The Morning NO x maximum in the forest atmosphere boundary layer M. Alaghmand1, P. B. Shepson1,2,3, T. K. Starn4, B. T. Jobson5, H. W. Wallace5, M. A. Carroll6, S. B. Bertman7, B. Lamb5, S. L. Edburg5, X. Zhou8, E. Apel9, D. Riemer10, P. Stevens11, and F. Keutsch12 1Purdue University, Dept. of Chemistry, West Lafayette, IN, USA 2Dept. of Earth and Atmospheric Sciences, West Lafayette, IN, USA 3Purdue Climate Change Research Center, West Lafayette, IN, USA 4West Chester University, Dept. of Chemistry, West Chester, PA, USA 5Washington State University, Dept. of Civil and Environmental Engineering, Pullman, WA, USA 6University of Michigan, Dept. of Atmospheric, Oceanic, and Space Sciences, Ann Arbor, MI, USA 7Western Michigan University, Dept. of Chemistry, Kalamazoo, MI, USA 8Wadsworth Center, SUNY-Albany, NY, USA 9National Center for Atmospheric Research, Boulder, CO, USA 10RSMAS, University of Miami, Miami, FL, USA 11Indiana University, School of Public and Environmental Affairs, Bloomington, IN, USA 12University of Wisconsin, Madison, Dept. of Chemistry, Madison, WI, USA
Received: 22 August 2011 – Accepted: 11 October 2011 – Published: 28 October 2011
Abstract. During the 1998, 2000, 2001, 2008, and 2009 summer intensives of the Program
for Research on Oxidants: PHotochemistry, Emissions and Transport (PROPHET),
ambient measurement of nitrogen oxides (NO + NO2 = NOx) were
conducted. NO and NOx mole fractions displayed a diurnal pattern with
NOx frequently highest in early morning. This pattern has often been
observed in other rural areas. In this paper, we discuss the potential sources and
contributing factors of the frequently observed morning pulse of NOx.
Of the possible potential contributing factors to the observed morning pulse of NO and NOx, we
find that surface-layer transport and slow upward mixing from soil
emissions, related to the thermodynamic stability in the nocturnal boundary
layer (NBL) before its morning breakup are the largest contributors. The
morning NOx peak can significantly impact boundary layer chemistry,
e.g. through production of HONO on surfaces, and by increasing the
importance of NO3 chemistry in the morning boundary layer.
Citation: Alaghmand, M., Shepson, P. B., Starn, T. K., Jobson, B. T., Wallace, H. W., Carroll, M. A., Bertman, S. B., Lamb, B., Edburg, S. L., Zhou, X., Apel, E., Riemer, D., Stevens, P., and Keutsch, F.: The Morning NO x maximum in the forest atmosphere boundary layer, Atmos. Chem. Phys. Discuss., 11, 29251-29282, doi:10.5194/acpd-11-29251-2011, 2011.