Technically, it’s the change of the total transmittance with respect to pressure. In general, it describes the layer of the atmosphere from which the radiation measured by a particular satellite channel was emitted.

Nothing has been done to account for varying surface types and we use a blanket value of 1.0 (100%) for emissivity in these calculations.

It depends on the band, please see: this plot to get an idea how how view angle affects forward model calculations. For the bands we’re looking at we expect to see brightness temperature decrease with increasing view angle. You can also visit this page to see how weighting functions for the future Imager (ABI) and current Imager vary based on the atmosphere and angle.

It depends on the band, please see: this PowerPoint Slide to see the calculations. All of the calculations for ABI bands get warmer, most by approximately 1 degree.

We encourage you to click around, comparing weighting functions from high altitudes to low altitudes; from cloudy scenes to clear scenes; dry scenes to wet scenes; etc. Pay attention to where the different bands peak during these situations – this may tell you a lot about the amount of water vapor in the atmosphere or where vertically it appears. But this page is also here to debunk some myths about satellite bands, namely that certain bands peak at certain heights in the atmosphere. Where a band peaks is really dependent on the vertical profile and the satellite view angle!

Weighting functions are calculated from RAOB data at the stations shown on the map. If there is a station you would like to see added, which is in the GOES domain, contact us and we’ll add it. Rarely there are times when stations don’t report; more commonly raob data does not pass quality control and thus a weighting function plot is not made for that time period.

Weighting functions calculated from GFS data are on a 5×5 Latitude/Longitude grid.

The weighting functions are calculated with a model that assumes clear-sky conditions. This obviously is not always a good assumption; view the calculated brightness temperatures on these plots with some suspicion for cloudy scenes.

Brightness temperatures on the plots are calculated from a forward model, not measured from the satellite.

The “Temp Profile” is the temperature profile from the RAOB and the “Q Profile” is the mixing ratio profile, calculated from the RAOB. Temperature is in degrees Kelvin (K) and mixing ratio units are gram-per-kilogram (g/kg). Users can see how temperature and mixing ratio varied with height for the atmospheric profile used to create the weighting function plot. Mixing ratio is plotted instead of relative humidity for two reasons: that is what is used in the weighting function calculation and because mixing ratio is a more absolute term since relative humidity is also a function of temperature. This feature was added on 19 May 2006 due to user request.

The forward model we use is called the Pressure-Layer Fast Algorithm for Atmospheric Transmittances (Hannon et al. 1996).

Hannon, S., L. L. Strow, and W. W. McMillan, 1996: Atmospheric infrared fast transmittance models: A comparison of two approaches. Proc. Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research, Denver, CO. Inter. Soc. for Opt. Eng., 94-105.

No. There is no solar reflection information used in these forward model calculations.

For the GOES-R series ABI you can choose any combination of the 10 IR bands.