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Climate Data Change: Atmospheric Water Content

Posted by Frank Lansner (frank) on 27th February, 2014
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Specific atmospheric water content

Positive feedbacks rely on increased water content in the atmosphere. So, without increasing water amounts in the atmosphere, there is no basis for the severe consequences of CO2 emissions.

From the NCEP reanalysis we learn the following about specific water content for different pressure levels in the atmosphere:

 
Fig 1
For the shown period we see a general slight decline in specific atmospheric water content although the surface data (1000 mb) shows a slight increase, especially after 1970.

A row of data types are available from the NCEP/NCAR Reanalysis. They write:
“The NCEP/NCAR Reanalysis 1 project is using a state-of-the-art analysis/forecast system to perform data assimilation using past data from 1948 to the present.”

The graph on fig 1 was created using data from:
http://wattsupwiththat.com/2008/06/21/a-window-on-water-vapor-and-planetary-temperature-part-2/
Link to all data that workd today from ESRL/NOAA:

http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries1.pl 

 

 

Fig 2
Writings on NOAA (and Tamino) show “Specific Humidity” as a steady increase from around 1970.

NOAA: http://www.ncdc.noaa.gov/bams-state-of-the-climate/2009-time-series/humidity
Tamino: http://tamino.wordpress.com/2010/08/08/urban-wet-island/

NOAA just describe these data as “Specific Humidity” and Tamino (“Open Mind”) describes:

“One of the interesting graphs is multiple estimates of specific humidity (the amount of water vapor in the atmosphere). In a warming world, specific humidity is expected to increase because a warmer atmophere will naturally hold more water vapor. Because water vapor is also a greenhouse gas (in fact, its the most prominent one in our atmosphere) this leads to one of the expected feedback mechanisms of man-made global warming.”

However, all sources to NOAA/Tamino “Specific Humidity” are strictly limited to Specific humidity data for the surface (1000mb) layer.
Obviously, Climate feedback is not depending simply on humidity at the surface.
 

    
Fig 3
Here is a direct comparison of the NCEP specific humidity data from fig 1 for 1000 mb and then the surface data from Dai/hadCruH(Willett-Jones)/Berry. The overall trend is the same and thus it seems that the NCEP data for these years have been confirmed.

  

Fig 4
Thus, the data chosen by NOAA/Tamino for Specific humidity matches NCEP data, but NOAA only show data after 1970 and most importantly: They only show the surface data resulting in an increasing trend for “Specific Humidity”.

On of the data series used by NOAA, “HadCRUH” is taken from the writing willett-Jones:
“Recent Changes in Surface Humidity: Development of the HadCRUH Dataset”

The Willett-Jones team states for these surface data:
“…the first rigorously homogenized and quality controlled global gridded (5° by 5°) monthly mean anomaly humidity dataset in q and RH suitable for use in climate studies…”

They write: “Suitable for use in climate studies”.
Which climate studies needs surface humidity only?

It appears, that even in recent decades of rapid warming after 1978 there is no general rise in atmospheric water concentration unlike the surface layer.
Thus, the stagnating perhaps even declining water content in the atmosphere do not support that water is contributing to positive feedbacks.
Positive feedbacks – if true – should rely on other mechanisms than increased water content in the atmosphere.

Willet-Jones 2008: http://www.metoffice.gov.uk/hadobs/hadcruh/data/Willettetal2008.pdf
Dai 2005 : http://www.cgd.ucar.edu/cas/adai/papers/Dai_JC06-sfcHumidity.pdf
  
 

Last changed: 29th March, 2014 at 01:56:14

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