Present study investigates the role of gravity waves in the generation of equatorial plasma bubbles (EPBs) during geomagnetic quiet conditions using co-located observations from Gadanki (13.5oN, ...79.2° E) an all sky airglow imager, Gadanki Ionospheric Radar Interferometer (GIRI) and Ionosonde observations from Tirunelveli (8.7° N, 77.8° E). To avoid any changes occurring in the background ionosphere, four consecutive nights of observation during 03–06 February 2014 is used. Out of these four nights, three nights (i.e., 03, 05 and 06 February 2014) exhibit occurrence of EPBs in the OI 630 nm airglow emission and radar plumes and there is no bubble occurrence during one night, though the ionospheric peak altitude (h′F) value is more than 350 km in all these nights. During these four nights the structures observed in the E-region drifts and gravity waves noted in the mesospheric OH emissions are analyzed. It is found that there are common periodic oscillations in the OH peak emission altitude and E-region in three nights (03, 04 and 05 February 2014). The mesospheric gravity wave structures are ray traced to their potential sources in the lower atmosphere and also for the possibility of their propagation to the E-region. Our results suggest that apart from horizontal wavelength and amplitudes, the propagation angle of gravity wave may also be important for seeding of the Rayleigh-Taylor (R-T) instability. Thus, it gives an insight about the role of lower – middle and upper atmospheric coupling on the occurrence of the noted EPBs.
•Out of four consecutive quiet geomagnetic condition nights, EPB occurrence is observed on three nights•Even gravity wave with small amplitude also can trigger EPB when a strong irregularity exists in the E-region•Reverse ray tracing results suggest that waves observed in the present study is of lower atmospheric origin
The present work is the first of a two‐part paper on the Embrace Magnetometer Network. In this part, we present the new Embrace Magnetometer Network (Embrace MagNet) in South America, which is ...originally planned to cover most of the eastern portion of the Southern America longitudinal sector by installing and operating fluxgate magnetometer stations. We discuss the purpose and scientific goals of the network, associated with aeronomy and space weather. We provide details on the instrumentation, location of the sensors, sensitivity matching process, gain matching process, and magnetometer installation. In addition, we present and discuss details about the data storage, near‐real time display, and availability.
Plain Language Summary
This manuscript introduces the reader to the new Embrace Magnetometer Network (Embrace MagNet), which is located in South America and is based on fluxgate magnetometer. Its main purpose is to fulfill the gap in magnetic measurements, which are suitable for space weather purpose. Details on the instrumentation, location of the sensors, sensitivity matching process, gain matching process, and magnetometer installation are provided in this first of a two‐part paper on the Embrace MagNet. The accompanying paper provides information on the first scientific findings.
Key Points
Magnetic measurements in South America ready for space weather
Magnetic station measurement with near‐observatory data quality
New real‐time data providing proxy for Dst, and the new Ksa magnetic indices
The present work shows the preliminary results from the analysis for developing an ionospheric scale index map based on the Disturbance Ionosphere indeX (DIX). This index aims to target all the ...different user groups affected by ionospheric disturbances, for example, the navigation, positioning, and satellite communication users, in a simple and straightforward approach. Therefore, we used the vertical total electron content (VTEC) over South America to calculate the total electron content (TEC) maps covering latitudes from 60°S to 20°N and longitudes from 90°W to 30°W, with 0.5° × 0.5° resolution. Afterward, the DIX maps are obtained to reveal the variation of the TEC over an average quiet ionosphere background. In order to illustrate the use of the map index, the ionospheric disturbances after and during the 17–23 December 2015 intense geomagnetic storm and the 2015 Saint Patrick magnetic storm are discussed, highlighting the disturbances in the DIX at different latitudinal ranges and under different magnetic conditions.
Key Points
The new ionospheric index accounts for latitudinal dependence of the ionospheric response to external and internal low‐latitude dynamics
It was provided in a regional map format covering South America
The Global Navigation Satellite System (GNSS) database used in the present work comprised files from 200 receivers in South America
This study examines the variability of the ionospheric content during the period around the 2015 Saint Patrick magnetic storm and when equatorial plasma bubbles (EPBs) are observed during the quiet ...time over South America during two other events. It uses the ionospheric scales index map based on the disturbance ionospheric index (DIX). The results are compared to the traces of the ionograms obtained at three different ionospheric stations (Fortaleza, Campo Grande, and Cachoeira Paulista) in Brazil acquired in the same period and at the same time rate. The index is based on the TEC map developed at the “Brazilian Studies and Monitoring of Space Weather” (Embrace/INPE). It covers the whole South America (latitudes from 20°N to 60°S and longitudes from 90°W to 30°W) with 0.5° × 0.5° resolution cells (60 × 60 km2). Among the results, the DIX map revealed some patches of “Disturbed” and “Weakly Disturbed” ionospheric conditions during the magnetically quiet time before the storm, which were associated with range and frequency Spread‐F over the same area as observed in ionograms. Also, the information from the southern portion of the dip equator showed a transition from occurrences of Spread‐F prior to sunrise to a condition favorable enough to develop a F3 layer after sunrise.
Key Points
We illustrate the capability of the new ionospheric index that accounts for external drivers and internal low latitude ionosphere dynamics
DIX maps are compared with ionosonde data and all‐sky images over South America
During quiet times DIX maps reveal weak ionospheric disturbances collocated with the footprints of the EPBs not seen by other instruments
The present work is the second of a two‐part paper on the Embrace Magnetometer Network. In this part, we provide some of the first scientific findings that we have already achieved with this network. ...We identified the diurnal and the seasonal natural variations of the H component. We provided the precise determination of sudden storm commencements and sudden impulse. We showed that the ΔH amplitudes derived from the Embrace MagNet during intense magnetic storm are in very good agreement with the Dst index. We showed that it is possible to investigate the effects on the solar quiet ionospheric current systems as a response to the X‐class solar flares occurring during daytime under magnetically quiet conditions.
Key Points
Magnetic measurements in South America ready for space weather
Magnetic station measurement with near‐observatory data quality
New‐real‐time data providing proxy for Dst and the new Ksa magnetic indices
Plain Language Summary
This manuscript is the second of a two‐part paper and provides the reader with the first scientific findings from the new Embrace Magnetometer Network (Embrace MagNet), which is located in South America and is based on fluxgate magnetometer. The main purpose of this network is to fulfill the gap in magnetic measurement, which are suitable for space weather purpose. Details on the network description and its qualification are provided in the first paper.
This paper presents the Intertropical Convergence Zone (ITCZ) as the possible source mechanism of the medium-scale traveling ionospheric disturbances (MSTIDs) propagating to the southeast direction ...over the South American region. Using the data collected by the GNSS dual-frequency receivers network from January 2014 to December 2019, detrended TEC maps were generated to identify and characterize 144 MSTIDs propagating southeastward over the South American low-latitude and equatorial region. We also used images from the Geostationary Operational Environmental Satellite (GOES) 13 and 16 in the infrared (IR) and water vapor (WV) channel, and reanalisys data from the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) to study the daily features and seasonal migration of ITCZ. In the winter, when ITCZ migrates to the northern hemisphere around 10–15° N, 20 MSTIDs propagated southeastward. During summer, when the ITCZ lies within the continent, around 0–5° S 80 MSTIDs were observed to propagate southeastward; in the equinoxes (spring and fall), 44 MSTIDs were observed. Again, the MSTIDs propagating southeastward showed a clear seasonality of their local time dependence; in summer, the MSTIDs occurred frequently in the evening hours, whereas those in winter occurred during the daytime. We also found for the first time that the day-to-day observation of ITCZ position and MSTIDs propagation directions were consistent. With regard to these new findings, we report that the MSTIDs propagating southeastward over the South American region are possibly induced by the atmospheric gravity waves, which are proposed as being generated by the ITCZ in the troposphere. The mean distribution of the horizontal wavelength, period, and phase velocity are 698 ± 124 km, 38 ± 8 min, and 299 ± 89 m s−1, respectively. For the first time, we were able to use MSTID propagation directions as a proxy to study the source region.
Using data collected by the GNSS dual-frequency receivers network, de-trended TEC maps were generated to identify and characterize the medium-scale traveling ionospheric disturbances (MSTIDs) over ...the South American equatorial region (latitude: 0∘ to 15∘ S and longitude: 30∘ to 55∘ W) during solar cycle 24 (from January 2014 to December 2019). A total of 712 MSTIDs were observed during quiet geomagnetic conditions. The Frequency of occurrence of MSTID is high during the solar maximum and low in the minimum phase. This might be due to the solar cycle dependence of gravity wave activity in the lower atmosphere and gravity wave propagation conditions in the thermosphere. The predominant daytime MSTIDs, representing 80% of the total observations, occurred in winter (June-August season in the southern hemisphere) with the secondary peak in the equinox; while the evening time MSTIDs, representing 18% of the entire events, occurred in summer (December to February season) and equinox (March to May and September to November), and the remaining 2% of the MSTIDs were observed during nighttime. The seasonal variation of the MSTID events was attributed to the source mechanisms generating them, the wind filtering and dissipation effects, and the local time dependency. The horizontal wavelengths of the MSTIDs were mostly concentrated between 500 and 800 km, with the mean value of 667 ± 131 km. The observed periods ranged from 30 to 45 min with the mean value of 36 ± 7 min. The observed horizontal phase speeds were distributed around 200 to 400 m/s, with the corresponding mean of 301 ± 75 m/s. The MSTIDs in the winter solstice and equinoctial months preferentially propagated northeastward and northwestward. Meanwhile, during the summer solstice, they propagated in all directions. The anisotropy of the propagation direction might be due to several reasons: the wind and dissipative filtering effects, ion drag effects, the primary source region, and the presence of the secondary or tertiary gravity waves in the thermosphere. Atmospheric gravity waves from strong convective sources might be the primary precursor for the observed equatorial MSTIDs. In all seasons, we noted that the MSTIDs propagating southeastward were probably excited by the likely gravity waves generated by the intertropical convergence zone (ITCZ).
The residue from commercial propolis extraction may have significant antioxidant power in food technology. However, among the challenges for using the propolis co-product as an inhibitor of lipid ...oxidation (LO) in baked goods is maintaining its bioactive compounds. Therefore, this study aimed to determine the propolis co-product extracts' capability to reduce LO in starch biscuit formulated with canola oil and stored for 45 days at 25 °C. Two co-product extracts were prepared: microencapsulated propolis co-product (MECP) (with maltodextrin) and lyophilized propolis co-product (LFCP), which were subjected to analysis of their total phenolic content and antioxidant activity (AA). Relevant antioxidant activity was observed using the methods of analysis employed. The spray-drying microencapsulation process showed an efficiency of 63%. The LO in the biscuits was determined by the thiobarbituric acid reactive substances (TBARS) test and fatty acid composition by gas chromatography analysis. Palmitic, stearic, oleic, linoelaidic, linoleic, and α-linolenic acids were found in biscuits at constant concentrations throughout the storage period. In addition, there was a reduction in malondialdehyde values with the addition of both propolis co-product extracts. Therefore, the propolis co-product extracts could be utilized as a natural antioxidant to reduce lipid oxidation in fatty starch biscuit.
Interleukin-18 (IL-18) is a cytokine that belongs to the IL-1 family. Endometriosis is strongly associated with sub-fertility, and affects about 15% of women of reproductive age. IL-18 may favor the ...progression of endometriosis. The objective of the present study was to determine the concentration of IL-18 in the serum and peritoneal fluid of infertile women with endometriosis. Forty infertile and 25 fertile women were screened in a teaching hospital. Thirty-four infertile patients with minimal or mild endometriosis and 22 fertile controls were enrolled in the study. The primary outcome was the estimate of IL-18 levels and the secondary outcome was the correlation between serum and peritoneal levels of IL-18. There were no differences between the two groups regarding age, body mass index and levels of peritoneal fluid IL-18 (mean +/- SD): 290.85 +/- 173.02 pg/mL for infertile women vs 374.21 +/- 330.15 pg/mL for controls; or serum IL-18: 391.07 +/- 119.71 pg/mL for infertile women vs 373.42 +/- 129.11 pg/mL for controls. However, a positive association was found between serum and peritoneal IL-18 levels in patients with endometriosis: r = 0.794, P = 0.0001. All measurements were carried out at the same time by the Human IL-18 Immuno Assay ELISA kit (MBL Co. Ltd., Japan). The present study did not find evidence supporting the hypothesis that IL-18 levels are associated with infertility in women with minimal and mild endometriosis, although a positive correlation was detected in these women between peritoneal and serum levels of IL-18.
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