1ff2a446-cbfa-4498-9240-9ad162a4e006 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/ 2012-03-28T18:17:30 ISO 19115:2003/19139 1.0 Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m a.s.l.) ACP - Special Issue 2010-07-02T00:00:00 Atmospheric Chemistry and Physics Vol.10 Special Issue:" Atmospheric brown cloud in the Himalayas." 5859-5872 Atmospheric Chemistry and Physics, 10, 5859-5872, 2010 Special Issue:" Atmospheric brown cloud in the Himalayas." 1680-7316 Intense anthropogenic emissions over the Indian sub-continent lead to the formation of layers of particulate pollution that can be transported to the high altitude regions of the Himalaya-Hindu Kush (HKH). Aerosol particles contain a substantial fraction of strongly absorbing material, including black carbon (BC), organic compounds (OC), and dust all of which can contribute to atmospheric warming, in addition to greenhouse gases. Using a 3-year record of continuous measurements of aerosol optical properties, we present a time series of key climate relevant aerosol properties including the aerosol absorption and scattering coefficients as well as the single-scattering albedo (w0). Results of this investigation show substantial seasonal variability of these properties, with long range transport during the pre- and post-monsoon seasons and efficient precipitation scavenging of aerosol particles during the monsoon season. The monthly averaged scattering coefficients range from 0.1 Mm-1 (monsoon) to 20 Mm-1 while the average absorption coefficients range from 0.5 Mm-1 to 3.5 Mm-1. Both have their maximum values during the premonsoon period (April) and reach a minimum during Monsoon (July–August). This leads to dry w0 values from 0.86 (pre-monsoon) to 0.79 (monsoon) seasons. Significant diurnal variability due to valley wind circulation is also reported. Using aerosol optical depth (AOD) measurements,we calculated the resulting direct local radiative forcing due to aerosols for selected air mass cases. We found that the presence of absorbing particulate material can locally induce an additional top of the atmosphere (TOA) forcing of 10 to 20 W m-2 for the first atmospheric layer (500 m above surface). The TOA positive forcing depends on the presence of snow at the surface, and takes place preferentially during episodes of regional pollution occurring on a very regular basis in the Himalayan valleys. Warming of the first atmospheric layer is paralleled by a substantial decrease of the amount of radiation reaching the surface. The surface forcing is estimated to range from -4 to -20 W m-2 for small-scale regional pollution events and large-scale pollution events, respectively. The calculated surface forcing is also very dependent on surface albedo, with maximum values occurring over a snow-covered surface. Overall, this work presents the first estimates of aerosol direct radiative forcing over the high Himalaya based on in-situ aerosol measurements, and results suggest a TOA forcing significantly greater than the IPCC reported values for green house gases. This work was carried out in the framework of the UNEP – ABC (Atmospheric Brown Clouds) and EvK2CNR – SHARE (Stations at High Altitude for Research on the Environment) projects. 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 An Interactive Open Access Journal of the European Geosciences Union S. Marcq CNRS Laboratory of Meteorology Physics - Laboratory of Glaciology 54, rue Molière Saint-Martin d’Hères cedex BP 96 F-38402 France http://lgge.osug.fr/ WWW:LINK-1.0-http--partners Paolo Laj CNRS Laboratory of Meteorology Physics - Laboratory of Glaciology +33 685628874 +33 473405132 24,Avenue des Landais Aubiere Cedex 63177 France aj@lgge.obs.ujf-grenoble.fr http://wwwobs.univ-bpclermont.fr/ WWW:LINK-1.0-http--partners J. C. Roger Blaise Pascal University ,CNRS +33 675157675 +33 473405136 24,Avenue des Landais Aubière Cedex 63177 France roger@opgc.univ-bpclermont.fr http://wwwobs.univ-bpclermont.fr/opgc/ WWW:LINK-1.0-http--partners Paolo Villani Blaise Pascal University ,CNRS +33 473407678 +33 473405136 24,Avenue des Landais Aubière Cedex 63177 France p.villani@opgc.univ-bpclermont.fr http://wwwobs.univ-bpclermont.fr/opgc/ WWW:LINK-1.0-http--partners Karine Sellegri Blaise Pascal University,CNRS +33 473407394 +33 473405136 24,Avenue des Landais Aubière Cedex 63177 France K.Sellegri@opgc.univ-bpclermont.fr http://wwwobs.univ-bpclermont.fr/opgc/ WWW:LINK-1.0-http--partners 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 http://www.isac.cnr.it/ WWW:LINK-1.0-http--partners 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 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 Giampietro Verza Ev-K2-CNR Via San Bernardino, 145 Bergamo BG 24126 Italy gianpietro.verza@evk2cnr.org http://www.evk2cnr.org Michael H. Bergin Georgia Institute of Technology, Civil and Environmental Engineering +1 4048949723 790 Atlantic Drive N.W. Atlanta GA 30332-0355 United States of America mike.bergin@ce.gatech.edu http://people.ce.gatech.edu/~mhbergin/ WWW:LINK-1.0-http--related https://geoportal.mountaingenius.org/geonetwork/srv/eng/resources.get?uuid=1ff2a446-cbfa-4498-9240-9ad162a4e006&fname=mountain_witness__s.png thumbnail png SHARE Atmospheric Brown Clouds Himalayas Nepal Climate Observatory-Pyramid Nepal Aerosol optical properties radiative forcing aerosol optical depth eng climatologyMeteorologyAtmosphere 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 " https://geoportal.mountaingenius.org/webapp/srv/en/resources.get?id=1674&fname=acp-10-5859-2010.pdf&access=private WWW:DOWNLOAD-1.0-http--download acp-10-5859-2010.pdf Full Text(pdf):"Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m a.s.l.)". http://www.atmos-chem-phys.net/10/5859/2010/acp-10-5859-2010.html WWW:LINK-1.0-http--related Abstract:"Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m a.s.l.)". 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 " ACP (Atmospheric Chemistry and Physics) - Special Issue Atmospheric brown cloud in the Himalayas. Editor(s): G. McFiggans and J. J. Schauer "Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m a.s.l.)". S. Marcq, P. Laj, J. C. Roger, P. Villani, K. Sellegri, P. Bonasoni, A. Marinoni, P. Cristofanelli, G. P. Verza, and M. Bergin. Atmos. Chem. Phys., 10, 5859-5872, 2010.