scholarly journals A height resolved global view of dust aerosols from the first year CALIPSO lidar measurements

2008 ◽  
Vol 113 (D16) ◽  
Author(s):  
Dong Liu ◽  
Zhien Wang ◽  
Zhaoyan Liu ◽  
Dave Winker ◽  
Charles Trepte
Keyword(s):  
First Year ◽  
Dust Aerosols ◽  
Global View ◽  
Lidar Measurements

scholarly journals First-Year Operation of a New Water Vapor Raman Lidar at the JPL Table Mountain Facility, California

2008 ◽  
Vol 25 (8) ◽  
pp. 1454-1462 ◽  
Author(s):  
Thierry Leblanc ◽  
I. Stuart McDermid ◽  
Robin A. Aspey
Keyword(s):  
Water Vapor ◽  
Current System ◽  
First Year ◽  
Raman Lidar ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Table Mountain ◽  
Lidar Measurements ◽  
Better Than ◽  
Good Agreement

Abstract A new water vapor Raman lidar was recently built at the Table Mountain Facility (TMF) of the Jet Propulsion Laboratory (JPL) in California and more than a year of routine 2-h-long nighttime measurements 4–5 times per week have been completed. The lidar was designed to reach accuracies better than 5% anywhere up to 12-km altitude, and with the capability to measure water vapor mixing ratios as low as 1 to 10 ppmv near the tropopause and in the lower stratosphere. The current system is not yet fully optimized but has already shown promising results as water vapor profiles have been retrieved up to 18-km altitude. Comparisons with Vaisala RS92K radiosondes exhibit very good agreement up to at least 10 km. They also revealed a wet bias in the lidar profiles (or a dry bias in the radiosonde profiles), increasing with altitude and becoming significant near 10 km and large when approaching the tropopause. This bias cannot be explained solely by well-known too-dry measurements of the RS92K in the upper troposphere and therefore must partly originate in the lidar measurements. Excess signal due to residual fluorescence in the lidar receiver components is among the most likely candidates and is subject to ongoing investigation.

scholarly journals The mobile Water vapor Aerosol Raman LIdar and its implication in the framework of the HyMeX and ChArMEx programs: application to a dust transport process

2014 ◽  
Vol 7 (6) ◽  
pp. 1629-1647 ◽  
Author(s):  
P. Chazette ◽  
F. Marnas ◽  
J. Totems
Keyword(s):  
Water Vapor ◽  
Raman Lidar ◽  
Scientific Application ◽  
Dust Transport ◽  
New Device ◽  
Dust Aerosols ◽  
Lidar Measurements ◽  
Lidar Ratio ◽  
Observation Tools ◽  
Water Vapor Mixing Ratio

Abstract. The increasing importance of the coupling of water and aerosol cycles in environmental applications requires observation tools that allow simultaneous measurements of these two fundamental processes for climatological and meteorological studies. For this purpose, a new mobile Raman lidar, WALI (Water vapor and Aerosol LIdar), has been developed and implemented within the framework of the international HyMeX and ChArMEx programs. This paper presents the key properties of this new device and its first applications to scientific studies. The lidar uses an eye-safe emission in the ultraviolet range at 354.7 nm and a set of compact refractive receiving telescopes. Cross-comparisons between rawinsoundings performed from balloon or aircraft and lidar measurements have shown a good agreement in the derived water vapor mixing ratio (WVMR). The discrepancies are generally less than 0.5 g kg−1 and therefore within the error bars of the respective instruments. A detailed study of the uncertainty of the WVMR retrieval was conducted and shows values between 7 and 11%, which is largely constrained by the quality of the lidar calibration. It also proves that the lidar is able to measure the WVMR during daytime over a range of about 1 km. In addition the WALI system provides measurements of aerosol optical properties such as the lidar ratio (LR) or the particulate depolarization ratio (PDR). An important example of scientific application addressing the main objectives of the HyMeX and ChArMEx programs is then presented, following an event of desert dust aerosols over the Balearic Islands in October 2012. This dust intrusion may have had a significant impact on the intense precipitations that occurred over southwestern France and the Spanish Mediterranean coasts. During this event, the LR and PDR values obtained are in the ranges of ~45–63 ± 6 and 0.10–0.19 ± 0.01 sr, respectively, which is representative of dust aerosols. The dust layers are also shown to be associated with significant WVMR, i.e., between 4 and 6.7 g kg−1.

First year of Rayleigh lidar measurements of middle atmosphere temperatures above davis, Antarctica

2003 ◽  
Vol 32 (5) ◽  
pp. 771-776 ◽  
Author(s):  
A.R. Klekociuk ◽  
M.M. Lambert ◽  
R.A. Vincent ◽  
A.J. Dowdy
Keyword(s):  
Middle Atmosphere ◽  
First Year ◽  
Lidar Measurements ◽  
Rayleigh Lidar

scholarly journals Lidar Measurements of Dust Aerosols during Three Field Campaigns in 2010, 2011 and 2012 over Northwestern China

Atmosphere ◽  
2018 ◽  
Vol 9 (5) ◽  
pp. 173 ◽  
Author(s):  
Tian Zhou ◽  
Hailing Xie ◽  
Jianrong Bi ◽  
Zhongwei Huang ◽  
Jianping Huang ◽  
...  
Keyword(s):  
Complex Mixture ◽  
Northwestern China ◽  
Maximum Height ◽  
Near Surface ◽  
Dust Aerosols ◽  
High Particle ◽  
Lidar Measurements ◽  
Vertical Distributions ◽  
Field Campaigns ◽  
The Relationship

Ground-based measurements were carried out during field campaigns in April–June of 2010, 2011 and 2012 over northwestern China at Minqin, the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) and Dunhuang. In this study, three dust cases were examined, and the statistical results of dust occurrence, along with physical and optical properties, were analyzed. The results show that both lofted dust layers and near-surface dust layers were characterized by extinction coefficients of 0.25–1.05 km−1 and high particle depolarization ratios (PDRs) of 0.25–0.40 at 527 nm wavelength. During the three campaigns, the frequencies of dust occurrence retrieved from the lidar observations were all higher than 88%, and the highest frequency was in April. The vertical distributions revealed that the maximum height of dust layers typically reached 7.8–9 km or higher. The high intensity of dust layers mostly occurred within the planetary boundary layer (PBL). The monthly averaged PDRs decreased from April to June, which implies a dust load reduction. A comparison of the relationship between the aerosol optical depth at 500 nm (AOD500) and the Angstrom exponent at 440–870 nm (AE440–870) confirms that there is a more complex mixture of dust aerosols with other types of aerosols when the effects of human activities become significant.

scholarly journals The mobile Water vapor Aerosol Raman LIdar and its implication in the frame of the HyMeX and ChArMEx programs: application to a dust transport process

2013 ◽  
Vol 6 (6) ◽  
pp. 10653-10698 ◽  
Author(s):  
P. Chazette ◽  
F. Marnas ◽  
J. Totems
Keyword(s):  
Water Vapor ◽  
Ultra Violet ◽  
Raman Lidar ◽  
Scientific Application ◽  
Dust Transport ◽  
New Device ◽  
Dust Aerosols ◽  
Lidar Measurements ◽  
Observation Tools ◽  
Water Vapor Mixing Ratio

Abstract. The increasing importance of the coupling of water and aerosol cycles in environmental applications requires observation tools which allow simultaneous measurements of these two fundamental processes for climatological and meteorological studies. In this purpose, a new mobile Raman lidar, WALI (Water vapor and Aerosol LIDAR), has been developed and implemented within the framework of the international HyMeX/IODA-MED and ChArMEx programs. This paper presents the key properties of this new device and its first applications to scientific studies. The lidar uses an eye-safe emission in the ultra-violet range at 354.7 nm and a set of compact refractive receptors. Cross-comparisons between rawindsoundings performed from balloon or aircraft and lidar measurements have shown a good agreement in the derived water vapor mixing ratio (WVMR). The discrepancies are generally less than 0.5 g kg−1 and therefore within the error bars of the instruments. A detailed study of the uncertainties was conducted and shows a 7 to 11% accuracy of the WVMR retrieval, which is largely constrained by the quality of the calibration. It also proves that the lidar is able to measure the WVMR during the day over a range of about 1 km. The WALI system otherwise provides measurements of aerosol optical properties such as the lidar ratio (LR) or the particulate depolarization ratio (PDR). An important example of scientific application addressing the main objectives of the HyMeX and ChArMEx programs is then presented, following an event of desert dust aerosols over the Balearic Islands. This dust intrusion may have had a significant impact on the intense precipitations that occurred over southwestern France and the Spanish Mediterranean coasts. During this event, the LR and PDR values obtained are in the ranges of ~ 45–63 ± 6 sr and 0.1–0.19 ± 0.01, respectively, which is representative of dust aerosols. The dust layers are also shown to be associated with significant WVMR, i.e. between 4 and 6.7 g kg−1.

scholarly journals A calculus student’s understanding of graphical approach to the derivative through quantitative reasoning

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Aytug Ozaltun-Celik
Keyword(s):  
Mathematical Modelling ◽  
Rate Of Change ◽  
Quantitative Reasoning ◽  
First Year ◽  
Instantaneous Rate ◽  
Graphical Approach ◽  
Global View ◽  
Concept Of Function ◽  
Support Students ◽  
Mental Actions

The concept of derivative is used in many areas including applied problems and requiring mathematical modelling in different disciplines. One of the most important approaches for teaching the derivative is to support students in visualizing the concept. Also, it is necessary to shift researchers and teachers’ focuses to students’ dynamic mental actions while learning derivative in order to conduct effective teaching process. With this necessity, I focused on the perspective of quantitative reasoning related to the graphical approach to the derivative. This study aims to reveal a calculus student’s mental actions related to the graphical approach to the derivative. The data were collected from a first-year calculus student engaged in the task requiring graphical interpretation of the derivative. Results showed that the student’s understanding of the slope shaped her inferences about the tangent line because the quantity of ratio is prior knowledge for learning the instantaneous rate of change. Besides, as the student had the idea of correspondence related to the concept of function, she had difficulties in interpreting the global view of the derivate. This result suggests that having global view of the derivative requires a strong understanding of function and rate.

scholarly journals Estimation of Direct Radiative Forcing of Asian Dust Aerosols with Sun/Sky Radiometer and Lidar Measurements at Gosan, Korea

2004 ◽  
Vol 82 (1) ◽  
pp. 115-130 ◽  
Author(s):  
Jae-Gwang WON ◽  
Soon-Chang YOON ◽  
Sang-Woo KIM ◽  
Ann JEFFERSON ◽  
Ellsworth G DUTTON ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Asian Dust ◽  
Dust Aerosols ◽  
Lidar Measurements ◽  
Direct Radiative Forcing
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