北京上空下三角钾层的激光雷达观测与研究

Lidar Observations and Studies of the Lower-triangle Potassium Layer over Beijing

利用2010年11月至2011年10月和2013年5月至2014年4月两年的观测数据发现一种特殊的钾层,称其为下三角钾层.下三角钾层的峰值密度随时间逐渐增加,峰值密度所在高度不断降低,钾原子浓度随高度的升高先迅速增加,然后又缓慢减少.当下三角钾层出现时,90 km以下的柱密度显著增加,而90 km以上的柱密度变化不大,导致钾层总的柱密度明显增加.一月是下三角钾层出现时长最多且出现率最高的月份,这可能与大气半日潮汐的季节变化有关.下三角钾层的频繁出现使钾层一月份的柱密度和峰值密度分别增加15.7%和12.9%,而质心高度却降低0.18km.将下三角钾层与同时同地观测的钠层进行比较,结果显示当钾原子浓度增加时,钠原子浓度却变化不大.假设不存在特殊的源注入,结合钾层模型与钠层模型中的化学反应及其相应的化学反应速率,可以推测下三角钾层中增加的钾原子主要来自KO_2,部分来自KOH.

A special behavior of the potassium layer in the mesopause region has been discovered over Beijing, China （40.4°N, l16.0°E） from two-year long data sets, during November 2010 to October 2011 and May 2013 to April 2014. This peculiar potassium layer is termed as the lower-triangle potassium layer. The peak density of the lower-triangle potassium layer increases gradually and the height of the peak density evidently descends with time. The concentration of the potassium atoms first increases rapidly and then decreases slowly along with the increasing height. When the lower-triangle potassium layer appeared, the column density below 90 km increased significantly, but the column density above 90 km changed little. Then the whole column density increased obviously. There are the longest occurrence time and the highest occurrence ratio of the lower triangle potassium layer in January, which could be related to seasonal variations of the atmospheric semidiurnal tides. The frequent appearance of the lower-triangle potassium layer has made the average column density and peak density increase by 15.7% and 12.9% respectively, but the centroid height decrease by 0.18kin in January. The comparisons between the lower-triangle potassium layer and the sodium layer at the same time and location show that the concentration of sodium atoms had no obvious change when the concentration of potassium atoms increased remarkably. Assuming that there were no special sources injecting into the metal layers, according to the chemical reactions and relevant chemical reaction rates in potassium model and sodium model, it can be speculated that the increasing potassium atoms in the lower-triangle potassium layer were mainly converted from KO2, and partly from KOH.