Correcting for Undercounting of Lightning Flashes by Space‐Based Optical Sensors
Correcting for Undercounting of Lightning Flashes by Space‐Based Optical Sensors
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DOI：
10.1029/2023jd038855
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发表时间：
2023-12
期刊：
影响因子：
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通讯作者：
P. J. McFarland;W. Brune
中科院分区：
文献类型：
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作者：
P. J. McFarland;W. Brune
全球闪电的准确测量对于了解现在和未来的大气电量、组成和气候是至关重要的。最新的空间闪电探测器，地球同步闪电映射器(GLM)，是第一个被放置在地球静止轨道上的探测器，可以连续观测到大部分美洲大陆。在GLM之前，热带降雨测量任务(TRMM)卫星上的闪电成像传感器(LIS)收集了闪电测量，根据这些测量得出了许多闪电气候，包括全球模式中使用的那些。然而，这项研究发现，GLM和2017年放置在国际空间站(ISS)上的第二个类似LIS都以类似的速度探测闪电，与地面闪电测绘阵列(LMA)相比，它们的闪电计数偏低。由于卫星天顶角、在温度为−10°C的高度的雷达反射率、闪光高度和雷暴极性，GLM平均少算了7.0%的闪电，最大值超过120%。据估计，LIS平均低估了闪电5.6%，最高可达75.0%，这是−10°C雷达反射率、闪光高度和雷暴极性的函数。GLM和LIS闪电欠计数因子或比例因子(SF)的初步预测公式使用冰水含量、平衡水平、闪光高度和卫星天顶角，所有这些都可以在模型中得到。开发这些方程是为了鼓励在全球模式中更新闪电参数，并可能增加模拟闪电对大气电路、成分、化学和气候变化的影响。
Accurate measurements of global lightning are essential for understanding present and future atmospheric electricity, composition, and climate. The latest space‐based lightning detector, the Geostationary Lightning Mapper (GLM), was the first to be placed in geostationary orbit, with a continuous view of most of the American continents. Prior to the GLM, the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite collected lightning measurements from which numerous lightning climatologies have been developed, including those used in global models. However, this study finds that both the GLM and a second, similar LIS placed on the International Space Station (ISS) in 2017 detect lightning at similar rates and are undercounting lightning compared to ground‐based Lightning Mapping Arrays (LMAs). The GLM undercounts lightning by an average factor of 7.0, reaching a maximum over 120 as a function of satellite zenith angle, radar reflectivity at a height where the temperature is −10°C, flash height, and thunderstorm polarity. The LIS is estimated to undercount lightning by an average factor of 5.6, reaching a maximum of 75.0 as a function of radar reflectivity at the −10°C level, flash height, and thunderstorm polarity. Preliminary predictive equations for the GLM and LIS lightning undercount factor, or scaling factor (SF), use ice‐water content, equilibrium level, flash height, and satellite zenith angle, all of which can be derived in models. These equations are developed to encourage updating lightning parameterizations within global models and will likely increase modeled lightning's effects on atmospheric electrical circuits, composition, chemistry, and climate change.