Rayleigh-scattering calculations for the terrestrial atmosphere

Bucholtz, Anthony

doi:10.1364/ao.34.002765

Cited by 612 publications

(449 citation statements)

References 15 publications

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“…The parameters characterizing this type of scattering are well documented in the literature (e.g., McCartney, 1976). The total cross section for Rayleigh scattering in a standard atmosphere (15 • C and 1013.25 hPa), σ std m , is calculated as in Bucholtz (1995), i.e., without the approximation for the refractive index. This is, in turn, computed from the equations provided by Peck and Reeder (1972).…”

Section: Molecular Referencementioning

confidence: 99%

A permanent Raman lidar station in the Amazon: description, characterization, and first results

Barbosa¹,

Barja²,

Pauliquevis

et al. 2014

Atmos. Meas. Tech.

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Abstract.A permanent UV Raman lidar station, designed to perform continuous measurements of aerosols and water vapor and aiming to study and monitor the atmosphere from weather to climatic time scales, became operational in the central Amazon in July 2011. The automated data acquisition and internet monitoring enabled extended hours of daily measurements when compared to a manually operated instrument. This paper gives a technical description of the system, presents its experimental characterization and the algorithms used for obtaining the aerosol optical properties and identifying the cloud layers. Data from one week of measurements during the dry season of 2011 were analyzed as a mean to assess the overall system capability and performance. Both Klett and Raman inversions were successfully applied. A comparison of the aerosol optical depth from the lidar and from a co-located Aerosol Robotic Network (AERONET) sun photometer showed a correlation coefficient of 0.86. By combining nighttime measurements of the aerosol lidar ratio (50-65 sr), back-trajectory calculations and fire spots observed from satellites, we showed that observed particles originated from biomass burning. Cirrus clouds were observed in 60 % of our measurements. Most of the time they were distributed into three layers between 11.5 and 13.4 km a.g.l. The systematic and long-term measurements being made by this new scientific facility have the potential to significantly improve our understanding of the climatic implications of the anthropogenic changes in aerosol concentrations over the pristine Amazonia.

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Section: Molecular Referencementioning

confidence: 99%

A permanent Raman lidar station in the Amazon: description, characterization, and first results

Barbosa¹,

Barja²,

Pauliquevis

et al. 2014

Atmos. Meas. Tech.

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“…Inclusion of interactive refraction is required as the operational measurements are used in the retrieval rather than fixed values of SZA. Calculation of the atmospheric refractive index follows that of Bucholtz (1995). The refracted ray path is calculated by using Snell's law in circular symmetry to obtain the geometric impact parameter:…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

“…From this equation the SZA associated with any point along the path is calculated, which in turn can be used to calculate the path lengths for each discrete layer of the forward model atmosphere. The Rayleigh scattering cross-sections and phase functions are taken from Bucholtz (1995). Mie scattering crosssections and phase functions are also included for scattering and absorption from atmospheric aerosols.…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

A new Dobson Umkehr ozone profile retrieval method optimising information content and resolution

et al. 2015

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Abstract. The standard Dobson Umkehr methodology to retrieve coarse-resolution ozone profiles used by the National Oceanographic and Atmospheric Administration uses designated solar zenith angles (SZAs). However, some information may be lost if measurements lie outside the designated SZA range (between 60 • and 90 • ), or do not conform to the fitting technique. Also, while Umkehr measurements can be taken using multiple wavelength pairs (A, C and D), past retrieval methods have focused on a single pair (C). Here we present an Umkehr inversion method that uses measurements at all SZAs (termed operational) and all wavelength pairs. (Although, we caution direct comparison to other algorithms.)Information content for a Melbourne, Australia (38 • S, 145 • E) Umkehr measurement case study from 28 January 1994, with SZA range similar to that designated in previous algorithms is shown. When comparing the typical single wavelength pair with designated SZAs to the operational measurements, the total degrees of freedom (independent pieces of information) increases from 3.1 to 3.4, with the majority of the information gain originating from Umkehr layers 2 + 3 and 4 (10-20 km and 25-30 km respectively). In addition to this, using all available wavelength pairs increases the total degrees of freedom to 5.2, with the most significant increases in Umkehr layers 2 + 3 to 7 and 9+ (10-40 and 45-80 km). Investigating a case from 13 April 1970 where the measurements extend beyond the 90 • SZA range gives further information gain, with total degrees of freedom extending to 6.5. Similar increases are seen in the information content. Comparing the retrieved Melbourne Umkehr time series with ozonesondes shows excellent agreement in layers 2 + 3 and 4 (10-20 and 25-30 km) for both C and A + C + D-pairs. Retrievals in layers 5 and 6 (25-30 and 30-35 km) consistently show lower ozone partial column compared to ozonesondes. This is likely due to stray light effects that are not accounted for in the forward model, and under represented stratospheric aerosol.

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“…probe, suitable for pulsed beams of this type, had a calibration uncertainty of 5%, the largest individual contribution to the yield uncertainty. Based on Rayleigh scattering calculations as discussed in [14] and taking into account that fluorescence light is emitted isotropically, it then was possible to calculate the number of ADC counts per isotropically emitted 337 nm photon per meter. In order to be able to take measurements at different pressures inside the chamber, coated glass windows with close to 100% transmission efficiency in the UV range were attached to both beam ports.…”

Section: Optical Calibration and Simulationmentioning

confidence: 99%

“…Here, N ADC is the signal counts recorded for each PMT, N ped is the number of pedestal counts measured in the respective signal channel, E is the laser pulse energy, P , and T are the pressure and temperature measured in the chamber, and k 0 accounts for the light background from scattering of the laser beam with the chamber material. S = 4.3 · 10 7 photons m is the expected Rayleigh scattering rate of 337.13 nm light calculated from the expressions in [14] for standard pressure (760 torr), and temperature (288.15 K). After the χ 2 minimiza- Figure 2.…”

Section: Optical Calibration and Simulationmentioning

confidence: 99%