The NIMO Monte Carlo model for box-air-mass factor and radiance calculations

Hay, T.; Bodeker, G. E.; Kreher, K.; Schofield, Robyn; Liley, Ben; Scherer, Martin; McDonald, A. J.

doi:10.1016/j.jqsrt.2012.02.005

Cited by 8 publications

(7 citation statements)

References 53 publications

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“…For selected days during the CHARLEX study, where at least three viewing elevation angles pass the quality and cloud filters, volume mixing ratios were retrieved from the MAX-DOAS DSCDs following the so-called O 4 method [Wagner, 2004] to estimate the scattering properties of the atmosphere and using the NIMO fully spherical Monte Carlo radiative transfer model [Hay et al, 2012]. This procedure is explained in detail in a previous paper on ship-based MAX-DOAS measurements in the eastern Pacific .…”

Section: Resultsmentioning

confidence: 99%

Glyoxal observations in the global marine boundary layer

et al. 2014

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Glyoxal is an important intermediate species formed by the oxidation of common biogenic and anthropogenic volatile organic compounds such as isoprene, toluene, and acetylene. Although glyoxal has been shown to play an important role in urban and forested environments, its role in the open ocean environment is still not well understood, with only a few observations showing evidence for its presence in the open ocean marine boundary layer (MBL). In this study, we report observations of glyoxal from 10 field campaigns in different parts of the world's oceans. These observations together represent the largest database of glyoxal in the MBL. The measurements are made with similar instruments that have been used in the past, although the open ocean values reported here, average of about 25 parts per trillion by volume (pptv) with an upper limit of 40 pptv, are much lower than previously reported observations that were consistently higher than 40 pptv and had an upper limit of 140 pptv, highlighting the uncertainties in the differential optical absorption spectroscopy method for the retrieval of glyoxal. Despite retrieval uncertainties, the results reported in this work support previous suggestions that the currently known sources of glyoxal are insufficient to explain the average MBL concentrations. This suggests that there is an additional missing source, more than a magnitude larger than currently known sources, which is necessary to account for the observed atmospheric levels of glyoxal. Therefore, it could play a more important role in the MBL than previously considered.

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Section: Resultsmentioning

confidence: 99%

Glyoxal observations in the global marine boundary layer

et al. 2014

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“…The data were then averaged for 30 min to improve the signal to noise ratio. For DOAS retrieval of IO using the QDOAS software (Fayt and Van Roozendael, 2011), cross-sections of IO (Gómez Martín et al, 2005), NO 2 (Vandaele et al, 1997), H 2 O (Rothman et al, 2003), O 4 (Hermans, 2002), O 3 (Burrows et al, 1999) and Ring (following Chance and Spurr, 1997) were fitted to the spectra together with a 2nd order polynomial. The instrument alternated between two different spectral windows to allow the retrieval of BrO (318-358 nm) and IO (416-456 nm) spectral features.…”

Section: Measurement Techniquesmentioning

confidence: 99%

“…Surface IO mixing ratios were retrieved from the MAX-DOAS DSCDs using the O 4 slant columns measured during the study by the "O 4 method", similar to other groups (e.g., Wagner et al, 2004;Sinreich et al, 2010) and validated by the NIMO fully spherical Monte Carlo radiative transfer model (Hay et al, 2012) where possible, which is described in detail in the SI. Only the 1 • elevation angle data were used for retrieval using the O 4 method, while all the elevation angles were used for retrieving IO mixing ratios using the radiative transfer model (RTM).…”

Section: Measurement Techniquesmentioning

confidence: 99%

Latitudinal distribution of reactive iodine in the Eastern Pacific and its link to open ocean sources

et al. 2012

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Ship-based Multi-Axis Differential Optical Absorption Spectroscopy measurements of iodine monoxide (IO) and atmospheric and seawater Gas Chromatography-Mass Spectrometer observations of methyl iodide (CH3I) were made in the Eastern Pacific marine boundary layer during April 2010 as a part of the HaloCarbon Air Sea Transect-Pacific (HaloCAST-P) scientific cruise. The presence of IO in the open ocean environment was confirmed, with a maximum differential slant column density of 5 × 1013 molecules cm−2 along the 1° elevation angle (corresponding to approximately 1 pptv) measured in the oligotrophic region of the Southeastern Pacific. Such low IO mixing ratios and their observed geographical distribution are inconsistent with satellite estimates and with previous understanding of oceanic sources of iodine. A strong correlation was observed between reactive iodine (defined as IO + I) and CH3I, suggesting common sources. In situ measurements of meteorological parameters and physical ocean variables, along with satellite-based observations of Chlorophyll a (Chl a) and Chromophoric Dissolved Organic Matter (CDOM) were used to gain insight into the possible sources of iodine in this remote environment. Surprisingly, reactive iodine showed a negative correlation (> 99% confidence) to Chl a and CDOM across the cruise transect. However, a significant positive correlation (> 99% confidence) with sea surface temperature (SST) and salinity instead suggests a widespread abiotic source related to the availability of aqueous iodine and to temperature

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“…Differential box-AMFs were determined using the NIMO full spherical Monte Carlo radiative transfer model (Hay et al, 2012). The model simulates backward photon trajectories from the instrument to the top of the atmosphere (TOA) using the Monte Carlo technique.…”

Section: Box-amf Calculationsmentioning

confidence: 99%

Iodine monoxide in the north subtropical free troposphere

et al. 2012

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Abstract. Iodine monoxide (IO) differential slant column densities (DSCD) have been retrieved from a new multi-axis differential optical absorption spectroscopy (MAX-DOAS) instrument deployed at the Izaña subtropical observatory as part of the Network for the Detection of Atmospheric Composition Change (NDACC) programme. The station is located at 2370 m a.s.l., well above the trade wind inversion that limits the top of the marine boundary layer, and hence is representative of the free troposphere. We report daily observations from May to August 2010 at different viewing angles. During this period, the spectral signature of IO was unequivocally detected on every day of measurement. A mean IO DSCD of 1.52×10 13 molecules cm −2 was observed at the 5 • instrument elevation angle (IEA) on clear days using a single zenith reference for the reported period, with a day-to-day variability of 33 % at one standard deviation. Based on the simulation of the DSCDs using radiative transfer calculations with five different hypothesized IO profiles, the IO mixing ratio is estimated to range between 0.2 and 0.4 pptv in the free troposphere. Episodes of Saharan dust outbreaks were also observed, with large increases in the DSCDs at higher IEA, suggesting an enhancement of IO inside the dust cloud.

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The NIMO Monte Carlo model for box-air-mass factor and radiance calculations

Cited by 8 publications

References 53 publications

Glyoxal observations in the global marine boundary layer

Glyoxal observations in the global marine boundary layer

Latitudinal distribution of reactive iodine in the Eastern Pacific and its link to open ocean sources

Iodine monoxide in the north subtropical free troposphere

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