[R-sig-Geo] Spatial interpolation of rainfall timeseries with e.g. spacetime

[Fabian Ries]

Dear all,

I work on rainfall-runoff processes in a semi-arid area. I have time
series of about 15 rainfall stations within a small area (300 sqkm) and
want to perform spatial interpolation (idw or kriging) on a 5min-timestep.
Runoff processes respond in my research area often to short peaks of
rainfall intensity - therefore I need to work on this short time
intervals. 

First I would like to perform spatial interpolation on a 5 min time step
but exclude time intervals with no rain so I receive a data set with about
5000 time steps for a single year.
Second I want to build sums of hourly, daily, monthly and yearly rainfall
on a grid base to apply water balance calculations.
Finally I want to create a regular time series of mean rainfall over my
watersheds on the 5 min time steps by the use of spatial polygons.

In the beginning I tried to realize simple IDW interpolation considering
the time steps with rainfall in a for-loop but I get stuck in the
aggregation step for hourly, daily, ... rainfall because of the time gaps
in my data deleting the no rain time steps.
Then I found the package spacetime which seems to offer exactly the
functionality I need. Following the Ireland wind example I could not
understand how to modify the example with kriging using simple IDW method.
Can someone give me a hint how to apply IDW over a spatial time series?

I had also problems applying extract(grid, raster, fun=mean) on
spatialpolygonsdataframe and spatialgriddataframe. Is it only working for
the class spatialpolygons?
I import my polygons by using readOGR(Š) and the raster by
read.asciigrid(Š).

The rainfall data I use has the following format:

Station	Station01	Station02	Station03	Station04	Station05	Station06	Station
07	Station08	Station09
PosX	180000	195900	181950	192150	179550	176750	182950	170400	173100
PosY	157550	150950	154550	141650	154700	157050	158450	147800	133500
01.03.2012 00:05	0	0	0	0	0	0	0.0	0.2	0.2
01.03.2012 00:10	0	0	0	0	0	0	0.0	0	0.1
01.03.2012 00:15	0	0	0	0	0	0	0.0	0.4	0.1
01.03.2012 00:20	0.2	0	0	0	0.2	0	0.0	0.2	0.1
01.03.2012 00:25	0.2	0	0.2	0	0.4	0.4	0.2	0.4	0.1
01.03.2012 00:30	0	0	0.4	0	0.4	0.2	0.4	0.6	0.1
01.03.2012 00:35	0.2	0	0.2	0	0.2	0.2	0.2	0.6	0.1
01.03.2012 00:40	0.2	0	0.2	0	0.4	0.2	0.2	0.8	0.0
01.03.2012 00:45	0	0	0.4	0	0.4	0.4	0.4	0.4	0.0
01.03.2012 00:50	0.2	0	0.4	0	0.2	0.2	0.4	0.2	0.0
01.03.2012 00:55	0.2	0	0	0	0.6	0.2	0.0	0.2	0.0
01.03.2012 01:00	0	0	0.4	0	0.2	0.2	0.4	0.2	0.1
01.03.2012 01:05	0.2	0	0.2	0	0.2	0.2	0.2	0	0.1
01.03.2012 01:10	0.2	0	0.2	0	0.2	0.2	0.2	0	0.0
01.03.2012 01:15	0	0	0	0	0.2	0.4	0.0	0	0.0
01.03.2012 01:20	0	0	0.2	0	0	0	0.2	0	0.0
01.03.2012 01:25	0	0	0	0	0.2	0.2	0.0	0	0.0
01.03.2012 01:30	0	0	0	0	0	0	0.0	0	0.0
01.03.2012 01:35	0.2	0	0	0	0	0	0.0	0	0.0
01.03.2012 01:40	0	0	0	0	0	0	0.0	0	0.0
01.03.2012 01:45	0	0	0	0	0	0	0.0	0	0.0
01.03.2012 01:50	0	0	0	0	0	0	0.0	0	0.0
01.03.2012 01:55	0	0	0	0	0	0	0.0	0	0.0
01.03.2012 02:00	0	0	0	0	0	0	0.0	0	0.0


Any help is kindly appreciated.
Best regards
Fabian