On eddy accumulation with limited conditional sampling to measure air-surface exchange
An analysis of turbulence data collected at a height of 12.3 m above grasslands was carried out to illustrate some of the limitations and possible improvements in methods to compute vertical fluxes of trace substances by the eddy accumulation technique with conditional sampling. The empirical coefficient used in the technique has a slight dependence on atmospheric stability, which can be minimized by using a threshold vertical velocity equal to approximately 0.75{sigma}{sub w}, below which chemical sampling is suspended. This protocol results in a smaller chemical sample but increases the differences in concentrations by approximately 70%. For effective conditional sampling when mass is being accumulated in a trap or reservoir, the time of sampling during updrafts versus downdrafts should be measured and used to adjust estimates of the mean concentrations.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10114057
- Report Number(s):
- ANL/ER/CP-80341; CONF-940115-19; ON: DE94005112
- Resource Relation:
- Conference: 8. Joint conference on applications of air pollution meterology. 74. American Meteorological Society annual meeting,Nashville, TN (United States),23-28 Jan 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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