The impact of atmospheric stratification on a space-borne Doppler wind lidar

1998 ◽  
Vol 45 (8) ◽  
pp. 1583-1599 ◽  
Author(s):  
J. M. Vaughan ◽  
D. W. Brown ◽  
D. V. Willetts
Keyword(s):  
Atmospheric Stratification ◽  
Wind Lidar ◽  
The Impact ◽  
Doppler Wind Lidar

scholarly journals Relationship between wind observation accuracy and the ascending node of the sun-synchronous orbit for the Aeolus-type spaceborne Doppler wind lidar

2021 ◽  
Vol 14 (7) ◽  
pp. 4787-4803
Author(s):  
Chuanliang Zhang ◽  
Xuejin Sun ◽  
Wen Lu ◽  
Yingni Shi ◽  
Naiying Dou ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Background Radiation ◽  
The Sun ◽  
Wind Observation ◽  
Rayleigh Channel ◽  
Wind Lidar ◽  
The Impact ◽  
Doppler Wind Lidar

Abstract. The launch and operation of the first spaceborne Doppler wind lidar (DWL), Aeolus, is of great significance for observing the global wind field. Aeolus operates on a sun-synchronous dawn–dusk orbit to minimize the negative impact of solar background radiation (SBR) on wind observation accuracy. Future spaceborne DWLs may not operate on sun-synchronous dawn–dusk orbits due to their observational purposes. The impact of the local time of ascending node (LTAN) crossing of sun-synchronous orbits on the wind observation accuracy was studied in this paper by proposing two given Aeolus-type spaceborne DWLs operating on the sun-synchronous orbits with LTANs of 15:00 and 12:00 LT. On these two new orbits, the increments of the averaged SBR received by the new spaceborne DWLs range from 39 to 56 mW m−2 sr−1 nm−1 under cloud-free skies near the summer and winter solstices, which will lead to uncertainties of 0.19 and 0.27 m s−1 in the increment of the averaged Rayleigh channel wind observations for 15:00 and 12:00 LT orbits using the instrument parameters of Aeolus with 30 measurements per observation and 20 laser pulses per measurement. This demonstrates that Aeolus operating on the sun-synchronous dawn–dusk orbit is the optimal observation scenario, and the random error caused by the SBR will be larger on other sun-synchronous orbits. Increasing the laser pulse energy of the new spaceborne DWLs is used to lower the wind observation uncertainties, and a method to quantitatively design the laser pulse energy according to the specific accuracy requirements is proposed in this study based on the relationship between the signal-to-noise ratio and the uncertainty of the response function of the Rayleigh channel. The laser pulse energies of the two new spaceborne DWLs should be set to 70 mJ based on the statistical results obtained using the method. The other instrument parameters should be the same as those of Aeolus. Based on the proposed parameters, the accuracies of about 77.19 % and 74.71 % of the bins of the two new spaceborne DWLs would meet the accuracy requirements of the European Space Agency (ESA) for Aeolus. These values are very close to the 76.46 % accuracy of an Aeolus-type spaceborne DWL when it is free of the impact of the SBR. Moreover, the averaged uncertainties of the two new spaceborne DWLs are 2.62 and 2.69 m s−1, which perform better than that of Aeolus (2.77 m s−1).

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.

scholarly journals Assimilation of DAWN Doppler Wind Lidar Data During the 2017 Convective Processes Experiment (CPEX): Impact on the Precipitation and Flow Structure

2020 ◽  
Author(s):  
Svetla Hristova-Veleva ◽  
Sara Q. Zhang ◽  
F. Joseph Turk ◽  
Ziad S. Haddad ◽  
Randy C. Sawaya
Keyword(s):  
Weather Forecasting ◽  
Convective Precipitation ◽  
Cold Pool ◽  
Near Surface ◽  
Convective Processes ◽  
Precipitation Structure ◽  
Wind Lidar ◽  
Individual Variables ◽  
The Impact ◽  
Doppler Wind Lidar

Abstract. An improved representation of the 3-D air motion and precipitation structure through forecast models and assimilation of observations is vital for improvements in weather forecasting capabilities. However, there is little independent data to properly validate a model forecast of precipitation structure when the underlying dynamics are evolving on short convective times scales. Using data from the JPL Ku/Ka-band Airborne Precipitation Radar (APR-2) and the 2-um Doppler Aerosol Wind (DAWN) lidar collected during the 2017 Convective Processes Experiment (CPEX), the NASA Unified Weather Research and Forecasting (WRF) Ensemble Data Assimilation System (EDAS) modeling system was used to quantify the impact of the high resolution, sparsely-sampled DAWN measurements on the analyzed variables and on the forecast when the DAWN winds were assimilated. Overall, the assimilation of the DAWN wind profiles had a discernible impact to the wind field and the evolution and timing of the 3-D precipitation structure. Analysis of individual variables revealed that the assimilation of the DAWN winds resulted in important and coherent modifications of the environment. It led to increase of the near surface convergence, temperature and water vapor, creating more favorable conditions for the development of convection exactly where it was observed (but not present in the control run). Comparison to APR-2 and observations by the Global Precipitation Measurement (GPM) satellite shows a much-improved forecast after the assimilation of the DAWN winds – development of precipitation where there was none, more organized precipitation where there was some, and a much more intense and organized cold pool, similar to the analysis of the dropsonde data. Onset of the vertical evolution of the precipitation showed similar radar-derived cloud top heights, but delayed in time. While this investigation was limited to a single CPEX flight date, the investigation design is appropriate for further investigation of the impact of airborne Doppler wind lidar observations upon short-term convective precipitation forecasts.

scholarly journals Sensitivity of Aeolus HLOS winds to temperature and pressure specification in the L2B processor

2021 ◽  
Author(s):  
Matic Šavli ◽  
Vivien Pourret ◽  
Christophe Payan ◽  
Jean-François Mahfouf
Keyword(s):  
Error Estimate ◽  
Weather Prediction ◽  
Horizontal Line ◽  
Model Errors ◽  
Space Agency ◽  
Atmospheric Stratification ◽  
Wind Lidar ◽  
Temperature And Pressure ◽  
Nwp Model ◽  
The Impact

Abstract. The retrieval of wind from the first Doppler wind lidar of Europen Space Agency (ESA) launched in space in August 2018 is based on a series of corrections necessary to provide observations of a quality useful for Numerical Weather Prediction (NWP). In this paper we examine properties of the Rayleigh-Brillouin correction necessary for the retrieval of horizontal line-of-sight wind (HLOS) from a Fabry-Perot interferometer. This correction is taking into account the atmospheric stratification, namely temperature and pressure information that are provided by a NWP model as suggested prior launch. Since NWP models contain errors the main goal in the study is to evaluate the impact of these errors on the HLOS sensitivity by comparing the Integrated Forecast System (IFS) and Action de Recherche Petite Echelle Grande Echelle (ARPEGE) global model temperature and pressure short term forecasts collocated with the Aeolus orbit. The model error is currently not taken into account in the computation of the HLOS error estimate since its contribution is believed small. This study largely confirms this statement to be a valid assumption, although it also shows that model errors could locally (i.e. jet-stream regions, below 700 hPa over both earth poles and as well in stratosphere) be significant. For a future Aeolus follow-on missions this study suggests to consider realistic estimations of model errors in the HLOS retrieval algorithms, since this will lead to an improved estimation of the Rayleigh-Brillouin sensitivity uncertainty contributing to the HLOS error estimate and better exploitation of space lidar winds in NWP systems.

Aeolus Calibration, Validation and Science Post-Launch Campaigns

2021 ◽  
Author(s):  
Thorsten Fehr ◽  
Vassilis  Amiridis ◽  
Jonas von Bismarck ◽  
Sebastian Bley ◽  
Cyrille Flamant ◽  
...  
Keyword(s):  
Deep Convection ◽  
Essential Element ◽  
Saharan Dust ◽  
Aerosol Layer ◽  
Satellite Mission ◽  
Wide Range ◽  
Wind Lidar ◽  
The Tropics ◽  
The Impact ◽  
Doppler Wind Lidar

<p>ESA supported airborne and ground-based campaigns constitute an essential element in the development and operation of satellite missions, providing the opportunity to test novel observation technologies, acquire representative data for the development of the mission concepts, processors and use cases, as well as in their calibration and validation phases once in orbit.</p><p>For the Aeolus Doppler Wind Lidar satellite mission, ESA has implemented a campaign programme that started in 2007 and has continued beyond the launch of the mission on 22. August 2018. Building on the successful WindVal-I and –II campaigns with DLR’s A2D and 2µm Doppler Wind Lidar systems on-board the DLR Falcon aircraft, a number of validation campaigns have been successfully implemented: WindVal-III in November 2018, AVATAR-E in May 2019, and AVATAR-I in September 2019. In addition, ESA supported the CNES pre-Stratéole-2/TAPAPA campaign with eight stratospheric balloons having been launched from the Seychelles in November/December 2019 providing unique upper level wind data in the Tropics. The validation by stratospheric balloons has been extended in the frame of a collaboration with Loon LLC for a test case covering the months August and September 2019.</p><p>As the largest impact of the Aeolus observations is expected in the Tropics, and in particular over the Tropical oceans, ESA, in close collaboration with NASA and European partners, is currently implementing a Tropical campaign in July 2021.  With its base in Cape Verde the activity comprises both airborne and ground-based activities addressing the tropical winds and aerosol validation, as well as a wide range of science objectives. The location is unique as it allows the study of the Saharan Aerosol layer, African Easterly Waves and Jets, the Tropical Easterly Jet, as well as deep convection in ITCZ and tropical cyclogenesis, with a focus on the impact of Saharan dust on micro-physics in tropical cloud systems. The campaign builds on remote and in-situ observations from aircraft (DLR Falcon-20, the Safire Falcon-20, the NASA DC-8 and an Aerovizija/UNG light aircraft) and drone systems, as well as an extensive aerosol and cloud measurement programme with a range of lidar, radar and radiometer systems coordinated by NOA.</p><p>This paper will provide a summary of the Aeolus campaign activities, focussing on the completed and planned post launch campaigns.</p>

scholarly journals An Observing System Simulation Experiment (OSSE) to Assess the Impact of Doppler Wind Lidar (DWL) Measurements on the Numerical Simulation of a Tropical Cyclone

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Lei Zhang ◽  
Zhaoxia Pu
Keyword(s):  
Numerical Simulation ◽  
Tropical Cyclone ◽  
Mesoscale Model ◽  
Weather Prediction ◽  
Three Dimensional ◽  
Wrf Model ◽  
Wind Lidar ◽  
Wind Profiles ◽  
The Impact ◽  
Doppler Wind Lidar

The importance of wind observations has been recognized for many years. However, wind observations—especially three-dimensional global wind measurements—are very limited. A satellite-based Doppler Wind Lidar (DWL) is proposed to measure three-dimensional wind profiles using remote sensing techniques. Assimilating these observations into a mesoscale model is expected to improve the performance of the numerical weather prediction (NWP) models. In order to examine the potential impact of the DWL three-dimensional wind profile observations on the numerical simulation and prediction of tropical cyclones, a set of observing simulation system experiments (OSSEs) is performed using the advanced research version of the Weather Research and Forecasting (WRF) model and its three-dimensional variational (3DVAR) data assimilation system. Results indicate that assimilating the DWL wind observations into the mesoscale numerical model has significant potential for improving tropical cyclone track and intensity forecasts.

scholarly journals Evaluation and Impact Factors of Doppler Wind Lidar during Super Typhoon Lekima (2019)

2021 ◽  
Author(s):  
Xu Wang ◽  
Shengming Tang ◽  
Yun Guo ◽  
Jie Tang ◽  
Shuai Zhang
Keyword(s):  
Wind Speed ◽  
Impact Factors ◽  
Observation Data ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Super Typhoon ◽  
Average Wind ◽  
Wind Lidar ◽  
The Impact ◽  
Doppler Wind Lidar

Abstract. Doppler wind lidar (DWL) has been shown to obtain fairly accurate wind speeds in normal wind conditions. However, the evaluation of DWL winds under typhoon conditions is less common. This study evaluated the accuracy of wind data measured by two types of DWLs (WindPrint S4000 and WindCube V2), and investigated the impact of factors (e.g., precipitation and humidity) on the DWL-observed wind speed and direction. Data were collected from joint observations in Baoshan, Zhoushan and Taizhou (China) by the Shanghai Typhoon Institute during the passage of Super Typhoon Lekima in 2019. The DWL observations were compared with measured data from balloon-borne radiosonde released at the same location. The results showed that the 1-min average wind speed and direction of WindPrint S4000 were more consistent with the instantaneous observation data of the sounding balloon than those of WindCube V2. The applicability of DWL was poor when the precipitation intensity was larger than 50 mm · h−1. The DWL wind speed bias significantly increased when the relative humidity exceeded 85 %. When the drift distance of the sounding balloon (ldrift) was less than 1 km, the DWL wind speed bias decreased with an increase of ldrift, whereas it increased with an increase of ldrift when the drift exceeded 1.5 km. Within a radius of 700 km, the root mean square of wind speeds between DWL and sounding balloon measurements showed a trend of increasing as the distance from the typhoon center decreased.

scholarly journals On the relationship between wind observation accuracy and the ascending node of sun-synchronous orbit for the Aeolus-type spaceborne Doppler wind lidar

2020 ◽  
Author(s):  
Chuanliang Zhang ◽  
Xuejin Sun ◽  
Wen Lu ◽  
Yingni Shi ◽  
Naiying Dou ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Weather Prediction ◽  
The Sun ◽  
Wind Observation ◽  
Wind Lidar ◽  
The Impact ◽  
The Relationship ◽  
Doppler Wind Lidar

Abstract. The launch and operation of first spaceborne Doppler wind lidar (DWL) Aeolus is of great significance in observing global wind field. Aeolus operates on the sun-synchronous dawn-dusk orbit to minimize the negative impact of solar background radiation (SBR) on wind observation accuracy. For that the future spaceborne DWLs may not operate on sun-synchronous dawn-dusk orbits due to their observation purposes, the impact of the local time of ascending node (LTAN) crossing of sun-synchronous orbits on the wind observation accuracy was studied in this paper by proposing two added Aeolus-type spaceborne DWLs operated on the sun-synchronous orbits with LTAN of 15:00 and 12:00 combined with Aeolus. On the two new orbits, the increments of averaged SBR received by the new spaceborne DWLs range from 39 to 56 mW m−2 sr−1 nm−1 under clear skies, which will lead to the increment of averaged wind observation uncertainties from 0.3 to 0.4 m/s in the troposphere and from 0.9 to 1.4 m/s in the stratosphere. Increasing laser pulse energy of the new spaceborne DWLs is used to lower the wind observation uncertainties. Furthermore, a method to quantitatively design the laser pulse energy according to specific accuracy requirements is given in this paper based on the relationship between the signal noise ratio and the uncertainty of response function of Rayleigh channel of Aeolus-type spaceborne DWLs. The laser pulse energy of the two new spaceborne DWLs is set to 80 mJ based on the statistical results according to the method, meanwhile other instrument parameters are the same as those of Aeolus. Based on the parameter proposal, the accuracy of above 85 % bins of the new spaceborne DWLs would meet the accuracy requirements of European Space Agency (ESA) for Aeolus, which would improve the forecast results of Numerical Weather Prediction. And the averaged observation uncertainties show the high consistence in observation accuracy of the three spaceborne DWLs, which can be used for joint observation.

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