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Title: How can mountaintop CO 2 observations be used to constrain regional carbon fluxes?

Abstract

Despite the need for researchers to understand terrestrial biospheric carbon fluxes to account for carbon cycle feedbacks and predict future CO 2 concentrations, knowledge of these fluxes at the regional scale remains poor. This is particularly true in mountainous areas, where complex meteorology and lack of observations lead to large uncertainties in carbon fluxes. Yet mountainous regions are often where significant forest cover and biomass are found – i.e., areas that have the potential to serve as carbon sinks. As CO 2 observations are carried out in mountainous areas, it is imperative that they are properly interpreted to yield information about carbon fluxes. In this paper, we present CO 2 observations at three sites in the mountains of the western US, along with atmospheric simulations that attempt to extract information about biospheric carbon fluxes from the CO 2 observations, with emphasis on the observed and simulated diurnal cycles of CO 2. We show that atmospheric models can systematically simulate the wrong diurnal cycle and significantly misinterpret the CO 2 observations, due to erroneous atmospheric flows as a result of terrain that is misrepresented in the model. This problem depends on the selected vertical level in the model and is exacerbatedmore » as the spatial resolution is degraded, and our results indicate that a fine grid spacing of ~4 km or less may be needed to simulate a realistic diurnal cycle of CO 2 for sites on top of the steep mountains examined here in the American Rockies. In conclusion, in the absence of higher resolution models, we recommend coarse-scale models to focus on assimilating afternoon CO 2 observations on mountaintop sites over the continent to avoid misrepresentations of nocturnal transport and influence.« less

Authors:
ORCiD logo [1];  [1];  [1]; ORCiD logo [2]
  1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Atmospheric Sciences
  2. National Center for Atmospheric Research, Boulder, CO (United States). Earth Observing Lab.
Publication Date:
Research Org.:
Univ. of Utah, Salt Lake City, UT (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
1355135
Alternate Identifier(s):
OSTI ID: 1368184
Grant/Contract Number:
SC0010624; SC0010625
Resource Type:
Journal Article: Published Article
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 9; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Lin, John C., Mallia, Derek V., Wu, Dien, and Stephens, Britton B. How can mountaintop CO2 observations be used to constrain regional carbon fluxes?. United States: N. p., 2017. Web. doi:10.5194/acp-17-5561-2017.
Lin, John C., Mallia, Derek V., Wu, Dien, & Stephens, Britton B. How can mountaintop CO2 observations be used to constrain regional carbon fluxes?. United States. doi:10.5194/acp-17-5561-2017.
Lin, John C., Mallia, Derek V., Wu, Dien, and Stephens, Britton B. Wed . "How can mountaintop CO2 observations be used to constrain regional carbon fluxes?". United States. doi:10.5194/acp-17-5561-2017.
@article{osti_1355135,
title = {How can mountaintop CO2 observations be used to constrain regional carbon fluxes?},
author = {Lin, John C. and Mallia, Derek V. and Wu, Dien and Stephens, Britton B.},
abstractNote = {Despite the need for researchers to understand terrestrial biospheric carbon fluxes to account for carbon cycle feedbacks and predict future CO2 concentrations, knowledge of these fluxes at the regional scale remains poor. This is particularly true in mountainous areas, where complex meteorology and lack of observations lead to large uncertainties in carbon fluxes. Yet mountainous regions are often where significant forest cover and biomass are found – i.e., areas that have the potential to serve as carbon sinks. As CO2 observations are carried out in mountainous areas, it is imperative that they are properly interpreted to yield information about carbon fluxes. In this paper, we present CO2 observations at three sites in the mountains of the western US, along with atmospheric simulations that attempt to extract information about biospheric carbon fluxes from the CO2 observations, with emphasis on the observed and simulated diurnal cycles of CO2. We show that atmospheric models can systematically simulate the wrong diurnal cycle and significantly misinterpret the CO2 observations, due to erroneous atmospheric flows as a result of terrain that is misrepresented in the model. This problem depends on the selected vertical level in the model and is exacerbated as the spatial resolution is degraded, and our results indicate that a fine grid spacing of ~4 km or less may be needed to simulate a realistic diurnal cycle of CO2 for sites on top of the steep mountains examined here in the American Rockies. In conclusion, in the absence of higher resolution models, we recommend coarse-scale models to focus on assimilating afternoon CO2 observations on mountaintop sites over the continent to avoid misrepresentations of nocturnal transport and influence.},
doi = {10.5194/acp-17-5561-2017},
journal = {Atmospheric Chemistry and Physics (Online)},
number = 9,
volume = 17,
place = {United States},
year = {Wed May 03 00:00:00 EDT 2017},
month = {Wed May 03 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.5194/acp-17-5561-2017

Citation Metrics:
Cited by: 3works
Citation information provided by
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  • Despite the need for researchers to understand terrestrial biospheric carbon fluxes to account for carbon cycle feedbacks and predict future CO 2 concentrations, knowledge of these fluxes at the regional scale remains poor. This is particularly true in mountainous areas, where complex meteorology and lack of observations lead to large uncertainties in carbon fluxes. Yet mountainous regions are often where significant forest cover and biomass are found – i.e., areas that have the potential to serve as carbon sinks. As CO 2 observations are carried out in mountainous areas, it is imperative that they are properly interpreted to yield informationmore » about carbon fluxes. In this paper, we present CO 2 observations at three sites in the mountains of the western US, along with atmospheric simulations that attempt to extract information about biospheric carbon fluxes from the CO 2 observations, with emphasis on the observed and simulated diurnal cycles of CO 2. We show that atmospheric models can systematically simulate the wrong diurnal cycle and significantly misinterpret the CO 2 observations, due to erroneous atmospheric flows as a result of terrain that is misrepresented in the model. This problem depends on the selected vertical level in the model and is exacerbated as the spatial resolution is degraded, and our results indicate that a fine grid spacing of ~4 km or less may be needed to simulate a realistic diurnal cycle of CO 2 for sites on top of the steep mountains examined here in the American Rockies. In conclusion, in the absence of higher resolution models, we recommend coarse-scale models to focus on assimilating afternoon CO 2 observations on mountaintop sites over the continent to avoid misrepresentations of nocturnal transport and influence.« less
  • Time series are presented of radiocarbon and C-13 contents in atmospheric carbon dioxide over eastern Europe (southern Poland), covering the periods 1983-1994 and 2000-2004. The carbon isotope composition was measured in biweekly composite samples of atmospheric CO{sub 2}, collected about 20 m above the local ground level. The data for 2 observational sites are presented: I) city of Krakow (50{sup o} 04'N, 19{sup o} 55'E; 220 m asl; for 1983-1994 and 2000-2004); and ii) Kasprowy Wierch, Tatra Mountains (49{sup o} 14'N, 19{sup o} 56'E; 1989 m asl; for 2000-2004). The latter site is considered a regional reference station, relatively freemore » of anthropogenic influences. During the period 1983-1994, observations in the Krakow area revealed a gradual decrease of C-14 content with a broad minimum around 1991 and a small increase by about 10 parts per thousand in the subsequent years. {delta}C-13 also changes with time, showing a decreasing trend from approximately -9.6 parts per thousand in 1983, with a slope of -0.02 parts per thousand/yr. The observed trends for both isotopes coincide well with a substantial reduction of coal consumption in Poland and partial replacement of coal by natural gas, especially in urban regions. After 2000, the {delta}C-13 slightly increases, reaching a mean value of -10 parts per thousand in 2004, while {delta}C-14 is below the reference level by similar to 3.5 parts per thousand. Observations at Kasprowy Wierch (regional reference station) also reflect a diminishing input of fossil carbon into the regional atmosphere. The fossil component in atmospheric CO{sub 2}, calculated with the aid of C-14 data available for the 2 study periods, shows a reduction of anthropogenic input by a factor of 2, which is confirmed by annual statistics of coal consumption.« less
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