A possible deficiency in estimates of wet deposition obtained from data generated by the NADP/NTN network

Claassen, Hans C.; Halm, Douglas R.

doi:10.1016/1352-2310(94)00182-k

Cited by 17 publications

(19 citation statements)

References 26 publications

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“…Testing undertaken to determine experimentally the rate and amount of precipitation needed to initiate the uncovering sequence indicates that for application of fine droplets at a rate ≈0.02 mL s −1 there is no systematic variability with temperature or wind speed, and WD capture would conservatively commence after approximately 15 s. However, the data suggest the delay to sample capture may increase to 5 minutes for liquid application to the sensor head of approximately 0.001 mL s −1 (equivalent to a rainfall rate of 1.4 mm h −1 ). These results thus offer some empirical evidence for the assertions of Claassen and Halm (1995) that the data collected using this type of instrument represent conservative estimates of the actual WD flux due to exclusion of some (likely non-negligible) fraction of light precipitation events.…”

Section: Discussionmentioning

confidence: 74%

“…Prado-Fiedler, 1990), though the variance explanation for the power law fit is lower than in a study by Garban et al (2004) of bulk N deposition collected at sites in France. Hence, although tests conducted at lower flow rates yielded highly varying triggering times due to difficulties in consistent application of such low liquid volumes using a spray bottle, the results of these experiments offer some empirical evidence for the assertions of Claassen and Halm (1995) that the data collected using this type of instrument represent conservative estimates of the actual WD flux due to exclusion of some (likely non-negligible) fraction of light precipitation events.…”

Section: Evaluation Of the Aerochem Wet-dry Samplermentioning

confidence: 84%

“…The accuracy of WD estimates is, however, dependent on the efficiency of the moisture sensor to initiate the uncovering of the collection device at the onset of precipitation. Substantial delay in sensor triggering has implications for atmosphere-surface exchange (Claassen and Halm, 1995), because while the potential exclusion of light precipitation events or the initial stages of a precipitation event does not lead to substantial bias in volume collections, high ion concentrations have been observed in low rainfall events and at the beginning of precipitation events. Thus, testing was undertaken to determine experimentally the rate and amount of precipitation needed to initiate the uncovering sequence.…”

Section: Evaluation Of the Aerochem Wet-dry Samplermentioning

confidence: 96%

“…Huber and Iroume, 2001;Bockheim and Crowley, 2002;Levia and Frost, 2003), and is possibly dependent on forest type (Huber and Iroume, 2001). • Precipitation regime: The concentration of many ions exhibits at least a quasiexponential dependence on precipitation amount and/or intensity (Claassen and Halm, 1995;Minoura and Iwasaka, 1997). Accordingly Hansen et al (1994) found the major part of the dominant of inorganic ions was deposited in the first 2 mm of the rain events at a forest site in the Netherlands.…”

Section: Introduction and Synthesis Of Previous Researchmentioning

confidence: 99%

See 3 more Smart Citations

Liquid and Chemical Fluxes in Precipitation, Throughfall and Stemflow: Observations from a Deciduous Forest and a Red Pine Plantation in the Midwestern U.S.A.

Pryor

Barthelmie

2005

Water Air Soil Pollut

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Wet deposition (WD), throughfall (TF) and stemflow (SF) measurements undertaken in a deciduous forest show 85% of the WD liquid flux is observed as TF and approximately 2% as SF. TF and SF were observed to be enriched in base cations and accordingly had an average pH of 6.1 and 5.9, respectively relative to a WD pH of 5.1. The seasonal variability of TF pH below the deciduous canopies was more pronounced than that of WD though both exhibited a growing season maximum, and there is evidence that the seasonal variability of TF pH below the pines is inverted relative to the deciduous canopies likely due to enhanced dust capture and buffering by calcium carbonate. TF ion concentrations differed significantly between deciduous and pine canopies during the growing season, and there is some evidence that variation in sky view factor of 0.18-0.22 is sufficient to manifest statistically differing TF composition below sugar maples. The total atmospheric flux of inorganic nitrogen to the forest is approximately 14-18 kg-N ha −1 yr −1 with approximately half taken up by the canopy. Associated experiments designed to quantify uncertainties in the nutrient fluxes included laboratory tests of the Aerochem automated wet-dry sampler. These experiments indicate the delay in initiating sample collection is less than half a minute for rainfall rates above 1 cm h −1 , but may increase substantially for lower precipitation rates.

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Section: Discussionmentioning

confidence: 74%

Section: Evaluation Of the Aerochem Wet-dry Samplermentioning

confidence: 84%

Section: Evaluation Of the Aerochem Wet-dry Samplermentioning

confidence: 96%

Section: Introduction and Synthesis Of Previous Researchmentioning

confidence: 99%

See 2 more Smart Citations

Liquid and Chemical Fluxes in Precipitation, Throughfall and Stemflow: Observations from a Deciduous Forest and a Red Pine Plantation in the Midwestern U.S.A.

Pryor

Barthelmie

2005

Water Air Soil Pollut

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“…We focus on the average number of rainy days per month during winter, because the monthly aerosol concentrations are more strongly affected by the number of rainy days (even with small precipitation amounts) rather than by the total intensity of the monthly precipitation (Claassen and Halm, 1995). We define a rainy day as a day with precipitation > 1 mm at a given gridbox.…”

Section: Appendix Bmentioning

confidence: 99%

Investigations on aerosols transport over micro- and macro-scale settings of West Africa

Emetere

2016

Environmental Engineering Research

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Abstract. Numerical model scenarios of future climate depict a global increase in temperatures and changing precipitation patterns, primarily driven by increasing greenhouse gas (GHG) concentrations. Aerosol particles also play an important role by altering the Earth's radiation budget and consequently surface temperature. Here, we use the general circulation aerosol model ECHAM5-HAM, coupled to a mixed layer ocean model, to investigate the impacts of future air pollution mitigation strategies in Europe on winter atmospheric circulation over the North Atlantic. We analyse the extreme case of a maximum feasible end-of-pipe reduction of aerosols in the near future (2030), in combination with increasing GHG concentrations. Our results show a more positive North Atlantic Oscillation (NAO) mean state by 2030, together with a significant eastward shift of the southern centre of action of sea-level pressure (SLP). Moreover, we show a significantly increased blocking frequency over the western Mediterranean.By separating the impacts of aerosols and GHGs, our study suggests that future aerosol abatement may be the primary driver of both the eastward shift in the southern SLP centre of action and the increased blocking frequency over the western Mediterranean. These concomitant modifications of the atmospheric circulation over the Euro-Atlantic sector lead to more stagnant weather conditions that favour air pollutant accumulation, especially in the western Mediterranean sector. Changes in atmospheric circulation should therefore be included in future air pollution mitigation assessments. The indicator-based evaluation of atmospheric circulation changes presented in this work will allow an objective firstorder assessment of the role of changes in wintertime circulation on future air quality in other climate model simulations.

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The Role of Allochthonous Inputs of Dissolved Organic Carbon on the Hypolimnetic Oxygen Content of Reservoirs

et al. 2008

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Hypolimnetic oxygen content in lentic ecosystems has traditionally been modeled as a function of variables measured at the epilimnion, or that are supposed to drive epilimnetic processes, like total phosphorus load. However, in man-made reservoirs the river inflow can plunge into deep layers, directly linking the hypolimnion with the surrounding watershed. In these circumstances, organic matter carried by the river can influence the hypolimnetic oxygen content without important intervention of epilimnetic processes. Taking long-term data from two reservoirs in Spain, we applied an empirical regression approach to show that the dissolved organic matter carried by the river is the main driver shaping the hypolimnetic oxygen content. By contrast, typical variables commonly included in the modeling of the oxygen content in the hypolimnion (nutrient concentrations, chlorophyll a, and dissolved organic carbon measured in the water column) did not show any significant correlation.Interpretations from this regression approach were supported by a comparison between the monthly oxygen consumption in the hypolimnion and the monthly dissolved organic carbon load from the river inflow. We also revisited the prediction of the year-to-year variability of the Nürnberg's anoxic factor in four reservoirs from Spain and USA, explicitly including the allochthonous sources in the equations. These sources were significant predictors of the anoxic factor, especially in those systems subject to relatively high human impact. Thus, effects of allochthonous dissolved organic carbon should always be considered in empirical modeling and management of reservoir hypolimnetic processes related to oxygen content (e.g. anoxia, nutrient internal loading, or phosphorus cycle resilience).

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A possible deficiency in estimates of wet deposition obtained from data generated by the NADP/NTN network

Cited by 17 publications

References 26 publications

Liquid and Chemical Fluxes in Precipitation, Throughfall and Stemflow: Observations from a Deciduous Forest and a Red Pine Plantation in the Midwestern U.S.A.

Liquid and Chemical Fluxes in Precipitation, Throughfall and Stemflow: Observations from a Deciduous Forest and a Red Pine Plantation in the Midwestern U.S.A.

Investigations on aerosols transport over micro- and macro-scale settings of West Africa

The Role of Allochthonous Inputs of Dissolved Organic Carbon on the Hypolimnetic Oxygen Content of Reservoirs

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