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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
> > > > Hi Guys, > > > > Can you give me a quick ABC on how to do back trajectories in the > > IDV? > > > > One group of students here at the PASI will be working on transport > > of Saharan dust to the Caribbean, and it would be very useful to > > be able to illustrate the likely origins of air parcels sampled. > > > > This will be used Friday afternoon in a computer lab. > > > > Thanks in advance... > > > > Cheers, > > > > Tom > > Tom, > It is very easy to do. > 1)Open a globe view window. > > 2)Load a dataset, gfs 1 degree, you may need more than one dataset since it > takes pretty long time to move dust from Saharan to Caribbean, if so, > aggregate them. > > 3)In the field Selector, select momentum > derived > Grid 3D trajectory, > click create display, when a window popup, select the colored by parameter. > Note: it would be good to use property window to subset the time, use every > other, or something, otherwise, it is too big to load every time step. > > 4)In the trajectory control, select level to 85000, inital area as > "Rectangle", and check the "Backward trajectory" box, and draw a rectangle > in the globe view window around the Caribbean region, and click "Create > Trajectory" > > The only thing I worry about is the internet speed if you are getting data > from remote server. > > After the trajectory display created: 1)In the control, select Times tab, and change the time mode to: Start time as Relative to End Time, offset to -6 hour, and End time: from Animation Time. 2) You can use the animation widget to run the animation backward. 3) Note: you need to aggregate 2 gfs data to cover the period of movement, but there should be no time overlapped. have fun! Yuan > Yuan > > > -- > > +----------------------------------------------------------------------------+ > > * Tom Yoksas UCAR Unidata > > Program * > > * (303) 497-8642 (last resort) P.O. Box > > 3000 * > > * address@hidden Boulder, CO 80307 * > > * Unidata WWW Service > > http://www.unidata.ucar.edu/ * > > +----------------------------------------------------------------------------+ > > > > > Ticket Details =================== Ticket ID: HVX-641068 Department: Support IDV Priority: Normal Status: Closed