Influence of meteoric smoke particles on the incoherent scatter measured with EISCAT VHF

IF 1.7 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS
Tinna L. Gunnarsdottir, Ingrid Mann, Wuhu Feng, Devin R. Huyghebaert, Ingemar Haeggstroem, Yasunobu Ogawa, Norihito Saito, Satonori Nozawa, Takuya D. Kawahara
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Abstract

Abstract. Meteoric ablation in the Earth's atmosphere produces particles of nanometer size and larger. These particles can become charged and influence the charge balance in the D region (60–90 km) and the incoherent scatter observed with radar from there. Radar studies have shown that, if enough dust particles are charged, they can influence the received radar spectrum below 100 km, provided the electron density is sufficiently high (>109 m3). Here, we study an observation made with the EISCAT VHF radar on 9 January 2014 during strong particle precipitation so that incoherent scatter was observed down to almost 60 km altitude. We found that the measured spectra were too narrow in comparison to the calculated spectra. Adjusting the collision frequency provided a better fit in the frequency range of ± 10–30 Hz. However, this did not lead to the best fit in all cases, especially not for the central part of the spectra in the narrow frequency range of ±10 Hz. By including a negatively charged dust component, we obtained a better fit for spectra observed at altitudes of 75–85 km, indicating that dust influences the incoherent-scatter spectrum at D-region altitudes. The observations at lower altitudes were limited by the small number of free electrons, and observations at higher altitudes were limited by the height resolution of the observations. Inferred dust number densities range from a few particles up to 104 cm−3, and average sizes range from approximately 0.6 to 1 nm. We find an acceptable agreement with the dust profiles calculated with the WACCM-CARMA (Whole Atmosphere Community Climate Model-Community Aerosol Radiation Model for Atmospheres) model. However, these do not include charging, which is also based on models.
流星烟雾颗粒对 EISCAT 甚高频测量的非相干散射的影响
摘要地球大气层中的流星烧蚀会产生纳米级或更大的粒子。这些微粒可能会带电,并影响 D 区(60-90 公里)的电荷平衡以及从那里用雷达观测到的非相干散射。雷达研究表明,如果有足够多的尘埃粒子带电,只要电子密度足够高(>109 立方米),它们就会影响 100 千米以下的接收雷达频谱。在此,我们研究了 EISCAT VHF 雷达于 2014 年 1 月 9 日在强粒子降水期间进行的一次观测,当时观测到的非相干散射可达近 60 千米高度。我们发现,与计算出的光谱相比,测量出的光谱过于狭窄。调整碰撞频率可在 ± 10-30 Hz 的频率范围内提供更好的拟合。然而,这并不是在所有情况下都能达到最佳拟合效果,尤其是在 ±10 Hz 的窄频率范围内的光谱中心部分。通过加入带负电荷的尘埃成分,我们在 75-85 公里高度观测到的光谱得到了更好的拟合效果,这表明尘埃影响了 D 区域高度的非相干散射光谱。低空观测受到自由电子数量较少的限制,而高空观测则受到观测高度分辨率的限制。推断的尘埃数量密度范围从几个颗粒到 104 cm-3,平均尺寸范围约为 0.6 到 1 nm。我们发现与 WACCM-CARMA(全大气层群气候模型-大气层群气溶胶辐射模型)模型计算出的尘埃剖面图的吻合度可以接受。不过,这些数据并不包括充电,充电也是基于模型的。
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来源期刊
Annales Geophysicae
Annales Geophysicae 地学-地球科学综合
CiteScore
4.30
自引率
0.00%
发文量
42
审稿时长
2 months
期刊介绍: Annales Geophysicae (ANGEO) is a not-for-profit international multi- and inter-disciplinary scientific open-access journal in the field of solar–terrestrial and planetary sciences. ANGEO publishes original articles and short communications (letters) on research of the Sun–Earth system, including the science of space weather, solar–terrestrial plasma physics, the Earth''s ionosphere and atmosphere, the magnetosphere, and the study of planets and planetary systems, the interaction between the different spheres of a planet, and the interaction across the planetary system. Topics range from space weathering, planetary magnetic field, and planetary interior and surface dynamics to the formation and evolution of planetary systems.
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