Estimating the ozone budget in the boundary layer by use of aircraft measurements of ozone eddy flux and mean concentration

Abstract

A fast response chemiluminescent ozone sensor was mounted in a National Center for Atmospheric Research Queen Air aircraft instrumented for air motion, temperature, and humidity measurements. The vertical flux of ozone was then obtained by the eddy correlation technique for several flights in the day‐time atmospheric boundary layer over eastern Colorado. Because of the range and mobility of the aircraft, this technique can be utilized for a wide variety of situations. For example, a flight leg over an interstate highway shows large negative fluctuations in O3 due to vehicular emission of NO that are well correlated with positive temperature and vertical velocity fluctuations. On one flight the significant terms in the mean ozone concentration budget (and also, for comparison, the sensible heat and humidity budgets) were evaluated from the airplane measurements. For this flight, which occurred under clear skies over range and cropland about 100 km northeast of Denver, the time rate of change of ozone density in the lower half of the boundary layer was about 2.4 ng m−3 s−1. This was several times larger than the contributions by horizontal advection and the divergence of the vertical eddy flux of ozone. Thus, most of the observed increase in ozone concentration must have been the result of internal photochemical production of ozone. This may be the first well‐documented example where the rate of O3 increase with time is shown to be balanced by photochemical production of O3. The deposition velocity of ozone for this case was about 0.47 cm s−1.

Measuring Biogenic Volatile Organic Compounds (BVOCs) from Vegetation in Terms of Ozone Reactivity

“…CLDs are capable of sensitive and real-time monitoring of gaseous ozone. Note that when CLDs are utilized to quantify ozone concentrations in humid samples, the reduction in the chemiluminescence signal due to the quenching effect of water vapor can be important (Mattews et al, 1977;Lenschow et al, 1981;Ridley et al, 1992). In this study, however, the use of dual CLDs is expected to reduce/remove the interference of water vapor.…”

“…For CLD analyzers, water vapor in the sample gas has a quenching effect and can reduce the sensitivity of the ozone detector (Mattews et al, 1977;Lenschow et al, 1981;Ridley et al, 1992). When a CLD is adopted for the R O3 measurement of a humid sample such as emissions from a plant, the reduction in the ozone signal due to water vapor can cause potential interference in Eq.…”

Quantifying sources and sinks of reactive gases in the lower atmosphere using airborne flux observations

“…The EC technique affords a direct measure of vertical fluxes, which are sensitive to both surface and in situ processes. Previous work, for example, has applied airborne EC methodology to study ozone [Lenschow et al, 1981] and isoprene [Karl et al, 2013;Misztal et al, 2014]. Figure 1 summarizes key parameters derived in our analysis.…”

The NASA Carbon Airborne Flux Experiment (CARAFE): instrumentation and methodology

“…Airborne EC has elucidated surface-atmosphere exchange processes for more than 3 decades (Dabberdt et al, 1993;Desjardins et al, 1982;Lenschow et al, 1981;Ritter et al, 1992Ritter et al, , 1994Ritter et al, , 1990Sellers et al, 1997). Recent GHG applications include evaluations of net ecosystem exchange (NEE) over complex ecosystems (Miglietta et al, 2007;Zulueta et al, 2013) and quantification of CH 4 emissions from shale gas production regions , agricultural areas (Desjardins et al, 2018;Hiller et al, 2014), and Arctic biomes (Sayres et al, 2017).…”