Inelastic scattering in ocean water and its impact on trace gas retrievals from satellite data

Vountas, Marco; Richter, Andreas; Wittrock, F.; Burrows, J. P.

doi:10.5194/acp-3-1365-2003

Cited by 56 publications

(84 citation statements)

References 23 publications

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“…However, these results do not include correction for Raman scattering contribution to filling-in of Fraunhofer lines, which would be necessary for a solid comparison. Our study shows that although it was possible to estimate inelastic processes with the DOAS method (Vountas et al 1998(Vountas et al , 2003(Vountas et al , 2007, it is difficult to use this approach to retrieve CDOM fluorescence from hyperspectral satellite data, mainly because of dominant effects of other inelastic processes (RRS, VRS). However, our modeling studies prove that for coastal areas, where VRS is weak, fluorescence of humic-like CDOM is a significant source of filling-in.…”

Section: Resultsmentioning

confidence: 99%

“…Other inelastic processes have been already retrieved from hyperspectral satellite data with the Differential Optical Absorption Spectroscopy (DOAS) method (e.g. Vountas et al 1998Vountas et al , 2003Vountas et al , 2007. In this work we test the use of the filling-in signal originating from CDOM fluorescence to characterize CDOM composition and concentration independent from chlorophyll.…”

Section: Introductionmentioning

confidence: 99%

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Detecting CDOM Fluorescence Using High Spectrally Resolved Satellite Data: A Model Study

Wolanin

Розанов

Dinter

et al. 2015

Towards an Interdisciplinary Approach in Earth System Science

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Absorption and fluorescence of CDOM are widely used to characterize its concentration and composition, both in situ and with remote sensing techniques. As fluorescence is an inelastic scattering process, it can potentially be observed in filling-in of Fraunhofer lines with the DOAS method in high spectrally resolved satellite data. Here, we perform a theoretical model study and preliminary DOAS retrieval on SCIAMACHY data in order to test the feasibility of such an approach. Our results show that retrieving CDOM fluorescence is difficult, due to its relatively weak signal in global oceans (in comparison to Raman scattering of clear water) and varying broad spectral features. Detailed studies of the synergistic use of narrow and broad fluorescence features, and an appropriate scheme to account for disturbance effects of Raman scattering, are needed for further investigating the retrieval of CDOM fluorescence.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Detecting CDOM Fluorescence Using High Spectrally Resolved Satellite Data: A Model Study

Wolanin

Розанов

Dinter

et al. 2015

Towards an Interdisciplinary Approach in Earth System Science

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“…Vibrational Raman scattering has been suggested to play a role for zenith sky DOAS measurements of stratospheric absorbers at high SZA (Platt et al, 1997), as well as for liquid water in the oceans (Vountas et al, 2003). Vibrational Raman scattering on gas-phase molecules is today not typically considered in the analysis of MAX-DOAS spectra, which treat only the rotational component of Raman scattering to calculate the Ring reference spectrum (Chance and Spurr, 1997;Vountas et al, 1998;Platt and Stutz, 2008;Wagner et al, 2009).…”

Section: Discussion Of Rms Limitations Of Field Measurementsmentioning

confidence: 99%

The CU ground MAX-DOAS instrument: characterization of RMS noise limitations and first measurements near Pensacola, FL of BrO, IO, and CHOCHO

et al. 2011

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Abstract. We designed and assembled the University of Colorado Ground Multi AXis Differential Optical Absorption Spectroscopy (CU GMAX-DOAS) instrument to retrieve bromine oxide (BrO), iodine oxide (IO), formaldehyde (HCHO), glyoxal (CHOCHO), nitrogen dioxide (NO 2 ) and the oxygen dimer (O 4 ) in the coastal atmosphere of the Gulf of Mexico. The detection sensitivity of DOAS measurements is proportional to the root mean square (RMS) of the residual spectrum that remains after all absorbers have been subtracted. Here we describe the CU GMAX-DOAS instrument and demonstrate that the hardware is capable of attaining RMS of ∼6 × 10 −6 from solar stray light noise tests using high photon count spectra (compatible within a factor of two with photon shot noise).Laboratory tests revealed two critical instrument properties that, in practice, can limit the RMS: (1) detector non-linearity noise, RMS NLin , and (2) temperature fluctuations that cause variations in optical resolution (full width at half the maximum, FWHM, of atomic emission lines) and give rise to optical resolution noise, RMS FWHM . The nonlinearity of our detector is low (∼10 −2 ) yet -unless actively controlled -is sufficiently large to create RMS NLin of up to 2 × 10 −4 . The optical resolution is sensitive to temperature changes (0.03 detector pixels • C −1 at 334 nm), and temperature variations of 0.1 • C can cause RMS FWHM of ∼1 × 10 −4 . Both factors were actively addressed in the design of the CU GMAX-DOAS instrument. With an integration time of 60 s Correspondence to: R. Volkamer (rainer.volkamer@colorado.edu) the instrument can reach RMS noise of 3 × 10 −5 , and typical RMS in field measurements ranged from 6 × 10 −5 to 1.4 × 10 −4 .The CU GMAX-DOAS was set up at a coastal site near Pensacola, Florida, where we detected BrO, IO and CHO-CHO in the marine boundary layer (MBL), with daytime average tropospheric vertical column densities (average of data above the detection limit), VCDs, of ∼2 × 10 13 molec cm −2 , 8 × 10 12 molec cm −2 and 4 × 10 14 molec cm −2 , respectively. HCHO and NO 2 were also detected with typical MBL VCDs of 1 × 10 16 and 3 × 10 15 molec cm −2 . These are the first measurements of BrO, IO and CHOCHO over the Gulf of Mexico. The atmospheric implications of these observations for elevated mercury wet deposition rates in this area are briefly discussed. The CU GMAX-DOAS has great potential to investigate RMS-limited problems, like the abundance and variability of trace gases in the MBL and possibly the free troposphere (FT).

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“…The effect of clean water oceanic regions on trace gas retrievals from satellite nadir measurements has been noted before Vountas et al, 2003;Lerot Fig. 3.…”

Section: Extension Of the Fitting Windowmentioning

confidence: 99%

“…The individual lines are offset for clarity. (Vountas et al, 2003). Inclusion of a calculated vibrational Raman correction spectrum would be preferable, but so far led to inconsistencies over land, which need to be solved before it can be relied on.…”

Section: Figmentioning

confidence: 99%

An improved NO<sub>2</sub> retrieval for the GOME-2 satellite instrument

et al. 2011

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Abstract. Satellite observations of nitrogen dioxide (NO 2 ) provide valuable information on both stratospheric and tropospheric composition. Nadir measurements from GOME, SCIAMACHY, OMI, and GOME-2 have been used in many studies on tropospheric NO 2 burdens, the importance of different NO x emissions sources and their change over time. The observations made by the three GOME-2 instruments will extend the existing data set by more than a decade, and a high quality of the data as well as their good consistency with existing time series is of particular importance.In this paper, an improved GOME-2 NO 2 retrieval is described which reduces the scatter of the individual NO 2 columns globally but in particular in the region of the Southern Atlantic Anomaly. This is achieved by using a larger fitting window including more spectral points, and by applying a two step spike removal algorithm in the fit. The new GOME-2 data set is shown to have good consistency with SCIAMACHY NO 2 columns. Remaining small differences are shown to be linked to changes in the daily solar irradiance measurements used in both GOME-2 and SCIA-MACHY retrievals.In the large retrieval window, a not previously identified spectral signature was found which is linked to deserts and other regions with bare soil. Inclusion of this empirically derived pseudo cross-section significantly improves the retrievals and potentially provides information on surface properties and desert aerosols.Using the new GOME-2 NO 2 data set, a long-term average of tropospheric columns was computed and high-pass filtered. The resulting map shows evidence for pollution from several additional shipping lanes, not previously identified in satellite observations. This illustrates the excellent signal to noise ratio achievable with the improved GOME-2 retrievals.

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Inelastic scattering in ocean water and its impact on trace gas retrievals from satellite data

Cited by 56 publications

References 23 publications

Detecting CDOM Fluorescence Using High Spectrally Resolved Satellite Data: A Model Study

Detecting CDOM Fluorescence Using High Spectrally Resolved Satellite Data: A Model Study

The CU ground MAX-DOAS instrument: characterization of RMS noise limitations and first measurements near Pensacola, FL of BrO, IO, and CHOCHO

An improved NO<sub>2</sub> retrieval for the GOME-2 satellite instrument

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Inelastic scattering in ocean water and its impact on trace gas retrievals from satellite data

Cited by 56 publications

References 23 publications

Detecting CDOM Fluorescence Using High Spectrally Resolved Satellite Data: A Model Study

Detecting CDOM Fluorescence Using High Spectrally Resolved Satellite Data: A Model Study

The CU ground MAX-DOAS instrument: characterization of RMS noise limitations and first measurements near Pensacola, FL of BrO, IO, and CHOCHO

An improved NO&lt;sub&gt;2&lt;/sub&gt; retrieval for the GOME-2 satellite instrument

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An improved NO<sub>2</sub> retrieval for the GOME-2 satellite instrument