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 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.

Ultrahigh laser pulse energy and power generation at 10 kHz

2012 ◽  
Vol 37 (15) ◽  
pp. 3231 ◽  
Author(s):  
Frederik Fuest ◽  
Michael J. Papageorge ◽  
Walter R. Lempert ◽  
Jeffrey A. Sutton
Keyword(s):  
Power Generation ◽  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy

Intelligent Attenuator For Laser Pulse Energy And Power Stabilization

1983 ◽  
Author(s):  
Malcolm S. White ◽  
Raymond W. Wyatt ◽  
Anthony G. Brett
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Power Stabilization

scholarly journals Understanding of BeCu Interaction Characteristics with a Variation of ns Laser-Pulse Duration

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1423 ◽  
Author(s):  
Dongkyoung Lee
Keyword(s):  
Laser Pulse ◽  
Pulse Duration ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Laser Spot ◽  
Main Body ◽  
Crater Size ◽  
Stamping Process ◽  
Cut Quality ◽  
Mechanical Cutting

An inspection process using a Spring Contact Probe (SCP) is an essential step in the semiconductor-manufacturing process. Many plungers, which are the main body of the SCP, are manufactured by a stamping process. After the stamping process, mechanical cutting is applied and the plunger body may be damaged. Thus, to improve cut quality and productivity while minimizing body damage, laser spot cutting can be used. To fully utilize this technology, it is necessary to investigate interaction characteristics of beryllium copper (BeCu) during laser spot cutting. Effects of a total irradiated laser-pulse energy (1 mJ ~1000 mJ ) and pulse duration (100 ns ~8 ns ) on the material-removal zone, thermal depth, and crater size are examined. The crater size can be affected by the localization of heating dominantly. An incubation model is applied to investigate the correlation between crater size and laser-pulse energy. Surface morphology characteristics such as edge separation, small particles, spatter motion, and soaring-up motion are observed.

Study on Laser Welding of Phone Nuts

2013 ◽  
Vol 815 ◽  
pp. 778-781
Author(s):  
Xiao Hong Wu
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Laser Pulse ◽  
Laser Welding ◽  
Pulse Energy ◽  
Pulse Width ◽  
Peak Power ◽  
Laser Pulse Energy ◽  
304 Stainless Steel ◽  
Power Pulse

Used YAG pulse laser to weld 304 stainless steel nuts, studied about the parameters such as peak power, pulse width, defocus distance impacting on the performance of the joints welded by laser. The studies showed that the tensile strength and torque of the nuts increased as the peak power and the pulse width increased.Burn through in welding easy occur when laser pulse energy is too big, pulse width is too wide or defocus distance is too low.

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