Stratospheric aerosol measurements by dual polarisation lidar

Vaughan, G.; Wareing, D. P.

doi:10.5194/acp-4-2441-2004

Cited by 10 publications

(5 citation statements)

References 11 publications

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“…Unfortunately, the data base of Fromm et al (2003) shows no results above 30 km and even above 25 km the observational error becomes increasingly important. Other lidar soundings from mid-latitudes confirm our results on higher backscatter ratios in winter, even if the absolute numbers are slightly smaller than ours (Vaughan and Wareing, 2004). The aerosol soundings demonstrate the necessity of correction methods for Rayleigh temperature retrievals in the 30 km range and below.…”

Section: Comparison With Other Observationssupporting

confidence: 83%

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Seasonal variation of nocturnal temperatures between 1 and 105 km altitude at 54° N observed by lidar

et al. 2008

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Abstract. Temperature soundings are performed by lidar at the mid-latitude station of Kühlungsborn (Germany, 54° N, 12° E). The profiles cover the complete range from the lower troposphere (~1 km) to the lower thermosphere (~105 km) by simultaneous and co-located operation of a Rayleigh-Mie-Raman lidar and a potassium resonance lidar. Observations have been done during 266 nights between June 2002 and July 2007, each of 3–15 h length. This large and unique data set provides comprehensive information on the altitudinal and seasonal variation of temperatures from the troposphere to the lower thermosphere. The remaining day-to-day-variability is strongly reduced by harmonic fits at constant altitude levels and a representative data set is achieved. This data set reveals a two-level mesopause structure with an altitude of about 86–87 km (~144 K) in summer and ~102 km (~170 K) during the rest of the year. The average stratopause altitude is ~48 km throughout the whole year, with temperatures varying between 258 and 276 K. From the fit parameters amplitudes and phases of annual, semi-annual, and quarter-annual variations are derived. The amplitude of the annual component is largest with amplitudes of up to 30 K in 85 km, while the quarter-annual variation is smallest and less than 3 K at all altitudes. The lidar data set is compared with ECMWF temperatures below about 70 km altitude and reference data from the NRLMSISE-00 model above. Apart from the temperature soundings the aerosol backscatter ratio is measured between 20 and 35 km. The seasonal variation of these values is presented here for the first time.

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Section: Comparison With Other Observationssupporting

confidence: 83%

“…The atmosphere is assumed to be aerosol free above this altitude, in good agreement with other observations (e.g. Vaughan and Wareing, 2004). The aerosol correction provides a data set of backscatter ratios in a height region that is rarely covered by regular aerosol soundings from lidars and satellites.…”

Section: Description Of the Lidar Systemsmentioning

confidence: 56%

Seasonal variation of nocturnal temperatures between 1 and 105 km altitude at 54° N observed by lidar

et al. 2008

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“…As an example, the distribution of particles larger than 10 nm radius is shown in Figure 6. At altitudes lower than 30 km the sulfuric acid rich stratospheric background aerosol, which is not included in the model, becomes important [ Vaughan and Wareing , 2004; Deshler et al , 2003]. This aerosol may react with the meteoric material, and thus alter the distribution shown in Figure 6.…”

Section: General Resultsmentioning

confidence: 99%

Global and temporal distribution of meteoric smoke: A two‐dimensional simulation study

et al. 2008

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[1] Meteoric material entering Earth's atmosphere ablates in the mesosphere and is then expected to recondense into tiny so-called ''smoke particles.'' These particles are thought to be of great importance for middle atmosphere phenomena like noctilucent clouds, polar mesospheric summer echoes, metal layers, and heterogeneous chemistry. Commonly used one-dimensional (1-D) meteoric smoke profiles refer to average global conditions and yield of the order of a thousand nanometer sized particles per cubic centimeter at the mesopause, independent of latitude and time of year. Using the first two-dimensional model of both coagulation and transport of meteoric material we here show that such profiles are too simplistic, and that the distribution of smoke particles indeed is dependent on both latitude and season. The reason is that the atmospheric circulation, which cannot be properly handled by 1-D models, efficiently transports the particles to the winter hemisphere and down into the polar vortex. Using the assumptions commonly used in 1-D studies results in number densities of nanometer sized particles of around 4000 cm À3 at the winter pole, while very few particles remain at the Arctic summer mesopause. If smoke particles are the only nucleation kernel for ice in the mesosphere this would imply that there could only be of the order of 100 or less ice particles cm À3 at the Arctic summer mesopause. This is much less than the ice number densities expected for the formation of ice phenomena (noctilucent clouds and polar mesospheric summer echoes) that commonly occur in this region. However, we find that especially the uncertainty of the amount of material that is deposited in Earth's atmosphere imposes a large error bar on this number, which may allow for number densities up to 1000 cm À3 near the polar summer mesopause. This efficient transport of meteoric material to the winter hemisphere and down into the polar vortex results in higher concentrations of meteoric material in the Arctic winter stratosphere than previously thought. This is of potential importance for the formation of the so-called stratospheric condensation nuclei layer and for stratospheric nucleation processes.Citation: Megner, L., D. E. Siskind, M. Rapp, and J. Gumbel (2008), Global and temporal distribution of meteoric smoke: A twodimensional simulation study,

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“…The calibration constant C is determined within the aerosol free stratosphere, such that VDR approaches the molecular background value of 1.4% due to Rayleigh scattering, which mainly depends on the bandwidth of the interference filters used in the system [ Bridge and Buckingham , 1966; Behrendt and Nakamura , 2002]. A complete calibration of the system, considering cross talk between the two channels as proposed by Vaughan and Wareing [2004], has not been performed, yet. Hence, a systematic bias in our depolarization values cannot be ruled out.…”

Section: Data Setmentioning

confidence: 99%

Lidar measurements of the Kasatochi aerosol plume in August and September 2008 in Ny‐Ålesund, Spitsbergen

Hoffmann¹,

Ritter²,

Stock³

et al. 2010

J. Geophys. Res.

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The eruptions of the Kasatochi volcano on 7 and 8 August 2008 led to an enhanced stratospheric aerosol load which was studied with the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar (MPL) at the French‐German Arctic Research Base AWIPEV in Ny‐Ålesund, Spitsbergen at 78.55°N, 11.56°E. During all KARL measurements from 15 August to 24 September 2008 (approximately 30 h of data), we detected distinct layers of enhanced aerosol backscatter in the lower stratosphere and the tropopause region, whose origination at the Kasatochi site can be shown by trajectory calculations. We found a 125% increase in aerosol optical depth compared to the mean values from 2004 to 2007 at 3 weeks after the eruption, validated by sunphotometer measurements. Differences in volume depolarization and color ratio signatures of the layers indicate a sinking movement of the bigger particles to the layer bottom. Furthermore, within higher stratospheric aerosol layers monitored after 25 August 2008, we observed the volume depolarization maximum to be up to 0.8 km below the backscatter maximum. Backscatter and depolarization measurements from 1 September 2008, on which data were collected over 13 h during daylight and darkness, are analyzed in detail. Calculations of the lidar ratio in the lowest aerosol layer as well as the estimation of microphysical parameters of the aerosol particles were performed.

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Stratospheric aerosol measurements by dual polarisation lidar

Cited by 10 publications

References 11 publications

Seasonal variation of nocturnal temperatures between 1 and 105 km altitude at 54° N observed by lidar

Seasonal variation of nocturnal temperatures between 1 and 105 km altitude at 54° N observed by lidar

Global and temporal distribution of meteoric smoke: A two‐dimensional simulation study

Lidar measurements of the Kasatochi aerosol plume in August and September 2008 in Ny‐Ålesund, Spitsbergen

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