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Seasonal and latitudinal variation of noctilucent cloud altitudes

We present a summary of ∼1500 hours of lidar measurements of noctilucent cloud (NLC) altitudes at Kühlungsborn (54°N), ALOMAR (69°N), and Spitsbergen (78°N). Mean centroid altitudes (zc) are 82.75 km, 83.33 km, and 83.68 km, respectively. Standard deviations σ representing geophysical variability are ∼0.7–1.6 km. Errors of mean heights Δzc are much smaller (60–340 m). Several processes which are not yet fully understood influence zc. Therefore, σ is a better measure of uncertainties in zc compared to Δzc. The increase of NLC heights with latitude is very small (43 ± 65 m/deg) and statistically not significant. At ALOMAR zc varies with season by up to ∼1–1.5 km. NLC heights accumulate around climatological temperatures of 145 K at 69°N and 78°N (higher at 54°N). The LIMA model nicely reproduces observations and indicates that non‐variation of NLC heights at polar latitudes is caused by temperature uniformity: the 145 K isotherm varies in height by less than 250 m from the pole to 60°N.