NO2 seasonal evolution in the north subtropical free troposphere

• DOI: 10.5194/acp-15-10567-2015
• Publication Date: 2015-09-25T05:23:44Z
• Authors: M. Gil-Ojeda; M. Navarro-Comas; L. Gómez-Martín; J. A. Adame; A. Saiz-Lopez; C. A. Cuevas; Y. González; O. Puentedura; E. Cuevas; J.-F. Lamarque; D. Kinninson; S. Tilmes
• Keywords: Seasonality

Abstract. Three years of multi-axis differential optical absorption spectroscopy (MAXDOAS) measurements (2011–2013) have been used for estimating the NO2 mixing ratio along a horizontal line sight from high mountain subtropical observatory Izaña, at 2370 m a.s.l. (NDACC station, 28.3° N, 16.5° W). The method is based on path calculation O2–O2 collisional complex 477 nm band which measured simultaneously to column density, and applicable under low aerosol-loading conditions. MAXDOAS technique, applied in mode free troposphere, minimizes impact contamination resulting arrival marine boundary layer (MBL) air masses thermally forced upwelling breeze during middle hours day. Comparisons with situ observations show that most measuring period, insensitive or very slightly sensitive breeze. Exceptions are found pollution events southern wind On these occasions, evidence fast, efficient irreversible transport surface troposphere found. Background volume (vmr), representative remote range 20–45 pptv. observed seasonal evolution shows an annual wave where peak phase solar radiation. Model simulations chemistry–climate CAM-Chem model good agreement measurements, further investigate possible drivers seasonality Izaña.