the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Pseudo-random modulation continuous wave narrowband sodium temperature/wind lidar
- 1Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- 2CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- 3CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei, Anhui, China
- These authors contributed equally to this work.
- 1Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- 2CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- 3CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei, Anhui, China
- These authors contributed equally to this work.
Abstract. We report the first Pseudo-random Modulation Continuous Wave (PMCW) narrowband sodium temperature/wind lidar developed at the University of Science and Technology of China (USTC). The laser system uses an 1178 nm diode seed-laser and a fiber Raman amplifier with a fiber-coupled Acoustic Optical Modulator (AOM) to generate a narrowband 589.158 nm light with a power output of 1.5 W at v0, v+ and v_ frequencies. Based on an innovative technique and algorithm, the main beam and the residual beam modulated by Electro-Optic Modulator (EOM) with M-code are separately directed to the vertical and eastward directions. The 3-frequency light is designed in timing with the multiple-period 127-bit M-code groups. The uncertainties of the temperature and wind with the vertical and temporal resolutions of 1 km and 30 min/1 hr under the clear-sky condition are estimated to be 5.0 K and 10 m/s, respectively at the sodium peak. The temperature and wind results are in good agreement with those observed by satellite and nearby ground-based meteor radar, demonstrating the reliability of the PMCW narrowband sodium lidar system for measuring mesopause region temperature and wind.
Xin Fang et al.
Status: open (until 10 Feb 2023)
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RC1: 'Comment on egusphere-2022-1387', Bifford Williams, 30 Jan 2023
reply
This paper describes a new lidar and shows initial observations using the PMCW technique that has been discussed for years but has not been used operationally. The paper is well written and the results look good. I just have a few small comments and I do not need to see the paper again before publication unless other reviewers have significant concerns.
1. The writing is generally good and understandable but it could use a read over by a native English speaker to fix some prepositions, etc.
2. In the Introduction, the authors mention useing this smaller laser for space observations. What is the effect of of the large ground backscatter signal on the PMCW method. This can't easily be avoided with a large baseline like the near-field signal in a ground-based system
3. Section 2: For the EOM, what are the 0 and 1 levels? Many EOM's are 10% and 90% splitting. How does this code impurity affect the results?
4. Section 3: Your fiber AOM is more properly described as an AO frequency shifter, since frequency shifting is the main goal. That also avoids any confusion with your EO modulator. Similarly, figures 1 and 2 use different terms for the same device: PPLN vs SHG, you might want to pick one for clarity,
5. Have you sent any of the output yellow beam (before the EOM) into the Dopper Free to check for frequency offsets/broadening in the 2nd fiber amplifier?
6. For Figure 7a and 8: At 1km/1hour resolution it would be very rare to see any true vertical winds of more than 1-2 m/s, based on many observations with much higher SNR Na systems. So much of the signal in Figure 7a is likely noise. How do the measured vertical winds compare with your PMCW error calculations? You should add error bars to Figure 8.
7. Section 5, line 260: "And the zonal wind..." -> "The zonal wind..."
Xin Fang et al.
Xin Fang et al.
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