How can temperature measurments made from space be accurate when greenhouse gas absorbs the surface heat?

Question

If the atmosphere is absorbing heat from the surface of Earth how can the measurments from space get the correct temperature of the surface of Earth?

Answer 1

I think people put a little too much faith in satellites.  I expect they are a tool for augmenting all the other means of monitoring the weather.

Obviously the big advantage of satellites is they move around very quickly, and one satellite can cover a very large area, but imagine trying to take the temperature of something100 km away.  You could use blackbody radiation, but only at night and only if there was no cloud cover.  You would still be affected by the varing optical properties of the atmosphere.

Maybe it's no wonder that James Hanson can get such contrarian results from satellite data.

Answer 2

How can the surface temperature be measured?  The earth emits blackbody radiation characteristic of temperature.  See the Planck distribution.  Some frequencies are absorbed by the atmosphere (mainly by H2O and CO2) while other frequencies pass through the atmosphere with little absorption.  A key point that is often missed is that the energy absorbed by atmospheric gasses is re-emitted at virtually the same frequencies that were absorbed.  The ratio of intensity for  two "atmospheric window" bands is sufficient to determine the temperature.  

How can the temperature of the atmosphere be measured?

When a molecule absorbs radiation, it does so at a set of discrete frequencies described by vibrational and rotational quantum numbers.  Only some transitions are allowed by the symmerty of the molecule.  The intensity is determined by the transition dipole moment, the density of states, and the temperature.  The quantum numbers are determined by frequency and the density of states can be calculated directly from the quantum number.  For low quantum numbers (harmonic approximation) the dipole moment is constant and the temperature can be determined directly by comparing two or more rotational absorption bands of known quantum number.  The calculation is possible, but more complex in the anharmonic region (which does not apply in this case because the upper states are not populated at atmospheric temperatures.)  You can learn more by looking up P,Q and R branches of rotational spectra.  I have used this method in some low temperature experiments as a check on thermocouple readings in the 4.2 K (liquid helium) - 20 K range because thermocouples are not very sensitive in this range.

Answer 3

Because we spit on polluters.

Answer 4

I guess you're right,and everybody else is wrong. How clever! If something is way beyond your level of comprehension,then all you have to do is simply question it's very existence. Do you even understand how satellites work? It's not like they hang a thermometer on the side of it! Nice try though,keep trying. You just might win a Nobel Prize!

Answer 5

Extremely accurate! I worked with weather satellite systems for several years.  This is not a new game to them, they have been using these and adjusting them for over 50 years. The also measure many other things like ice thickness, and soil moisture.

My bad I read too quick. I went back and reread the question and now I am thoroughly convinced that I am dyslexic. I know they have sensors that can measure surface temperature, I think they use Algorithms to clean up the data.

Answer 6

This is a technique called "remote sensing".

The instruments used in space are calibrated in laboratories before they are sent (like any other sensor) and using algorithms with respect to field measurements.

> surface temperature of the ocean

See SST (Sea surface temperature).

Answer 7

They have sensors on buoys that give feed back to the satellites.Haven't heard of any deep water sensors,just surface.

Here's a link about the new systems out.(UAH) is reassessing bad data from the old satellites due to orbital decay.They are not for sure if this can even be done.

Answer 8

They sprinkle pixy dust on them first.

Answer 9

Satellites do not measure "temperature" as such. They measure radiances in various wavelength bands, which must then be mathematically inverted to obtain indirect inferences of temperature. The resulting temperature profiles depend on details of the methods that are used to obtain temperatures from radiances. As a result, different groups that have analyzed the satellite data to calculate temperature trends have obtained a range of values. Among these groups are Remote Sensing Systems (RSS) and the University of Alabama in Huntsville (UAH).

Edit: The results from satellites do need to tinkered with (or corrected). Orbital decay needs to be accounted for. And because each layer of the atmosphere is at a different temperature, the results have to be adjusted to make sure that the layer that you want to be measures actually is the one being measured.

These results are most useful when used with observations from the ground: global warming, rapid polar ice loss, increasing sea level rises, worldwide melting glaciers…

Answer 10

They have sophisticated instruments which use different wavelengths and different types of waves and photography to measure these things.

Answer 11

Which specific temperatures are you talking about?  There are tons of temperatures that are relevant in differing ways.  Nevertheless, infrared is easily quantified.