“Refractivity-from-clutter” based on local empirical refractivity model<xref rid="cpb_27_12_128401fn1" ref-type="fn">*</xref><fn id="cpb_27_12_128401fn1"><label>*</label><p>Project supported by the National Natural Science Foundation of China (Grant Nos. 41775027 and 41405025).</p></fn>

“Refractivity-from-clutter” based on local empirical refractivity model**

Project supported by the National Natural Science Foundation of China (Grant Nos. 41775027 and 41405025).

Zhao Xiaofeng^†

(color online) Clutter echo (signal-to-noise ratio, measured in unit dB) from SPANDAR at the time of 17:40 UT, 18:10 UT, 18:32 UT, and 19:00 UT April 02, 1998.