天气和气候预测通常是做统计后,天气,和数值技术。统计方法取决于可观测的大气变量之间的相互关系及其对气候的影响行为。尽管统计方法提供一定的广泛的天气和气候系统的趋势,他们发现有限作为气候系统是高度非线性和简单的任意两个变量之间的相关性并不总是提供估计的任何变量尤其是长期像季节。符类方法在系统分析银行的大规模趋势动力系统基于一系列观察图表符类图表。然而这种方法受到翻译的技巧,不能申请时间超出几天由于大气系统固有的可变性。大气动力学模型是基于大气的物理和动力学过程,因此提供了依据客观定量预测不断变化的大气状况;但是他们的成功取决于初始和边界条件的准确性和恰当使用的物理模型。大气环流模型(AGCMs)是用来模拟全球气候模式的趋势。GCM模拟提供大规模的移动信息系统的压力,空气质量,和相关的气候在世界的各个部分。然而,预测的全球大气环流模型有一个限制区域特征由于粗分辨率。 The GCMs find a limited application when it comes to the disaster mitigation and decision making aspects where much finer quantitative predictions along with precise time of occurrence of a weather event is the necessary key information required by the administrators. The availability of regional models with horizontal resolutions of 30–50 km permits simulating the fine scale seasonal weather patterns to study the regional climatic characteristics more precisely. The theoretical limit for the useful daily weather forecast is about 10–14 days, but in practical application, the current limit is about 5–7 days. For longer periods of about months or seasons average temperature and precipitation can only be assessed; however the skill of such forecasts is low. The developments of numerical models provide the basis for an improved understanding of monthly and seasonal weather variation and for an enhanced ability to predict them with reasonable skill. Even a small improvement in the skill of extended range forecasting of extreme weather events may be helpful to take necessary precautions and to minimize weather-related losses or deaths and is important for substantial economic benefit.
寒潮天气情况在2006年1月1日至31日在图中进行了描述
2利用NCEP再分析资料表面压力和重力势500 hPa高度。分析表明,在2006年1月1日00 utc,低压系统坐落在欧洲中部。头的槽是细长的波罗的海。大气层的厚度(即。,geopotential difference) from surface to 500 hPa is seen to increase from Northern Europe to Southern Europe. After five days, that is, at 00UTC of 5 January, the whole region is completely replaced with high pressure system, and the low pressure is limited to a small region over east of Iceland. Over that region thickness of the geopotential is high and moved toward south of the region and with encircled lower thickness of geopotential observed over Central Europe and neighbor hood. The thickness of the geopotential increased over entire region, and it last up to 14 January with minor day-by day variations. The synoptic flow pattern was more or less constant during this whole period. At 00UTC of 15 January the weather map show well-defined low pressure systems observed over south of Iceland, north-eastern parts of Green land, and north-eastern parts of Central Europe. A well-defined high-pressure system with high geopotential thickness is located over Central Europe. A well-defined trough region is observed at west of Central Europe and also over North eastern parts of the Central Europe. From this day onwards the thickness of the height contours slowly started decreasing over Central Europe, and after two days the weather map showed that the axis of the trough is extended from the East of the Iceland to Central Europe also another trough region developed from north-eastern parts of Central Europe. Well-defined low-and-high pressure systems are observed, and the southward progress of the cold wave is observed. This type of weather pattern is almost observed up to 18 January. After this day onwards the low pressure system moved towards Iceland, and high pressure system started moving towards the Central Europe and was sustained up to 26 January and then it started moves towards west and then north. This narrow zone of high pressure system is associated with low pressure systems in both east and west. During this period another branch of cold wave also slowly developed and started progressing from North east of the Central Europe towards Europe and that was sustained up to 26 January and then slowly disappeared.
3所示。模型配置和初始化
ARW nonhydrostatic原始方程模式开发的国家大气研究中心(NCAR)是用于本研究。ARW是一个灵活的先进的中尺度大气模拟系统是便携式和高效的并行计算平台的范围(
18,
19]。模型高阶数值运算和质量守恒特性(
20.]。目前研究单个域的模型设计了30公里水平分辨率。温带天气系统是相对缓慢的移动系统和大型规模,选择域面积约为3000×3000平方
·37.2992公里(6.7624 e - - e;42.605 n - 61.1074 - n)涵盖了大部分欧洲中部及邻区(图
1)。物理模型用于模拟包括Kain-Firstch方案对流,长波辐射快速辐射传输模型,对行星边界层湍流延世大学计划,WSM三级简单冰方案明确水分过程(表
1)。模型集成了31天从00 UTC的1月1日开始,2006年研究运动波前的冷。
我们的第一个目标是测试是否31天模型模拟与观测提供合理的协议在这个时间表,以便能够设计出一种实时预测策略后使用大规模的模型预测GFS或其它全球提供季节性预测的模型。因此在目前的研究中,模型的初始条件给出了从NCEP再分析资料
21)可以在2.5×2.5度分辨率对应00 UTC 1 2006年1月。地形、土地覆盖和土壤类型数据的研究来自美国地质调查局地形数据分辨率的10分钟(约18公里)。提供的时变横向边界条件在整个过程中,每6小时间隔NCEP再分析资料。
之间的一个详细的比较分析是由新兵1度分辨率分析数据和模型模拟产品的2 m空气温度和风速925 hPa水平评估温度的空间趋势和水平平流运动由ARW模拟。每日平均值计算极端寒冷天的温度在2 m,风在925 hPa新兵和模型输出和呈现在图
5。1月19日风流动的空间分布显示了强大的气旋环流的存在在东南部地区的域模型和新兵数据和强劲的东风流在北部地区的域。这些环流特性很好地模拟ARW模型从新兵数据。温度模式几乎是相同的模型和新兵数据除了更高温度下的面积相对较大的轮廓ARW模拟。这表明该模型产生了比新兵数据稍微温暖的气氛。新兵数据显示强大的低温东北部不是模拟的模型。模型显示一个相对温暖的地区西北域比新兵数据的一部分。1月20日气旋环流朝着东方,和一个反气旋环流是观察在北域模型和新兵的西方部分数据。模拟温度模式同意新兵数据但更高温度下的面积轮廓相对较大因此指示模型的温度温暖的偏见。在接下来的24小时的气旋环流已经到西波兰模型和新兵。 On 21 January the model temperatures are seen to be roughly 5 to 10°C lower over western part of the domain than the values from the FNL data. In all three days (19-21 Jan) westerly flow is noticed over western parts of the domain especially in the central and lower latitudes in both model and FNL data, and the wind is gradually intensified from 19 to 21 January. The simulated flow patterns are noted to agree well with the FNL but with little higher intensity. Also the fine-scale features are well resolved in the simulation which may be because of the model higher resolution than FNL. On 22 January the flow pattern was altered to easterly/northeasterly over much of the domain except for a small region in the northwestern portion where the flow had changed to southwesterly indicating the onset of an anticyclone. In the next day, that is, on 23 Jan the anticyclonic circulation was fully established over the whole Baltic Sea and neighborhood regions.These flow features are well simulated by the model. The simulated spatial temperature distribution also agreed well with FNL data but with a warm bias (about 5 to 10°C) indicating less intensity of the simulated cold wave.
2006年1月18日,一个低压系统是位于波兰西南部地区和邻近地区,和高压系统(未显示)是位于东北地区的领域中观察到的新兵。这种模式模拟的模型,但与低压系统位于捷克共和国和高压位于东北地区的域。高压系统造成低温在这方面明显低于其他地区的域。2006年1月19日,低压系统搬到东南部域的新兵数据和仿真。同时,与此同时,高压系统开始向西南域的一部分。位势的厚度减少超过整个地区的欧洲中部,但相对较高的小区域南西部地区。这些特性将导致空气温度在这些地区一直减少到最低从前面几节中讨论。1月20日,低和高压力系统持续小倾向东南和西北,分别和一个新的低压系统出现在西北的一部分域模型和新兵。位势高度模式表明,更高的轮廓位势高度集中在西南域的一部分,所有其他剩余面积较低的厚度。高压系统保持很长一段时间在欧洲的中部地区,北部和东北部的部分领域,这些地区的气温显著下降。 The temperature reached below
- - - - - -20°C的每月最低大部分中部地区。2008年1月21日,低压系统从西北向西南移动部分,位于沿海地区的丹麦和波兰的核心部分。同时,高压系统仍控制在东北域的一部分。位势高度进一步减少的厚度在整个地区,除了南域的一部分。这些特性以及模拟的模型和新兵数据吻合较好。然而,模拟低压系统的强度略低,和低压中心位置的系统模拟在波兰南部及其相邻的部分。1月22日,低压系统从域消失,和高压系统占领整个域。在这一天位势模式表示高厚度在西北域的一部分,低厚度超过剩余部分。在这种高压系统的中心部分域名记录很低温度模拟的模型。1月23日,一个完善的高压系统的位置是在域的中心部分,在波兰在接下来的48小时。 The geopotential pattern is almost similar to that of the previous day but with slightly higher thickness and a shift towards the east. Under this stable high pressure system especially over Poland the temperatures reached their monthly minimum values in those two days as low record. This prolonged cold wave situation could be simulated by the model. After 23 January the temperatures increased gradually in the northeastern part of the domain, and the high pressure system disappeared slowly. By 25 January, 2006 the temperature increased and reached its normal value over entire Europe.