Hi Martin, There is a newer interpolation method in the pipeline, but not yet available. The libcf library being developed by Unidata and a group of collaborators will give us faster tools for interpolating between grids. We are paying close attention to this development and will implement it in Ferret as soon as it's ready. When there's a beta version of the interpolation code, and other capabilities available, we will add it as an option for people to experiment with. Here's the link to the information about libcf: http://www.unidata.ucar.edu/software/libcf/ With the existing tools in Ferret, if all your data has the same curvilienar grid and are interpolating to the same rectilinear grid, you can re-use the map function. This speeds up the entire process quite a lot, and it's the reason we have two functions; one to compute the map and the other to apply it. The SHADE command only fills each grid box with the corresponding color. It's not doing any interpolation. The curvilinear version of the shade command can use curvlinear coordinate variables that define either the edges of the grid cells or their centers. Here it looks like the grid defines the centers - else their size would be one larger than the grid size of the data fields. yes? use "ascat_20100111_005400_metopa_16755_eps_o_125_1018_ovw.l2.nc" yes? sh dat currently SET data sets: 1> ./ascat_20100111_005400_metopa_16755_eps_o_125_1018_ovw.l2.nc (default) name title I J K L TIME time 1:82 1:3259 ... ... LAT latitude 1:82 1:3259 ... ... LON longitude 1:82 1:3259 ... ... WVC_INDEX cross track wind vector cell nu 1:82 1:3259 ... ... MODEL_SPEED model wind speed at 10 m 1:82 1:3259 ... ... MODEL_DIR model wind direction at 10 m 1:82 1:3259 ... ... ICE_PROB ice probability 1:82 1:3259 ... ... ICE_AGE ice age (a-parameter) 1:82 1:3259 ... ... WVC_QUALITY_FLAG wind vector cell quality 1:82 1:3259 ... ... WIND_SPEED wind speed at 10 m 1:82 1:3259 ... ... WIND_DIR wind direction at 10 m 1:82 1:3259 ... ... BS_DISTANCE backscatter distance 1:82 1:3259 ... ... A nice way to visualize a grid is to define a "checkerboard" variable, which alternates 1 and zero over the grid, based on the variable we're looking at. yes? let checkerboard = 0*wind_speed+mod(i+j,2) yes? shade/hlim=50e:150e/vlim=-80:0/pal=greyscale/lev=(0,2,1) checkerboard, lon, lat So I think what looks in your shade.gif image like data smeared across the middle of this swath is really just the way the shape of the cells changes. The question is why the regridded data has a gap in that area. There should be many points within the 1-degree radius that you've chosen, to use in the interpolation. I don't understand that, but will try to look into it. Ansley On 2/18/2011 8:42 AM, Martin Schmidt wrote: Hi Ferreters, |