Large horizontal gradients in atmospheric CO at the synoptic scale as seen by spaceborne Measurements of Pollution in the Troposphere

[1] We have examined the influence of synoptic processes on the distribution of atmospheric CO as observed by the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument. In the MOPITT data, large horizontal gradients in CO, coherent at the synoptic scale, have been observed. The concentration of CO varies rapidly by as much as 50–100% across distances of ∼100 km, forming distinct boundaries in the CO distribution. These can last one to several days and span horizontal distances of 600–1000 km. On average, such events were observed in the MOPITT CO daily images once every 3–4 days over North America in spring and summer 2000. We focused on three case studies over North America in August 2000 to understand the mechanisms responsible for the large gradients in CO. Through an analysis of meteorological data from the National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis, parcel trajectory modeling, and global three-dimensional chemical transport modeling, we found that the large horizontal gradients typically reflect the differential vertical and horizontal transport of air with different chemical signatures. In the first case, the large gradients in CO over North Dakota resulted from the lifting ahead of a cold front that transported boundary layer air enriched with CO from forest fires in Montana, combined with the descent of clean air from the Canadian Prairies behind the front. In the second case, the large gradients over northeastern Texas were produced by the convective lifting over Arkansas of air with high concentrations of CO from the oxidation of volatile organic compounds and the onshore transport of clean air from the Gulf of Mexico. In the third case, we examined an example of outflow of surface pollution from North America by a cyclone. The largest gradients in this case were observed along the boundary between the boundary layer air transported by the warm conveyor belt ahead of the cold front and the clean air transported from the Atlantic by the semipermanent high-pressure system in the central Atlantic. Our results demonstrate that MOPITT can capture the influence of synoptic processes on the horizontal and vertical distribution of CO. The large gradients in CO observed on synoptic scales represent valuable information that can be exploited to improve our understanding of atmospheric CO. In particular, these results suggest that the MOPITT observations provide a useful data set with which to address a range of issues from air quality on local/regional scales to long-range transport of pollution on continental/global scales.

[1]  The distribution of pollutants near a frontal surface: A comparison between field experiment and modeling , 1986 .

[2]  R. Dickerson,et al.  Thunderstorms: An Important Mechanism in the Transport of Air Pollutants , 1987, Science.

[3]  R. Daley.  Atmospheric Data Analysis , 1991 .

[4]  Drummond.  Measurements of Pollution in the Troposphere (Mopitt) , 1992 .

[5]  D. Edwards,et al.  Retrieval of tropospheric carbon monoxide for the MOPITT experiment , 1998 .

[6]  G. Vaughan,et al.  Chemical air mass differences near fronts , 1998 .

[7]  J. Chan,et al.  Synoptic conditions associated with high carbon monoxide episodes at a coastal station in Hong Kong , 1999 .

[8]  D. Edwards,et al.  Radiative transfer modeling for the EOS Terra satellite Measurement of Pollution in the Troposphere (MOPITT) instrument , 1999 .

[9]  Daniel J. Jacob,et al.  Introduction to Atmospheric Chemistry , 1999 .

[10]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[11]  D P Edwards,et al.  Cloud Detection and Clearing for the Earth Observing System Terra Satellite Measurements of Pollution in the Troposphere (MOPITT) Experiment. , 2001, Applied optics.

[12]  D. Jacob,et al.  Global modeling of tropospheric chemistry with assimilated meteorology : Model description and evaluation , 2001 .

[13]  M. Beekmann,et al.  Tracer analysis of transport from the boundary layer to the free troposphere , 2001 .

[14]  A. Thorpe,et al.  Mechanisms for pollutant transport between the boundary layer and the free troposphere , 2001 .

[15]  A. Stohl.  A 1-year Lagrangian ``climatology'' of airstreams in the Northern Hemisphere troposphere and lowermost stratosphere , 2001 .

[16]  J. Lelieveld,et al.  Synoptic tracer gradients in the upper troposphere over central Canada during the Stratosphere-Troposphere Experiments by Aircraft Measurements 1998 summer campaign , 2002 .

[17]  J. Lamarque,et al.  Operational carbon monoxide retrieval algorithm and selected results for the MOPITT instrument , 2003 .

[18]  Jane Liu,et al.  On the CO2 exchange between the atmosphere and the biosphere: the role of synoptic and mesoscale processes , 2003 .

[19]  Merritt N. Deeter,et al.  Asian Outflow and Trans-Pacific Transport of Carbon Monoxide and Ozone Pollution: An Integrated Satellite, Aircraft, and Model Perspective , 2003 .

[20]  Bryan N. Duncan,et al.  Transport pathways for Asian pollution outflow over the Pacific: Interannual and seasonal variations , 2003 .

[21]  Jennifer A. Logan,et al.  An assessment of biofuel use and burning of agricultural waste in the developing world , 2003 .

[22]  Thomas P. Kurosu,et al.  Mapping isoprene emissions over North America using formaldehyde column observations from space , 2003 .

[23]  R. Martin,et al.  Application of empirical orthogonal functions to evaluate ozone simulations with regional and global models , 2003 .

[24]  R. Martin,et al.  Interannual and seasonal variability of biomass burning emissions constrained by satellite observations , 2003 .

[25]  Tao Wang,et al.  Characterizing the temporal variability and emission patterns of pollution plumes in the Pearl River Delta of China , 2003 .

[26]  Mian Chin,et al.  Sources of carbonaceous aerosols over the United States and implications for natural visibility , 2003 .

[27]  Merritt N. Deeter,et al.  Identification of CO plumes from MOPITT data: Application to the August 2000 Idaho‐Montana forest fires , 2003, Geophysical Research Letters.

[28]  J. Lamarque,et al.  Validation of Measurements of Pollution in the Troposphere (MOPITT) CO retrievals with aircraft in situ profiles , 2004 .

[29]  Merritt N. Deeter,et al.  Vertical resolution and information content of CO profiles retrieved by MOPITT , 2004 .

[30]  David G. Streets,et al.  Improved quantification of Chinese carbon fluxes using CO2/CO correlations in Asian outflow , 2004 .

[31]  John C. Gille,et al.  Comparative inverse analysis of satellite (MOPITT) and aircraft (TRACE-P) observations to estimate Asian sources of carbon monoxide , 2004 .

[32]  Michael B. McElroy,et al.  A nested grid formulation for chemical transport over Asia: Applications to CO , 2004 .

[33]  Merritt N. Deeter,et al.  Evidence of vertical transport of carbon monoxide from Measurements of Pollution in the Troposphere (MOPITT) , 2004 .

[34]  R. Martin,et al.  North American Pollution Outflow and the Trapping of Convectively Lifted Pollution by Upper-Level Anticyclone , 2005 .

[35]  D. Jacob,et al.  Impact of new laboratory studies of N2O5 hydrolysis on global model budgets of tropospheric nitrogen oxides, ozone, and OH , 2005, Geophysical Research Letters.

[36]  Jane Liu,et al.  Satellite mapping of CO emission from forest fires in Northwest America using MOPITT measurements , 2005 .