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能量参数在中川机场雷暴预测中的应用 总被引：1，自引：0，他引：1
我国目前的大气探空网, 其时空观测密度尚不足以捕捉强对流天气信号.采用中尺度数值模式MM5对发生在兰州中川机场的5次雷暴天气进行模拟, 利用模拟结果并结合地面观测资料, 计算、分析了雷暴发生、发展过程中一些对流活动指数的变化, 结果表明, 对流有效位势能量(CAPE)和对流抑制能量(CIN)对中川机场雷暴预测有较好的指示意义, 当CAPE＞20 J·kg -1 时就可能出现雷暴, ＞100 J·kg -1 时雷暴较强;经过地面资料修正的CAPE能够更准确地预测雷暴发生时间, 描述雷暴发展过程中的能量积累和释放过程;同时指出, 使用数值模式预测雷暴时, 积分时间不易过长. 相似文献
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北京地区雷暴大风预报研究 总被引：30，自引：8，他引：30
利用NCEP1°×1°分析场资料,对北京地区2000—2005年夏季和2006年5—6月出现的30个雷暴大风日对流有效位能(CAPE)、对流抑制能量(CIN)、大气可降水量(PWAT)、垂直速度(ω)、相对湿度(RH)和抬升指数(LI)等物理量平均场进行了研究。结果表明,在雷暴大风发生之前,CAPE有一个明显增大的过程,与之相对应,CIN有一个减少的过程。垂直速度和相对湿度垂直-时间剖面图显示,在雷暴大风发生前,对流层低层一般为上升运动,来自大气中、上层的干冷空气及其伴随的下沉气流有利于不稳定层结的增强;雷暴大风发生当日的20时,大尺度环境场为较强的上升运动控制,上升运动可达到对流层顶高度附近,与之配合,大气中层(600hPa左右)存在一相对湿度为70%的高值区,其中55%的相对湿度高度可伸展到300hPa,大气可降水量达到最大值,抬升指数最小;从22时左右开始,随着不稳定层结的破坏,500hPa以下逐渐转为下沉气流控制。通过与2004—2005年5—8月期间46个普通雷暴日和非雷暴日平均场对比分析还发现,大气可降水量对雷暴大风和普通雷暴有很好的指示意义,即普通雷暴要求大气中含有较高的可降水量,而雷暴大风则较低。认真分析不同类型雷暴大风多普勒雷达回波特征,尤其是多普勒速度图像是做好雷暴大风临近预报的关键。 相似文献
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Coastal marine boundary layer jets(CMBLJs)play an important role in coastal and inland rainfall in South China.Using 21 years of ERA5 and CMORPH rainfall data,two main CMBLJs are found,one on each side of Hainan Island(named BLJ-WEST and BLJ-EAST),which are always strengthened jointly.Both CMBLJs often occur in the pre-summer rainy season and exhibit an evident diurnal cycle with a maximum at night.With the emergence of the CMBLJs,rainfall is significantly enhanced in South China,particularly downstream of each CMBLJ.The response of rainfall to the CMBLJs is mainly attributed to convergence at the terminus of each CMBLJ,terrain-induced lifting,and relevant atmospheric stratification.Coastal rainfall downstream of the BLJ-WEST is much weaker than that downstream of the BLJ-EAST because of higher CIN over the Beibu Gulf,which is caused by lower temperature lapse rates and adiabatic heating in the lee of the Annamite Range.The inland rainfall increases along with CMBLJ intensity,whereas coastal rainfall reaches a maximum in the presence of moderate CMBLJs rather than stronger CMBLJs.Stronger CMBLJs induce stronger dynamic lifting but higher CIN near the coastal area.Additionally,CAPE near the coast does not become highest with strongest CMBLJs,because the CAPE generation contributed by coastal dynamic lifting can be offset by the negative contribution caused by the horizontal advection of cold and dry air from the Indochina Peninsula.Therefore,anomalous dynamic lifting,moisture flux convergence,and CAPE/CIN associated with CMBLJ intensity jointly result in anomalous rainfall. 相似文献
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