CEDAR: Atmosphere-Ionosphere Coupling as Revealed in Global Magnetic Field Perturbations

大气区域耦合、能量和动力学(Cedar)计划是一个基础广泛的、社区指导的高层大气研究计划，旨在了解从低层大气向上到大气电离上层的大气区域的行为。特别令人感兴趣的是低层大气与100-150公里附近的电离层的耦合，该电离层称为“发电机区域”。低层大气中风和温度的大范围波动变化称为热潮，是由于太阳每天从头顶经过而产生的加热，或者是由于热带纬度的水蒸气或平流层臭氧吸收太阳辐射而产生的。其他被称为行星波(PW)的大尺度波也可能是由低层大气中的天气活动引起的。这些大尺度波可能具有长达16天的周期和非常大的水平波长(数千公里)。这些波将传播到更高的海拔，在那里风、电离气体含量和地S磁场相互作用，产生电场和电流。这些反过来又会引起磁场扰动，而全球磁力计网络(141个站点)可以测量到这种扰动。低层大气中PW波和潮汐波的产生是高度多变的，因此，与这些波结构有关的风和温度分布每天将表现出很大的变化，可以通过对全球磁力仪数据应用复杂的分析程序来检测到。这种方法的部分研究动机是，发电机区域内产生的电场将向上映射到250公里以上的电离层，并在高海拔产生电子密度的可变性，这是成功的空间天气预报所需了解的，这已被列为国家优先事项。该奖项支持的研究将使用磁力计数据来确定电离层的可变性，以测量相对于稳态基线的磁场变化的经向和纬向分量。然后，可以根据可能的因素来考虑这种可变性的起源，以确定因果关系。该奖项代表了激动人心和具有变革性的科学的巨大潜力，因为对地面磁强计数据的全球分析将提供关于潮汐和PW造成的大气-电离层耦合的新见解，这是受当地时间电离层可变性采样性质限制的任何卫星观测系列所无法实现的。该奖项的更广泛影响是，一名埃及女研究生将在该奖项中获得博士学位，从而增强大气学界的文化多样性。该奖项的科学动机总结如下：(1)地球发电机区域(约100-150公里)？S大气层是白天主要通过中性风的发电机作用产生电场的地方；(2)这些电场对整个电离层的变化有深刻的影响；(3)发电机区域的可变性被认为源于太阳通量对电导率的影响，以及潮汐和PW中性风以及与地磁活动有关的扰动风施加的可变性；(4)这种可变性从未得到系统的全球观测量化；(5)有关发电机区域可变性的知识有助于深入了解上层电离层的可变性来源；(6)全球地面磁强计阵列能够提供上述知识。通过应用标准时间序列分析工具检查全球磁力仪数据，将力求了解电离层变化背后的因果因素，重点是这种电离层变化的很大一部分很可能是从下方进入该区域的大尺度波造成的。这些结果将与标准太阳和磁场指数的变化相比较，以寻找潮汐和PW之间因果关系的证据，这些潮汐和PW在低层大气中激发，其影响延伸到100-150公里的发电机区域，产生电场，然后沿着磁力线映射到F区电离层。它们产生的F区等离子体再分布带有这些潮汐和PW的空间和时间特征，以及在较低海拔产生或修改它们的过程的特征。

The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program, a broad-based, community-guided, upper atmospheric research program, is aimed at understanding the behavior of atmospheric regions from the lower atmosphere upward through the ionized upper layers of the atmosphere. Of particular interest is the coupling of the lower atmosphere to the ionized layer near 100-150 km that is called the "dynamo region". Large-scale wave variations of winds and temperatures in the lower atmosphere that are called thermal tides are generated by the heating caused by the daily passage of the Sun overhead or by the absorption of solar radiation by water vapor or stratospheric ozone at tropical latitudes. Other large-scale waves called planetary waves (PW) may also be caused by weather activity within the lower atmosphere. These large-scale waves may have periodicities as long as 16 days and very large horizontal wavelengths (thousands of km). These waves will propagate to higher altitudes where the winds, ionized gas content, and Earth?s magnetic field interact to generate electric fields and currents. These, in turn, will induce magnetic field perturbations that may be measured by the global network of magnetometers (141 sites). The production of PW and tidal waves within the lower atmosphere is highly variable, and consequently, the winds and temperature profiles associated with these wave structures will exhibit significant variability from day-to-day that can be detected through the application of sophisticated analysis procedures to the global magnetometer data. Part of the research motivation for this approach is that the electric fields generated within the dynamo region will map upward into the ionosphere above 250 km and generate variability of electron density at high altitudes that need to be understood for successful space weather forecasting, which has been given national priority. The research supported by this award would determine the ionospheric variability using the magnetometer data to measure the meridional and zonal components of magnetic field variations relative to a steady state baseline. The origins of this variability can then be considered in regard to possible factors to identify causal relationships. The award represents a strong potential for exciting and transformative science because the global analysis of ground magnetometer data will provide new insights into atmosphere-ionosphere coupling by tides and PW in a way that cannot be achieved by any satellite-based series of observations that is limited by the nature of local time sampling of the ionospheric variability. The broader impact of this award is that a woman Egyptian graduate student would be supported in her PhD work in this award thus enhancing the cultural diversity of the aeronomy community.The science motivation for this award is summarized by the following list of physical processes that need to be fully understood to understand space weather variability: (1) The dynamo region (ca.100-150 km) of Earth?s atmosphere is where electric fields are mainly generated through the dynamo action of neutral winds during daytime; (2) These electric fields have profound influences on the variability of the whole ionosphere; (3) Dynamo region variability is thought to originate from solar flux influences on electrical conductivity, and from the variability imposed by tidal and PW neutral winds, and disturbance winds associated with geomagnetic activity; (4) This variability has never been observationally quantified globally in a systematic way; (5) Knowledge concerning the variability of the dynamo region provides insight into the sources of variability for the overlying ionosphere; and (6) A global array of ground magnetometers exists that can provide the above knowledge. Examination of the global magnetometer data through application of standard time-series analysis tools would seek to understand the cause-effect factors underlying the ionospheric variability with the focus being that a major fraction of this ionospheric variability is likely to be caused by the large-scale waves reaching into this region from below. These results would be compared with variations of the standard solar and magnetic field indices to search for evidence of causal relationships between the tides and PW excited in the lower atmosphere and whose influences extend into the 100-150 km dynamo region generate electric fields that then map along magnetic field lines into the F region ionosphere. The F-region plasma redistributions that they produce carry with them the spatial and temporal signatures of these tides and PW, and of the processes that produced or modified them at lower altitudes.