Open AccessOH, HO 2 , and OH reactivity during the PMTACS–NY Whiteface Mountain 2002 campaign: Observations and model comparison
Author(s) -
Ren Xinrong,
Brune William H.,
Oliger Angelique,
Metcalf Andrew R.,
Simpas James B.,
Shirley Terry,
Schwab James J.,
Bai Chunhong,
Roychowdhury Utpal,
Li Yongquan,
Cai Chenxia,
Demerjian Kenneth L.,
He Yi,
Zhou Xianliang,
Gao Honglian,
Hou Jian
Publication year - 2006
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jd006126
Subject(s) - mixing ratio , reactivity (psychology) , evening , atmospheric sciences , ozone , meteorology , daytime , environmental science , atmospheric chemistry , box model , analytical chemistry (journal) , chemistry , physics , environmental chemistry , medicine , alternative medicine , pathology , astronomy
Hydroxyl (OH), hydroperoxy (HO 2 ) radicals, collectively known as HO x , and OH reactivity, were measured during the PMTACS–NY (PM2.5 Technology Assessment and Characteristics Study‐New York) summer 2002 intensive at Whiteface Mountain, Wilmington, New York. The measurement results of OH and HO 2 for 4 weeks are presented. Diurnal cycles show that the average noontime maximum mixing ratios were about 0.11 pptv (2.6 × 10 6 cm −3 ) for OH and 20 pptv for HO 2 . Measured HO 2 to OH ratios were typically between 40 and 400, which are greater than those obtained in polluted and semipolluted rural environments. Low but significant mixing ratios of OH and HO 2 persisted into early evening and were frequently observed during nighttime, consistent with previous studies in different environments. Steady state OH and HO 2 were calculated with a zero‐dimensional chemical model using a complete Regional Atmospheric Chemical Mechanism (RACM) and a parameterized RACM which was constrained to the measured OH reactivity. Good agreement was obtained between the complete RACM and the parameterized RACM models. On average, the complete RACM model reproduced the observed OH with a median measured‐to‐modeled OH ratio of 0.82 and daytime HO 2 with a median measured‐to‐modeled HO 2 ratio of 1.21. The reasonably good agreement in this study is inconsistent with the significant underestimation of OH in the Program for Research on Oxidants: Photochemistry, Emissions, and Transport in 1998 (PROPHET98) study at a similar forested site. HO x budget analysis indicates that OH was primarily from the photolysis of HONO and O 3 during the day and from O 3 + alkenes reactions at night. The main HO x loss was the self reaction of HO 2 . The good agreement between the measured and calculated OH reactivity in this environment contrasts with findings in the PROPHET2000 study, in which significant OH reactivity was missing and the missing OH reactivity was temperature‐dependent.