Generating NADP Deposition Maps using Cokriging

Chris Lehmann & Bob Larson*Data Management and Analysis

SubommitteeApril 2007

Cokriging

• Cokriging uses information from multiple variables. The main variable (Z1), and both autocorrelation with Z1 and cross-correlations between Z1 and other variables are used to make predictions

• If you have a sparse network of data (i.e., NADP sites) and a more dense network of data (i.e., NWS sites), co-kriging uses data from more dense network to aid interpolation of sparse nework.

What we tried

• Obtained NWS cooperative network from Midwest Regional Climate Center (MRCC)– Quality-assured for completeness– Removed outlier

• Cokrigged ammonium and sulfate against NWS data– ESRI ArcView 9.1 Geostatistical Analyst Wizard

• CAVEAT: Neither Bob nor I are geostatisticians.

AmmoniumKriging with 3rd Order Trend Removal

AmmoniumCokriging with 3rd Order Trend Removal

SulfateCokriging with 3rd Order Trend Removal

Discussion…

• Develop whitepaper on possible data interpolation procedures, their assumptions, and pro/cons?

• Find a real geostatistician?