scholarly journals Time evolution of monsoon low-level jet observed over an Indian tropical station during the peak monsoon period from high-resolution Doppler wind lidar measurements

2014 ◽  
Vol 119 (4) ◽  
pp. 1786-1795 ◽  
Author(s):  
R. D. Ruchith ◽  
P. Ernest Raj ◽  
M. C. R. Kalapureddy ◽  
Sachin M. Deshpande ◽  
K. K. Dani
Keyword(s):  
High Resolution ◽  
Time Evolution ◽  
Monsoon Period ◽  
Low Level ◽  
Lidar Measurements ◽  
Wind Lidar ◽  
Low Level Jet ◽  
Tropical Station ◽  
Doppler Wind Lidar

scholarly journals Aerosol Backscatter and Extinction Retrieval from Airborne Coherent Doppler Wind Lidar Measurements

2016 ◽  
Vol 119 ◽  
pp. 23001
Author(s):  
F. Chouza ◽  
O. Reitebuch ◽  
S. Groß ◽  
S. Rahm ◽  
V. Freudenthaler ◽  
...  
Keyword(s):  
Lidar Measurements ◽  
Wind Lidar ◽  
Aerosol Backscatter ◽  
Doppler Wind Lidar

scholarly journals The life cycle of nocturnal low-level clouds over southern West Africa analysed using high-resolution simulations

2016 ◽  
Author(s):  
Bianca Adler ◽  
Norbert Kalthoff ◽  
Leonhard Gantner
Keyword(s):  
Life Cycle ◽  
High Resolution ◽  
West Africa ◽  
Single Case ◽  
Monsoon Season ◽  
Cloud Formation ◽  
Field Campaign ◽  
Low Level ◽  
Low Level Jet ◽  
Spatio Temporal

Abstract. We performed a high-resolution numerical simulation to study the life cycle of extensive low-level clouds which frequently form over southern West Africa during the monsoon season. This study was made in preparation for a field campaign in 2016 within the Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) project and focuses on an area around the city of Save in southern Benin. Nocturnal low-level clouds evolve a few hundred metres above the ground around the same level as a distinct low-level jet. Several processes are found to determine the spatio-temporal evolution of these clouds including (i) significant cooling of the nocturnal atmosphere due to horizontal advection with the south-westerly monsoon flow during the first half of the night, (ii) vertical cold air advection due to gravity waves leading to clouds in the wave crests and (iii) enhanced convergence and upward motion upstream of existing clouds that trigger new clouds. The latter is caused by an upward shift of the low-level jet in cloudy areas leading to horizontal convergence in the lower part and to horizontal divergence in the upper part of the cloud layer. Although this single case study hardly allows for a generalisation of the processes found, the results added to the optimisation of the measurements strategy for the field campaign and the observations will be used to the test the hypotheses for cloud formation resulting from this study.

Elastic lidar measurements of summer nocturnal low level jet events over Baltimore, Maryland

2014 ◽  
Vol 72 (3-4) ◽  
pp. 311-333 ◽  
Author(s):  
Ruben Delgado ◽  
Scott D. Rabenhorst ◽  
Belay B. Demoz ◽  
Raymond. M. Hoff
Keyword(s):  
Low Level ◽  
Lidar Measurements ◽  
Low Level Jet

scholarly journals Impact of Lidar Data Assimilation on Low-Level Wind Shear Simulation at Lanzhou Zhongchuan International Airport, China: A Case Study

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1342
Author(s):  
Lanqian Li ◽  
Ningjing Xie ◽  
Longyan Fu ◽  
Kaijun Zhang ◽  
Aimei Shao ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Wind Shear ◽  
Three Dimensional ◽  
Wrf Model ◽  
Lidar Data ◽  
Positive Role ◽  
Low Level ◽  
Wind Lidar ◽  
The Impact ◽  
Doppler Wind Lidar

Doppler wind lidar has played an important role in alerting low-level wind shear (LLW). However, these high-resolution observations are underused in the model-based analysis and forecasting of LLW. In this regard, we employed the Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-VAR) system to investigate the impact of lidar data assimilation (DA) on LLW simulations. Eight experiments (including six assimilation experiments) were designed for an LLW process as reported by pilots, in which different assimilation intervals, assimilation timespans, and model vertical resolutions were examined. Verified against observations from Doppler wind lidar and an automated weather observing system (AWOS), the introduction of lidar data is helpful for describing the LLW event, which can represent the temporal and spatial features of LLW, whereas experiments without lidar DA have no ability to capture LLW. While lidar DA has an obviously positive role in simulating LLW in the 10–20 min after the assimilation time, this advantage cannot be maintained over a longer time. Therefore, a smaller assimilation interval is favorable for improving the simulated effect of LLW. In addition, increasing the vertical resolution does not evidently improve the experimental results, either with or without assimilation.

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