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Hi Josh- > Full Name: Josh Gelman > Email Address: address@hidden > Organization: PSU > Package Version: > Operating System: > Hardware: > Description of problem: Hello, > > Whenever I try to load a 3D field in IDV using a WRF ARW dataset, the time it > takes to load is extremely slow (up to a half hour sometimes). For 2D fields > it's nearly instantaneous. This only seems to happen with my WRF ARW > datasets. The rest load pretty fast. I am curious if there is any way to > resolve this issue? When you say "only seems to happend with my WRF ARW datasets", are you comparing them to standard (e.g. GFS) grids or WRF NMM datasets? Are you loading single levels or are you loading in the entire volume and trying to do cross sections or isosurfaces? The problem with the WRF netCDF files (NMM and ARW) is that they grids are staggered. To handle this, we need to hold both the native grid domain and a transform to pressure in memory. So at the outset, just loading in the grid is a double wammy. Your performance is going to depend on the size of the grid and number of timesteps as well. What are the dimensions of your grid? Any of the derived parameters have an added overhead of resampling the data from one point of the domain to another. For example, wind speed or wind vectors require resampling the V to the U domain. Those are grids that I've seen really bad performance on and the culprit is the resampling. Straight parameters like U wind or vapor pressure shouldn't take much longer than a standard unstaggered high resolution NAM grid. In general, we suggest that users postprocess the WRF netCDF data using WRF-POST or the Vis5D converter. These destagger the grids and output them on pressure levels as well as compute standard parameters like sea level pressure. There are also some steps you can take to improve performance listed at: http://www.unidata.ucar.edu/software/idv/docs/userguide/misc/PerformanceTuning.html > The computers I'm running IDV on have 16 GB of memory and 3 GHz processor > speed. When the data is loading slowly, is the memory monitor showing that you are maxing out on memory? Have you increased the default amount of memory that the IDV gets allocated? If not, see the performance tips above. Depending on your operating system, you'll only be able to use a subset of the total memory. > Thanks for any suggestions. I'm guessing that the slowdown is due to resampling which is painful for the staggered grids. But if you are seeing really slow loading on one of the main fields in the grid, then there is some other issue. Don Murray Ticket Details =================== Ticket ID: COT-972342 Department: Support IDV Priority: Normal Status: Open