Long-term NO<sub><i>x</i></sub> measurements in the remote marine tropical troposphere
-
Published:2021-04-27
Issue:4
Volume:14
Page:3071-3085
-
ISSN:1867-8548
-
Container-title:Atmospheric Measurement Techniques
-
language:en
-
Short-container-title:Atmos. Meas. Tech.
Author:
Andersen Simone T.ORCID, Carpenter Lucy J.ORCID, Nelson Beth S.ORCID, Neves Luis, Read Katie A., Reed ChrisORCID, Ward Martyn, Rowlinson Matthew J.ORCID, Lee James D.ORCID
Abstract
Abstract. Atmospheric nitrogen oxides (NO + NO2 = NOx) have been
measured at the Cape Verde Atmospheric Observatory (CVAO) in the tropical
Atlantic (16∘51′ N, 24∘52′ W) since October 2006.
These measurements represent a unique time series of NOx in the
background remote troposphere. Nitrogen dioxide (NO2) is measured via
photolytic conversion to nitric oxide (NO) by ultraviolet light-emitting
diode arrays followed by chemiluminescence detection. Since the measurements
began, a blue light converter (BLC) has been used for NO2
photolysis, with a maximum spectral output of 395 nm from 2006 to 2015 and of
385 nm from 2015 onwards. The original BLC used was constructed with a Teflon-like
material and appeared to cause an overestimation of NO2 when
illuminated. To avoid such interferences, a new additional photolytic
converter (PLC) with a quartz photolysis cell (maximum spectral output also
385 nm) was implemented in March 2017. Once corrections are made for the
NO2 artefact from the original BLC, the two NO2 converters are
shown to give comparable NO2 mixing ratios (BLC = 0.99 × PLC + 0.7 ppt, linear least-squares regression), giving confidence in the
quantitative measurement of NOx at very low levels. Data analysis
methods for the NOx measurements made at CVAO have been developed and
applied to the entire time series to produce an internally consistent and
high-quality long-term data set. NO has a clear diurnal pattern with a
maximum mixing ratio of 2–10 ppt during the day depending on the season and
∼ 0 ppt during the night. NO2 shows a fairly flat diurnal
signal, although a small increase in daytime NOx is evident in some
months. Monthly average mixing ratios of NO2 vary between 5 and 30 ppt
depending on the season. Clear seasonal trends in NO and NO2 levels can
be observed with a maximum in autumn and winter and a minimum in spring and summer.
Funder
Natural Environment Research Council
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference51 articles.
1. Alam, M. S., Crilley, L. R., Lee, J. D., Kramer, L. J., Pfrang, C., Vázquez-Moreno, M., Ródenas, M., Muñoz, A., and Bloss, W. J.: Interference from alkenes in chemiluminescent NOx measurements, Atmos. Meas. Tech., 13, 5977–5991, https://doi.org/10.5194/amt-13-5977-2020, 2020. 2. Andersen, S. T.: NOx measurements at the CVAO, EBAS, available at: http://ebas.nilu.no/Pages/DataSetList.aspx?key=45DB99FE2B7F4F97864ECF800E71E5D5, last access: 18 February 2021. 3. Atkinson, R.: Atmospheric chemistry of VOCs and
NOx, Atmos. Environ., 34, 2063–2101, https://doi.org/10.1016/S1352-2310(99)00460-4, 2000. 4. Atkinson, R., Baulch, D. L., Cox, R. A., Crowley, J. N., Hampson, R. F., Hynes, R. G., Jenkin, M. E., Rossi, M. J., and Troe, J.: Evaluated kinetic and photochemical data for atmospheric chemistry: Volume I - gas phase reactions of Ox, HOx, NOx and SOx species, Atmos. Chem. Phys., 4, 1461–1738, https://doi.org/10.5194/acp-4-1461-2004, 2004. 5. Buhr, M. P.: Solid-state light source photolytic nitrogen dioxide converter, US 7238328 B2, USA, USPTO,
available at: https://patents.google.com/patent/US7238328B2 (last access: 18 February 2021), 2007.
Cited by
10 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|