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Post by sigurdur on Mar 30, 2013 21:47:27 GMT
Howdy. Let's delve into the AH trends in the atmosphere. Here is a starter. Abstract The National Centers for Environmental Predic- tion (NCEP) reanalysis data on tropospheric humidity are examined for the period 1973 to 2007. It is accepted that radiosonde-derived humidity data must be treated with great caution, particularly at altitudes above the 500 hPa pressure level. With that caveat, the face-value 35-year trend in zonal-average annual-average specific humidity q is significantly negative at all altitudes above 850 hPa (roughly the top of the convective boundary layer) in the tropics and southern midlatitudes and at altitudes above 600 hPa in the northern midlatitudes. www.eike-klima-energie.eu/uploads/media/Paltridge_01.pdf |
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Post by sigurdur on Mar 30, 2013 21:51:52 GMT
journals.ametsoc.org/doi/pdf/10.1175/2009JCLI2879.1An Analysis of Tropospheric Humidity Trends from Radiosondes M ARK P. M C C ARTHY ,P.W.T HORNE , AND H. A. T ITCHNER Hadley Centre for Climate Change, Met Office, Exeter, United Kingdom (Manuscript received 6 October 2008, in final form 27 May 2009) ABSTRACT A new analysis of historical radiosonde humidity observations is described. An assessment of both known and unknown instrument and observing practice changes has been conducted to assess their impact on bias and uncertainty in long-term trends. The processing of the data includes interpolation of data to address known sampling bias from missing dry day and cold temperature events, a first-guess adjustment for known radiosonde model changes, and a more sophisticated ensemble of estimates based on 100 neighbor-based homogenizations. At each stage the impact and uncertainty of the process has been quantified. The adjust- ments remove an apparent drying over Europe and parts of Asia and introduce greater consistency between temperature and specific humidity trends from day and night observations. Interannual variability and trends at the surface are shown to be in good agreement with independent in situ datasets, although some steplike discrepancies are apparent between the time series of relative humidity at the surface. Adjusted trends, accounting for documented and undocumented break points and their uncertainty, across the extratropical Northern Hemisphere lower and midtroposphere show warming of 0.1–0.4 K decade 2 1 and moistening on the order of 1%–5% decade 2 1 since 1970. There is little or no change in the observed relative humidity in the same period, consistent with climate model expectation of a positive water vapor feedback in the extratropics with near-constant relative humidity.
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Post by nautonnier on Apr 1, 2013 2:18:20 GMT
journals.ametsoc.org/doi/pdf/10.1175/2009JCLI2879.1An Analysis of Tropospheric Humidity Trends from Radiosondes M ARK P. M C C ARTHY ,P.W.T HORNE , AND H. A. T ITCHNER Hadley Centre for Climate Change, Met Office, Exeter, United Kingdom (Manuscript received 6 October 2008, in final form 27 May 2009) ABSTRACT A new analysis of historical radiosonde humidity observations is described. An assessment of both known and unknown instrument and observing practice changes has been conducted to assess their impact on bias and uncertainty in long-term trends. The processing of the data includes interpolation of data to address known sampling bias from missing dry day and cold temperature events, a first-guess adjustment for known radiosonde model changes, and a more sophisticated ensemble of estimates based on 100 neighbor-based homogenizations. At each stage the impact and uncertainty of the process has been quantified. The adjust-
ments remove an apparent drying over Europe and parts of Asia and introduce greater consistency between
temperature and specific humidity trends from day and night observations. Interannual variability and trends at the surface are shown to be in good agreement with independent in situ datasets, although some steplike discrepancies are apparent between the time series of relative humidity at the surface. Adjusted trends, accounting for documented and undocumented break points and their uncertainty, across the extratropical Northern Hemisphere lower and midtroposphere show warming of 0.1–0.4 K decade 2 1 and moistening on the order of 1%–5% decade 2 1 since 1970. There is little or no change in the observed relative humidity in the same period, consistent with climate model expectation of a positive water vapor feedback in the extratropics with near-constant relative humidity. So the actual radiosonde values did not agree with their models so they 'adjusted them' to remove apparent drying. And they actually admit that they changed the input data to fit expectations in their abstract? Is it worth reading further in a paper when they adjust the input values to match what they want? |
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Post by sigurdur on Apr 1, 2013 2:31:51 GMT
naut: Yep, that paper is worth reading. Of course, your blood pressure may rise, but this is what is passing for science now days.
I read it, and came to no conclusion of confidence one way or the other.
Could have just as well stated, the Cow Jumped Over the Moon Last Night, but the folks who were sleeping missed it.
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Post by glennkoks on Apr 3, 2013 11:44:00 GMT
Here is a link from a study done in 2001 concerning trends in upper-tropospheric humidity thats worth a look. Water vapor is the most radiatively active greenhouse gas, and the process of water-vapor feedback may significantly amplify global warming induced by anthropogenic greenhouse gasses. Satellite radiance observations from the past 20 years, which are sensitive to the water vapor and temperature of the upper troposphere, provide the first global observations of trends in upper-tropospheric humidity. These decadal trends are strongly positive in the deep tropics, negative in the Southern Hemisphere subtropics and midlatitudes, and of mixed sign in the Northern Hemisphere subtropics and midlatitudes. The trends are shown to be consistent with atmospheric circulation changes observed in the past 20 years, including a tendency toward more El Niño-Southern Oscillation warm events and changes in transient eddy activity in the subtropics. onlinelibrary.wiley.com/doi/10.1029/2000GL012544/abstract |
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Post by steve on Apr 3, 2013 19:12:41 GMT
So the first paper says "The data is rubbish, but lets not ignore it till the problems are analysed" which is fair enough, I suppose, and the second paper attempts to analyse them.
Since the analysis gives a result people don't like, the analysis must be flawed.
Looking at the second paper, the things they identify include:
Two pretty basic issues that would cause historic humidity to appear higher than it really was. Seems pretty unscientific to ignore them because they are inconvenient.
Problems like this have to be dealt with all the time with data from imperfect systems. People are fully entitled to take different choices in dealing with the issues. Moaning because you don't like the choice doesn't cut the mustard. You'll end up as a bitter old man if that is all you do.
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Post by sigurdur on Apr 3, 2013 20:40:35 GMT
Steve:
I am not a bitter old man, as I think you know.
What concerns me is that without somewhat reliable data prior to the 21st Century, in regards to humidity, it is impossible to detect a trend one way or the other.
I find this very bothersome to say the least.
I will compliment you. You do not appear to be so wed to AGW that you aren't realistic. There have been some of the louder mouth Sueo Scientists who make claims that are just not backed up by current knowledge. Humidity is one of those claims.
Am I wrong in examining this and coming to the conclusion that we just don't know with a high confidence level what humidity levels have been over at least a 60 year period?
To me, the noise on a 5 or 10 year measurement is so large that all we can really say is there is humidity in the air. As far as trend? Your guess is as good as mine?
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Post by sigurdur on Apr 3, 2013 21:58:15 GMT
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Post by sigurdur on Apr 7, 2013 3:27:52 GMT
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Post by sigurdur on Apr 7, 2013 3:35:22 GMT
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Post by magellan on Apr 21, 2013 2:41:24 GMT
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Post by sigurdur on Apr 27, 2013 15:47:45 GMT
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Post by karlox on Apr 27, 2013 17:11:38 GMT
Total Atmosphere Water Vapor I understand is total water contained in our troposphere? up to estratosphere? I see in the left axis mm. Does it stand for liters/dm3? How is total water vapor measured? Sorry I don´t understand that measure... help please |
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Post by nautonnier on Apr 27, 2013 17:58:22 GMT
Total Atmosphere Water Vapor I understand is total water contained in our troposphere? up to estratosphere? I see in the left axis mm. Does it stand for liters/dm3? How is total water vapor measured? Sorry I don´t understand that measure... help please Karlox, I believe that scale is what is called 'vertically integrated liquid'. If all the water vapor were to be precipitated out of the column of air then that would be the number of millimetres of water at the bottom of the column. The problem AGW has is that I don't see anyway that CO2 levels can have a bearing on sea surface temperatures (or water of any type). Infrared and/or warmer air leads to more evaporation cooling the surface. Surely that is an AGW fail right there. |
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Post by sigurdur on Apr 27, 2013 22:03:36 GMT
I was trying to think of an example of radiative evaporation.
Just remembered one that most folks have prob read about, or even experienced.
Remember a few years ago the alarm in the Phoenix, Arizona area? The air temp was 45F at night, but there was a layer of ice on their vehicles.
The speed of evaporation actually froze the dew.
I hope that helps a little bit?
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