Journal of Earth System Science ( IF 1.9 ) Pub Date : 2021-05-12 , DOI: 10.1007/s12040-021-01604-3 S Indira Rani , Priti Sharma , John P George , M Das Gupta
Wind observations are critical for the better atmospheric analysis for Numerical Weather Prediction (NWP), particularly over the tropics. High-resolution direct wind observations are essential for defining smaller scales and deeper atmospheric structures. Recently launched Aeolus satellite delivers wind profiles that mostly satisfy these requirements, suitable for NWP assimilation. The main product from Aeolus is the horizontally projected Line of Sight wind component, a single component of wind, approximately zonal in nature over the tropics and more meridional over the Polar region, and the main limitation of this observation. Observing system experiments are conducted with the assimilation of individual components of radiosonde and pilot balloon winds to assess the impact of a single component of wind compared to the assimilation of full wind vector in the NCMRWF global assimilation and forecast system. Denial of the zonal component of wind in the assimilation system produced a larger observation increment (observation – model background) in the meridional wind than the full vector assimilation. In contrast, the observation increment of the zonal wind remains nearly the same, even after removing the meridional wind component from the assimilation system. Assimilation of both zonal and meridional components produced changes in the analysis fields of various meteorological variables; however, the zonal component plays a significant role in the tropics. Both wind components play an important role in controlling the humidity field, whereas only zonal components of wind impact the temperature field in the upper troposphere and lower stratosphere. Though the full vector wind assimilation produces a larger impact in the forecast fields of various meteorological variables, the zonal component has more impact than the meridional component. Verification of analysis and forecast wind against the satellite-derived atmospheric motion vectors clearly show the importance of both the horizontal components of winds in the lower troposphere. In contrast, the zonal component of wind alone has a high impact on the upper troposphere and lower stratosphere.
中文翻译:
同化探空仪风的各个组成部分:一项调查,以评估来自星载测量的单分量风对NWP的影响
风观测对于更好地进行数值天气预报(NWP)的大气分析至关重要,特别是在热带地区。高分辨率直接风观测对于定义更小尺度和更深层的大气结构至关重要。最近发射的风神卫星提供的风廓线基本上可以满足这些要求,适用于NWP同化。风神的主要产品是水平投影的视线风分量,是风的单个分量,在热带地区大致呈纬向带状,在极地地区更多为子午线,这是该观测的主要局限性。进行了观测系统实验,对无线电探空仪和飞行员气球的单个分量进行了同化,以评估单个分量对风的影响,并与NCMRWF全球同化和预报系统中对全风矢量的同化进行了比较。与全矢量同化相比,对同化系统中风的纬向分量的否定在子午风中产生了更大的观测增量(观测–模型背景)。相反,即使从同化系统中去除了子午风分量,纬向风的观测增量也几乎保持不变。纬向和经向分量的同化使各种气象变量的分析领域发生了变化。但是,纬向成分在热带地区起着重要作用。两种风成分在控制湿度场中都起着重要作用,而只有风的纬向成分影响对流层上层和平流层下层的温度场。尽管全矢量风同化在各种气象变量的预报领域中产生了较大的影响,但纬向分量比经向分量的影响更大。根据卫星衍生的大气运动矢量对分析风和预报风的验证清楚地表明,对流层低层风的两个水平分量都很重要。相反,仅风的纬向分量对高层的对流层和较低的平流层具有很大的影响。而只有风的纬向分量会影响对流层上层和平流层下层的温度场。尽管全矢量风同化在各种气象变量的预报领域中产生了较大的影响,但纬向分量比经向分量的影响更大。根据卫星衍生的大气运动矢量对分析风和预报风的验证清楚地表明,对流层低层风的两个水平分量都很重要。相反,仅风的纬向分量对高层的对流层和较低的平流层具有很大的影响。而只有风的纬向分量会影响对流层上层和平流层下层的温度场。尽管全矢量风同化在各种气象变量的预报领域中产生了较大的影响,但纬向分量比经向分量的影响更大。根据卫星衍生的大气运动矢量对分析风和预报风的验证清楚地表明,对流层低层风的两个水平分量都很重要。相反,仅风的纬向分量对高层的对流层和较低的平流层具有很大的影响。针对卫星衍生的大气运动矢量进行的分析和预报风的验证清楚地表明了对流层低层风的两个水平分量的重要性。相反,仅风的纬向分量对高层的对流层和较低的平流层具有很大的影响。根据卫星衍生的大气运动矢量对分析风和预报风的验证清楚地表明,对流层低层风的两个水平分量都很重要。相反,仅风的纬向分量对高层的对流层和较低的平流层具有很大的影响。