H. Harder , W. Pätz , A. Volz-Thomas , H. Fischer , T. Zenker
{"title":"Measurements of nitrogen oxides, ozone, and carbon monoxide during the FIELDVOC'94 campaign in Tábua","authors":"H. Harder , W. Pätz , A. Volz-Thomas , H. Fischer , T. Zenker","doi":"10.1016/S1465-9972(01)00005-8","DOIUrl":null,"url":null,"abstract":"<div><p>Measurements of NO,NO<sub><em>x</em></sub>,NO<sub><em>y</em></sub>,CO,O<sub>3</sub>,<em>J</em><sub>NO<sub>2</sub></sub> (the photolysis frequency of NO<sub>2</sub>) and of meteorological parameters made during the FIELDVOC'94 campaign in Tábua, Portugal, are described. The situation at the site was dominated by a land–sea breeze system coupled with thermal up-slope on the mountain ridge, which caused northwesterly flow from the coastal area during daytime and southeasterly flow at night. O<sub>3</sub> up to 100 ppbv was observed in photochemically aged air masses that reached the site in the afternoon from the coastal areas. At night, O<sub>3</sub> mixing ratios at the surface dropped below 10 ppbv. NO<sub><em>x</em></sub> mixing ratios varied between 200 pptv during daytime and 3 ppbv at night with peaks up to 6 ppbv. NO<sub><em>y</em></sub> (the sum of NO<sub><em>x</em></sub> and its oxidation products) varied between 1 and 6 ppbv and CO between 100 and 280 ppbv. Simultaneous measurements of NO<sub>2</sub> by photolytic conversion/NO-chemiluminescence and by tunable diode laser spectroscopy showed a tight correlation, in particular at night. Taking the identified difference in calibration between the two methods (8%) into account, the disagreement in the atmosphere, was ⩽2%, on average. Photochemical ozone formation in air transported from the coast was identified by a positive correlation between O<sub>3</sub> and the oxidation products of NO<sub><em>x</em></sub> referenced as NO<sub><em>z</em></sub>. The slope of 16 represents an upper limit to the efficiency of NO<sub><em>x</em></sub> in catalyzing ozone formation in air. The relatively high ozone formation efficiency is supported by the large O<sub>3</sub>/CO ratio of about 0.4. The correlation between CO and NO<sub><em>y</em></sub> indicates an upper limit for the CO/NO<sub><em>x</em></sub> emission ratio of 28.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 3","pages":"Pages 227-237"},"PeriodicalIF":0.0000,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(01)00005-8","citationCount":"16","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemosphere - Global Change Science","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1465997201000058","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 16
Abstract
Measurements of NO,NOx,NOy,CO,O3,JNO2 (the photolysis frequency of NO2) and of meteorological parameters made during the FIELDVOC'94 campaign in Tábua, Portugal, are described. The situation at the site was dominated by a land–sea breeze system coupled with thermal up-slope on the mountain ridge, which caused northwesterly flow from the coastal area during daytime and southeasterly flow at night. O3 up to 100 ppbv was observed in photochemically aged air masses that reached the site in the afternoon from the coastal areas. At night, O3 mixing ratios at the surface dropped below 10 ppbv. NOx mixing ratios varied between 200 pptv during daytime and 3 ppbv at night with peaks up to 6 ppbv. NOy (the sum of NOx and its oxidation products) varied between 1 and 6 ppbv and CO between 100 and 280 ppbv. Simultaneous measurements of NO2 by photolytic conversion/NO-chemiluminescence and by tunable diode laser spectroscopy showed a tight correlation, in particular at night. Taking the identified difference in calibration between the two methods (8%) into account, the disagreement in the atmosphere, was ⩽2%, on average. Photochemical ozone formation in air transported from the coast was identified by a positive correlation between O3 and the oxidation products of NOx referenced as NOz. The slope of 16 represents an upper limit to the efficiency of NOx in catalyzing ozone formation in air. The relatively high ozone formation efficiency is supported by the large O3/CO ratio of about 0.4. The correlation between CO and NOy indicates an upper limit for the CO/NOx emission ratio of 28.