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CORRECTION FOR THE IMPACTS OF COVARIANCE BETWEEN CONCENTRATION AND DEPOSITION VELOCITY OR CASTNET HNO, DEPOSITION ESTIMATES
Citation:
Sickles II, J E. AND D. S. Shadwick. CORRECTION FOR THE IMPACTS OF COVARIANCE BETWEEN CONCENTRATION AND DEPOSITION VELOCITY OR CASTNET HNO, DEPOSITION ESTIMATES. Presented at Sixth International Conference on Air Surface Exchange of Gases and Particles, Edinburgh, Scotland, July 3-7, 2000.
Impact/Purpose:
The primary objectives of this research are to:
Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;
Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;
Develop and validate multivariate models based on quantification studies;
Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;
Complete an initial draft (potentially web based) of a national landscape condition assessment.
This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.
Description:
The covariance between hourly concentration (C) and deposition velocity (V) for various atmospheric; species may act to bias the, deposition (D) computed from the product of the weekly average C and 'V. This is a potential problem for the CASTNet filter pack (FP) species, nitric acid (H.NO3'. Using ozone (03) behavior as a surrogate for the FP species, correction factors (CF) are developed to estimate this bias. Weekly CF for 03 depend on both site and season, and seasonal average weekly, C.F for 03 at a given site may be as high as 1.25. The seasonal magnitude of these CF is generally largest in summer and is ordered> summer > fall > spring > winter. The CF is driven to a large extent by the diurnal correlation between C and V (i.e., both are generally higher during the day and lower at night). However, since the diurnal C profile at elevated sites is relatively constant, the resulting correlation between C and V is small, and the CF at montane sites is generally negligible. The sampling protocol using daytime integrated sampling for a week and nighttime integrated sampling for a week captures the diurnal correlation between C and V adequately may be used to aggregate relatively unbiased weekly D estimates. Day-night CF for 03 are close to unity, and limited results suggest similar behavior for HN03. Using these limited FP results, the site- and seasonally-.specific weekly CF for 03 are refined to estimate the corresponding CF for HN03. Worst-case adjustments for IIN03 as high as 30% are indicated for summer periods at a given site,