank God engineers and not scientists build things.

Answer the question. If you prefer, how stable is the reading?

The accuracy can be within a 50mm radius bullseye, +-25mm either way of dead centre.

The precision of the readings can be within +-1mm of each other.

Good. So now you understand that when measuring the rate of change of sea level rise, the result will be better than 1mm.

There are a lot of provisos there of course. You're talking about the composite of every single reading over each year.

High precision, low accuracy is a common theme when measuring altitude.

Another example is aircraft altimeters. There are two types. One uses baromateric pressure and the other uses radar.

Regular calibration is needed to maintain accuracy, whereas precision is not affected. Many aircraft crashes have been caused by the altimeter being set incorrectly. The rate of descent is indicated quite precisely but the accuracy of the altitude is off.

When Jason 3 is launched next year, there will be a period where the readings are compared against Jason 2 to ensure that the accuracy is good, otherwise there will be a step change, like the ACRIM gap in the TSI satellites.

Can you also see why Willy Soon as an Astrophysics expert, should have known that?

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Ajax

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Re: Why satellites cannot measure sea level..??
Reply #106 - Sep 27^th, 2013 at 12:30pm

The bottom line is the accuracy for one reading can be within +-25mm or a 50mm drift or error margin..call it what you will....!!!

The next reading and the reading after that will be within +-1mm within the area of where the preceding reading was taken from.......or within the general vicinity....!!!!

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muso

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Re: Why satellites cannot measure sea level..??
Reply #107 - Sep 27^th, 2013 at 5:31pm

Ajax wrote on Sep 27^th, 2013 at 12:30pm:

The bottom line is the accuracy for one reading can be within +-25mm or a 50mm drift or error margin..call it what you will....!!!

The next reading and the reading after that will be within +-1mm within the area of where the preceding reading was taken from.......or within the general vicinity....!!!!

+/- 25mm systematic error. Drift is the wrong term. This systematic error could be due to any number of factors, but the main thing is that we don't need the exact measurement. It just has to be stable.

The technical data quotes a precision of better than 1mm per annum.

Why do you think Willie Soon lied about it? Wouldn't you think that an astrophysict would be able to check out those details quite easily?

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« Last Edit: Sep 27^th, 2013 at 5:39pm by muso »

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Ajax

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Re: Why satellites cannot measure sea level..??
Reply #108 - Sep 30^th, 2013 at 9:17am

muso wrote on Sep 27^th, 2013 at 5:31pm:

+/- 25mm systematic error. Drift is the wrong term. This systematic error could be due to any number of factors, but the main thing is that we don't need the exact measurement. It just has to be stable.

WTF are you talking about muso, its clear that the best satellites have an accuracy of +-25mm, giving them an error margin of 50mm.

Its black and white why are you trying to fudge the facts..???

Quote:

The technical data quotes a precision of better than 1mm per annum.

So what if the microwave beam can be fired within +-1mm of where the previous beam was fired......??????

The accuracy is still +-25mm or a 50mm drift.

If the first beam can land within the vicinity of the previous beam with a precision of +-1mm this doesn't mean that the accuracy of actually measuring the sea level is any better than +-25mm.

Quote:

Why do you think Willie Soon lied about it? Wouldn't you think that an astrophysict would be able to check out those details quite easily?

Maybe he wasn't talking about Jason....??????

Now stop telling me that the precision is better than 1mm.

This is not the accuracy....!!!!

The accuracy of the reading has +-25mm error margin.

The beam can be fired in the same vicinity to within 1mm of each other.

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muso

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Re: Why satellites cannot measure sea level..??
Reply #109 - Sep 30^th, 2013 at 5:56pm

I thought you understood, but I don't think that you're capable of it you do.

I think the problem is that you don't understand the concept of "systematic error". If there is an inherent precision of 1mm per annum, then an error of 25mm is by implication systematic in nature. In other words the error stays the same plus or minus 1mm.

Think millions of measurements over a year. The precision applies to the average or mean value.

Quote:

Maybe he wasn't talking about Jason....?

I'm less charitable - Willy Soon is lying through his teeth. Jason 2 is the only satellite designed for that purpose.

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« Last Edit: Sep 30^th, 2013 at 6:03pm by muso »

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Ajax

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Re: Why satellites cannot measure sea level..??
Reply #110 - Oct 1^st, 2013 at 1:46pm

muso wrote on Sep 30^th, 2013 at 5:56pm:

I thought you understood, but I don't think that you're capable of it you do.

I think the problem is that you don't understand the concept of "systematic error". If there is an inherent precision of 1mm per annum, then an error of 25mm is by implication systematic in nature. In other words the error stays the same plus or minus 1mm.

I understand perfectly thank you very much.

The accuracy of the microwave beam is +-25mm....(50mm error margin).

The precision with which the microwave beam can fired in the near vicinity of the previous measurement is within +-1mm.

There's nothing more to say, its black and white....????

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muso

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Re: Why satellites cannot measure sea level..??
Reply #111 - Oct 1^st, 2013 at 5:11pm

Ajax wrote on Oct 1^st, 2013 at 1:46pm:

muso wrote on Sep 30^th, 2013 at 5:56pm:

I thought you understood, but I don't think that you're capable of it you do.

I think the problem is that you don't understand the concept of "systematic error". If there is an inherent precision of 1mm per annum, then an error of 25mm is by implication systematic in nature. In other words the error stays the same plus or minus 1mm.

I understand perfectly thank you very much.

The accuracy of the microwave beam is +-25mm....(50mm error margin).

The precision with which the microwave beam can fired in the near vicinity of the previous measurement is within +-1mm.

There's nothing more to say, its black and white....????

As long as you realise that the "previous measurement" was the previous year in this context.

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Ajax

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Re: Why satellites cannot measure sea level..??
Reply #112 - Oct 4^th, 2013 at 11:04am

muso wrote on Oct 1^st, 2013 at 5:11pm:

Ajax wrote on Oct 1^st, 2013 at 1:46pm:

muso wrote on Sep 30^th, 2013 at 5:56pm:

I thought you understood, but I don't think that you're capable of it you do.

I think the problem is that you don't understand the concept of "systematic error". If there is an inherent precision of 1mm per annum, then an error of 25mm is by implication systematic in nature. In other words the error stays the same plus or minus 1mm.

I understand perfectly thank you very much.

The accuracy of the microwave beam is +-25mm....(50mm error margin).

The precision with which the microwave beam can fired in the near vicinity of the previous measurement is within +-1mm.

There's nothing more to say, its black and white....????

As long as you realise that the "previous measurement" was the previous year in this context.

YeeHaa

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1. There has never been a more serious assault on our standard of living than Anthropogenic Global Warming..Ajax
2. "One hour of freedom is worth more than 40 years of slavery & prison" Regas Feraeos

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