Measurement of NO₂ by the photolysis conversion technique during the Transport and Chemical Evolution Over the Pacific (TRACE‐P) campaign

Abstract

[1] An airborne instrument for in situ measurements of tropospheric nitrogen dioxide (NO 2 ) was developed using the photolytic conversion technique followed by chemiluminescence detection of NO. This instrument was used for the measurements of NO 2 on board the NASA P-3B aircraft during the Transport and Chemical Evolution Over the Pacific (TRACE-P) campaign. Comparison in the laboratory indicated less than 10% difference between our NO 2 instrument and two independent laser-induced fluorescence instruments in the NO 2 range of 30 parts per trillion by volume (pptv) to 50 ppbv. The magnitudes of potential errors in airborne tropospheric NO 2 measurements were further assessed using the TRACE-P data set. The systematic errors estimated for the median NO 2 mixing ratios, 70 pptv at 0-2 km (30 pptv at 2-8 km), were 19% (39%). The random errors for a 10 s integration time were estimated to be 5-10%, depending on altitude. The observed NO 2 mixing ratios were compared to those calculated by a photochemical box model. Overall, the calculated NO 2 values correlated very well with those observed (r 2 = 0.97), although the calculations were systematically higher than the observations by about 30%, except for the highest flight levels. The calculated/ observed NO 2 ratio remained nearly constant, having values close to 1.3 at 0-4 km, and decreased with altitude. The difference between the observed and model-calculated values, however, was within the combined uncertainty in the measurement and model calculation. The underlying causes for this difference are to be determined in future studies.

A transboundary transport episode of nitrogen dioxide as observed from GOME and its impact in the Alpine region

“…Similar values from different campaigns can be found in Warneck (2000). Ratios of up to 1 are found in the middle troposphere (Nakamura et al, 2003).…”

“…Furthermore, the NO 2 concentration is affected by the partitioning of NO x into NO and NO 2 which depends on the meteorological conditions, the abundance of reactive organic compounds and the altitude in the troposphere. During the Transport and Chemical Evolution over the Pacific (TRACE-P) campaign between February and April 2001 (Jacob et al, 2003), the bulk of the NO/NO 2 ratios have been found to be around 0.25 at near-ground levels (Nakamura et al, 2003). Similar values from different campaigns can be found in Warneck (2000).…”

“…4.6.2). A relatively long lifetime (24 h) is chosen because the photolysis is relatively weak in winter due to the increased solar zenith angle (Dickerson et al, 1982;Parrish et al, 1983;Wiegand and Bofinger, 2000). Furthermore, the loss of NO 2 through conversion with OH to HNO 3 is slow because the amount of OH is low in winter (Seinfeld and Pandis, 1998).…”

Nitrogen oxide measurements at rural sites in Switzerland: Bias of conventional measurement techniques

“…A good agreement was also observed with results from the DOAS system for a 2‐day period. Nakamura et al [2003] compared a photolytic converter instrument with two LIF instruments. Their laboratory tests revealed agreements with the LIF instruments of less than 10% difference.…”

The IAGOS NO<sub><i>x</i></sub> instrument – design, operation and first results from deployment aboard passenger aircraft

“…The most common measurement technologies for NO x are based on the chemiluminescence detection (CLD) for the indirect measurement of NO (Clough and Thrush, 1967;Ridley and Howlett, 1974;Drummond et al, 1985;Fahey et al, 1985). CLD instruments have often been coupled to a photolytic or catalytic converter to measure NO 2 and NO x by using a xenon lamp, blue-light converter or catalytic conversion of NO 2 into NO, prior to the CLD unit Ryerson et al, 2000;Nakamura et al, 2003;Pollack et al, 2010;Villena et al, 2012;Reed et al, 2016). NO 2 measurements at low-NO x conditions (below 0.1 ppbv) are close to the limit of detection (Yang et al, 2004), and depending on the installed converter each instrument might show interferences with other nitrogen-oxide-containing species (e.g., Reed et al, 2016).…”