In this paper, based on heavy rain numerical forecast model AREM(Advanced Regional Eta Model), two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and ARE...In this paper, based on heavy rain numerical forecast model AREM(Advanced Regional Eta Model), two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and AREM-3DVAR with the same data source(NCEP forecast field, surface data and radio-soundings) during the period from 21 May to 30 July 2008 to investigate the effect of the two initialization schemes on the rainfall simulation. The result suggests that:(1) the forecast TS score by the AREM-LAPS is higher than that by the AREM-3DVAR for rainfall in different areas, at different valid time and with different intensity, especially for the heavy rain, rainstorm and extremely heavy rain;(2) the AREM-3DVAR can generally simulate the average rainfall distribution, but the forecast area is smaller and rainfall intensity is weaker than the observation, while the AREM-LAPS significantly improves the forecast;(3) the AREM-LAPS gives a better forecast for the south-north shift of rainfall bands and the rainfall intensity variation than the AREM-3DVAR;(4) the AREM-LAPS can give a better reproduction for the daily change in the mean-rainfall-rate of the main rain band, and rainfall intensity changes in the eastern part of Southwest China, the coastal area in South China, the middle-lower valleys of Yangtze river, the Valleys of Huaihe river, and Shandong peninsula, with the rainfall intensity roughly close to the observation, while the rainfall intensity simulated by the AREM-3DVAR is clearly weaker than the observation, especially in the eastern part of Southwest China; and(5) the comparison verification between the AREM-LAPS and AREM-3DVAR for more than 10 typical rainfall processes in the summer of 2008 indicates that the AREM-LAPS gives a much better forecast than AREM-3DVAR in rain-band area, rainfall location and intensity, and in particular, the rainfall intensity forecast is improved obviously.展开更多
为了提高沙尘模式的预报准确率,通过在区域天气数值模式GRAPES(Global/Regional Assimilation and PrEdiction System)的三维变分同化系统中增加沙尘浓度这一控制变量的方法建立了GRAPES_3DVAR_DUST沙尘同化系统。利用中国北方8个观测...为了提高沙尘模式的预报准确率,通过在区域天气数值模式GRAPES(Global/Regional Assimilation and PrEdiction System)的三维变分同化系统中增加沙尘浓度这一控制变量的方法建立了GRAPES_3DVAR_DUST沙尘同化系统。利用中国北方8个观测站提供的沙尘PM10数据和沙尘模式(GRAPES_CUACE/Dust系统)提供的背景场,对2008年2月29日-3月1日发生在中国北方的一次沙尘暴天气进行了控制试验和一次同化与间断同化的敏感性试验,结果表明:(1)引入该同化系统后,一次同化和间断同化试验模拟的地面沙尘浓度分布较未同化的控制试验结果更接近卫星监测,而间断同化的结果又好于一次同化;(2)一次同化试验与控制试验对单站PM10浓度的演变预报较差;(3)间断同化试验较准确地再现了单站PM10浓度的连续演变;(4)间断同化试验效果整体上优于一次同化试验。总体而言,引入沙尘同化系统在一定程度上可以提高沙尘模式对沙尘天气的预报准确率。展开更多
广州地区的高温天气主要是受副热带高压和台风外围下沉气流的影响所致。文中采用BDA(Bogus Data Assimilation)方法,探讨BDA方案对广州地区台风背景条件下高温预报的改进能力。选取2005年7月中旬广州地区出现的高温天气进行研究。这是...广州地区的高温天气主要是受副热带高压和台风外围下沉气流的影响所致。文中采用BDA(Bogus Data Assimilation)方法,探讨BDA方案对广州地区台风背景条件下高温预报的改进能力。选取2005年7月中旬广州地区出现的高温天气进行研究。这是比较典型的受副热带高压和台风(海棠)共同影响造成高温的天气过程。分析有无采用BDA方案的模式初始场,结果表明:采用BDA方案同化Bogus模型可以调整台风中心位置和强度,使所得到的初始场中心位置与观测更为接近,台风强度(气压梯度力、风速)比未用Bogus的情况强,与观测值更为接近。数值模拟的结果表明,采用了BDA方案的敏感试验可以更好地预报台风路径和台风中心强度变化,从而更好地预报高温天气,对高温区分布、日平均温度大小等的预报都有改进。文中对引起这种预报差异的原因进行了讨论,并探讨高温预报改进的可能机制。大气下沉运动的增强是高温预报改进的主要原因。敏感试验由于广州中低层大气的水汽减少,大气的下沉增强,致使天空的云量减少,对太阳短波辐射的阻挡减小,从而地面吸收热量增多,温度升高,输送给大气的感热增加,大气温升高。采用BDA方案可以改进模式在台风"海棠"过程对广州高温的预报。展开更多
基金Scientific Research Projects Specially for Public Welfare Industries(GYHY200906010)National Natural Science Foundation of China(41075034)Project 1009 for Wuhan Heavy Rain Institute
文摘In this paper, based on heavy rain numerical forecast model AREM(Advanced Regional Eta Model), two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and AREM-3DVAR with the same data source(NCEP forecast field, surface data and radio-soundings) during the period from 21 May to 30 July 2008 to investigate the effect of the two initialization schemes on the rainfall simulation. The result suggests that:(1) the forecast TS score by the AREM-LAPS is higher than that by the AREM-3DVAR for rainfall in different areas, at different valid time and with different intensity, especially for the heavy rain, rainstorm and extremely heavy rain;(2) the AREM-3DVAR can generally simulate the average rainfall distribution, but the forecast area is smaller and rainfall intensity is weaker than the observation, while the AREM-LAPS significantly improves the forecast;(3) the AREM-LAPS gives a better forecast for the south-north shift of rainfall bands and the rainfall intensity variation than the AREM-3DVAR;(4) the AREM-LAPS can give a better reproduction for the daily change in the mean-rainfall-rate of the main rain band, and rainfall intensity changes in the eastern part of Southwest China, the coastal area in South China, the middle-lower valleys of Yangtze river, the Valleys of Huaihe river, and Shandong peninsula, with the rainfall intensity roughly close to the observation, while the rainfall intensity simulated by the AREM-3DVAR is clearly weaker than the observation, especially in the eastern part of Southwest China; and(5) the comparison verification between the AREM-LAPS and AREM-3DVAR for more than 10 typical rainfall processes in the summer of 2008 indicates that the AREM-LAPS gives a much better forecast than AREM-3DVAR in rain-band area, rainfall location and intensity, and in particular, the rainfall intensity forecast is improved obviously.
文摘为了提高沙尘模式的预报准确率,通过在区域天气数值模式GRAPES(Global/Regional Assimilation and PrEdiction System)的三维变分同化系统中增加沙尘浓度这一控制变量的方法建立了GRAPES_3DVAR_DUST沙尘同化系统。利用中国北方8个观测站提供的沙尘PM10数据和沙尘模式(GRAPES_CUACE/Dust系统)提供的背景场,对2008年2月29日-3月1日发生在中国北方的一次沙尘暴天气进行了控制试验和一次同化与间断同化的敏感性试验,结果表明:(1)引入该同化系统后,一次同化和间断同化试验模拟的地面沙尘浓度分布较未同化的控制试验结果更接近卫星监测,而间断同化的结果又好于一次同化;(2)一次同化试验与控制试验对单站PM10浓度的演变预报较差;(3)间断同化试验较准确地再现了单站PM10浓度的连续演变;(4)间断同化试验效果整体上优于一次同化试验。总体而言,引入沙尘同化系统在一定程度上可以提高沙尘模式对沙尘天气的预报准确率。
文摘广州地区的高温天气主要是受副热带高压和台风外围下沉气流的影响所致。文中采用BDA(Bogus Data Assimilation)方法,探讨BDA方案对广州地区台风背景条件下高温预报的改进能力。选取2005年7月中旬广州地区出现的高温天气进行研究。这是比较典型的受副热带高压和台风(海棠)共同影响造成高温的天气过程。分析有无采用BDA方案的模式初始场,结果表明:采用BDA方案同化Bogus模型可以调整台风中心位置和强度,使所得到的初始场中心位置与观测更为接近,台风强度(气压梯度力、风速)比未用Bogus的情况强,与观测值更为接近。数值模拟的结果表明,采用了BDA方案的敏感试验可以更好地预报台风路径和台风中心强度变化,从而更好地预报高温天气,对高温区分布、日平均温度大小等的预报都有改进。文中对引起这种预报差异的原因进行了讨论,并探讨高温预报改进的可能机制。大气下沉运动的增强是高温预报改进的主要原因。敏感试验由于广州中低层大气的水汽减少,大气的下沉增强,致使天空的云量减少,对太阳短波辐射的阻挡减小,从而地面吸收热量增多,温度升高,输送给大气的感热增加,大气温升高。采用BDA方案可以改进模式在台风"海棠"过程对广州高温的预报。
