The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational foreca...The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational forecasting to assess the stability of the atmosphere and predict the probability of severe thunderstorm development. One of the disadvantages of many of these indices is that they are mainly based on observations from plains. However, considering the Plateau＇s high elevation, most convective parameters cannot be applied directly, or their application is ineffective. The pre-convective environment on thunderstorm days in this region is investigated based on sounding data obtained throughout a five-year period（2006–10）.Thunderstorms occur over the Tibetan Plateau under conditions that differ strikingly from those in plains. On this basis,stability indices, such as the Showalter index（including SI and SICCL）, and the K index are improved to better assess the thunderstorm environments on the Plateau. Verification parameters, such as the true-skill statistic（TSS） and Heidke skill score（HSS）, are adopted to evaluate the optimal thresholds and relative forecast skill for each modified index. Lastly, the modified indices are verified with a two-year independent dataset（2011–12）, showing satisfactory results for the modified indices. For determining whether or not a thunderstorm day is likely to occur, we recommend the modified SICCLindex.展开更多
利用加入起电、放电参数化方案的数值模式[Weather Research and Forecasting Model(Version 3.7.1),WRF3.7.1_ELEC],分别对发生在青藏高原东北部青海大通地区和华北地区北京西部山区的两次雷暴过程进行模拟研究,对比分析两个不同地区...利用加入起电、放电参数化方案的数值模式[Weather Research and Forecasting Model(Version 3.7.1),WRF3.7.1_ELEC],分别对发生在青藏高原东北部青海大通地区和华北地区北京西部山区的两次雷暴过程进行模拟研究,对比分析两个不同地区雷暴个例的电荷结构特征差异及原因。结果表明:对发生在两个地区的雷暴个例,模式均能够较好地模拟出雷暴的移动方向、回波强度以及形状的变化特征。对比两个个例不同发展阶段雷暴云电荷结构可以看出,除了在发展旺盛阶段两个地区的雷暴云电荷结构自下而上均为“+-+-”的四层结构,在发展初始阶段和消亡阶段,两个地区雷暴云电荷结构明显不同。造成两个雷暴个例在雷暴云初始和消亡阶段电荷分布差异的主要原因是云中霰粒子混合比和有效液态水含量的差异。展开更多
The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges a...The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges at initial stage were analyzed by using the observation data. The results show that most of intracloud (IC) lightning flashes were polarities inverted in thunderstorms with tripole electric charge structure and occurred between negative charge region located in the middle of the thunderstorm and positive charge region located at the bottom of the thunderstorm. The radiation characteristics of discharge processes in cloud with longer lasting time involved in Cloud-to-Ground (CG) lightning flashes were similar to that of IC discharges.A lot of radiation pulses were produced in these discharge processes. Because the IC discharges took place at the bottom of thundercloud and were near the ground, they may produce more serious damage to equipment on the ground therefore should not be neglected in lightning protection.展开更多
A strong electric (E) field sounding system was designed to measure the vertical component of the E-fields, temperature, relative humidity and GPS data along the sounding path. In the summer of 2008, in situ measureme...A strong electric (E) field sounding system was designed to measure the vertical component of the E-fields, temperature, relative humidity and GPS data along the sounding path. In the summer of 2008, in situ measurements of E-field inside the thunderstorms were conducted in Pingliang, Gansu Provience, with the cooperation of an X-band weather radar. One E-field profile inside a thunderstorm was successfully acquired. The sounding data indicated four charge layers along the sounding trajectory, three in-side the thuderstorm and one at its lower boundary. The lower cloud boundary charge layer was negative, acting as a screening layer, and laid between 4.3 to 4.5 km a.s.l. The lower positive charge center (LPCC) existed between 4.5–5.3 km a.s.l. (from 3°C to -2°C); the main negative charge area was present between 5.4–6.6 km a.s.l. (-3°C to -10°C); the upper positive charge layer was between 6.7–7.2 km a.s.l. (-11°C to -14°C). The results support the tripole charge structure inside thunderstorms (above 0°C isotherm altitude), but the LPCC is much larger-than-usual in Chinese inland plateau.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41275128, 41375063 and 41206163)the Chengdu Institute of Plateau Meteorology Foundation
文摘The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational forecasting to assess the stability of the atmosphere and predict the probability of severe thunderstorm development. One of the disadvantages of many of these indices is that they are mainly based on observations from plains. However, considering the Plateau＇s high elevation, most convective parameters cannot be applied directly, or their application is ineffective. The pre-convective environment on thunderstorm days in this region is investigated based on sounding data obtained throughout a five-year period（2006–10）.Thunderstorms occur over the Tibetan Plateau under conditions that differ strikingly from those in plains. On this basis,stability indices, such as the Showalter index（including SI and SICCL）, and the K index are improved to better assess the thunderstorm environments on the Plateau. Verification parameters, such as the true-skill statistic（TSS） and Heidke skill score（HSS）, are adopted to evaluate the optimal thresholds and relative forecast skill for each modified index. Lastly, the modified indices are verified with a two-year independent dataset（2011–12）, showing satisfactory results for the modified indices. For determining whether or not a thunderstorm day is likely to occur, we recommend the modified SICCLindex.
文摘利用加入起电、放电参数化方案的数值模式[Weather Research and Forecasting Model(Version 3.7.1),WRF3.7.1_ELEC],分别对发生在青藏高原东北部青海大通地区和华北地区北京西部山区的两次雷暴过程进行模拟研究,对比分析两个不同地区雷暴个例的电荷结构特征差异及原因。结果表明:对发生在两个地区的雷暴个例,模式均能够较好地模拟出雷暴的移动方向、回波强度以及形状的变化特征。对比两个个例不同发展阶段雷暴云电荷结构可以看出,除了在发展旺盛阶段两个地区的雷暴云电荷结构自下而上均为“+-+-”的四层结构,在发展初始阶段和消亡阶段,两个地区雷暴云电荷结构明显不同。造成两个雷暴个例在雷暴云初始和消亡阶段电荷分布差异的主要原因是云中霰粒子混合比和有效液态水含量的差异。
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX1-SW-04)the National Natural Science Foundation of China(Grant No.40375004).
文摘The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges at initial stage were analyzed by using the observation data. The results show that most of intracloud (IC) lightning flashes were polarities inverted in thunderstorms with tripole electric charge structure and occurred between negative charge region located in the middle of the thunderstorm and positive charge region located at the bottom of the thunderstorm. The radiation characteristics of discharge processes in cloud with longer lasting time involved in Cloud-to-Ground (CG) lightning flashes were similar to that of IC discharges.A lot of radiation pulses were produced in these discharge processes. Because the IC discharges took place at the bottom of thundercloud and were near the ground, they may produce more serious damage to equipment on the ground therefore should not be neglected in lightning protection.
基金supported by the National Natural Science Foundation of China (Grant No. 40675008) Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KZCX2-YW-206)Hundred Tal-ents Program of CAS
文摘A strong electric (E) field sounding system was designed to measure the vertical component of the E-fields, temperature, relative humidity and GPS data along the sounding path. In the summer of 2008, in situ measurements of E-field inside the thunderstorms were conducted in Pingliang, Gansu Provience, with the cooperation of an X-band weather radar. One E-field profile inside a thunderstorm was successfully acquired. The sounding data indicated four charge layers along the sounding trajectory, three in-side the thuderstorm and one at its lower boundary. The lower cloud boundary charge layer was negative, acting as a screening layer, and laid between 4.3 to 4.5 km a.s.l. The lower positive charge center (LPCC) existed between 4.5–5.3 km a.s.l. (from 3°C to -2°C); the main negative charge area was present between 5.4–6.6 km a.s.l. (-3°C to -10°C); the upper positive charge layer was between 6.7–7.2 km a.s.l. (-11°C to -14°C). The results support the tripole charge structure inside thunderstorms (above 0°C isotherm altitude), but the LPCC is much larger-than-usual in Chinese inland plateau.
