First lidar observation of the mesospheric nickel layer

Ground‐based resonance lidar has been used to detect the mesospheric nickel (Ni) layer. The Ni layer is detected through absorption in the 3d 8 ( 3 F)4s 2 → 3d 9 ( 2 D)4p transition at 337.1 nm and reemission in both the 3d 9 ( 2 D)4p → 3d 8 ( 3 F)4s 2 and 3d 9 ( 2 D)4p → 3d 9 ( 2 D)4s transitions at 337.1 and 339.4 nm, respectively. Results from wintertime lidar observations on two nights (27–28 November and 20–21 December 2012) at Chatanika, Alaska (65°N, 147°W), are presented. The wintertime Ni layer has a peak concentration of 1.6 × 10 4 cm −3 at 87 km, with a column abundance of 2.7 × 10 10 cm −2 , centroid height of 88 km, and root‐mean‐square width of 6.4 km. The midwinter abundance of mesospheric iron (Fe) at Chatanika is 3.4 × 10 10 cm −2 , indicating a ratio of Fe to Ni of 1.2 in the upper atmosphere. This is significantly lower than the value of 18 for the ratio of Fe to Ni in chondrite meteorites.