Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model

Determining the sources of total nitrate (TNIT NO-3 + HNO3) reaching Antarctica is a long-standing challenge. Here we analyze the monthly sensitivity of surface-level TNIT in Antarctica to primary sources using a global 3-D chemical transport model, GEOS-Chem, and its adjoint. Modeled seasonal varia...

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Main Authors: Henze, Daven K., Lee, Hyung-Min, Alexander, Becky, Murray, Lee T.
Format: Other/Unknown Material
Language:unknown
Published: 2014
Subjects:
Online Access:http://hdl.handle.net/2060/20150022188
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spelling ftnasantrs:oai:casi.ntrs.nasa.gov:20150022188 2023-05-15T13:35:11+02:00 Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model Henze, Daven K. Lee, Hyung-Min Alexander, Becky Murray, Lee T. Unclassified, Unlimited, Publicly available March 5, 2014 application/pdf http://hdl.handle.net/2060/20150022188 unknown Document ID: 20150022188 http://hdl.handle.net/2060/20150022188 Copyright, Distribution under U.S. Government purpose rights CASI Meteorology and Climatology GSFC-E-DAA-TN22590 Atmospheric Environment(ISSN 1352-2310); Volume 89; 757-767 2014 ftnasantrs 2016-03-12T23:54:53Z Determining the sources of total nitrate (TNIT NO-3 + HNO3) reaching Antarctica is a long-standing challenge. Here we analyze the monthly sensitivity of surface-level TNIT in Antarctica to primary sources using a global 3-D chemical transport model, GEOS-Chem, and its adjoint. Modeled seasonal variation of TNIT concentrations shows good agreement with several measurement studies, given that the lack of post-depositional processing in the model leads to an expected underestimate of maximum values in November through January. Remote NOx sources have the greatest impact May-July, during when the model background concentrations are sensitive to NOx emissions from fossil fuel combustion, soil, and lightning originating from 25S to 65S. In this season, NOx is transported to Antarctica as TNIT, which is formed above continental source regions at an altitude of 5-11 km. In other seasons, more NOx is transported as a reservoir species (e.g., peroxyacetyl nitrate, PAN) through the free troposphere, transforming into TNIT within a cone of influence that extends to 35S and above 4 km altitude. Photolysis of PAN over Antarctica is the main driver of modeled NOx seasonality. Stratospheric production and loss of tracers are relatively unimportant in monthly sensitivities in GEOS-Chem, driving only a few percent of surface level variability of TNIT. A small peak concentration in August is captured by the model, although some measured values in August fall outside the range of simulated concentrations. Modifications to the model to represent sedimentation of polar stratospheric clouds (PSCs) lead to increased surface level August TNIT concentrations. However, this simple representation does not explicitly account for PSC particle deposition or disappearance of the tropopause in the middle of winter, and thus the influence of stratospheric nitrate sources estimated in this study is likely a lower bound. Other/Unknown Material Antarc* Antarctica NASA Technical Reports Server (NTRS)
institution Open Polar
collection NASA Technical Reports Server (NTRS)
op_collection_id ftnasantrs
language unknown
topic Meteorology and Climatology
spellingShingle Meteorology and Climatology
Henze, Daven K.
Lee, Hyung-Min
Alexander, Becky
Murray, Lee T.
Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model
topic_facet Meteorology and Climatology
description Determining the sources of total nitrate (TNIT NO-3 + HNO3) reaching Antarctica is a long-standing challenge. Here we analyze the monthly sensitivity of surface-level TNIT in Antarctica to primary sources using a global 3-D chemical transport model, GEOS-Chem, and its adjoint. Modeled seasonal variation of TNIT concentrations shows good agreement with several measurement studies, given that the lack of post-depositional processing in the model leads to an expected underestimate of maximum values in November through January. Remote NOx sources have the greatest impact May-July, during when the model background concentrations are sensitive to NOx emissions from fossil fuel combustion, soil, and lightning originating from 25S to 65S. In this season, NOx is transported to Antarctica as TNIT, which is formed above continental source regions at an altitude of 5-11 km. In other seasons, more NOx is transported as a reservoir species (e.g., peroxyacetyl nitrate, PAN) through the free troposphere, transforming into TNIT within a cone of influence that extends to 35S and above 4 km altitude. Photolysis of PAN over Antarctica is the main driver of modeled NOx seasonality. Stratospheric production and loss of tracers are relatively unimportant in monthly sensitivities in GEOS-Chem, driving only a few percent of surface level variability of TNIT. A small peak concentration in August is captured by the model, although some measured values in August fall outside the range of simulated concentrations. Modifications to the model to represent sedimentation of polar stratospheric clouds (PSCs) lead to increased surface level August TNIT concentrations. However, this simple representation does not explicitly account for PSC particle deposition or disappearance of the tropopause in the middle of winter, and thus the influence of stratospheric nitrate sources estimated in this study is likely a lower bound.
format Other/Unknown Material
author Henze, Daven K.
Lee, Hyung-Min
Alexander, Becky
Murray, Lee T.
author_facet Henze, Daven K.
Lee, Hyung-Min
Alexander, Becky
Murray, Lee T.
author_sort Henze, Daven K.
title Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model
title_short Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model
title_full Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model
title_fullStr Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model
title_full_unstemmed Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model
title_sort investigating the sensitivity of surface-level nitrate seasonality in antarctica to primary sources using a global model
publishDate 2014
url http://hdl.handle.net/2060/20150022188
op_coverage Unclassified, Unlimited, Publicly available
genre Antarc*
Antarctica
genre_facet Antarc*
Antarctica
op_source CASI
op_relation Document ID: 20150022188
http://hdl.handle.net/2060/20150022188
op_rights Copyright, Distribution under U.S. Government purpose rights
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