共查询到20条相似文献，搜索用时 15 毫秒
1.
GPS观测资料应用于中尺度数值预报模式的初步研究 总被引：12，自引：3，他引：12
利用建立在长江三角洲地区GPS观测网中 11个站点的可降水量资料 ,对 2 0 0 2年 6月 2 3～ 2 4日影响长江三角洲地区的降水过程进行了MM5模式初始湿度场调整和Nudging同化试验。试验表明 :利用GPS测量的可降水量对模式初始湿度场进行调整能明显增强模式初始场描述水汽分布的能力 ,从而有效地控制模式积分初期对可降水量预报的误差 ,并对模式 6h累积降水量预报有较明显的改善作用。利用Nudging技术同化GPS可降水量资料对MM5预报效果改善较小 ,并且Nudging系数的增加对预报效果的影响不大。总体上 ,利用GPS可降水量资料调整模式初始湿度场对模式 6h累积降水预报效果的改善明显好于连续Nudging同化。试验还表明 :GPS资料对模式初始湿度场调整改善模式对累积降水量的预报主要是通过改善网格降水预报来实现的 ,而Nudging同化主要是通过改善次网格降水而提高模式降水预报能力的。 相似文献
2.
大气红外探测器(AIRS)温、湿度反演产品的有效性检验及在数值模式中的应用研究 总被引：6，自引：0，他引：6
利用中国540个地面气象观测站点资料,对1和7月大气红外探测器(AIRS)的反演中国区域地面气温精度做了详细评估,分析了产生误差的原因。同时把AIRS的反演温、湿度廓线产品与T213数值预报产品进行比较,分析了它们之间的差异。为进一步考察AIRS温、湿度产品的有效性,我们把经过订正的AIRS地面气温以及温、湿度廓线产品分析同化到中尺度模式MM5中,用于华北降雪天气过程的对比模拟试验,分析AIRS反演产品对降雪量、水汽场、垂直速度场、散度场以及云物理过程等的影响。 相似文献
3.
利用建立在长江三角洲地区GPS观测网中13个站点的资料对2002年6月27~28日影响长江三角洲地区的降水过程进行了MM5背景误差调节和可降水量资料的三维变分同化试验。试验结果表明:背景误差对三维变分同化的效果起着关键作用,模式变量(u,v,T,p和q)误差的水平尺度与NMC方法的平均时间长度有直接的关系。利用NMC方法重新构建的背景误差更接近实际的背景误差。三维变分技术能有效地同化GPS可降水量资料。GPS可降水量资料的同化使用不仅能调整模式初始湿度场,而且也能相应地调整模式初始气压场、温度场和风场。GPS可降水量资料的同化有利于减小模式初始场对可降水量的分析误差,并且有利于减小模式积分初期(3~6 h)可降水量的预报误差。与没有进行GPS可降水量同化相比,通过GPS可降水量资料的三维变分同化,使MM5模式6 h和24 h累计降水能力得到提高,改善了MM5模式降水预报性能。总体上,GPS可降水量资料的变分同化有利于模式降水预报能力的提高。 相似文献
4.
Validation of the Atmospheric Infrared Sounder Retrieval Products over China and Their Application in Numerical Mode 
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下载免费PDF全文 The atmospheric infrared sounder (AIRS) instrument onboard Aqua Satellite is a high spectral resolution infrared sounder. In recent years, AIRS has gradually become the primary method of atmospheric vertical observations. To examine the validation of AIRS retrieval products (V3.0) over China, the AIRS surface air temperature retrievals were compared with the ground observations obtained from 540 meteorological stations in July 2004 and January 2005, respectively. The sources of errors were considerably discussed. Based on the error analysis, the AIRS retrieved surface air temperature products were systemically corrected. Moreover, the AIRS temperature and humidity profile retrievals were compared with T213 numerical forecasting products. Because T213 forecasting products are not the actual atmospheric states,to further verify the validation, the AIRS temperature and humidity profile products were assimilated into the MM5 model through the analysis nudging. In this paper, the case on February 14, 2005 in North China was simulated in detail. Then, we investigated the effects of AIRS retrievals on snowfall, humidity field,vertical velocity field, divergence field, and cloud microphysical processes. The major results are: (1) the errors of AIRS retrieved surface air temperature products are largely systematic deviations, for which the influences of terrain altitude and surface types are the major reasons; (2) the differences between the AIRS atmospheric profile retrievals and T213 numerical prediction products in temperature are generally less than
2 K, the differences in relative humidity are generally less than 25%; and (3) the AIRS temperature and humidity retrieval products can adjust the model initial field, and thus can improve the capacity of snowfall simulation to some extent. 相似文献
5.
The present study is conducted to verify the short-range forecasts from mesoscale model version5 (MM5)/weather research and forecasting (WRF) model over the Indian region and to examine the impact of assimilation of quick scatterometer (QSCAT) near surface winds, spectral sensor microwave imager (SSM/I) wind speed and total precipitable water (TPW) on the forecasts by these models using their three-dimensional variational (3D-Var) data assimilation scheme for a 1-month period during July 2006. The control (without satellite data assimilation) as well as 3D-Var sensitivity experiments (with assimilating satellite data) using MM5/WRF were made for 48 h starting daily at 0000 UTC July 2006. The control run is analyzed for the intercomparison of MM5/WRF short-range forecasts and is also used as a baseline for assessing the MM5/WRF 3D-Var satellite data sensitivity experiments. As compared to the observation, the MM5 (WRF) control simulations strengthened (weakened) the cross equatorial flow over southern Arabian sea near peninsular India. The forecasts from MM5 and WRF showed a warm and moist bias at lower and upper levels with a cold bias at the middle level, which shows that the convective schemes of these models may be too active during the simulation. The forecast errors in predicted wind, temperature and humidity at different levels are lesser in WRF as compared to MM5, except the temperature prediction at lower level. The rainfall pattern and prediction skill from day 1 and day 2 forecasts by WRF is superior to MM5. The spatial distribution of forecast impact for wind, temperature, and humidity from 1-month assimilation experiments during July 2006 demonstrated that on average, for 24 and 48-h forecasts, the satellite data improved the MM5/WRF initial condition, so that model errors in predicted meteorological fields got reduced. Among the experiments, MM5/WRF wind speed prediction is most benefited from QSCAT surface wind and SSM/I TPW assimilation while temperature and humidity prediction is mostly improved due to latter. The largest improvement in MM5/WRF rainfall prediction is due to the assimilation of SSM/I TPW. The assimilation of SSM/I wind speed alone in MM5/WRF degraded the humidity and rainfall prediction. In summary the assimilation of satellite data showed similar impact on MM5/WRF prediction; largest improvement due to SSM/I TPW and degradation due to SSM/I wind speed. 相似文献
6.
The atmospheric infrared sounder (AIRS) instrument onboard Aqua Satellite is a high spectral resolution infrared sounder. In recent years, AIRS has gradually become the primary method of atmospheric vertical observations. To examine the validation of AIRS retrieval products (V3.0) over China, the AIRS surface air temperature retrievals were compared with the ground observations obtained from 540 meteorological stations in July 2004 and January 2005, respectively. The sources of errors were considerably discussed. Based on the error analysis, the AIRS retrieved surface air temperature products were systemi-cally corrected. Moreover, the AIRS temperature and humidity profile retrievals were compared with T213 numerical forecasting products. Because T213 forecasting products are not the actual atmospheric states, to further verify the validation, the AIRS temperature and humidity profile products were assimilated into the MM5 model through the analysis nudging. In this paper, the case on February 14, 2005 in North China was simulated in detail. Then, we investigated the effects of AIRS retrievals on snowfall, humidity field, vertical velocity field, divergence field, and cloud microphysical processes. The major results are: (1) the errors of AIRS retrieved surface air temperature products are largely systematic deviations, for which the influences of terrain altitude and surface types are the major reasons; (2) the differences between the AIRS atmospheric profile retrievals and T213 numerical prediction products in temperature are generally less than 2 K, the differences in relative humidity are generally less than 25%; and (3) the AIRS temperature and humidity retrieval products can adjust the model initial field, and thus can improve the capacity of snowfall simulation to some extent. 相似文献
7.
In order to understand the impact of initial conditions upon prediction accuracy of short-term
forecast and nowcast of precipitation in South China, four experiments i.e. a control, an assimilation of
conventional sounding and surface data, testing with nudging rainwater data and the assimilation of
radar-derived radial wind, are respectively conducted to simulate a case of warm-sector heavy rainfall that
occurred over South China, by using the GRAPES_MESO model. The results show that (1) assimilating
conventional surface and sounding observations helps improve the 24-h rainfall forecast in both the area
and order of magnitude; (2) nudging rainwater contributes to a significant improvement of nowcast, and (3)
the assimilation of radar-derived radial winds distinctly improves the 24-h rainfall forecast in both the area
and order of magnitude. These results serve as significant technical reference for the study on short-term
forecast and nowcast of precipitation over South China in the future. 相似文献
8.
DRP-4DVar方法同化AIRS反演资料在一次江淮流域暴雨中的应用 总被引：2，自引：1，他引：1
利用经济省时的降维投影四维变分同化方法(DRP-4DVar),在2009年7月22～23日江淮流域的一次大暴雨过程中同化晴空条件下高光谱大气红外探测仪(AIRS)反演温度、湿度廓线,改进此次强降水过程的模拟。试验结果分析显示,同化AIRS反演的温度及湿度场后,基于四维变分同化系统的模式约束,能够改进湿度场、高度场、高低层散度场。从累积降水量偏差图及同化试验增量图可以看到,正降水量偏差对应于正湿度增量、负位势高度增量及低层负散度高层正散度增量,负降水量偏差则与之相反。同化试验较参照试验可更好地模拟出暴雨的天气形势、对暴雨的落区及强度有更好的反映。此外,从单次同化与连续同化的试验对比结果看出,连续同化试验结果较单次同化结果有进一步的改进,说明不断加入新的观测资料可以更好地模拟强降水过程。 相似文献
9.
10.
采用MM5模式及其三维变分系统(MM5/3DVAR)对我国夏季降雨进行了一个月的连续预测试验,并对试验结果进行评估.试验中首先采用"National Meteorological Center(NMC)"方法,将2005年8月的MM5模式的预测结果形成与试验区域和水平分辨率相匹配的背景误差场,并将其与全球背景误差场进行了对比分析,结果表明,采用2005年8月MM5模式预报结果生成的背景误差场的基本特征与系统提供的全球背景误差场相似,且长度尺度随着水平分辨率的提高而减小.之后,分别利用NCEP再分析资料(NCEP试验)、NCEP再分析资料基础上采用CRESSMAN方法分析观测资料(LITT试验)和NCEP再分析资料基础上采用3DVAR系统同化观测资料(3DVAR试验)形成模式预报初始场,再次对2005年8月降雨进行逐日连续预报.逐日降雨预报结果表明,相对NCEP试验,LITT试验中1 和10 mm的预报评分有明显提高,但 25 和 50 mm的预报评分却有所下降,而3DVAR试验的预报评分在10 mm以上均有明显提高.对于降雨期间的形势场预报,3个试验中,除温度场和湿度场外,其他变量场的均方根误差随高度增加而增加,但相比而言,3DVAR试验的均方根误差小于其他2个试验.3DVAR试验对降雨的明显改进,可能是因为其对与背景场信息差别比较大的反应中尺度系统的观测资料的分析结果比较靠近观测资料. 相似文献
11.
为提升高分辨率区域数值天气预报模式性能,基于高质量的ECMWF全球预报模式产品和动力谱逼近方法优势,本文以2019年重创浙江的超强台风“利奇马”为例,探讨了ECMWF驱动场水平风场谱逼近技术对浙江台风精细化预报性能的影响。结果表明:（1）谱逼近对路径预报影响较明显,逐小时路径误差最大修正可达80 km。谱逼近的垂直层次选取对于谱逼近效果有一定影响,总体上800 hPa高度以上谱逼近对台风路径和强度预报改进最佳。（2）谱逼近对浙江台风大风和强降水精细化预报均有大幅改进,对于8级以上大风ETS评分平均改进率为8.0%,最大改进率达20.8%;对最强日降水的暴雨、大暴雨以上降水TS评分改进幅度达11.8%、26.2%。（3）谱逼近对台风路径西偏和浙西南风雨高估的改进主要与对流层形势场及台风引导气流修正、近地层风力减弱、局地山脉地形降水增幅作用减弱有关。 相似文献
12.
LAPS同化GPS/PWV资料在暴雨预报中的应用研究 总被引：2，自引：1，他引：1
利用LAPS(Local Analysis and Prediction System)系统同化GPS(Global Positioning System)/PWV(Precipitable Water Vapor)资料,分析GPS/PWV资料对LAPS输出场的影响,并结合WRF模式,将LAPS输出场作为其初始场进行降水预报,进一步考察GPS/PWV资料对降水预报的作用。选取2009年6月28日湖北地区的一次强降水过程,设计三种方案进行试验。结果表明:同化GPS/PWV资料后对LAPS湿度场有显著的改善,而对高度场及风场的作用则不明显;GPS/PWV资料对区域平均可降水量的影响比雷达资料大一个量级;与此同时,利用多种评分方法对6 h累计降水做了检验,分析结果表明同化GPS/PWV资料能够有效地改进WRF模式的初始场,增加丰富的中小尺度信息,并对随后的确定性预报产生正影响。 相似文献
13.
非静力模式预报热带气旋路径个例试验 总被引：3，自引：0，他引：3
利用非静力模式（ＭＭ５Ｖ２）对９６１１号、９９０４号等北上热带气旋路径预报进行民试验。用松驰（Ｎｕｄｇｉｎｇ）四维同化方案和人造热带气旋（Ｂｏｇｕｓ ＴＣ）技术,使独ｔ－１２时刻的模式场（包括第一个Ｂｏｇｕｓ ＴＣ）通过预积分逐步逼近ｔｏ时刻的Ｂｏｇｕｓ ＴＣ和同时刻的观测资料场庆１９９９年能够得到相隔６ｈ一次的ＡＴ１０６Ｌ１９预报场后,分别在ｔ－１２、ｔ－ａ６和ｔｏ时刻各制做一个Ｂｏｇｕｓ ＴＣ 相似文献
14.
卫星云图反演资料质量控制方案在暴雨模拟中的对比研究 总被引：3，自引：3，他引：0
本文以2003年7月9～10日发生在江淮流域的暴雨过程为例,应用FY-2B卫星红外云图灰度资料,利用统计回归的反演方法求出高分辨率的温度和湿度的反演场用于改进预报的初始场。设计和对比了几种质量控制方案,再将控制后的反演场与常规资料进行同化,最后用MM5模式进行了模拟对比试验。结果表明：在模式的初始场中引入卫星云图反演场能反映出更为细致的中尺度结构,有效地增强了对降水有重要影响的高湿区;锋生函数质量控制方案改善模式的初始场,从而改善了MM5模式降水预报的落区和强度,提高了降水预报准确性及Ts评分。 相似文献
15.
Four-dimensional variational data assimilation experiments for a heavy rain case during the 2002 IOP in China 总被引：3，自引：0，他引：3
A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However,the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front,and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently,the heavy rainfall forecast was improved. 相似文献
16.
Impact of 4DVAR Assimilation of Rainfall Data on the Simulation of Mesoscale Precipitation Systems in a Mei-yu Heavy Rainfall Event 总被引：1，自引：0，他引：1
The multi-scale weather systems associated with a mei-yu front and the corresponding heavy precipitation during a particular heavy rainfall event that occurred on 4 5 July 2003 in east China were successfully simulated through rainfall assimilation using the PSU/NCAR non-hydrostatic, mesoscale, numerical model （MM5） and its four-dimensional, variational, data assimilation （4DVAR） system. For this case, the improvement of the process via the 4DVAR rainfall assimilation into the simulation of mesoscale precipitation systems is investigated. With the rainfall assimilation, the convection is triggered at the right location and time, and the evolution and spatial distribution of the mesoscale convective systems （MCSs） are also more correctly simulated. Through the interactions between MCSs and the weather systems at different scales, including the low-level jet and mei-yu front, the simulation of the entire mei-yu weather system is significantly improved, both during the data assimilation window and the subsequent 12-h period. The results suggest that the rainfall assimilation first provides positive impact at the convective scale and the influences are then propagated upscale to the meso- and sub-synoptic scales.
Through a set of sensitive experiments designed to evaluate the impact of different initial variables on the simulation of mei-yu heavy rainfall, it was found that the moisture field and meridional wind had the strongest effect during the convection initialization stage, however, after the convection was fully triggered, all of the variables at the initial condition seemed to have comparable importance. 相似文献
Through a set of sensitive experiments designed to evaluate the impact of different initial variables on the simulation of mei-yu heavy rainfall, it was found that the moisture field and meridional wind had the strongest effect during the convection initialization stage, however, after the convection was fully triggered, all of the variables at the initial condition seemed to have comparable importance. 相似文献
17.
基于国家气象中心GRAPES_Meso高分辨率区域模式,针对中尺度数值预报模式中预报雨带形成滞后问题,研究了潜热加热纳近方法在地面降水资料同化中的应用,以期提高短时数值天气预报的水平。2013年6月20日—7月20日的初步试验结果表明:通过调整模式潜热加热廓线,可以改进初始场中温、湿、风等要素的合理分布,增加降水区的对流不稳定性;潜热加热纳近方法可以缩短模式的调整适应 (spin-up) 时间,改进短时降水预报的落区和强度,提高3 h,6 h,12 h的降水预报TS,ETS评分;与传统的冷潜热加热纳近的试验结果相比,改进的暖潜热加热纳近试验对降水落区和强度的预报更接近观测,但强降水中心范围略大。 相似文献
18.
土壤湿度是影响天气和气候非常重要的因子之一,但目前针对土壤湿度可预报性的研究报道相对较少。该文在对BCC_CSM模式进行了适合的陆面初始化的条件下,设计了两组在中国东部地区采用不同土壤湿度初值的回报试验研究该地区土壤湿度的可预报性及初值对其可预报性影响问题。试验结果表明:BCC_CSM模式在真实的外场强迫下可以模拟出相对合理的土壤湿度;土壤湿度的可预报性在表层约为3候,随着深度的增加,土壤湿度的可预报性持续时间增加,在中层预报性甚至能达到月尺度以上;初值对于土壤湿度的预报存在影响,在表层影响时间约为2~3候,影响时间随着深度增加;浅层土壤湿度受降水的影响较大,浅层土壤湿度变化滞后降水变化约1~2 d,中层土壤湿度变化与降水变化存在5 d左右的滞后关系。 相似文献
19.