Lidar and Ceilometer Observations and Comparisons of Atmospheric Cloud Structure at Nagqu of Tibetan Plateau in 2014 Summer

Song, Xiaoquan; Zhai, Xiaochun; Liu, Liping; Wu, Songhua

doi:10.3390/atmos8010009

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…To investigate the temperature dependences of the optical and geometrical properties of cirrus, the simultaneous observations by WACAL and radiosonde are operated. Referring to the results measured by the co-located ceilometer of VAISALA CL31, the high clouds including cirrus occurred almost at nighttime and before dawn, especially the period beteen 18:00 UTC and 22:00 UTC (Song et al, 2017). Such a temporal distribution of the cirrus clouds is more conducive to the joint observations by the WACAL and radiosonde sounding.…”

Section: Tipex III Campaignmentioning

confidence: 79%

“…By this algorithm, cloud layers apparent in the return signal are identified. However, if the lower clouds were too thick to be penetrated, the higher clouds will not be detected and cannot be identified (Wu et al, 2015, Song et al, 2017. During this campaign, the cloud base heights determined by the WACAL and that from the co-located VAISALA CL31 ceilometer measurements were compared and the results were reported by Song et 5 al.…”

Section: Extraction Of the Cloud Base And Top Heightsmentioning

confidence: 97%

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Optical and Geometrical Properties of Cirrus Clouds over the Tibetan Plateau Measured by Lidar and Radiosonde Sounding at the Summertime in 2014

Dai

Song

et al. 2017

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Abstract. Optical and geometrical characteristics of cirrus clouds over Naqu (31.48°N,92.06°E), the Tibetan Plateau were determined from lidar and radiosonde measurements performed during the third TIbetan Plateau EXperiment of atmospheric sciences (TIPEX III) campaign from July to August 2014. For the analysis of the temperature dependence, the simultaneous observations by lidar and radiosonde were conducted. Cirrus clouds were generally observed ranging from 9.7 to 16.5 km above sea level (a.s.l.), with the cirrus middle temperatures in the range from −79.7 to −26.0 C  . The cloud thickness generally 15 differed from 0.12 to 2.55 km with a mean thickness of 1.22  0.70 km and 85.7% of the case studies had thickness smaller than 1.5 km. The retrievals of linear particle depolarization ratio, extinction coefficient and optical depth of cirrus clouds were performed. Moreover, the multiple scattering effect inside of cirrus cloud was corrected. The linear particle depolarization ratio of the cirrus clouds varied from 0.36 to 0.52, with a mean value of 0.44  0.037. The optical depth of all the cirrus clouds was between 0.01 and 3 following the scheme of Fernald-Klett method. Sub-visual, thin and opaque cirrus clouds were 20 observed at 9.52%, 57.14% and 33.34% of the measured cases, respectively. The temperature and thickness dependencies on optical properties were studied in detail. A maximum cirrus thickness of around 2 km was found at temperatures between −60 and −50 C  . This study shows that the cirrus mean extinction coefficient of the cirrus clouds increase with the increase of temperature. However, our measurements indicate that the linear particle depolarization ratio has the opposite change tendency along with temperature. The relationships between the presence of cirrus clouds and the temperature anomaly and deep 25Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-355 Manuscript under review for journal Atmos. Meas. Tech. Discussion started: 11 December 2017 c Author(s) 2017. CC BY 4.0 License. 2 convective activity are also discussed. The formation of cirrus clouds is also investigated and it has apparent relationship with the dynamic processes of Rossby wave and deep convective activity over the Tibetan Plateau. The cloud radiative forcing is calculated by Fu-Liou model and increases monotonously with the increase of optical depth.

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Section: Tipex III Campaignmentioning

confidence: 79%

Section: Extraction Of the Cloud Base And Top Heightsmentioning

confidence: 97%

Optical and Geometrical Properties of Cirrus Clouds over the Tibetan Plateau Measured by Lidar and Radiosonde Sounding at the Summertime in 2014

Dai

Song

et al. 2017

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“…Wu et al (2016) and Zhai et al (2017) have given a comprehensive description of CDL. The lidar has a semi-conductor single frequency seed laser that provides both the local oscillator reference beam for 25 heterodyne detection as well as the transmitted beam.…”

Section: Lidar Technology and Methodologymentioning

confidence: 99%

“…It is noted that the wind profile from lidar and radiosonde should be interpolated to the common height grid before comparison because of different spatial resolutions. The type of radiosonde is Model GTS1 digital radiosonde, the basic parameters of which are listed in Table 2 (Song et al, 2017). through the measurement altitude, but slightly southeasterly below 1.6 km , and then shifts to southwesterly above 1.6 km .…”

Section: Horizontal Wind Evaluationmentioning

confidence: 99%

Shipborne Wind Measurement and Motion-induced Error Correction by Coherent Doppler Lidar over Yellow Sea in 2014

Zhai¹,

Wu²,

Liu³

et al. 2017

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“…The temporal resolution of radial velocity is 0.5 s and the lidar results (black curves) averaged over at least 10 min after the launch of the radiosonde are compared with the radiosonde data (red curves). The type of radiosonde is Model GTS1 digital radiosonde with the basic parameters listed in Table 3 (Song et al, 2017). Figure 5 shows the horizontal wind profile during anchored measurement (mean ship speed equals to 0.27 ms −1 ) Fig.…”

Section: Horizontal Wind Evaluationmentioning

confidence: 99%

Shipborne Wind Measurement and Motion-induced Error Correction of a Coherent Doppler Lidar over the Yellow Sea in 2014

Zhai

Liu

et al. 2018

Atmos. Meas. Tech.

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Abstract. Shipborne wind observations by a coherent Doppler lidar (CDL) have been conducted to study the structure of the marine atmospheric boundary layer (MABL) during the 2014 Yellow Sea campaign. This paper evaluates uncertainties associated with the ship motion and presents the correction methodology regarding lidar velocity measurement based on modified 4-Doppler beam swing (DBS) solution. The errors of calibrated measurement, both for the anchored and the cruising shipborne observations, are comparable to those of ground-based measurements. The comparison between the lidar and radiosonde results in a bias of −0.23 ms −1 and a standard deviation of 0.87 ms −1 for the wind speed measurement, and 2. 48, 8.84 • for the wind direction. The biases of horizontal wind speed and random errors of vertical velocity are also estimated using the error propagation theory and frequency spectrum analysis, respectively. The results show that the biases are mainly related to the measuring error of the ship velocity and lidar pointing error, and the random errors are mainly determined by the signal-to-noise ratio (SNR) of the lidar backscattering spectrum signal. It allows for the retrieval of vertical wind, based on one measurement, with random error below 0.15 ms −1 for an appropriate SNR threshold and bias below 0.02 ms −1 . The combination of the CDL attitude correction system and the accurate motion correction process has the potential of continuous long-term high temporal and spatial resolution measurement for the MABL thermodynamic and turbulence process.

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Lidar and Ceilometer Observations and Comparisons of Atmospheric Cloud Structure at Nagqu of Tibetan Plateau in 2014 Summer

Cited by 16 publications

References 20 publications

Optical and Geometrical Properties of Cirrus Clouds over the Tibetan Plateau Measured by Lidar and Radiosonde Sounding at the Summertime in 2014

Optical and Geometrical Properties of Cirrus Clouds over the Tibetan Plateau Measured by Lidar and Radiosonde Sounding at the Summertime in 2014

Shipborne Wind Measurement and Motion-induced Error Correction by Coherent Doppler Lidar over Yellow Sea in 2014

Shipborne Wind Measurement and Motion-induced Error Correction of a Coherent Doppler Lidar over the Yellow Sea in 2014

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