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Hi Boris, Sorry for the silence on your previous inquiry. I am involved in something that has a very short deadline (end of Wednesday), and I don't have the time to answer questions in the depth that they deserve. re: > I have a case where an image has been deployed using data from bright (0-255) > and > I selected a shade to tell me the regions of CAPE (Convective Available > Potential > Energy) like in attached. My question is: how I can adjust these brightness > values > ??to actual values ?? of CAPE. FYI: your email did not include an attachment. The calculation of CAPE is not simple -- it requires use of several image sounder channels in a full physical retrieval. Unfortunately I do not know how to create a CAPE product from the sounder channels available on GOES. The folks at SSEC/CIMSS, on the other hand, do know how to create CAPE products using sounder channels from GOES in a physical retrieval. Their website shows examples of CAPE products that they create: http://cimss.ssec.wisc.edu/goes/rt/viewdata.php?product=ce_us The description that is available in the link at the bottom of the above page refers in general terms to the process used by CIMSS to create CAPE displays: "A look at the Convective Available Potential Energy (CAPE) as derived from the GOES-East and GOES-West Sounders is provided each hour. This is a new experimental feature in the suite of DPI displays. Recall that the nominal GOES Sounder field-of-view (fov) is 10 km at the satellite sub-point. Spatial averaging over a 3x3 fov box is currently employed to increase the signal-to-noise. This image is derived from the full physical retrieval algorithm. However, please note that this image is a "pseudo" DPI, having been re-created after the fact in a image format from the CAPE values available from the 3x3 retrievals, along with use of the 11um window channel (for those areas where no retrievals were made). The CAPE product displayed is an atmospheric stability parameter for a given vertical thermodynamic profile, which indicates the amount of positive (buoyant) energy available to an idealized parcel, ascending from the Level of Free Convection (LFC) to the Equilibrium Level (EL). The larger the value (or the "positive-energy area" under the parcel curve on a thermodynamic diagram), the more unstable would the atmosphere be. A CAPE of 1500 J/kg would indicate a modestly unstable airmass. The values are color-coded with brown/beige>blue>yellow at the more stable end while red>magenta/purple would indicate considerably more potential instability. (Note that transitions between colors beige/blue/yellow/red/magenta occur at CAPE values of 1000, 2000, 3000, and 4000 J/kg respectively). This enhancement table is experimental and suggestions for improvement are welcome. A time sequence of the images remains the best way to monitor stability trends." re: > If there is any formula, can guide me to convert the brightness values ?? > to units of CAPE? Since there was not image attached to your email, I don't know if you have created a CAPE product from multiple GOES sounder channels, or if you are thinking that one can identify/quantify CAPE values directly from satellite images (you can't, it is unfortunately not that easy). I suggest doing some web searches to see if you can find documentation on how to create CAPE (and other) products using information from satellite sounders. Cheers, Tom -- **************************************************************************** Unidata User Support UCAR Unidata Program (303) 497-8642 P.O. Box 3000 address@hidden Boulder, CO 80307 ---------------------------------------------------------------------------- Unidata HomePage http://www.unidata.ucar.edu **************************************************************************** Ticket Details =================== Ticket ID: QBR-849370 Department: Support McV Priority: Normal Status: Closed