Dry deposition monitoring over the Speulder forest. Description of the equipment and evaluation of the measuring methods

Publication

This report is part of a series of reports published to complete the projects Speuld (RIVM project 722108) and EC LIFE (93/NL/A23/NL/3547). The report describes a monitoring system for continuous determination of dry deposition fluxes of acidifying components to the Speulder forest, and evaluates the performance of the several instruments used in the system and of the system as a whole.

A detailed error analysis of the gas and particle fluxes derived from the data of the system, and some recommendations for final improvements and flux correction procedures are given as well. The error analysis shows that fluxes of SO2, NH3 and NO can be determined with acceptable accuracy. Systematic errors for NOx and NO2 are large, yielding on the average about 50 to 100% overestimation of the fluxes. These errors are mainly caused by interferences of HNO2, HNO3 and NH3. In future measurements, the systematic errors can be significantly reduced by correcting friction velocities and sensible heat fluxes for flow distortion, correcting sensible heat fluxes for the influence of moisture flux and horizontal wind velocity, and correcting gas concentrations for pressure effects and interferences.

The latter requires continuous determination of the interferents concentrations and concentration differences; the latter might also be estimated from parameterized deposition velocities. The correction procedures are described in this report. The uncertainties in fluxes of HNO2, HNO3 and HCl and particulate compounds were estimated to be 30% for acidic gases, 40% for acidic aerosols and basic cations and 50% for heavy metals. They are mainly a result of uncertainties in parameterized deposition velocities.

Authors

Mennen MG , Uiterwijk JW , Putten EM van , Hellemond J van , Wiese CJ , Regts TA , Hogenkamp JEM , Erisman JW , Bosveld FC , Wyers GP , Otjes RP

Specifications

Publication title
Dry deposition monitoring over the Speulder forest. Description of the equipment and evaluation of the measuring methods
Publication date
31 March 1997
Publication type
Publication
Publication language
English
Product number
90269