Fig. 4From: First imaging and identification of a noctilucent cloud from multiple sites in Hokkaido (43.2–44.4°N), JapanCalculated cross-correlation coefficients as a function of assumed altitude between 75 and 95 km. Vertical line indicates the altitude \(Z_{\text{s}} = 83.9\;{\text{km}}\) that yields the maximum correlation coefficientBack to article page