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Errors in Representing Regional Acid Deposition with Spatially Sparse Monitoring: Case Studies of the Eastern US Using Model Predictions
Citation:
SICKLES, II, J. E., D. Shadwick, J. V. KILARU, AND J. Grimm. Errors in Representing Regional Acid Deposition with Spatially Sparse Monitoring: Case Studies of the Eastern US Using Model Predictions. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 43(18):2855-2861, (2009).
Impact/Purpose:
Healthy Communities and Ecosystems - by providing new approaches to characterize landscape features, conditions, and change.
Description:
The current study uses case studies of model-estimated regional precipitation and wet ion deposition to estimate errors in corresponding regional values derived from the means of site-specific values within regions of interest located in the eastern US. The mean of model-estimated site-specific values for sites within each region was found generally to overestimate the corresponding model-estimated regional wet ion deposition. On an annual basis across four regions in the eastern US, these overestimates of regional wet ion deposition were typically between 5 and 25% and may be more exaggerated for individual seasons. Corresponding overestimates of regional precipitation were typically <5%, but may also be more exaggerated for individual seasons. Using 5-year periods, period-to-period relative changes determined from the mean of site-based modeled deposition for the current regional ensembles of sites generally overestimated the beneficial effect of pollutant emissions reductions in comparison to changes based on modeled regional estimates. Spatial heterogeneities of the wet ion deposition fields with respect to the sparse monitoring site locations prevented the monitoring sites considered in the current study from providing regionally representative results. Since the current case studies consider only those eastern US site locations that have supported concurrent wet and dry deposition monitoring, similar errors may be expected for dry and total deposition using results from the same monitoring site locations. Current case study results illustrate the approximate range of potential errors and suggest caution when inferring regional deposition from a network of sparse monitoring sites.