Preprints
https://doi.org/10.5194/amt-2020-202
https://doi.org/10.5194/amt-2020-202

  29 Jun 2020

29 Jun 2020

Review status: this preprint is currently under review for the journal AMT.

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

Chuanliang Zhang1,2, Xuejin Sun2, Wen Lu2, Yingni Shi1, Naiying Dou1, and Shaohui Li2 Chuanliang Zhang et al.
  • 1Mailbox 5111, Beijing 100094, China
  • 2College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China

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.

Chuanliang Zhang et al.

 
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Status: final response (author comments only)
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Chuanliang Zhang et al.

Chuanliang Zhang et al.

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Short summary
First spaceborne Doppler wind lidar (DWL) Aeolus operates on sun-synchronous dawn-dusk orbit to lower impact of solar background radiation (SBR) on wind observation accuracy. Increased SBR leads to increment of averaged wind observation uncertainties from 0.3 to 1.4 m/s compared between Aeolus and two added spaceborne DWLs operating on orbits with local ascending time of 15:00 and 12:00. Furthermore, quantitative design of laser pulse energy according to accuracy requirements is also proposed.