Search

On January 15, 2022, we observed various unusual atmospheric wave events over South America: Atmospheric pressure waves (Lamb mode) around 12:30 to 17:30 UT, tsunamis along the Chilean coast at around 17:00 to 19:00 UT, and ionospheric disturbances between 11:30 and 20:00 UT. We understand that these events were generated by the Tonga volcanic eruption that occurred at (20.55°S, 175.39°W) in South Pacific Ocean at 04:15 UT. Several traveling ionospheric disturbances (TIDs), the horizontal wavelengths of 330 to 1174 km and the phase speed of 275–544 m/s were observed before and after the Lamb wave passed over the continent and the arrival of the tsunami on the Chile coast. The observed TID characteristics suggest us that these waves might be generated by the two atmospheric events, Lamb wave and gravity waves induced by the tsunamis. This is the first time to report the signature of ionospheric disturbances over the South American continent generated by the huge volcanic eruption. Graphical Abstract

Using OI6300 airglow images collected over São João do Cariri (7.4∘ S, 36.5∘ W) from 2000 to 2007, the equatorial plasma bubble (EPB) zonal drifts were calculated. A strong day-to-day variability was observed in the EPB zonal drifts, which is directly associated with the very complex dynamics of the nighttime thermosphere–ionosphere system near the Equator. The present work investigated the contribution of the semidiurnal lunar tide M2 for the EPB zonal drifts. The M2 presented an amplitude of 3.1 m s−1 in the EPB zonal drifts, which corresponds to 5.6 % of the average drifts. The results showed that the M2 amplitudes in the EPB zonal drifts were solar cycle and seasonally dependent. The amplitude of the M2 was stronger during the high solar activity, reaching over 10 % of the EPB zonal drift average. Regarding the seasons, during the Southern Hemisphere summer, the M2 amplitude was twice as large (12 %) compared to the equinox ones. The seasonality agrees with other observations of the M2 in the ionospheric parameters such as vertical drifts and electron concentration, for instance. On the other hand, the very large M2 amplitudes found during the high solar activity agree with previous observations of the lunar tide in the ionospheric E region.

Using COSMIC-2 and METOP radio occultation measurements during the years 2020 and 2021, the study presents the first direct and independent relationship between the potential energy (Ep) in the stratosphere, precipitable water vapour (PWV), tropopause heights, and cold-point heights over South America. The South American continent comprises the tropical region, the Andes Mountain range, and the mid-latitude climates. The seasonal mean of the potential energy (Ep), the PWV, and the tropopause parameters height (TPH and CPH) were obtained to investigate the relationship between the SGW Epand the tropospheric parameters (PWV, TPH, and CPH). Around the Andes Mountains to the east, there is significantly less water vapour (PWV < 10 mm) and relatively high gravity wave Ep(Ep>8 kJ kg− 1). A good correlation of variability was found between the PWV and the lower stratospheric gravity wave (SGW) Epin summer over the tropical region (± 20◦). Our result affirmed the possibility that convective activity was a major driver of the tropical gravity waves over South America. In the subtropical (30◦-40◦) region, especially in the winter, the tropospheric parameters make little or no contribution to gravity wave activity in the region. The tropopause and the cold-point temperature showed an anti-correlation (r > − 0.6) with SGW over the South American tropics. The SGW activities in the tropical region showed an impact on the structure of the tropopause parameters, which could be a result of the convective activity in this region.

We observed a gravity wave (GW) signature in the OH emission layer in the upper mesosphere, and 4 hours later, a medium-scale traveling ionospheric disturbance (MSTID) in the OI 630 nm emission layer. Spectral analysis of the two waves did show that both have the same wave characteristics: wavelength, period, phase speed and propagation direction, respectively, 200 km, 60 min, 50 m/s, propagating southeastward. During the MSTID occurrence, concentric wavefronts were also observed in the ionosphere by detrended total electron content (dTEC) maps. From the gravity wave ray-tracing simulation for the mesospheric gravity wave, we found that the wave came from a tropospheric deep convection spot and propagated up to the 140 km altitude. Regarding the same wave characteristics between mesospheric GW and MSTID, two possible cases are investigated: a direct influence of the GW oscillation in the OI 630 nm emission height and the generation of a secondary wave during the GW breaking process. The concentric wave structure suggests the generation of a secondary wave after the primary wave was dissipated in the lower thermosphere. This is the first time to report an observational event of gravity wave propagation from the troposphere, mesosphere to thermosphere-ionosphere in the south American region.

Using OI6300 airglow images collected over São João do Cariri (7.4° S, 36.5° W) from 2000 to 2007, the equatorial plasma bubble (EPB) zonal drifts were calculated. A strong day-to-day variability was observed in the EPB zonal drifts due to the complexity in the dynamics of the nighttime thermosphere-ionosphere system near the equator. The present work investigated the contribution of the semidiurnal lunar tide M2 for the EPB zonal drifts. On average, the M2 contributes 5.6 % to the variability of the EPB zonal drifts, presenting an amplitude of 3.1 m/s. The results showed that the M2 amplitudes in the EPB zonal drifts were solar cycle and seasonal dependents. The amplitude of the M2 was stronger during the high solar activity reaching over 10 % of the EPB zonal drift average. Regarding the seasons, during the southern hemisphere summer, the M2 amplitude was twice larger (12 %) compared to the equinox ones. The seasonality agrees with other observations of the M2 in the ionospheric parameters such as vertical drifts and electron concentration, for instance. On the other hand, the very large M2 amplitudes found during the high solar activity must be further investigated.

In this study, OI 630.0 nm nightglow image data obtained from an all-sky imaging station located at Sao Joao do Cariri (7.4°S, 36.5°W), have been used to study the occurrence of equatorial plasma bubbles (EPBs) over the Brazilian equatorial region. The observations, which took place from September 2000 to December 2010 (almost eleven years), covered a significant part of solar cycle 23 (descending phase of SC23) and the very beginning of solar cycle 24 (ascending phase of SC24). There were 1337 nights of observations with 666 nights with EPB events, which translates to an occurrence rate of ∼ 49.8%. Of these nights, 1290 were considered quiet (Dst ≥ -50 nT) with ∼ 50% plasma bubbles occurrence rate. The occurrence of EPBs was studied under three solar activity phases – high solar activity phase (HSA, September 2000 – March 2004), moderate solar activity phase (MSA or descending phase, March 2004 – October 2006) and low solar activity phase (LSA, October 2006 – December 2010). The low solar activity phase is part of the peculiar solar cycle 24, considered the weakest in over a century with most sunspotless days (2008–2009). The maximum occurrence of bubbles, equal to 54.2%, was found during the HSA phase, with percentages characterizing MSA and LSA being respectively 52.4% and 45.8%. The analysis also showed clear seasonal variation in the EPB occurrence with maximum rates in summer, spring, autumn, and the minimum rates in winter for all solar activity phases. Overall, there was observed solar cycle variation in each season with maximum occurrence in HSA followed by MSA and then LSA except in autumn where higher occurrence rate was observed in LSA phase than in MSA phase.

OI 630.0 nm airglow observations, from a new observatory at Bom Jesus de Lapa, were used to study the interaction between EPBs (Equatorial Plasma Bubbles) and the MSTID (Medium-Scale Traveling Ionospheric Disturbance) over the Northeast region in Brazil. On the night of September 16 to 17, 2020, an EPB was observed propagating eastward, in an apparent fossil stage, until it interacted with a dark band electrified MSTID (eMSTID). After the interaction, four EPBs merged, followed by an abrupt southward development and bifurcations. Analysis of the data suggests that an eastward polarization electric field, induced by the dark band eMSTID, forced the EPB into an upward drift, growing latitudinally along the magnetic field lines and then bifurcating.

The occurrences of equatorial plasma bubble (EPB) irregularities over Asian and American sectors often show a different behavior due to significantly different geometries of the geomagnetic field. By using the GPS total electron content observations over equatorial and low latitudes sectors of Asian (about 120°E) and American (about 60°W) during 1997–2018, we present a comparative study of long-term occurrences of EPB kilometer-scale irregularities over the two longitude sectors. The results show that post-sunset EPB irregularities over the Asian sector were positively correlated with solar activity. However, in the American sector, such a positive dependence was not apparent in 2000–2002, which could be partly induced by limited data available during the high occurrence season of solar maximum when the GPS receivers frequently lost lock. The geomagnetic disturbance tends to inhibit the generation of EPB irregularities over both sectors during post-sunset but enhance their generation during post-midnight. The latitudinal distribution of EPB irregularities exhibited a double-peak structure centered within ± 10° (dip lat.), with the latitudinal limit below ± 25° at solar maximum in both sectors and below ± 20° and ± 10° at solar minimum in American and Asian sectors, respectively. Specifically, in the American sector, the occurrence rates were about two times higher than those in the Asian sector, and the occurrence rates in the northern hemisphere were apparently lower than those in the southern hemisphere. The enhanced ionization by particle precipitation over the South Atlantic Magnetic Anomaly region could cause the north–south asymmetry of occurrence rates of EPB irregularities. The results help in designing experiments to understand better the generation of EPB irregularities under the future international meridian circle project.

Nighttime airglow images observed at the low-latitude site of Sao Joao do Cariri (7.4S, 36.5W) showed the presence of a medium-scale atmospheric gravity wave (AGW) associated with the...

An interesting interaction between equatorial plasma bubbles (EPBs), medium-scale traveling ionospheric disturbance (MSTID), and midnight brightness wave (MBW) were observed at Cachoeira Paulista, ...

Using airglow data from an all-sky imager deployed at São João do Cariri (7.4∘ S, 36.5∘ W), the start times of equatorial plasma bubbles was studied in order to investigate the day-to-day variability of this phenomenon. Data from a period over 10 years were analyzed from 2000 to 2010. Semimonthly oscillations were clearly observed in the start times of plasma bubbles from OI6300 airglow images during this period of observation, and four case studies (September 2003, September–October 2005, November 2005 and January 2008) were chosen to show in detail this kind of modulation. Since the airglow measurements are not continuous in time, more than one cycle of oscillation in the start times of plasma bubbles cannot be observed from these data. Thus, data from a digisonde at São Luís (2.6∘ S, 44.2∘ W) in November 2005 were used to corroborate the results. Technical/climate issues did not allow one to observe the semimonthly oscillations simultaneously by the two instruments, but from October to November 2005 there was a predominance of this oscillation in the start times of the irregularities over Brazil. Besides, statistical analysis for the data in the whole period of observation has shown that the lunar tide, which has semimonthly variability, is likely the main forcing for the semimonthly oscillation in the start times of equatorial plasma bubbles. The presence of this oscillation can contribute to the day-to-day variability of equatorial plasma bubbles.

Mesospheric airglow measurements of two or three layers were used to characterize both vertical and horizontal parameters of gravity waves. The data set was acquired coincidentally from a multi-channel filter (Multi-3) photometer and an all-sky imager located at São João do Cariri (7.4∘ S, 36.5∘ W) in the equatorial region from 2001 to 2007. Using a least-square fitting and wavelet analysis technique, the phase and amplitude of each observed wave were determined, as well as the amplitude growth. Using the dispersion relation of gravity waves, the vertical and horizontal wavelengths were estimated and compared to the horizontal wavelength obtained from the keogram analysis of the images observed by an all-sky imager. The results show that both horizontal and vertical wavelengths, obtained from the dispersion relation and keogram analysis, agree very well for the waves observed on the nights of 14 October and 18 December 2006. The determined parameters showed that the observed wave on the night of 18 December 2006 had a period of ∼43.8±2.19 min, with the horizontal wavelength of 235.66 ± 11.78 km having a downward phase propagation, whereas that of 14 October 2006 propagated with a period of ∼36.00±1.80 min with a horizontal wavelength of ∼195±9.80 km, and with an upward phase propagation. The observation of a wave taken by a photometer and an all-sky imager allowed us to conclude that the same wave could be observed by both instruments, permitting the investigation of the two-dimensional wave parameter. Keywords. Atmospheric composition and structure (airglow and aurora) – electromagnetics (wave propagation) – history of geophysics (atmospheric sciences)

On 3 October 2005 a mesospheric front was observed over São João do Cariri (7.4∘ S, 36.5∘ W). This front propagated to the northeast and appeared in the airglow images on the west side of the observatory. By about 1.5 h later, it dissipated completely when the front crossed the local zenith. Ahead of the front, several ripple structures appeared during the dissipative process of the front. Using coincident temperature profile from the TIMED/SABER satellite and wind profiles from a meteor radar at São João do Cariri, the background of the atmosphere was investigated in detail. On the one hand, it was noted that a strong vertical wind shear in the propagation direction of the front produced by a semidiunal thermal tide was mainly responsible for the formation of duct (Doppler duct), in which the front propagated up to the zenith of the images. On the other hand, the evolution of the Richardson number as well as the appearance of ripples ahead of the main front suggested that a presence of instability in the airglow layer that did not allow the propagation of the front to the other side of the local zenith. Keywords. Atmospheric composition and structure (airglow and aurora) – meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

Periodic waves were observed in the OI6300 airglow images over São João do Cariri (36.5∘ W, 7.4∘ S) from 2012 to 2014 with simultaneous observations of the thermospheric wind using two Fabry–Pérot interferometers (FPIs). The FPIs measurements were carried out at São João do Cariri and Cajazeiras (38.5∘ W, 6.9∘ S). The observed spectral characteristics of these waves (period and wavelength) as well the propagation direction were estimated using two-dimensional Fourier analysis in the airglow images. The horizontal thermospheric wind was calculated from the Doppler shift of the OI6300 data extracted from interference fringes registered by the FPIs. Combining these two techniques, the intrinsic parameters of the periodic waves were estimated and analyzed. The spectral parameters of the periodic waves were quite similar to the previous observations at São João do Cariri. The intrinsic periods for most of the waves were shorter than the observed periods, as a consequence, the intrinsic phase speeds were faster compared to the observed phase speeds. As a consequence, these waves can easily propagate into the thermosphere–ionosphere since the fast gravity waves can skip turning and critical levels. The strength and direction of the wind vector in the thermosphere must be the main cause for the observed anisotropy in the propagation direction of the periodic waves, even if the sources of these waves are assumed to be isotropic. Keywords. Meteorology and atmospheric dynamics (waves and tides)

Using data from airglow an all sky imager and a coherent backscatter radar deployed at São João do Cariri (7.4° S, 36.5° W) and São Luís (2.6° S, 44.2° W), respectively, the start time of equatorial Spread-F were studied. Data from a period of over 10 years was investigated from 2000 to 2010. The semimonthly oscillations were clearly revealed in the start time of plasma bubbles from Oi6300 airglow images during three periods (September 2003, September–October 2005, November 2005 and January 2008). Since the airglow measurements are not continuous in time, more than one cycle of oscillation in the start time of plasma bubbles cannot be observed from these data. Thus, coherent backscatter radar data appeared as an alternative to investigate the start time of the ionospheric irregularities. Semimonthly oscillation were observed in the start time of plumes (November 2005) and bottom type Spread-F (November 2008) with at least one complete cycle. Technical/climate issues did not allowed to observe the semimonthly oscillations simultaneously by the two instruments, but from September to December 2005 there was a predominance of this spread-F start time oscillation over Brazil. The presence of this oscillation certainly contribute to the day-to-day variability of spread-F.

A ground-based network of GNSS receivers has been used to monitor equatorial plasma bubbles (EPBs) by mapping the total electron content (TEC map). The large coverage of the TEC map allowed us to monitor several EPBs simultaneously and get characteristics of the dynamics, extension and longitudinal distributions of the EPBs from the onset time until their disappearance. These characteristics were obtained by using TEC map analysis and the keogram technique. TEC map databases analyzed were for the period between November 2012 and January 2016. The zonal drift velocities of the EPBs showed a clear latitudinal gradient varying from 123 m s−1 at the Equator to 65 m s−1 for 35∘ S latitude. Consequently, observed EPBs are inclined against the geomagnetic field lines. Both zonal drift velocity and the inclination of the EPBs were compared to the thermospheric neutral wind, which showed good agreement. Moreover, the large two-dimensional coverage of TEC maps allowed us to study periodic EPBs with a wide longitudinal distance. The averaged values observed for the inter-bubble distances also presented a clear latitudinal gradient varying from 920 km at the Equator to 640 km at 30∘ S. The latitudinal gradient in the inter-bubble distances seems to be related to the difference in the zonal drift velocity of the EPB from the Equator to middle latitudes and to the difference in the westward movement of the terminator. On several occasions, the distances reached more than 2000 km. Inter-bubble distances greater than 1000 km have not been reported in the literature. Keywords. Ionosphere (equatorial ionosphere; ionospheric irregularities) – meteorology and atmospheric dynamics (thermospheric dynamics)

Airglow and wind measurements from the Brazilian equatorial region were used to investigate the presence and the effects of the 3–4-day ultrafast Kelvin waves in the MLT. The airglow integrated intensities of the OI557.7 nm, O2b(0-1) and OH(6-2) emissions, as well as the OH rotational temperature, were measured by a multichannel photometer, and the zonal and meridional wind components between 80 and 100 km were obtained from a meteor radar. Both instruments are installed in the Brazilian equatorial region at São João do Cariri (7.4∘ S, 36.5∘ W). Data from 2005 were used in this study. The 3–4-day oscillations appear intermittently throughout the year in the airglow. They were identified in January, March, July, August and October–November observations. The amplitudes induced by the waves in the airglow range from 26 to 40 % in the OI557.7 nm, 17 to 43 % in the O2b(0-1) and 15 to 20 % in the OH(6-2) emissions. In the OH rotational temperature, the amplitudes were from 4 to 6 K. Common 3–4-day oscillations between airglow and neutral wind compatible with ultrafast Kelvin waves were observed in March, August and October–November. In these cases, the amplitudes in the zonal wind were found to be between 22 and 28 m s−1 and the vertical wavelength ranges from 44 to 62 km. Evidence of the nonlinear interaction between the ultrafast Kelvin wave and diurnal tide was observed. Keywords. Atmospheric composition and structure (airglow and aurora) – meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

The present work reports seasonal characteristics of small- and medium-scale gravity waves in the mesosphere and lower thermosphere (MLT) region. All-sky images of the hydroxyl (NIR-OH) airglow emission layer over São João do Cariri (7.4∘ S, 36.5∘ W; hereafter Cariri) were obtained from September 2000 to December 2010, during a total of 1496 nights. For investigation of the characteristics of small-scale gravity waves (SSGWs) and medium-scale gravity waves (MSGWs), we employed the Fourier two-dimensional (2-D) spectrum and keogram fast Fourier transform (FFT) techniques, respectively. From the 11 years of data, we could observe 2343 SSGW and 537 MSGW events. The horizontal wavelengths of the SSGWs were concentrated between 10 and 35 km, while those of the MSGWs ranged from 50 to 200 km. The observed periods for SSGWs were concentrated around 5 to 20 min, whereas the MSGWs ranged from 20 to 60 min. The observed horizontal phase speeds of SSGWs were distributed around 10 to 60 m s−1, and the corresponding MSGWs were around 20 to 120 m s−1. In summer, autumn, and winter both SSGWs and MSGWs propagated preferentially northeastward and southeastward, while in spring the waves propagated in all directions. The critical level theory of atmospheric gravity waves (AGWs) was applied to study the effects of wind filtering on SSGW and MSGW propagation directions. The SSGWs were more susceptible to wind filtering effects than MSGWs. The average of daily mean outgoing longwave radiation (OLR) was also used to investigate the possible wave source region in the troposphere. The results showed that in summer and autumn, deep convective regions were the possible source mechanism of the AGWs. However, in spring and winter the deep convective regions did not play an important role in the waves observed at Cariri, because they were too far away from the observatory. Therefore, we concluded that the horizontal propagation directions of SSGWs and MSGWs show clear seasonal variations based on the influence of the wind filtering process and wave source location. Keywords. Atmospheric composition and structure (airglow and aurora) – electromagnetics (wave propagation) – history of geophysics (atmospheric sciences)

Made available in DSpace on 2019-10-04T12:34:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 CONACyT Posgrado en Ciencias de la Tierra, UNAM Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) CONACYT CONACYT-AEM DGAPA-PAPIIT Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) DGAPA-PAPIIT project NSF National Science Foundation NASA-ROSES UNAM-PAPIIT The present work is the first of a two-part weather study of the ionospheric Total Electron Content (TEC), based on data collected by four ground-based Global Navigation Satellite System networks that cover the whole Latin America from the Patagonia to the north of Mexico. From the best of our knowledge, the maps presented here are the first TEC maps obtained using ground-based data that covers the entire Latin America region, which represent an advance to the space weather monitoring and forecasting of the ionosphere. This work provides a qualitative and quantitative daytime analysis of the ionospheric TEC variation, which encompasses: (a) the response of TEC to the solar flux at midday; (b) the seasonal variation of TEC in different latitudinal ranges; and (c) the North-South asymmetry of TEC over Latin America. The response to the solar flux is based on day-to-day TEC variations during two periods of different solar activity conditions: 2011 (ascending phase) and 2014 (maximum). The approximations of meridional wind component derived from Horizontal Wind Model-14 model and h(m)F(2) obtained from International Reference Ionosphere model were used. Equinoctial asymmetries with an opposite configuration in high and moderate solar activity were identified in the TEC variation. For 2011, it was related to the solar flux change. However, in 2014, according to the h(m)F(2) variation, the influence of neutral wind becomes dominant. Among the results, we highlight an absence of winter anomaly in the Northern Hemisphere in 2014 and a stronger annual anomaly for latitudes under -20 degrees. Univ Autonoma Nuevo Leon, Fac Ciencias Fis Matemat, LANCE, Monterrey, Mexico Inst Nacl Pesquisas Espaciais, Sao Jose Dos Campos, Brazil Univ Nacl Autonoma Mexico, Inst Geofis, Unidad Michoacan, LANCE, Morelia, Michoacan, Mexico Inst Fed Educ Ciencia & Tecnol Sao Paulo, Jacarei, Brazil MIT, Haystack Observ, Westford, MA 01886 USA Univ Nacl Autonoma Mexico, Unidad Morelia, Escuela Nacl Estudios Super, Morelia, Michoacan, Mexico Univ Nacl Autonoma Mexico, Inst Geofis, Unidad Michoacan, CONACyT, Morelia, Michoacan, Mexico Univ Estadual Paulista, Dept Cartog, Presidente Prudente, Brazil Univ Estadual Paulista, Dept Cartog, Presidente Prudente, Brazil CNPq: 303643/2017-0 CONACYT: LN 293598 CONACYT: PN 2015-173 CONACYT: 220981 CONACYT: 253760 CONACYT: 256012 CONACYT: 2017-01-5955 CONACYT: 253691 CONACYT-AEM: 2017-01-292684 DGAPA-PAPIIT: IN106916 DGAPA-PAPIIT: IN104213 DGAPA-PAPIIT: IN109315-3 DGAPA-PAPIIT: IN104818-3 FAPESP: 2014/11198-9 CAPES: 1622967 DGAPA-PAPIIT project: IN101718 NSF: AGS-1242204 National Science Foundation: EAR-1338091 NASA-ROSES: NNX12AQ08G UNAM-PAPIIT: IA107116 UNAM-PAPIIT: IN118119

Using airglow images observed at São João do Cariri (7.4ºS, 36.5ºW; dip angle: -11ºS) from September 2000 to April 2007, plasma bubblezonal drifts for ninety-seven geomagnetically quiet nights (Dst index higher than -30 nT) were calculated. The plasma bubble eastward averaged drifts presented an increase from 18:00 to 22:00 local time (LT), and followed by a deceleration. The plasma bubbles observed during high solar activity were faster after 22:00 LT. Eastward drifts observed during the summer, after 21:00 LT, were higher than drifts observed during the equinox months. Few nights had plasma bubble eastward drifts higher than 100 m/s and almost all bubbles disappeared after 02:00 LT. Averaged zonal drifts observed between -9.5 and -5.5ºS were almost constant, primarily,around 23:00 LT. Usando imagens de aeroluminescência coletadas em São João do Cariri (7,4ºS, 36,5ºW; latitude de dipolo magnético: -11ºS) no período de setembro de 2000 a abril de 2007, foi possível calcular a deriva zonal de bolhas de plasma em noventa e sete noites geomagneticamente calmas (índice Dst maior que -30 nT). As derivas zonais médias das bolhas de plasma aumentaram das 18:00 até as 22:00 horas locais (HL) e desaceleraram em seguida. As bolhas de plasma observadas durante a atividade solar alta foram mais rápidas após as 22:00 HL. As derivas zonais de bolhas de plasma no verão, depois das 21:00 HL, foram maiores que nos meses de equinócio. Poucas noites apresentaram bolhas de plasma com derivas superiores a 100 m/s e quase todas as bolhas desapareceram depois das 02:00 HL.As derivas médias zonais observadas entre -9,5 e -5,5ºS foram praticamente constantes, principalmente, por volta das 23:00 HL.

Neste trabalho, o parâmetro η de Krassovsky, foi utilizado para investigar as amplitudes e fases das variações periódicas das emissões de airglow do O2(0-1) e do OH(6-2). As observações foram realizadas por meio de fotômetro em Rikubetsu (43,5ºN; 143,8ºE), Japão, no período compreendido entre março de 2004 e agosto de 2005, em colaboração com o grupo do Laboratório do Ambiente Solar-Terrestre da Universidade de Nagoya (STEL-LAB). Os valores médios obtidos foram de |η| = 5,3 ± 1,7 e Φ = -40,2º± 30,6º para a emissão do O2; e |η| = 8,0 ± 4,7 e Φ = -41,9º± 41,4º para a emissão do OH. Em ambas as emissões, houve uma boa concordância dos resultados obtidos com aqueles presentes na literatura. Porém, deve ser enfatizado que os modelos concordam melhor com os valores de |η| do que para Φ. Para a emissão do OH, foram obtidos valores de |η| mais elevados do que normalmente é verificado em trabalhos experimentais. Esses resultados se ajustam muito bem ao modelo de Schubert et al. (1991), para uma onda de gravidade com comprimento horizontal de 100 km. In this work, the Krassovsky's η parameter, was used to investigate the amplitudes and phases of periodic variations of O2(0-1) and OH(6-2) airglow emissions. The data set was obtained from photometer measurements at Rikubetsu (43.5ºN, 143.8ºE), Japan, from March 2004 to August 2005, under collaboration with STEL-LAB (Solar-Terrestrial Environment Laboratory), Nagoya University. The results showed |η| = 5.3 ± 1.7 and Φ = -40.2º± 30.6º for O2 emission, and|η| = 8.0 ± 4.7 and Φ = -41.9º± 41.4º for OH emission. There is a good agreement between the results obtained in this work with the previous results. But, it must be emphasized that the models for Φ don't predict the results as good as the models for |η|. It was found the existence of larger |η| values for the OH emission, so that there are few results in literature concerning of this high values. Comparing it with the models of Schubert et al. (1991), it was observed that they have good correlation with the model for a gravity wave with a horizontal wavelength of 100 km.

Background: Gastric carcinoma occurs at a high rate in alcoholic Japanese men. Inactive heterozygous aldehyde dehydrogenase-2 (ALDH2*1/2*2) and macrocytosis (mean corpuscular volume [MCV] ≥ 106 fl) enhance the risk for esophageal carcinoma, which frequently occurs with gastric carcinoma in this population. Whether alcoholism affects Helicobacter pylori-induced chronic atrophic gastritis (CAG) is unknown. Methods: This study of Japanese alcoholic men with (n = 45) and without (n = 281) gastric carcinoma included assessment of H. pylori IgG antibody, serum pepsinogen-confirmed CAG, MCV, and ALDH2 genotype. Results: The gastric carcinoma cases had a significantly higher age-adjusted prevalence of H. pylori-positivity (78%vs 57%), CAG (78%vs 42%), ALDH2*1/2*2 (36%vs 14%), MCV ≥106 fl (38%vs 20%), and concurrent esophageal/oropharyngolaryngeal carcinoma (18%vs 5%) than controls. Among gastric cancer-free controls, the prevalence of CAG was higher than generally reported in Japan, regardless of H. pylori status (H. pylori-positive, 56%vs 35–36% for Japanese general population; H. pylori-negative, 8%vs 1–3%). Alcoholism may accelerate the progression of CAG. Each of these factors increased the risk of gastric carcinoma (ORs = 3.7 for H. pylori-positive, 2.7 for non-severe CAG, 8.7 for severe CAG, 3.5 for ALDH2*1/2*2, 2.5 for MCV ≥106 fl, and 3.7 for concurrent carcinoma). A multivariate analysis showed that CAG and ALDH2*1/2*2 were independently related to the risk of gastric carcinoma. Combinations of CAG and ALDH2*1/2*2 showed greater risks of gastric carcinoma (ORs = 4.0 for non-severe CAG alone, 17.6 for severe CAG alone, 9.7 for ALDH2*1/2*2 alone, 17.1 for non-severe CAG plus ALDH2*1/2*2, and 39.2 for severe CAG plus ALDH2*1/2*2). Conclusions: Combining blood tests for H. pylori, CAG, MCV and ALDH2 genotype could offer a new means of predicting risk of gastric carcinoma in Japanese alcoholic men.

Perfis de temperatura obtidos pelo satélite CHAMP nos anos de 2001 a 2005 foram utilizados para determinar a atividade de ondas de gravidade na região da baixa estratosfera sobre a América do Sul. Os resultados encontrados para a energia potencial integrada, entre 24 e 34 km de altitude, mostraram uma variação interanual na atividade de ondas de gravidade, com uma maior atividade de ondas em torno da região equatorial. Para melhor avaliar a variação da atividade de ondas de gravidade, foi determinada a energia potencial média integrada entre (10ºN-10ºS) e (100ºO- 20ºO). Os resultados da energia potencial média mostraram uma variação sazonal da atividade de ondas de gravidade. O inverno foi a estação do ano com a menor atividade de ondas, enquanto que a primavera apresentou um aumento na atividade de ondas. A atividade de ondas de gravidade na baixa estratosfera, inferida através da energia potencial média, apresenta claramente um aumento nos anos de 2002 e 2004 e uma diminuição nos anos de 2003 e 2005. Stratospheric gravity wave activities were deduced from GPS radio occultation temperature profiles obtained by CHAMP satellite between 2001 and 2005. Potential energy profiles are used to analyze the gravity wave activity over South America. The results showed an inter-annual variation of the potential energy integrated between 24 and 34 km of altitude. The gravity wave activity is more concentrated around the equatorial region. In order to evaluate the seasonal variation of the gravity wave activity, a mean potential energy was determined over (10ºN-10ºS) and (100ºW-20ºW). The results showed a lower gravity wave activity during winter time, while during spring time the mean potential energy showed an increase in the wave activity. The results of the mean potential energy also showed that the gravity wave activity in the lower stratosphere exhibits a higher wave activity during 2002 and 2004 and a lower wave activity during 2003 and 2005.

Simultaneous observations of the atmospheric neutral winds in the mesosphere and lower thermosphere (MLT) by meteor radar have been carried out at SJodo Cariri (7.4 ◦ S, 36.5 ◦ W) and Cachoeira Paulista (22.7 ◦ S, 45.0 ◦ W). From the wind variability we investigate the atmospheric planetary-scale quasi-two-day waves, which were present at both the sites during the winter of 2004 and summer of 2004/2005. The amplitude of the meridional component was larger than that of the zonal component, reaching a maximum value of � 60 m/s at the equatorial site and � 25 m/s at the low latitude site during the winter. During the January-February period the 2-day wave was very similar at the two sites, with a maximum amplitude of � 50 m/s. The phase propagation with height shows a descending mode and upward energy propagation. The vertical wavelength estimated for Cachoeira Paulista (40-67 km) was longer than for SJodo Cariri (30-35 km), for all of the observed events. Cross-spectral analysis showed a significant coherence between the quasi-two-day oscillations observed at the two sites. From the phase difference between the two sites we concluded that SJodo Cariri leads Cachoeira Paulista. These results denote that amplitude peak at 36.5 ◦ W and subsequently at 45 ◦ W, compatible

The advent of new satellite missions, ground-based instrumentation networks, and the development of whole atmosphere models over the past decade resulted in a paradigm shift in understanding the variability of geospace, that is, the region of the atmosphere between the stratosphere and several thousand kilometers above ground where atmosphere-ionosphere-magnetosphere interactions occur. It has now been realized that conditions in geospace are linked strongly to terrestrial weather and climate below, contradicting previous textbook knowledge that the space weather of Earth's near space environment is driven by energy injections at high latitudes connected with magnetosphere-ionosphere coupling and solar radiation variation at extreme ultraviolet wavelengths alone. The primary mechanism through which energy and momentum are transferred from the lower atmosphere is through the generation, propagation, and dissipation of atmospheric waves over a wide range of spatial and temporal scales including electrodynamic coupling through dynamo processes and plasma bubble seeding. The main task of Task Group 4 of SCOSTEP's CAWSES-II program, 2009 to 2013, was to study the geospace response to waves generated by meteorological events, their interaction with the mean flow, and their impact on the ionosphere and their relation to competing thermospheric disturbances generated by energy inputs from above, such as auroral processes at high latitudes. This paper reviews the progress made during the CAWSES-II time period, emphasizing the role of gravity waves, planetary waves and tides, and their ionospheric impacts. Specific campaign contributions from Task Group 4 are highlighted, and future research directions are discussed.

In this paper, we investigate the role of eastward and upward propagating fast (FK) and ultrafast Kelvin (UFK) waves in the day-to-day variability of equatorial evening prereversal vertical drift and post sunset generation of spread F/plasma bubble irregularities. Meteor wind data from Cariri and Cachoeira Paulista (Brazil) and medium frequency (MF) radar wind data from Tirunelveli (India) are analyzed together with Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) temperature in the 40- to 100-km region to characterize the zonal and vertical propagations of these waves. Also analyzed are the F region evening vertical drift and spread F (ESF) development features as diagnosed by Digisonde (Lowell Digisonde International, LLC, Lowell, MA, USA) operated at Fortaleza and Sao Luis in Brazil. The SABER temperature data permitted determination of the upward propagation characteristics of the FK (E1) waves with propagation speed in the range of 4 km/day. The radar mesosphere and lower thermosphere (MLT) winds in the widely separated longitude sectors have yielded the eastward phase velocity of both the FK and UFK waves. The vertical propagation of these waves cause strong oscillation in the F region evening prereversal vertical drift, observed for the first time at both FK and UFK periodicities. A delay of a few (approximately 10) days is observed in the F region vertical drift perturbation with respect to the corresponding FK/UFK zonal wind oscillations, or temperature oscillations in the MLT region, which has permitted a direct identification of the sunset electrodynamic coupling process as being responsible for the generation of the FK/UFK-induced vertical drift oscillation. The vertical drift oscillations are found to cause significant modulation in the spread F/plasma bubble irregularity development. The overall results highlight the role of FK/UFK waves in the day-to-day variability of the ESF in its occurrence season.

目的:多形腺腫の特に筋上皮細胞の多様性を確認するために, 電子顕微鏡的および免疫組織化学的検討を行った.対象:細胞学的および組織学的に多形腺腫と診断された5例に, 電子顕微鏡的観察および免疫組織化学的染色 (cytokeratin, GFAP, vimentin, S-100, SMA) を行った.結果:(1) 多形腺腫の構成細胞は腺管細胞とそれ以外の細胞に分類でき, 腺管細胞は正常唾液腺の介在部腺管細胞に, それ以外の細胞は正常筋上皮細胞と所見が類似した.(2) 腺管以外の細胞は多様な細胞変化がみられ, 結合性の類円形～ 短紡錘形細胞はdesmosome結合が多く観察され, またcytokeratinに弱陽性を示し上皮性性格をもっていた.(3) 結合性が乏しく, 剥離性の紡錘形～ 扁平化生様細胞は正常筋上皮細胞と所見が最もよく一致した.(4) 粘液腫様背景にみられる星状～小円形細胞はpinocytotic vesiclesやglycogenなどが発達し, proteoglycan穎粒の産生がみられ, 軟骨化生様細胞に類似した.またGFAP, vimentin, S-100が陽性を示し多様な問葉系性格を呈した.(5) 時に腺管細胞の一部にglycogen, intermediate filamentの豊富な予備細胞または筋上皮細胞と思われる細胞が観察された.考察:この腫瘍の発生由来には唾液腺介在部の細胞が関係していると考えられた.特に多様な細胞変化は腫瘍性筋上皮細胞が主体を占め, この細胞は形態の多様性とともに性格の多様性もみられた.