English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. We present shipborne measurements of NOx (≡ NO + NO2) and NOy (≡ NOx+ gas- andparticle-phase organic and inorganic oxides of nitrogen) in summer 2017 aspart of the expedition “Air Quality and climate change in the Arabian BAsin” (AQABA). The NOx and NOz (≡ NOy-NOx)measurements, made with a thermal dissociation cavity ring-down spectrometer(TD-CRDS), were used to examine the chemical mechanisms involved in theprocessing of primary NOx emissions and their influence on the NOybudget in chemically distinct marine environments, including theMediterranean Sea, the Red Sea, and the Arabian Gulf, which were influencedto varying extents by emissions from shipping and oil and gas production.Complementing the TD-CRDS measurements, NO and NO2 data sets from achemiluminescence detector (CLD) were used in the analysis. In all regions,we find that NOx is strongly connected to ship emissions, both viadirect emission of NO and via the formation of HONO and its subsequentphotolytic conversion to NO. The role of HONO was assessed by calculatingthe NOx production rate from its photolysis. Mean NO2 lifetimeswere 3.9 h in the Mediterranean Sea, 4.0 h in the Arabian Gulf, and5.0 h in the Red Sea area. The cumulative loss of NO2 during thenight (reaction with O3) was more important than daytime losses(reaction with OH) over the Arabian Gulf (by a factor 2.8) and over the RedSea (factor 2.9), whereas over the Mediterranean Sea, where OH levels werehigh, daytime losses dominated (factor 2.5). Regional ozone productionefficiencies (OPEs; calculated from the correlation between Ox andNOz, where Ox= O3+ NO2) ranged from 10.5 ± 0.9 to 19.1 ± 1.1. This metric quantifies the relative strength ofphotochemical O3 production from NOx compared to the competingsequestering into NOz species. The largest values were found over theArabian Gulf, consistent with high levels of O3 found in that region(10–90 percentiles range: 23–108 ppbv). The fractional contribution ofindividual NOz species to NOy exhibited a large regionalvariability, with HNO3 generally the dominant component (on average33 % of NOy) with significant contributions from organic nitrates(11 %) and particulate nitrates in the PM1 size range (8 %).

Reactive nitrogen around the Arabian Peninsula and in the Mediterranean Sea during the 2017 AQABA ship campaign