Journal of Atmospheric and Solar-Terrestrial Physics最新文献

Characterization of gravity wave events detected in the low ionosphere at the Brazilian Antarctic Station 巴西南极站低电离层探测到的重力波事件的特征

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-11-10 DOI: 10.1016/j.jastp.2024.106383

Luís Tiago Medeiros Raunheitte , Emilia Correia , Jean Pierre Raulin , José Valentin Bageston

Here we present the characteristics of three distinct types of Gravity Wave (GW) events as detected in the low ionosphere using very low frequencies (VLF) radio measurements performed at the EACF, Brazilian Antarctic Station Comandante Ferraz (62° 5′ 6″ S, 58° 24′ 12″ W), on King George Island. GWs in the low ionosphere produce oscillations in the electron density, which can be detected as amplitude and phase fluctuations of the VLF signals. The properties of the GW events are obtained using Morlet's Wavelet analysis, which gives the period of the waves, and their occurrence time. The period and duration of the GW events obtained using the VLF technique presented good agreement with ones previously obtained from airglow observations from a co-located all-sky imager. The VLF detection of the mesospheric front showed the same morphology seen with the imager with four crests identified, and the wave activity presented similar period range (∼4–16 min) as observed by airglow (∼6 min) with a period peak of 14 min equal to the spectral analysis of the concurrent OH temperature data. The activity associated with the band event presented similar period of ∼10 min (imager observed 13 min), same duration of 4 h as well as peak intensity just before 05:00 UT. The ripple detection showed the same period of 8 min as the airglow observations and similar duration of around 25 min. By considering two distinct VLF paths it was also possible to analyze the direction and velocity of propagation for the mesospheric front event, which gives 96.0 (±4.8) ms⁻¹ in the East direction in agreement with the velocity of ∼92 ms⁻¹ in the Northeast direction obtained from the airglow observations.

本文介绍了在乔治王岛巴西南极站 Comandante Ferraz（南纬 62°5′6″，西经 58°24′12″）的 EACF，利用甚低频无线电测量在低电离层探测到的三种不同类型的重力波（GW）事件的特征。低电离层中的全球风暴潮会产生电子密度振荡，这可以通过甚低频信号的振幅和相位波动探测到。利用莫雷特小波分析法可获得全球波事件的特性，从而得出波的周期及其发生时间。利用甚低频技术获得的全球瓦事件的周期和持续时间与之前通过同地全天空成像仪观测气辉获得的周期和持续时间非常吻合。对中间层锋面的甚低频探测显示了与成像仪相同的形态，确定了四个波峰，波活动的周期范围（∼4-16 分钟）与气辉观测到的相似（∼6 分钟），周期峰值为 14 分钟，与同期 OH 温度数据的光谱分析结果相同。与波段事件相关的活动呈现出相似的周期（10 分钟）（成像仪观测到的是 13 分钟），持续时间同样为 4 小时，峰值强度就在世界标准时间 05:00 之前。波纹探测显示的周期与气辉观测的周期相同，为 8 分钟，持续时间相似，约为 25 分钟。通过考虑两条不同的甚低频路径，还可以分析出中间层前沿事件的传播方向和速度，东向的传播速度为 96.0（±4.8）毫秒-1，与气辉观测中获得的东北方向的传播速度∼92 毫秒-1 相一致。

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引用次数: 0

Comparative assessment of empirical random forest family's model in simulating future streamflow in different basin of Sarawak, Malaysia 模拟马来西亚沙捞越州不同流域未来河水流量的经验随机森林族模型的比较评估

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-11-02 DOI: 10.1016/j.jastp.2024.106381

Zulfaqar Sa’adi , Shamsuddin Shahid , Mohammed Sanusi Shiru , Kamal Ahmed , Mahiuddin Alamgir , Mohamad Rajab Houmsi , Lama Nasrallah Houmsi

In Sarawak, a region highly vulnerable to climate change, the translation of climate-induced changes in rainfall to river flow is non-linear, presenting a challenge for water resource managers. This research investigates the impact of climate change on hydrological processes in Sarawak, Malaysia, with a specific focus on assessing future spatiotemporal variations in streamflow. The families of Random Forest (RF) empirical models based on data mining techniques were compared and utilized to develop a continuous hydrologic model. Then, by incorporating rainfall and evapotranspiration future projection prepared based on RF past performance statistical downscaling, the top performing RF empirical hydrological model was used for future streamflow projection. The results showed that despite an expected increase in rainfall, the RFR (Random Forest by Randomization) empirical hydrological model demonstrated a potential decrease in river runoff due to heightened evapotranspiration demands associated with rising temperatures. The examination of climate-induced alterations in both rainfall and evapotranspiration patterns revealed a consistent decrease in river discharges during the early to middle period across Sarawak, followed by a shift towards an increasing trend by the end of the 21st century. The central region along the Rajang basin exhibited a prevailing decrease in river discharge, with contrasting patterns in the last part of the century. The northern region displayed diverse trends, with some basins experiencing decreases in river runoff despite augmented rainfall, emphasizing the heterogeneity in response. By employing empirical models, and projecting future scenarios, the study contributes to a better understanding of climate change impacts on hydrology in the region, essential for effective water resource management and environmental conservation.

在沙捞越这个极易受气候变化影响的地区，由气候引起的降雨量变化对河流流量的影响是非线性的，这给水资源管理者带来了挑战。本研究调查了气候变化对马来西亚沙捞越水文过程的影响，重点是评估未来河流流量的时空变化。研究人员比较了基于数据挖掘技术的随机森林（RF）经验模型系列，并将其用于开发连续水文模型。然后，通过结合基于 RF 过去性能统计降尺度编制的降雨量和蒸散量未来预测，将性能最好的 RF 经验水文模型用于未来溪流预测。结果表明，尽管预计降雨量会增加，但 RFR（随机化随机森林）经验水文模型显示，由于气温升高导致蒸散需求增加，河流径流量可能会减少。对气候引起的降雨和蒸散模式变化的研究表明，沙捞越全境的河流排水量在早中期持续减少，到 21 世纪末则呈上升趋势。拉让盆地沿岸的中部地区的河流排水量普遍减少，在本世纪末出现了截然不同的模式。北部地区呈现出不同的趋势，一些流域尽管降雨量增加，但河流径流量却减少了，这凸显了响应的不一致性。通过采用经验模型和预测未来情景，该研究有助于更好地了解气候变化对该地区水文的影响，这对有效的水资源管理和环境保护至关重要。

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引用次数: 0

Air-sea interactions and Bay of Bengal basin wide variability with respect to long tracked cyclone ‘Viyaru’ 海气相互作用和孟加拉湾海盆大范围变化与长轨迹气旋 "维亚鲁 "有关

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-11-01 DOI: 10.1016/j.jastp.2024.106382

Gopi Krishna Podapati , Pushpalatha Tadivalasa , Sreenivas Pentakota , Dandi A. Ramu , Sagar V. Gade

The Bay of Bengal (BoB) is a potentially active region for the formation of the Tropical Cyclones (TCs) and accounts for about 6% of the global annual total number of tropical storms. These TCs occur during the pre-monsoon (March–May) and post-monsoon (October–November) seasons over the BoB. Among all the pre-monsoon cyclones that occurred from 1993 to 2019, we have identified that the “Viyaru” is a typical one originated in the southern BoB, propagated approximately through the middle of the bay, and made landfall over the northern BoB. The cyclonic storm Viyaru caused a basin-scale sea surface cooling of 0.35 °C by increasing the mixed layer depth by 3.5 m over the Bay of Bengal. An analysis of mixed layer heat budget terms infers that reduced short wave radiation and increased latent heat fluxes as the key factors responsible for basin-wide cooling associated with the Viyaru cyclone. We have also found that the enhanced entrainment processes even after the dissipation of the Viyaru cyclone had resulted in a post-cyclone basin-wide cooling tendency over the Bay of Bengal. The present study exemplifies the role of a pre-monsoon cyclone (Viyaru) in impacting the Bay of Bengal basin-scale variability of surface Physical Oceanographic variables and associated processes.

孟加拉湾（BoB）是热带气旋（TCs）形成的潜在活跃区域，每年的热带风暴数量约占全球总数的 6%。这些热带气旋多发生在季风前（3 月至 5 月）和季风后（10 月至 11 月）的季节。在 1993 年至 2019 年发生的所有季风前气旋中，我们发现 "维亚鲁 "是一个典型的气旋，它起源于渤海湾南部，大约从渤海湾中部传播，并在渤海湾北部登陆。气旋风暴 "维亚鲁 "使孟加拉湾上空的混合层深度增加了 3.5 米，造成海盆尺度海面降温 0.35 °C。对混合层热量预算项的分析表明，短波辐射的减少和潜热通量的增加是造成与 Viyaru 气旋有关的全海盆降温的关键因素。我们还发现，即使在维亚鲁气旋消散后，增强的夹带过程也导致了气旋后孟加拉湾全海盆降温的趋势。本研究说明了季风前气旋（维亚鲁气旋）在影响孟加拉湾海盆尺度表面物理海洋学变量变化及相关过程方面所起的作用。

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引用次数: 0

Observation of sporadic E layer altitude partially modulated by the Traveling Ionospheric Disturbances at high latitudes over Zhongshan station 在中山站上空观测到部分受高纬度移动电离层扰动调制的零星 E 层高度

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-24 DOI: 10.1016/j.jastp.2024.106377

Alicreance Hiyadutuje , Michael J. Kosch , John Bosco Habarulema , Xiangcai Chen , Judy A.E. Stephenson , Tshimangadzo Merline Matamba , Mpho Tshisaphungo

At Zhongshan (69° S, 76° E) Antarctica we investigate the sporadic

E

(

E s

)-layer virtual height modulation, observed by an ionosonde, during the passage of the Medium-Scale Traveling Ionospheric Disturbances (MSTIDs), observed by a SuperDARN radar. Two events were identified, on 04 October 2011 at 07:00 - 12:00 UT and 29 February 2012 at 00:00 - 04:00 UT with periods of

\sim

15.0 and

\sim

12.0 min, respectively. The magnitude of average height modulation of the

E s

-layer was

\sim

3.7 to

\sim

17.1 and

\sim

0.5 to

\sim

7.3 km, respectively, with the same periods as the MSTIDs. Ray tracing during the events shows that the likely MSTID propagation was up to

\sim

300 km in the ionospheric

F

-region. The computed ion vertical drift velocity using SuperDARN radar and magnetometer data, and

E s

-layer altitude modulation observed by the ionosonde have moderate to strong positive correlation of 0.71 ± 0.22 and 0.51 ± 0.16, respectively. We show that the MSTIDs polarization electric field, which is mapped down from the

F

-region along the near-vertical magnetic field, moderately contributes to the modulation of the

E s

layer altitude via the

E \times B

drift mechanism.

在南极洲中山（南纬 69°，东经 76°），我们调查了电离层虚拟高度调制（由电离层探测仪观测）和中尺度移动电离层扰动（由超级雷达网雷达观测）通过期间的零星情况。确定了两个事件，分别发生在 2011 年 10 月 4 日世界时 07:00 - 12:00 和 2012 年 2 月 29 日世界时 00:00 - 04:00，周期分别为 15.0 分钟和 12.0 分钟。Es层的平均高度调制幅度分别为∼3.7至∼17.1和∼0.5至∼7.3 km，周期与MSTID相同。事件期间的光线跟踪显示，MSTID 在电离层 F 区域的传播可能高达 ∼300 公里。利用 SuperDARN 雷达和磁强计数据计算的离子垂直漂移速度与电离层高度调制观测到的电离层高度调制具有中等到较强的正相关性，分别为 0.71 ± 0.22 和 0.51 ± 0.16。我们的研究表明，MSTIDs极化电场是从F区沿近垂直磁场向下映射的，它通过E×B漂移机制对Es层高度的调制有适度的贡献。

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引用次数: 0

On the low-latitude ionospheric irregularities under geomagnetically active and quiet conditions using NavIC observables: A spectral analysis approach 利用 NavIC 观测数据研究地磁活跃和安静条件下的低纬度电离层不规则性：光谱分析方法

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-22 DOI: 10.1016/j.jastp.2024.106369

Sumanjit Chakraborty , Abhirup Datta

Ionospheric irregularities and associated scintillations under geomagnetically active/quiet conditions have detrimental effects on the reliability and performance of space- and ground-based navigation satellite systems, especially over the low-latitude region. The current work investigates the low-latitude ionospheric irregularities using the phase screen theory and the corresponding temporal Power Spectral Density (PSD) analysis to present an estimate of the outer irregularity scale sizes over these locations. The study uses simultaneous L5 signal C/N

_{o}

observations of NavIC (a set of GEO and GSO navigation satellite systems) near the northern crest of EIA (Indore: 22.52

^{\circ}

N, 75.92

^{\circ}

E, dip: 32.23

^{\circ}

N) and in between the crest and the dip equator (Hyderabad: 17.42

^{\circ}

N, 78.55

^{\circ}

E, dip: 21.69

^{\circ}

N). The study period (2017–2018) covers disturbed and quiet-time conditions in the declining phase of the solar cycle 24. The PSD analysis brings forward the presence of irregularities, of the order of a few hundred meters during weak-to-moderate and quiet-time conditions and up to a few km during the strong event, over both locations. The ROTI values validate the presence of such structures in the Indian region. Furthermore, only for the strong event, a time delay of scintillation occurrence over Indore, with values of 36 min and 50 min for NavIC satellites (PRNs) 5 and 6, respectively, from scintillation occurrence at Hyderabad is observed, suggesting a poleward evolution of irregularity structures. Further observations show a westward propagation of these structures on this day. This study brings forward the advantage of utilizing continuous data from the GEO and GSO satellite systems in understanding the evolution and propagation of the ionospheric irregularities over the low-latitude region.

地磁活跃/安静条件下的电离层不规则现象和相关闪烁对空间和地面导航卫星系统的可靠性和性能有不利影响，特别是在低纬度地区。目前的工作利用相屏理论和相应的时间功率谱密度分析对低纬度电离层不规则现象进行了研究，提出了对这些地点外部不规则现象规模大小的估计。该研究使用了在 EIA 北部波峰附近（印多尔：22.52∘N，75.92∘E，倾角：32.23∘N）和波峰与倾角赤道之间（海得拉巴：17.42∘N，78.55∘E，倾角：21.69∘N）的 NavIC（一组地球同步轨道和地球同步轨道导航卫星系统）的 L5 信号 C/No 同步观测。研究时段（2017-2018 年）涵盖了太阳周期 24 递减阶段的扰动和静止状态。PSD 分析表明，这两个地点存在不规则现象，在弱至中等强度和静止期间为几百米，在强事件期间可达几千米。ROTI 值验证了印度地区存在此类结构。此外，仅在强事件中，NavIC 卫星（PRNs）5 号和 6 号在印多尔上空发生闪烁的时间与海德拉巴发生闪烁的时间分别延迟了 36 分钟和 50 分钟，这表明不规则结构是向极地演化的。进一步的观测表明，这些结构在这一天向西传播。这项研究提出了利用地球同步轨道和地球静止轨道卫星系统的连续数据来了解低纬度地区电离层不规则结构的演变和传播的优势。

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引用次数: 0

Impact of aerosols on atmospheric electrification over East and West Africa 气溶胶对东非和西非大气电气化的影响

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-22 DOI: 10.1016/j.jastp.2024.106375

B. Mmame , C. Ngongondo

Studies have shown that atmospheric aerosols can modify cloud microphysics. The influence of atmospheric aerosols on mechanisms that lead to generation of lightning is very complex and not fully understood. Recent studies have also revealed that, west Africa has high concentration of atmospheric aerosols due to localized wind which diverge from Sahara desert to this area. This study investigates the impact of atmospheric aerosols on lightning flash rate over east and west Africa by utilizing aerosol optical depth (AOD) from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data, convective available potential energy (CAPE), potential temperature, surface relative humidity, clouds and lightning flash rate. Pearson correlation and partial correlation have been applied between lightning flash rate and AOD, humidity, clouds, CAPE as well as potential temperature. Quantitative results show that there is a strong positive correlation (

\sim

0.75) between lightning flash rate and aerosols under low concentration of aerosols (AOD

\leq

0.6) due to aerosol microphysics effect. In the presence of high aerosol concentration (AOD

>

0.6), the correlation coefficient between lightning flash rate and aerosols is somehow weak (

\sim

0.45) due to decrease in the number of ice particles as well as radiation effect of aerosols. However, the correlation coefficient between lightning flash rate and CAPE, clouds and potential temperature are all positive under both high and low concentration of atmospheric aerosols.

研究表明，大气气溶胶可以改变云的微物理学。大气气溶胶对导致闪电产生的机制的影响非常复杂，尚未完全清楚。最近的研究还表明，由于从撒哈拉沙漠分流到该地区的局部风，西非的大气气溶胶浓度很高。本研究利用现代研究和应用回顾分析第 2 版（MERRA-2）再分析数据中的气溶胶光学深度（AOD）、对流可用势能（CAPE）、势温、表面相对湿度、云层和闪电率，研究了大气气溶胶对非洲东部和西部闪电率的影响。雷闪率与 AOD、湿度、云、CAPE 和位势温度之间采用了皮尔逊相关性和部分相关性分析。定量结果表明，由于气溶胶微物理效应，在气溶胶浓度较低（AOD ≤ 0.6）的情况下，雷闪率与气溶胶之间存在较强的正相关性（∼0.75）。在气溶胶浓度较高（AOD > 0.6）的情况下，由于冰颗粒数量的减少以及气溶胶的辐射效应，闪电闪烁率与气溶胶之间的相关系数较弱（∼0.45）。然而，在大气气溶胶浓度较高和较低的情况下，雷闪率与 CAPE、云和势温之间的相关系数均为正值。

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引用次数: 0

Changes in turbulent processes caused by atmospheric gravity waves from troposphere 对流层大气重力波引起的湍流过程变化

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-22 DOI: 10.1016/j.jastp.2024.106364

Liudmyla Kozak , Istvan Ballai , Viktor Fedun , Elena A. Kronberg , Aljona Bloecker , Bohdan Petrenko

We have determined that changes in temperature and wind speed recorded in the Earth‘s upper atmosphere above tropospheric sources (hurricanes) can be explained by the propagation of atmospheric gravity waves (AGW). We carried out modeling of the propagation of AGW with a period of 65 min and

k_{x} = 1 0^{- 5}

m⁻¹ using multi-layer methods in a non-homogeneous, non-isothermal atmosphere, taking into account viscosity and thermal conductivity. We obtained that disturbances in the horizontal component of the velocity are five times greater than the increase in the vertical component of the velocity, and temperature changes can reach 30 K. We should note that the disturbances of temperature and pressure as a result of AGW spreading are superimposed onto the usual view of changes of pressure and temperature with the altitude and reach the maximum amplitude in the range from 90 to 100 km. The obtained changes in the temperature of the upper atmosphere and the velocity with height as a result of the presence of AGW made it possible to estimate the values of the coefficients of turbulent viscosity and thermal conductivity in the upper atmosphere of the Earth above tropospheric energy sources. Intensification of turbulent processes was recorded in the range of altitudes from 75 to 100 km.

我们已经确定，在对流层源（飓风）上方的地球高层大气中记录到的温度和风速变化可以用大气重力波（AGW）的传播来解释。我们使用多层方法在非均质、非等温大气中对周期为 65 分钟、kx=10-5 m-1 的 AGW 传播进行了建模，并考虑了粘度和导热性。我们得到的结果是，速度水平分量的扰动比速度垂直分量的增加大五倍，温度变化可达 30 K。我们应该注意到，AGW 传播导致的温度和压力扰动与压力和温度随高度变化的通常观点相叠加，并在 90 至 100 千米范围内达到最大振幅。由于存在 AGW，高层大气温度和速度随高度的变化得以估算对流层能量源上方地球高层大气的湍流粘度和热传导系数的值。在 75 至 100 公里的高度范围内记录到湍流过程的加剧。

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引用次数: 0

Dynamical complexity and multifractal analysis of geomagnetic activities at high temporal scales over three solar cycles 三个太阳周期高时间尺度地磁活动的动态复杂性和多分形分析

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-21 DOI: 10.1016/j.jastp.2024.106380

Samuel Ogunjo , Joshua Akinsusi , Babatunde Rabiu , Ibiyinka Fuwape

Activities in geospace occur at different time scales. Understanding geomagnetic activity at high temporal scales will give insight into fast dynamics in geospace. This study aims to investigate dynamical complexities in geomagnetic activities at a high temporal scale across three solar cycles. Geomagnetic activities, as represented by 5-min SYM-H data, were considered in this study over three solar cycles (22–24) from 1986 to 2019. Chaos analysis using sample entropy, Lyapunov exponent, and correlation dimension indicates that the geomagnetic activities are driven by intrinsic complex and chaotic processes. Positive Lyapunov exponent values between 0.13 and 0.18, 0.15–0.18, and 0.16–0.19 were obtained for solar cycles 22, 23, and 24 respectively. Furthermore, geomagnetic activities were also found to have multifractal structures driven by high fractal exponents with fine structures. A positive relationship was obtained between the annual mean values of SYM-H and the degree of complexity. It is concluded that geomagnetic activities have a short prediction horizon.

地球空间的活动发生在不同的时间尺度上。了解高时间尺度的地磁活动将有助于深入了解地球空间的快速动力学。本研究旨在研究三个太阳周期中高时间尺度地磁活动的动态复杂性。本研究考虑了从 1986 年到 2019 年三个太阳周期（22-24）中以 5 分钟 SYM-H 数据为代表的地磁活动。利用样本熵、Lyapunov 指数和相关维度进行的混沌分析表明，地磁活动是由内在的复杂混沌过程驱动的。太阳周期 22、23 和 24 的李亚普诺夫指数分别为 0.13 至 0.18、0.15 至 0.18 和 0.16 至 0.19。此外，研究还发现地磁活动具有多分形结构，由具有精细结构的高分形指数驱动。SYM-H 的年平均值与复杂程度之间存在正相关关系。结论是地磁活动的预测范围较短。

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引用次数: 0

Aspect sensitivity measurement of backscattering radar echoes from 205 MHz Stratosphere–Troposphere radar at a tropical coastal station 在热带海岸站测量 205 MHz 平流层-对流层雷达反向散射雷达回波的高宽比灵敏度

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-19 DOI: 10.1016/j.jastp.2024.106367

Dhanya R. , Anju Pradeep , Rakesh V. , Abhilash S. , K. Mohankumar , Sivan C. , Rejoy Rebello , Prabhath H. Kurup

Aspect sensitivity in VHF radar refers to the extent to which the power and spectrum width of echoes vary with changes in the zenith angle, which is related to the backscattering process. The scattering of clear air signals is primarily caused by Fresnel reflection, anisotropic scattering, and isotropic scattering. The aspect sensitivity and accuracy of moment and wind estimation in clear air radars are influenced by the beam width, beam pointing angle from zenith, and atmospheric conditions. This study proposes a method to determine the sensitivity of the recently developed Stratosphere–Troposphere (ST) wind profile Radar in Cochin, India (10.04°N, 76.33°E). The radar operates at a distinct frequency of 205 MHz in the far VHF band. The experiment is conducted at an altitude of 5 to 20 km above the ground by adjusting the beam’s orientation with a resolution of 2°in both the east–west and north-south directions. The estimation of wind components is subject to uncertainty due to the varying aspect angles caused by the distinct dispersion properties in this height range. The study found that power variance is lowest between 6 and 12 km in both north-south and east–west directions, while daily fluctuations in aspect-sensitive echoes complicate wind component estimation. Correlation length (

ζ

) ranges from 0.5 to 15 m, indicating various air scattering processes. Notably,

θ_{s}

is smaller near the zenith and increases with tilt angles, exceeding 20°up to 14 km before declining at higher altitudes, indicating significant anisotropy at elevated levels. The wide range of R factor values (0.1 to 0.9) across different heights causes significant ambiguity in wind estimation. In this study, the impact of various aspect sensitivity parameters on wind estimation on days with clear air has been analyzed.

甚高频雷达的频谱灵敏度是指回波的功率和频谱宽度随天顶角变化而变化的程度，这与后向散射过程有关。晴空信号的散射主要由菲涅尔反射、各向异性散射和各向同性散射引起。晴空雷达的方位灵敏度和时刻及风估算精度受波束宽度、波束与天顶的指向角和大气条件的影响。本研究提出了一种方法来确定最近在印度科钦（北纬 10.04°，东经 76.33°）开发的平流层-对流层（ST）风廓线雷达的灵敏度。该雷达的工作频率为 205 兆赫，属于远甚高频波段。实验在离地面 5 至 20 千米的高度进行，通过调整波束的方向，东西和南北方向的分辨率均为 2°。在这一高度范围内，由于不同的频散特性造成了不同的纵横角，因此对风分量的估算存在不确定性。研究发现，南北向和东西向 6 至 12 千米范围内的功率方差最小，而纵横向敏感回波的日波动使风分量估算复杂化。相关长度（ζ）从 0.5 米到 15 米不等，表明存在各种空气散射过程。值得注意的是，θs 在天顶附近较小，并随倾斜角的增大而增大，在 14 千米以内超过 20°，然后在更高的高度下降，这表明在高空有明显的各向异性。不同高度的 R 因子值范围很广（0.1 至 0.9），导致风力估算非常模糊。在这项研究中，分析了各种高程灵敏度参数对晴朗天气风力估算的影响。

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引用次数: 0

Differential responses of total ozone content to solar activity parameters at two Saudi Arabian locations 沙特阿拉伯两地臭氧总量对太阳活动参数的不同反应

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2024-10-18 DOI: 10.1016/j.jastp.2024.106379

Abdullrahman Maghrabi, Mayson Alghamdi

This study examines the correlations between Total Ozone Content (TOC) at two locations in Saudi Arabia—Abha and Jeddah—and various solar activity indicators (sunspot numbers, solar radio flux) and cosmic rays, using data spanning from 1979 to 2023. The research employs correlation analyses and spectral techniques, such as Fast Fourier Transform and wavelet analysis, to explore these relationships.

The results reveal significant non-zero correlations between changes in TOC at both Saudi sites and the studied solar activity indicators and cosmic rays, with these correlations varying in strength and significance across different solar cycles and seasons.

Spectral analysis suggests the presence of several periodicities in the TOC data from both sites, including cycles of 3.9 years, 2.63 years, 1.65 years, 1.1–1.2 years, 325 days (∼0.88 years), 285–293 days (∼0.78–0.80 years), 273 days (∼0.75 years), 249-232 days (∼0.68 years), and 202-188 days (∼0.52 years). Notable shared periodicities between TOC and solar activity and cosmic rays data include ∼2.6 years, 3.8–3.9 years, 1.56 years, 325 days, 273 days, and 166 days.

The findings from both correlation and spectral analyses suggest a potential connection between variations in TOC and solar activity at the specific locations studied. This aligns with previous research indicating that increased UV radiation during periods of high solar activity enhances ozone production, particularly at lower latitudes, and that increased magnetic activity reduces the influx of cosmic rays into the heliosphere, impacting atmospheric ionization.

本研究利用从 1979 年到 2023 年的数据，研究了沙特阿拉伯两个地点--阿布哈和吉达--的臭氧总含量（TOC）与各种太阳活动指标（太阳黑子数、太阳射电通量）和宇宙射线之间的相关性。研究采用了相关性分析和光谱技术（如快速傅立叶变换和小波分析）来探索这些关系。研究结果表明，沙特两个站点的总有机碳变化与所研究的太阳活动指标和宇宙射线之间存在显著的非零相关性，这些相关性在不同太阳周期和季节的强度和重要性各不相同。频谱分析表明，两个观测点的 TOC 数据存在若干周期性变化，包括 3.9 年、2.63 年、1.65 年、1.1-1.2年、325天（∼0.88年）、285-293天（∼0.78-0.80年）、273天（∼0.75年）、249-232天（∼0.68年）和202-188天（∼0.52年）。TOC与太阳活动和宇宙射线数据之间显著的共同周期包括：2.6年、3.8-3.9年、1.56年、325天、273天和166天。这与之前的研究结果一致，即太阳活动频繁时紫外线辐射增加会促进臭氧生成，尤其是在低纬度地区；磁活动增加会减少宇宙射线流入日光层，从而影响大气电离。

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引用次数: 0