8e0040ad-be1d-4a3c-8072-74692f64c623 eng 2f8f7474-e97d-4ba4-bb6a-424b05b23adb Ev-K2-CNR +39 035 3230511 +39 035 3230551 Via San Bernardino 145 Bergamo BG 24126 Italy metadata@evk2cnr.org http://www.evk2cnr.org/ 2012-04-02T09:02:10 ISO 19115:2003/19139 1.0 Tropospheric ozone variations at the Nepal climate observatory – pyramid (Himalayas, 5079 m a.s.l.) and influence of stratospheric intrusion events 2010-07-16T00:00:00 Atmospheric Chemistry and Physics, 10 Special Issue"Atmospheric brown cloud in the Himalayas." 6537-6549 Atmospheric Chemistry and Physics, 10, 6537-6549, 2010 Special Issue"Atmospheric brown cloud in the Himalayas." 1680-7316 The paper presents the first 2-years of continuous surface ozone (O3) observations and systematic assessment of the influence of stratospheric intrusions (SI) at the Nepal Climate Observatory at Pyramid (NCO-P; 27°57' N, 86°48' E), located in the Southern Himalayas at 5079 m a.s.l. Continuous O3 monitoring has been carried out at this GAW-WMO station in the framework of the Ev-K2-CNR SHARE and UNEP ABC projects since March 2006. Over the period March 2006–February 2008, an average O3 value of 49±12 ppbv (±1?) was recorded, with a large annual cycle characterized by a maximum during the pre-monsoon (61±9 ppbv) and a minimum during the monsoon (39±10 ppbv). In general, the average O3 diurnal cycles had different shapes in the different seasons, suggesting an important interaction between the synoptic-scale circulation and the local mountain wind regime. Short-term O3 behaviour in the middle/lower troposphere (e.g. at the altitude level of NCO-P) can be significantly affected by deep SI which, representing the most important natural input for tropospheric O3, can also influence the regional atmosphere radiative forcing. To identify days possibly influenced by SI at the NCO-P, analyses were performed on in-situ observations (O3 and meteorological parameters), total column O3 data from OMI satellite and air-mass potential vorticity provided by the LAGRANTO back-trajectory model. In particular, a specially designed statistical methodology was applied to the time series of the observed and modelled stratospheric tracers. On this basis, during the 2-year investigation, 14.1% of analysed days were found to be affected by SI. The SI frequency showed a clear seasonal cycle, with minimum during the summer monsoon (1.2%) and higher values during the rest of the year (21.5%). As suggested by the LAGRANTO analysis, the position of the subtropical jet stream could play an important role in determining the occurrence of deep SI transport on the Southern Himalayas. In order to estimate the fraction of O3 due to air-mass transport from the stratosphere at the NCO-P, the 30 min O3 concentrations recorded during the detected SI days were analysed. In particular, in-situ relative humidity and black carbon observations were used to exclude influence from wet and polluted air-masses transported by up-valley breezes. This analysis led to the conclusion that during SI O3 significantly increased by 27.1% (+13 ppbv) with respect to periods not affected by such events. Moreover, the integral contribution of SI (O3S) to O3 at the NCO-P was also calculated, showing that 13.7% of O3 recorded at the measurement site could be attributed to SI. On a seasonal basis, the lowest SI contributions were found during the summer monsoon (less than 0.1%), while the highest were found during the winter period (24.2%). These results indicated that, during non-monsoon periods, high O3 levels could affect NCO-P during SI, thus influencing the variability of tropospheric O3 over the Southern Himalayas. Being a powerful regional greenhouse gas, these results indicate that the evaluation of the current and future regional climate cannot be assessed without properly taking into account the influence of SI to tropospheric O3 in this important area. Copernicus GmbH (Copernicus Publications) +49 5519003390 +49 55190033970 Bahnhofsallee 1e Göttingen 37081 Germany info@copernicus.org http://www.copernicus.org/ WWW:LINK-1.0-http--related Paolo Cristofanelli Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399597 +39 0516399652 Via Gobetti,101 Bologna BO 40129 Italy p.cristofanelli@isac.cnr.it http://www.isac.cnr.it/ WWW:LINK-1.0-http--partners Alessandro Bracci Institute for Atmospheric Science and Climate(ISAC)-CNR +39 0649934266 Via Fosso del Cavaliere, 100 Roma ROMA 00133 Italy www.isac.cnr.it Angela Marinoni Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399597 +39 0516399652 Via Gobetti,101 Bologna BO 40129 Italy a.marinoni@isac.cnr.it http://www.isac.cnr.it/ WWW:LINK-1.0-http--partners Michael Sprenger Institute for Atmospheric and Climate Science,ETH +41 446333623 Universitätstrasse 16 Zürich 8092 Switzerland michael.sprenger@env.ethz.ch www.env.ethz.ch Ubaldo Bonafè Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399583 Via Gobetti,101 Bologna BO 40129 Italy U.Bonafe@isac.cnr.it www.isac.cnr.it Francescopiero Calzolari Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399582 Via Gobetti,101 Bologna BO 40129 Italy F.Calzolari@isac.cnr.it www.isac.cnr.it Rocco Duchi Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399584 Via Gobetti,101 Bologna BO 40129 Italy R.Duchi@isac.cnr.it www.isac.cnr.it Fabrizio Roccato Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399628 Via Gobetti,101 Bologna BO 40129 Italy F.Roccato@isac.cnr.it www.isac.cnr.it Paolo Bonasoni Institute of Atmospheric Sciences and Climate (ISAC) - CNR +39 0516399590 +39 0516399652 Via Gobetti,101 Bologna BO 40129 Italy p.bonasoni@isac.cnr.it www.isac.cnr.it Paolo Laj CNRS Laboratory of Meteorology Physics - Laboratory of Glaciology +33 685628874 +33 473405132 Avenue des Landais Aubiere Cedex 63177 Italy aj@lgge.obs.ujf-grenoble.fr http://wwwobs.univ-bpclermont.fr/ Elisa Vuillermoz Ev-K2-CNR +39 0353230513 +39 0353230551 Via San Bernardino, 145 Bergamo BG 24126 Italy elisa.vuillermoz@evk2cnr.org http://www.evk2cnr.org/ H. Venzac Blaise Pascal University , CNRS +33 473407678 +33 473405136 24, avenue des Landais Aubière Cedex 63177 Italy h.venzac@opgc.univ-bpclermont.fr http://wwwobs.univ-bpclermont.fr Jean-Marc Pichon Blaise Pascal University, CNRS +33 473407824 +33 473405136 24, avenue des Landais Aubière Cedex 63177 France j.m.pichon@opgc.univ-bpclermont.fr http://wwwobs.univ-bpclermont.fr/ https://geoportal.mountaingenius.org/geonetwork/srv/eng/resources.get?uuid=8e0040ad-be1d-4a3c-8072-74692f64c623&fname=mountain_witness__s.png thumbnail png Atmospheric Brown Clouds Himalayas Nepal Nepal Climate Observatory-Pyramid Tropospheric ozone variations stratospheric intrusion events SHARE ABC eng climatologyMeteorologyAtmosphere geoscientificInformation environment 80.0522 88.1946 26.3684 30.4247 http://www.atmos-chem-phys.net/special_issue162.html WWW:LINK-1.0-http--link The book contains the scientific papers published by EvK2Cnr researchers in a special issue of Atmospheric Chemistry and Physics, entitled "Atmospheric brown clouds in the Himalayas " http://www.atmos-chem-phys-discuss.net/10/1483/2010/acpd-10-1483-2010.html WWW:LINK-1.0-http--related Abstract:Tropospheric ozone variations at the Nepal climate observatory – pyramid (Himalayas, 5079 m a.s.l.) and influence of stratospheric intrusion events. https://geoportal.mountaingenius.org/webapp/srv/en/resources.get?id=1647&fname=acp-10-6537-2010.pdf&access=private WWW:DOWNLOAD-1.0-http--download acp-10-6537-2010.pdf Full Text(pdf):"Tropospheric ozone variations at the Nepal climate observatory – pyramid (Himalayas, 5079 m a.s.l.) and influence of stratospheric intrusion events" The book contains the scientific papers by EvK2Cnr researchers in a special issue of Atmospheric Chemistry and Physics, entitled "Atmospheric brown clouds in the Himalayas " Editor(s): G. McFiggans and J. J. Schauer "Tropospheric ozone variations at the Nepal Climate Observatory-Pyramid (Himalayas, 5079 m a.s.l.) and influence of deep stratospheric intrusion events" P. Cristofanelli, A. Bracci, M. Sprenger, A. Marinoni, U. Bonafè, F. Calzolari, R. Duchi, P. Laj, J.M. Pichon, F. Roccato, H. Venzac, E. Vuillermoz, and P. Bonasoni. Atmos. Chem. Phys., 10, 6537-6549, 2010. www.atmos-chem-phys.net/10/6537/2010/ doi:10.5194/acp-10-6537-2010