Lightning Detection And Ranging (LDAR II) Operation, Evaluation, and Analyses in the Houston Environmental Aerosol Thunderstorm (HEAT) Project

国家闪电探测网络（NLDN）的数据显示，休斯顿及其周边地区的云对地雷击比周围农村地区多50%。 对这种休斯顿闪电异常（HLA）的几种解释已经提出。 一个是城市上空白天较高的表面温度（“城市热岛”）可能是对流增加、风暴发展和闪电的原因。 另一个是德克萨斯州沿海地区的海风环流可能倾向于组织低层辐合，以有利于城市上空的对流。 还有一种观点认为，城市上空污染气溶胶的增加可能会影响云的微物理过程，从而改变云内电荷的产生和分布，促进闪电放电的发生。 该奖项支持在休斯顿及其周边地区的实地观测，这将有助于通过提供有关闪电特征的新的和更完整的信息来解释HLA。 一个由12个甚高频接收站组成的网络，称为闪电探测和测距系统（LDAR），将在2005年、2006年和2007年的风暴季节运行，以测量闪电的时间和位置。 NLDN仅提供云对地闪光的大致位置，而LDAR系统基本上可以检测到所有闪光-云内闪光以及地面闪光-具有很高的准确性和精度。 此外，LDAR还提供了闪电起始位置、闪电放电通道的配置、电荷降低的高度、云对地撞击的极性、峰值电流的估计以及其他闪电特征等信息。 这些观测将与德克萨斯州空气质量委员会主持的休斯顿地区空气质量和污染扩散的广泛研究同时进行，称为德克萨斯州空气质量实地研究。 这项研究包括使用一对多普勒雷达来测量空气运动和风暴结构，以及对浮质和微量气体进行地面和空中测量。 LDAR观测和空气质量实地研究的支持数据将为污染，空气运动，风暴结构和闪电之间的关系提供新的见解，这将有助于解释休斯顿闪电异常。 该研究的更广泛影响包括利用LDAR数据改进恶劣天气预报的潜力，以及在解决有关雷暴微物理和电气结构的长期问题方面取得的进展。

Data from the National Lightning Detection Network (NLDN) indicate that there are about 50% more cloud-to-ground lightning strikes in and around Houston than over the surrounding rural areas. Several explanations of this Houston Lightning Anomaly (HLA) have been suggested. One is that the higher daytime surface temperature over the city (the "urban heat island") may account for increased convection, storm development, and hence lightning. Another is that the sea breeze circulation in the Texas coastal region may tend to organize low-level convergence in a way to favor convection over the city. Still another is that the increased loading of pollution aerosols over the city may affect cloud microphysical processes in a way that modifies the generation and distribution of electrical charge within clouds, promoting the occurrence of lightning discharges. This award supports field observations in and around Houston that will help to explain the HLA by providing new and more complete information on the characteristics of the lightning. A network of twelve VHF receiving stations called the Lightning Detection and Ranging system (LDAR) will be operated during the storm seasons of 2005, 06, and 07 to measure the time and location of lightning flashes. Whereas the NLDN provides only the approximate locations of cloud-to-ground flashes, the LDAR system detects essentially all flashes - those within cloud as well as those to the ground - with great accuracy and precision. Moreover, the LDAR provides information on the location of lightning initiation, the configuration of lightning discharge channels, the altitude from which electrical charge is lowered, the polarity of cloud-to-ground strokes, estimates of peak currents, and other lightning characteristics. The observations will be carried out in parallel with an extensive study of air quality and the dispersion of pollution in the Houston area under the auspices of the Texas Commission on Air Quality, called the Texas Air Quality Field Study. That study includes the operation of a pair of Doppler radars for measuring air motions and storm structure as well as surface and airborne measurements of aerosols and trace gases. Together the LDAR observations and the supporting data from the Air Quality Field Study will provide new insight on the relations between pollution, air motions, storm structure, and lightning, which will help to explain the Houston Lightning Anomaly. Broader impacts of the study include the potential for improved forecasts of severe weather using LDAR data and progress towards resolving long-standing questions about the microphysical and electrical structure of thunderstorms.