Exchange of ozone and highly reactive nitrogen compounds between the atmosphere and biosphere

1
Exchange of ozone and highly reactive nitrogen
compounds between the atmosphere and biosphere
Gerhard Kramm
Atmospheric Science Group Geophysical
Institute University of Alaska Fairbanks Septembe
r 10, 2003
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Content

• Motivation
• Theoretical background
• Balance equation for reactive trace species
• Techniques to measure vertical fluxes directly
• Eddy covariance techniques
• Eddy accumulation techniques ?
• Ground chamber techniques (ecological studies)
• Mass balance method
• Techniques to determine vertical fluxes
  indirectly
• Variance method
• Aerodynamic method
• Inferential method
• relaxed eddy accumulation (not preferred)
• Summary and Outlook

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• Motivation

NO, NO2, NH3 VOCs O3, SO2, HNO3
VOCs
NO, N2O, NO2
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• Theoretical Background

Balance Equation of Reactive Trace Species

• Macroscopic system

• Turbulent system

Hesselbergs averaging calculus (1926)
with
and
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Segregation effects (Kramm and Meixner, 2000)
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Intensity of segregation
Requires, at least, second-order-closure models
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Equation of Continuity
Turbulent system
Macroscopic system
Eulerian form
?
with
Euler operator
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Simplifications to obtain a tractable equation
set
Steady-state conditions

• prerequisite to represent an ensemble average by
• a time average

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Horizontal homogeneity
?
?
Equation of continuity
Steady-state condition
Horizontal homogeneity
?
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Extrapolation prescriptions
Highly reactive trace species
Long-lived species (constant flux approximation)
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Definition of an exchange velocity
deposition velocity
exhalation velocity
?
Horizontal homogeneity (Kramm, Dlugi, Mölders,
2003)
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Source Kramm Dlugi (1994)
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Damköhler (1940)
1. HO2 HO2 ? H2O2 7. NO3 Isoprenes ?
P 2. HNO3 NH3 ? NH4NO3 8. OH Isoprenes ?
P 3. O3 NO ? NO2 O2 9. OH Monoterpenes
? P 4. O3 Isoprenes ? Products (P) 10. O3
Olefins ? P 5. O3 Monoterpenes ? P 11. O3
NO2 ? NO3 O2 6. NO3 Monoterpenes ? P
Source Kramm Dlugi (1994)
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h
Eddy covariance techniques
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Eddy covariance techniques
Source Nestlen et al. (1993), Kramm and Meixner
(2002)
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Source Tennekes Lumley (1978)
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Test to Identify Stationary States
Allan-variance criterion (Allan, 1966)
Allan-Variance sA2
Source Werle et al. (1996)
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Percival Guttorp (1994)
with Haar (1910) wavelet coefficient
Sample average of k consecutive observations
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Generated time series data
Source Kramm et al. (1999)
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Allan variance
Source Kramm et al. (1999)
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Diurnal variation of mean concentrations
Source Nestlen et al. (1993)
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Diurnal variation of eddy fluxes
Source Nestlen et al. (1993)
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Frequency-weighted co-spectra
Source Kramm et al. (2003)
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Frequency weighted co-spectra
Source Kramm et al. (2003)
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Intensity of segregation
Source Kramm Meixner (2000)
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Intensity of segregation
Source Kramm Meixner (2000)
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Influence of segregation effects
Source Kramm Meixner (2000)
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Mass balance method
x
x Dx
fertilized soil
Kramm, Dlugi Mölders (2003)
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?
?
Conclusion Very crude method, but often the only
one
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Aerodynamic Method
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NO, NO2, NH3 VOCs O3, SO2, HNO3
VOCs
NO, N2O, NO2
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NO - NO2 - O3 Cycle
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Source Kramm et al. (1991)
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Comparison 1st-order closure vs. 2nd-order
closure
No segregation effects
Source Kramm Dlugi (1994)
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Source Norbert Beier, University of Munich,
Germany
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Ground chamber values
Eddy fluxes
Source Meixner et al. (1990), Kramm et al. (1991)
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NO - NO2 - O3 - NO3 N2O5 - HNO3
Cycle (Nighttime chemistry)
NO O3 ? NO2 O2 NO2 O3 ? NO3 O2 NO3
NO ? 2 NO2 MNO3 NO2 ? N2O5
MN2O5 ? NO2 NO3 N2O5 H2O ? 2 HONO2
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Source Kramm et al. (1995)
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Inferential Method (Hicks et al., 1987)
Prerequisite Flux is height-invariant
mi was introduced by Kramm (1989)
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Resistance network for the vegetation-soil system
CR
rt
rst rint rcu rw,f
1 - sf sf
Cint Ccu Cw,f
foliage
1 - sf sf
rmt Cf rmt,fg
rmt,g rsl rw,sl
1 - sw,sl sw,sl
soil
Csl Cw,st
Source Kramm Dlugi (1994)
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Possible basis for the inferential method
Source Hicks Matt (1988)
Source Nestlen et al. (1993)
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Source Hicks Matt (1988)
Source Kramm et al. (2003)
No basis for the inferential method
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Source Kramm et al. (2003)
Source Hicks Matt (1988)
No basis for the inferential method
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Source Müller et al. (1993)
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• Summary and Outlook

• Summary
• It was shown that
• vertical fluxes of highly reactive trace
  species
• can be affected by chemical reactions,
• eddy covariance measurements have to be
  analyzed
• carefully to identify the influence of
  chemical reactions,
• the mass balance method is a very crude method,
  
• but often the only one,
• the aerodynamic method can provide reliable
  results,
• but currently there is only a poor data basis
  for evaluation,
• the eddy flux of ozone hardly varies with
  height,
• where ozone is mainly deposited,
• nitric oxide and nitrogen dioxide can be both
• emitted and deposited, the vertical eddy
  fluxes are
• strongly affected by chemical reactions,

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• segregation effects must not be ignored,
• the inferential method should only be applied
• in the case of long-lived nitrogen trace
  species.
• Outlook
• What we need are
• (further) development of fast-response chemical
  analyzers,
• sophisticated field experiments carried out
  over low
• vegetation, where more than one measurement
  level
• is considered,
• sophisticated field experiments carried out
  over and
• within canopies of tall vegetation,
• sophisticated field experiments performed over
• heterogeneous terrain,
• higher-order closure models.