Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains
The variability of trace gases such as carbon monoxide (CO) at surface monitoring stations is affected by meteorological forcings that are particularly complicated over mountainous terrain. A detailed understanding of the impact of meteorological forcings on trace gas variability is challenging, but...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Stockholm University Press
2015-05-01
|
| Series: | Tellus: Series B, Chemical and Physical Meteorology |
| Subjects: | |
| Online Access: | http://www.tellusb.net/index.php/tellusb/article/view/25659/pdf_8 |
| _version_ | 1828365423603613696 |
|---|---|
| author | Temple R. Lee Stephan F. J. De Wekker Sandip Pal Arlyn E. Andrews Jonathan Kofler |
| author_facet | Temple R. Lee Stephan F. J. De Wekker Sandip Pal Arlyn E. Andrews Jonathan Kofler |
| author_sort | Temple R. Lee |
| collection | DOAJ |
| description | The variability of trace gases such as carbon monoxide (CO) at surface monitoring stations is affected by meteorological forcings that are particularly complicated over mountainous terrain. A detailed understanding of the impact of meteorological forcings on trace gas variability is challenging, but is vital to distinguish trace gas measurements affected by local pollutant sources from measurements representative of background mixing ratios. In the present study, we investigate the meteorological and CO characteristics at Pinnacles (38.61 N, 78.35 W, 1017 m above mean sea level), a mountaintop monitoring site in northwestern Virginia, USA, in the Appalachian Mountains, from 2009 to 2012, and focus on understanding the dominant meteorological forcings affecting the CO variability on diurnal timescales. The annual mean diurnal CO cycle shows a minimum in the morning between 0700 and 0900 LST and a maximum in the late afternoon between 1600 and 2000 LST, with a mean (median) daily CO amplitude of 39.2±23.7 ppb (33.2 ppb). CO amplitudes show large day-to-day variability. The largest CO amplitudes, in which CO mixing ratios can change >100 ppb in <3 h, occur in the presence of synoptic disturbances. Under fair weather conditions, local- to regional-scale transport processes are found to be more important drivers of the diurnal CO variability. On fair weather days with northwesterly winds, boundary layer dilution causes a daytime CO decrease, resembling the variability observed atop tall towers in flat terrain. Fair weather days with a wind shift from the northwest to the south are characterised by an afternoon CO increase and resemble the variability observed at mountaintops influenced by the vertical transport of polluted air from adjacent valleys. |
| first_indexed | 2024-04-14T05:30:58Z |
| format | Article |
| id | doaj.art-5ffa945d1139486d8ab318a32641879f |
| institution | Directory Open Access Journal |
| issn | 1600-0889 |
| language | English |
| last_indexed | 2024-04-14T05:30:58Z |
| publishDate | 2015-05-01 |
| publisher | Stockholm University Press |
| record_format | Article |
| series | Tellus: Series B, Chemical and Physical Meteorology |
| spelling | doaj.art-5ffa945d1139486d8ab318a32641879f2022-12-22T02:09:47ZengStockholm University PressTellus: Series B, Chemical and Physical Meteorology1600-08892015-05-0167011910.3402/tellusb.v67.2565925659Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian MountainsTemple R. Lee0Stephan F. J. De Wekker1Sandip Pal2Arlyn E. Andrews3Jonathan Kofler4 Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA NOAA Earth System Research Laboratory, Boulder, CO, USA NOAA Earth System Research Laboratory, Boulder, CO, USAThe variability of trace gases such as carbon monoxide (CO) at surface monitoring stations is affected by meteorological forcings that are particularly complicated over mountainous terrain. A detailed understanding of the impact of meteorological forcings on trace gas variability is challenging, but is vital to distinguish trace gas measurements affected by local pollutant sources from measurements representative of background mixing ratios. In the present study, we investigate the meteorological and CO characteristics at Pinnacles (38.61 N, 78.35 W, 1017 m above mean sea level), a mountaintop monitoring site in northwestern Virginia, USA, in the Appalachian Mountains, from 2009 to 2012, and focus on understanding the dominant meteorological forcings affecting the CO variability on diurnal timescales. The annual mean diurnal CO cycle shows a minimum in the morning between 0700 and 0900 LST and a maximum in the late afternoon between 1600 and 2000 LST, with a mean (median) daily CO amplitude of 39.2±23.7 ppb (33.2 ppb). CO amplitudes show large day-to-day variability. The largest CO amplitudes, in which CO mixing ratios can change >100 ppb in <3 h, occur in the presence of synoptic disturbances. Under fair weather conditions, local- to regional-scale transport processes are found to be more important drivers of the diurnal CO variability. On fair weather days with northwesterly winds, boundary layer dilution causes a daytime CO decrease, resembling the variability observed atop tall towers in flat terrain. Fair weather days with a wind shift from the northwest to the south are characterised by an afternoon CO increase and resemble the variability observed at mountaintops influenced by the vertical transport of polluted air from adjacent valleys.http://www.tellusb.net/index.php/tellusb/article/view/25659/pdf_8mountaintop monitoringcarbon monoxideair qualityplanetary boundary layervertical mixinghorizontal wind shift |
| spellingShingle | Temple R. Lee Stephan F. J. De Wekker Sandip Pal Arlyn E. Andrews Jonathan Kofler Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains Tellus: Series B, Chemical and Physical Meteorology mountaintop monitoring carbon monoxide air quality planetary boundary layer vertical mixing horizontal wind shift |
| title | Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains |
| title_full | Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains |
| title_fullStr | Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains |
| title_full_unstemmed | Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains |
| title_short | Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains |
| title_sort | meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the appalachian mountains |
| topic | mountaintop monitoring carbon monoxide air quality planetary boundary layer vertical mixing horizontal wind shift |
| url | http://www.tellusb.net/index.php/tellusb/article/view/25659/pdf_8 |
| work_keys_str_mv | AT templerlee meteorologicalcontrolsonthediurnalvariabilityofcarbonmonoxidemixingratioatamountaintopmonitoringsiteintheappalachianmountains AT stephanfjdewekker meteorologicalcontrolsonthediurnalvariabilityofcarbonmonoxidemixingratioatamountaintopmonitoringsiteintheappalachianmountains AT sandippal meteorologicalcontrolsonthediurnalvariabilityofcarbonmonoxidemixingratioatamountaintopmonitoringsiteintheappalachianmountains AT arlyneandrews meteorologicalcontrolsonthediurnalvariabilityofcarbonmonoxidemixingratioatamountaintopmonitoringsiteintheappalachianmountains AT jonathankofler meteorologicalcontrolsonthediurnalvariabilityofcarbonmonoxidemixingratioatamountaintopmonitoringsiteintheappalachianmountains |