Hi Marc, re: assumption that McIDAS AREAs made from level 1b data work in McIDAS-X > Yes, he also made IR and VIS images from it. Very good. re: McIDAS Lite can not read Level 1B "formatted" files directly > > Ok, and I don't think it can read those leve 1b either. re: do you have one or two examples of converted images that I could take a look at > Well I am still not able to read it in Mcidas V. I do have one file that > he converted to AREA format but I am in the US right now without any FTP > setup. OK. > I will be back in Switzerland next week but in the meantime, if you are > there, would you have any way for me to send the file to you to check it? Depending on the size, you could send me 1 image via email. If you decide to do this, please send the image to my personal email address, address@hidden re: What do you mean by "cloud information"? > Well I mean cloud information as to retrieve the cloud-base-heights > (or cloud-top-heights) from the images using Mcidas V. I am trying to > retrieve these parameters to verify the height of the PBL and to infer the > cloud rolls height. Actually, I am collaborating with a colleague and the > poster > is due near the end of this Janurary. OK. > > My friend said that Mcidas cannot do this type of analysis. I would need an > > algorithm to do this. Is this true? The images themselves can not provide either cloud base/top height. The IR images simply provide the temperature of the layer of clouds being viewed. In order to interpret the values, one must understand use the weighting function for the channel being viewed (e.g., 10.7 um for the BAND=4 images from GOES, etc.) and possibly have soundings that relate the thermal profile to height above ground. This, I believe, is what your friend was referring to. > Ok, if there is a way to retrieve the cloud-base-heights from the AREA format > files that would be great using Mcidas V. Let me know if this is possible. It is not directly possible to infer the cloud base/top heights from satellite imagery directly. This is not a failing of McIDAS-X/-V, but, rather, a simple fact. Products that depict the cloud base/top heights are created using combinations of images in multiple wavelength channels (which have different weighting functions) and possibly temporally close sounding data or model output. You may want to read through the web pages from the Cooperative Institute for Meteorological Satellite Studies (CIMSS) of the Space Science an Engineering Center (SSEC) at the University of Wisconsin-Madison for more information on what is involved in creating products like cloud-top pressure: CIMSS HomePage www.cimss.ssec.wisc.edu The CIMSS Realtime GOES Page http://cimss.ssec.wisc.edu/goes/realtime/grtmain.html Cloud Top Pressure http://cimss.ssec.wisc.edu/goes/realtime/grtmain.html#ctop "Cloud Products Derived from the GOES Sounders Combined GOES-East and GOES-West Cloud Top Pressure Cloud top pressure (CTP) is derived from GOES-East and GOES-West Sounder radiance information routinely at hourly intervals. Calculations, using the CO2 Absorption Technique, are made at each field of view. The image is then color enhanced to display 50 hPa intervals where clouds have been identified. Due to the low-level atmospheric signal being dominated by surface emissions, this technique is less reliable for near surface clouds. For a more detailed explanation of this technique, see the CIMSS GOES Automated Service Observing System (ASOS) page. A wider view of the CTP DPI is obtained using all available sectors observed from both the GOES-East and GOES-West Sounders." > Thanks again for your help! No worries. 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: OXG-395498 Department: Support McIDAS Priority: Normal Status: Closed
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