Observations of the effects of temperature on atmospheric HNO3, ΣANs, ΣPNs, and NOx: evidence for a temperature-dependent HOx source D. A. Day1, P. J. Wooldridge1, and R. C. Cohen1,2,3 1Department of Chemistry; University of California, Berkeley; Berkeley, CA, 94720, USA 2Department of Earth and Planetary Science; University of California, Berkeley; Berkeley, CA, 94720, USA 3Energy and Environment Technologies Division; Lawrence Berkeley National Laboratory; Berkeley, CA, 94720, USA
Abstract. We describe observations of atmospheric reactive nitrogen compounds
including NO, NO2, total peroxy nitrates, total alkyl nitrates, and
HNO3 and their correlation with temperature. The measurements were made
at a rural location 1315 m a.s.l. on the western slope of the Sierra Nevada
Mountains in California during summer of 2001. The ratio of HNO3 to its
source molecule, NO2, and the ratio of HNO3 to all other higher
oxides of nitrogen (NOz) both increase with increasing temperature.
Analysis of these increases suggests they are due to a steep increase in OH
of between a factor of 2 and 3 over the range 18–32°C. Total peroxy
nitrates decrease and total alkyl nitrates increase over the same
temperature range. The decrease in the total peroxy nitrates is shown to be
much less than expected if the rate of thermal decomposition were the sole
important factor. This observation is consistent with the increase in OH
inferred from the temperature trends in the HNO3/NO2 ratio.
Citation: Day, D. A., Wooldridge, P. J., and Cohen, R. C.: Observations of the effects of temperature on atmospheric HNO3, ΣANs, ΣPNs, and NOx: evidence for a temperature-dependent HOx source, Atmos. Chem. Phys., 8, 1867-1879, doi:10.5194/acp-8-1867-2008, 2008.