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

大气区域的耦合、能量学和动力学（CEDAR）计划是一个基础广泛、社区指导的高层大气研究计划，旨在了解从低层大气向上通过电离的高层大气的大气区域的行为。特别令人感兴趣的是低层大气与被称为“发电机区”的100-150公里附近的电离层的耦合。低层大气中风和温度的大尺度波动变化被称为热潮汐，它是由太阳每天从头顶经过所引起的加热或由热带纬度地区的水蒸气或平流层臭氧吸收太阳辐射所产生的。其他被称为行星波（PW）的大尺度波也可能由低层大气中的天气活动引起。这些大尺度波可能具有长达16天的周期性和非常大的水平波长（数千公里）。这些波将传播到更高的高度，在那里风，电离气体含量，和地球？磁场相互作用产生电场和电流。反过来，这些将引起磁场扰动，这可能由全球磁力计网络（141个站点）测量。低层大气中PW和潮汐波的产生是高度可变的，因此，与这些波浪结构相关的风和温度剖面图将表现出显著的日常变化，这可以通过对全球磁力计数据应用复杂的分析程序来检测。采用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，并在高海拔地区产生电子密度的变化，这需要了解成功的空间天气预报，这已被列为国家优先事项。该奖项支持的研究将利用磁力计数据确定电离层变率，以相对于稳态基线测量磁场变化的经向和纬向分量。这种可变性的起源可以考虑到可能的因素，以确定因果关系。该奖项代表了令人兴奋和变革科学的强大潜力，因为对地面磁力计数据的全球分析将提供潮汐和PW对大气-电离层耦合的新见解，这是任何基于卫星的系列观测所无法实现的，这些观测受到当地时间电离层变异性采样的性质的限制。该奖项更广泛的影响是，一名埃及女研究生将获得该奖项的博士学位，从而增强了航空学界的文化多样性。该奖项的科学动机总结为以下物理过程列表，这些物理过程需要充分了解以了解空间天气变化：(1)地球的发电机区域（约100-150公里）？S大气圈白天电场主要通过中性风的发电机作用产生；(2)这些电场对整个电离层的变率有深远的影响；(3)发电机区变率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相关的扰动风所施加的变率；(4)这种变率从未在全球范围内以系统的方式进行观测量化；(5)关于发电机区变率的知识提供了对上覆电离层变率来源的洞察；(6)全球的地面磁力计阵列可以提供上述知识。通过应用标准时间序列分析工具对全球磁力计数据进行检查，将寻求了解电离层变率背后的因果因素，重点是电离层变率的主要部分可能是由从下面进入该区域的大尺度波引起的。这些结果将与标准太阳和磁场指数的变化进行比较，以寻找在低层大气中激发的潮汐和PW之间因果关系的证据，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区等离子体重新分布携带着这些潮汐和PW的空间和时间特征，以及在较低海拔产生或改变它们的过程。

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.