I am starting a new thread based on a hint from Bill Huber in the following thread:

http://forums.arcgis.com/threads/3142-Spatial-Analyst-Zonal-Statistics-error-related-to-9.3-SP-1

Does ArcGIS Desktop (toolbox, geoprocessor) handle Kriging with output in regions defined as polygon feature class or raster?

As explained in the aforementioned thread, I have rasters of components of a wind field, and I want to compute the flow through edges of a multi-scale grid. I initially created buffers around the edges and I was performing a Zonal Statistics of each component using buffers as zonal features. Bill mentioned that a better option would/could be to use a Kriging tool that estimates averages directly in my buffers.

I didn't find such an option either in the tools from the toolbox or directly using the Geostatistical Wizard.

Any help with this would be much appreciated, because Zonal Statistics has some "natural" limitations that are difficult for me to cope with.

Best regards,

Cedric

http://forums.arcgis.com/threads/3142-Spatial-Analyst-Zonal-Statistics-error-related-to-9.3-SP-1

Does ArcGIS Desktop (toolbox, geoprocessor) handle Kriging with output in regions defined as polygon feature class or raster?

As explained in the aforementioned thread, I have rasters of components of a wind field, and I want to compute the flow through edges of a multi-scale grid. I initially created buffers around the edges and I was performing a Zonal Statistics of each component using buffers as zonal features. Bill mentioned that a better option would/could be to use a Kriging tool that estimates averages directly in my buffers.

I didn't find such an option either in the tools from the toolbox or directly using the Geostatistical Wizard.

Any help with this would be much appreciated, because Zonal Statistics has some "natural" limitations that are difficult for me to cope with.

Best regards,

Cedric

Thank you for your post! Please find below a description of what I am doing, with illustrations (corresponding to the letters) in the attached file. I took a rough resolution so it is easier to see.

A. I have a vector field of wind velocity, whose components in U(lon) and V(lat) directions are given on a regular (angular-) grid of points.

B. This field is given every 6 hours over a year. I am interested in the yearly average flow at each location per direction and per sense, so I separate positive and negative components, and generate yearly average components per sense: U+, U-, V+, V-, that are somehow 4 scalar fields, but that can be seen as well as 4 vector fields of components along Lon, Lat +/-axes.

C. I want to compute flows between cells of a multi-scale grid, that doesn�??t match �?? for obvious reasons - the aforementioned locations. I have to determine average orthogonal wind speed along each edge, to be in an Arakawa C-type situation to some extent.

D. So my first idea, and this is what is implemented at this point, was to interpolate each component and to obtain �??averages per edge�?�. I am using Kriging for the interpolation (because is make sense to me to converge towards a mean value when we are far from locations were the wind field is given)..

E. If I want the output flow for a grid cell, I need to know average values of: U+ for the Eastern edge, U- for the Western edge, V+ for the Northern edge, and V- for the Southern edge. I don�??t know how to obtain an average value along an edge, so I thought that it makes sense to create a rectangular buffer around each edge (here the widths have been exaggerated) and to perform a zonal stat of each component on each corresponding edge.

F. To avoid overlaps that would be problematic when converting buffers to a raster for the zonal stat, I actually do it in two steps: one with horizontal rectangular buffers and one with vertical rectangular buffers.

I think that I cannot use Green�??s theorem or the divergence theorem for this purpose (am I right?), because my surfaces are indeed in the z direction (orthogonal to U+,U-,V+,V-) and I assume the wind speed profile to be constant over each step of my z-discretization (sigma surfaces). I was really excited by your idea however, because it could be very relevant for computing flows in the z direction, through cells bottoms and tops.

I have no experience with focal statistics. To some extent it seems that I am somehow emulating it by creating buffers and performing a zonal statistics, but I don�??t know at this point how to perform a focal statistics around objects of different lengths (the edges) in one or two operations. Is it obvious for you that I should use a focal statistics?

Thank you again for your post and for the discussion!

Cedric