基于天气预报模式预报阿里天文站大气光学湍流

Forecast of Atmosphere Optical Turbulence at Ali Site by Weather Research and Forecasting Model

利用气象模式预报大气光学湍流,能够使地基望远镜根据不同的大气视宁度条件,选取相应的观测目标和终端设备,还可以优化自适应光学系统性能和激光器打击目标的发射时机。介绍了采用天气预报模式建立的大气光学湍流预报方法。利用该预报方法,采用数值和分析两种模型,分别提前3d、2d和1d预报出2011年11月6日夜间阿里天文站的气象参数、大气光学湍流强度Cn2廓线和视宁度。共计6次的预报结果均显示近地面层、边界层2km高度以及对流层12km高度存在强湍流层。与单星闪烁测量层析(SICDAR)的实测数据对比结果表明,本预报方法能够反映大气光学湍流廓线的结构特征。预报的视宁度反映出夜间的增大趋势和差分像运动视宁度仪(DIMM)实测结果相似。

The optical turbulence forecasting by meteorological model can provide fundamental information for the flexible scheduling of observation and instruments of ground-based telescope, optimized the performance of adaptive optics and the opportunity of destroying object by laser. An optical turbulence forecast system has been established with the weather research and forecasting model. Based on this system and two optical turbulence parameterization methods, numerical model and analytical model, the meteorological parameters, Cn2 profiles and seeing at Ali site on November 06, 2011 are forecasted in advance on November 04, 05 and 06 respectively. Strong turbulence layers near ground, 2 km in boundary layer and 12 km in troposphere are discovered from the 6 forecasted results. The comparison between forecasted results and single star scintillation detection and ranging measurements shows that this forecasting system could provide the structure characteristics of Cn2 profiles. It also could provide the increasing trend of seeing results over night, similar to the result with differential image motion monitoring.