Horizontal winds in the mesosphere at high latitudes

A total of 146 meteorological rocket flights applying the ‘falling sphere’ technique are used to obtain horizontal winds in the mesosphere at polar latitudes, namely at the Andøya Rocket Range (69°N, 125 flights), at Spitsbergen (78°N, 10 flights), and at Rothera (68°S, 11 January flights only). Nearly all flights took place around noon or midnight, i.e., in the same phase of the semidiurnal tide. Meridional winds at 69°N show a clear diurnal tidal variation which is not observed in the zonal winds. The zonal wind climatology shows a transition from summer to winter conditions with the zero wind line propagating upward from 40 km (end of August) to 80 km (end of September). Zonal winds are smaller at Spitsbergen compared to Andøya which is in line with a common angular velocity at both stations. Meridional winds at noon are of similar magnitude at all three stations and are directed towards the north and south pole, respectively. Horizontal and meridional winds generally agree with empirical models, except for the zonal winds at Antarctica which are similar to the NH, whereas there is a significant SH/NH difference in CIRA-1986.     

Proposals for an Indian standard tropical atmosphere up to 50 km

In an earlier report [1] the authors proposed an Indian Standard Tropical Atmosphere (ISTA1) from mean sea level to 20 km. This proposal describes adequately the mean conditions from 0° to about 30°N. The present work extends ISTA1 to the higher altitude of 50 km based oni. World Data Center A reports on Rocket firings [2],ii. M-100 rocket data for Thumba, India [3],iii. Northern Reference Atmospheres data of Cole and Kantor [4], andiv. Southern Reference Atmospheres data of Koshelkov [5].The proposed atmosphere, called ISTA7, has a sea level temperature of 30°C and a constant lapse rate of 6.5°C/km up to 16 km, as in ISTA1; from a temperature of -74°C at this altitude, there is a constant lapse rate of -2.3°C/km up to 46 km where the temperature is -5°C; the temperature remains constant thereafter up to 50 km. The fact that variations with longitude are weak except at very high latitudes [4], together with the fact that around 50 km, the temperature increases from low to high latitudes, lead us to propose a constant temperature of -5°C between 46 and 50 km, even though this temperature is slightly higher (by about 5°C) than the Thumba data.$\text{1}$/     

Hybrid quadri-ionic model of the lower ionosphere

An ion model of the lower ionosphere is proposed. It consists of four positive ions: O₂⁺, NO⁺ and two cluster ions - a simpler CI₁ and a more complex CI₂. This model well explains the normal component of the winter anomaly (WA) in the D-region, which is recorded by absorption measurements on short radiowaves and rocket experiments at middle (40°N) and high (70°) latitudes. The higher values of the electron density during the winter appear as a result of the lower recombination because of smaller rates of cluster ion formation, i.e. the normal WA can be explained and modelled by the regular seasonal variations of composition, temperature and density.     

冬季西北地区临近空间气象火箭探测数据分析

在获取冬季西北地区一次临近空间气象火箭探测数据后,将火箭探测温度、密度与MSIS00模式和TIMED/SABER卫星数据进行对比,并将火箭探测风场与HWM07模式和MERRA再分析资料进行对比,分析火箭探测温度误差组成,计算各项温度修正量。结果表明:火箭、卫星、MSIS00模式获取的温度和密度随高度整体变化趋势一致;相对于MSIS00模式,火箭和卫星实测数据能够反映出更多的变化细节,且二者在细节上具有较多一致性。火箭实测风场与MERRA的一致性较好,而与HWM07模式差异较大,在平流层中部火箭探测风场明显强于HWM07模式。相对于HWM07模式和MERRA,火箭探测风场能够体现更多细节,在22 km和45 km附近均探测到较强的风切变。在火箭探测温度的各项修正量中,气动加热、温度滞后、支撑结构热传导及测量电流焦耳效应带来的影响较大,该影响整体上随着高度降低而逐渐减小。分析表明,本次气象火箭获取的探测数据是有效可靠的,但在数据处理方法尤其是温度误差修正等方面还需不断迭代完善。      

Proposal for a reference model of the middle atmosphere of the southern hemisphere

Available rocketsonde information has been used to compile tables of monthly mean temperature, pressure, density and zonal wind for the middle atmosphere of the southern hemisphere with the purpose of revising similar tables presented to COSPAR earlier. The altitude range is 25 to 80 km in steps of 5 km. The latitude range is 0° to 70°S with a 10° step. The compatability of different sets of temperature measurements is discussed. Mean values of temperature, pressure and zonal wind obtained for the southern hemisphere are compared with northern hemisphere model values. Large differences between the hemispheres (up to 20°C in temperature, 20–30% in pressure, 30–50 m/s in wind) imply that reference atmospheres such as CIRA should be complemented by southern hemisphere climatology.     

Periodic and aperiodic ozone variations in the middle and upper stratosphere

Umkehr, ozonesonde and satellite observations were used to determine the height/latitude distribution of the amplitude and phase of the periodic components of the variation of the ozone mixing ratio in the middle and upper stratosphere. The amplitude of the first (annual) harmonic is small in the subtropics and increases to a maximum at polar latitudes. It also increases with height in the mid and upper stratosphere to an apparent maximum just below the stratopause. The second (semi-annual) harmonic has an amplitude that is largest in tropical regions and in subpolar regions at a level of about 40 km. There seems to be very little ozone variation above 30 km with dominant periods close to the quasi-biennial period of total ozone observed in the tropics. The percent of the total variance of the ozone mixing ratio accounted for by the first harmonic is larger than 60 percent at all heights from 20° – 60° latitude in both hemispheres (except near 40 km in the Northern Hemisphere). The percent of the total variance accounted for by the second harmonic is maximum at a height of about 40 km in the tropics and at subpolar latitudes where, as mentioned, its amplitude is also largest.The phase of the first harmonic shows a marked transition from a winter/spring maximum below 30 km to a summer maximum at 30 km, changing rapidly to a maximum in winter in both hemispheres. The regions of minimum amplitude of the annual variation and the marked phase shifts with height both indicate the separation by levels of the dominant physical control mechanisms on the periodic changes of the ozone mixing ratio in the middle and upper stratosphere. Changes below 30 km respond primarily to dynamic influences in the lower stratosphere while above 30 km the periodic variations result mainly from photochemical processes. Above 40 km these variations are strongly temperature dependent.     

High altitude flights in equatorial regions

A thorough analysis of balloon flights made from Hyderabad, India (Latitude 17°28′N, Longitude 78°35′E), and other equatorial sites has been made. It has been shown that limited success is expected for flights made from equatorial latitudes with balloons made out of natural colour polyethylene film, since the best known balloon film in the world today viz. Winzen Stratofilm is tested for low temperature brittleness only at ?80°C., whereas the tropopause temperatures over equatorial latitudes vary between ?80°C and ?90°C. The success becomes even more critical when flights are made with heavy payloads and larger balloons particularly at night when in the absence of solar radiation the balloon film becomes more susceptible to low temperature brittle failure. It is recommended that in case of capped balloons longer caps should be used to fully cover the inflated protion of the balloon at the higher level equatorial tropopause. It is also advised that the conditions such as wind shears in the tropopause should be critically studied before launching and a day with the tropopause temperature nearer to ?80°C should be chosen. Special care also should be taken while handling the balloon on ground and during launching phase. Properties of Winzen Stratofilm have been critically studied and fresh mandates have been recommended on the basis of limiting values of film stresses which caused balloon failures in the equatorial tropopause. It is also emphasized that the data on such flights is still meagre especially for flights with heavy payloads and larger balloons. It has been also shown that it is safest to use balloons made out of grey coloured film which retains its flexibility with the absorption of solar radiation, the success obtained with such balloons so far being 100%. The drawback, however, is that these balloons cannot be used for night flights. Stratospheric wind regimes over Hyderabad are also discussed with a view to determine the period over which long duration flights can be made. The data available, however, is meagre and it is recommended that more frequent special wind ascents be made to collect adequate statistical data from which reliable conclusions could be drawn through critical analysis.     

Responses of the upper middle atmosphere (60–110 km) to the stratwarms of the four pre-map winters (1978/9–1981/2)

The global developments of the four stratospheric events (～20–50 km) are described, using balloon, satellite and rocket data. Winds data for heights of 60–95 km, derived from L.F. drift (52°N, 15°E; Europe) and M.F. radar (52°N, 107°W; Canada), are then compared with the stratospheric data. There is clear evidence that the preliminary planetary waves often penetrate strongly to ～90 km, and that mean wind reversals also occur. However, there are dramatic differences between European and Canadian mesospheric responses.     

Recent results on the Venus atmosphere from pioneer Venus radio occultations

Radio occultation measurements of the temperature structure of the Venus atmosphere have been obtained during seven occultation “seasons” extending from December 1978 to December 1983. Approximately 123 vertical profiles of temperature from about 40 km to about 85 km altitudes have been derived. Since these measurements cover latitudes from both poles to the equator, they have shown the latitudinal dependence of thermal structure. There is a smooth transition from the troposphere to the mesosphere at latitudes below about 45°, with the tropopause at about 56 km. The troposphere then rises to about 62 km in the “collar cloud” region between about 60° and 80° latitude, where a strong temperature inversion (up to 30 K) is present. In the polar areas, 80°–90°, the mesosphere becomes isothermal and there is no inversion. This latitudinal behavior is related to the persistent circulation pattern, in which a predominantly zonal retrograde motion at latitudes below 45° gradually changes to a circumpolar vortex at the “collar cloud” latitudes. Indeed, the radio occultation data have been used in a cyclostrophic balance model to derive zonal winds in the Venus atmosphere, which showed a mid-latitude (50°–55°) jet with a speed of about 120–140 ms^?1 at about 70 km altitude /1,2/. The observations obtained in 1983 and 1984 have shown that above the tropopause there is considerable temporal variability in the detailed thermal structure, suggesting that the persistent circulation pattern is subject to weather-like variability.     

Study of seasonal variation of winds in upper stratosphere over Hyderabad

A predictability of the stratospheric zonal winds above 38 km during the turnaround is an essential parameter for planning of the high-altitude scientific balloon flights. This information is more relevant in the case of Hyderabad balloon facility which is closer to equator and has much more unstable wind reversal patterns which appears to have changed enormously during the last decade probably in correlation with the global warming. With a majority of our flights reaching the altitudes of 38–42 km and the requirement of long float durations, a prior knowledge of wind pattern during the summer and winter turnaround seasons is highly desirable. Furthermore, the flight operation corridor for balloon flights from Hyderabad is limited to 400 km and though in the west direction there are flat lands, in all other three directions, the landscape is dotted by water bodies, reserve forests and hilly terrain, and therefore need of such a data is essential. In order to establish the climatology of the stratospheric winds and study their inter-annual variability over Hyderabad for the turnaround periods, we have made a detailed analysis of the United Kingdom Meteorological office data between 2000 and 2007, to derive average wind parameters (magnitude, direction) at different ceiling altitudes above 38 km. These results can be used only as general trend of stratospheric wind and should not be the limitation of the UKMO Data.     

基于瑞利激光雷达对格尔木地区中间层逆温层特征分析

利用MARMOT （Middle Atmosphere Remote Mobile Observatory in Tibet）激光雷达对2014年7月至12月格尔木（36.25°N,94.54°E）上空的中间层逆温层MIL （Mesosphere Inversion Layer）事件进行研究分析.格尔木MIL现象的发生频率为53.8%,其中冬季（12月）发生频率最高,达76%;秋季（9-10月）较高,为60%;夏季（7-8月）发生频率较低,为29%.2014年7月至12月观测到的MIL逆温幅度主要分布在5～20K,平均逆温幅度为15.9K.秋季逆温层底部高度较高,主要分布在77～84km,冬季和夏季逆温层底部高度较低,主要分布在64～74km.逆温层底部高度平均为75.1km.逆温层的平均宽度为8.7km,由夏季到冬季呈递增趋势.      

Semi-annual variations of chlorophyll concentration on the Eastern Tropical Pacific coast of Mexico

An analysis of the main remotly sensed oceanographic variables was conducted to characterize the dominant drivers that modulate the spatial-temporal variability of coastal phytoplankton biomass in the northern limit of the Eastern Tropical Pacific. The phytoplankton biomass was analyzed using monthly average satellite chlorophyll (Chlo) concentration data from MODIS sensors for the period 2003–2017. Oceanographic conditions were analyzed by considering (i) Sea Surface Temperature (SST) high-resolution data from the GHRSST project, (ii) wind stress calculated with data from the zonal and meridional components of the CCMP product, (iii) climatological precipitation, and (iv) climatological river flow. Chlo time series and spatial variability were analyzed using Hovmöller diagrams and Empirical Orthogonal Functions (EOF), respectively. A strong semi-annual signal in Chlo concentration along the coast was observed: the first peak occurs in winter-spring (5.0 mg·m⁻³) and a second one in summer-autumn (6.5 mg·m⁻³). A high year-round average of Chlo concentration (3.0–15.0 mg·m⁻³) was maintained by a 10 km wide along-shore coast, with maximum values spatially associated with river mouths, of which Santiago river registered the highest Chlo values (20.0 mg·m⁻³). Surface oceanographic conditions showed a marked annual cycle with warmer conditions (30–31 °C) from July to October and colder ones (23–24 °C) from December to April; during the cold period, seasonal wind stress stimulated coastal upwelling. The EOF showed that 70% of Chlo concentration variability was controlled by the semi-annual pattern, which responded to coastal upwelling conditions during cold period, while rivers outflows influenced high Chlo concentration during the warm period. These results highlighted the importance for land-ocean interface to sustain coastal ecosystems' biological production and the major role of watersheds as sources of nutrients to maintain high biological production during warm periods in transitional tropical-subtropical zones.     

Measurement of turbulent kinetic energy dissipation rates in the mesosphere by a 3 MHz Doppler radar

A new narrow beam Doppler radar operating at 3.17 MHz has been installed close to the Andøya Rocket Range in Andenes, Norway in summer 2002 in order to improve the ground based capabilities for measurements of turbulence in the mesosphere. The main feature of the radar is a Mills Cross transmitting/receiving antenna consisting of 29 crossed half-wave dipoles. In combination with the modular transceiver system this provides high flexibility in beam forming and pointing. In general, vertical and oblique beams with a minimum one way half-power full-beam width (HPFW) of 6.6° are used. The observations are usually performed with a height resolution of 1 km and with off-zenith beams at 7.3° directed towards NW, NE, SE, and SW. Turbulence intensities have been estimated from the width of the observed signal spectra using an computationally intensive correction method which requires precise knowledge of the antenna radiation pattern. The program uses real-time measurements of the wind field in all determinations. Turbulent kinetic energy dissipation rates based on radar observations are presented and compared with corresponding climatological summer and winter profiles from rocket measurements, as well as with single profiles from model runs for selected periods from September 2003 to Summer 2004. The mean turbulent kinetic energy dissipation rates based on these radar measurements are about 5 mW/kg at 60 km altitude and about 20 mW/kg at 80 km, in reasonable agreement with mean turbulence intensities obtained from previous rocket soundings at Andenes.     

Structure of the equatorial lower ionosphere from the Thumba Langmuir probe experiments

A Langmuir probe designed and developed at the Physical Research Laboratory, Ahmedabad has been used on a variety of rockets since 1966 from the Thumba Equatorial Rocket Launching Station, TERLS (8°31'N, 76°52'E, dip.lat. 0°47'S) to study the structure of the equatorial lower ionosphere. Good quality data is available from a set of twenty five rocket flights conducted during the period 1966 to 1978. This data has been obtained using a single standardised instrument at a single location and using a uniform procedure for data reading and analysis, and adopting a calibration procedure to convert the measured probe currents into electron densities which involves a height dependent calibration factor. The data has been used to establish the gross features of the equatorial lower ionosphere under daytime, night time, morning twilight and evening twilight periods.     

中国廊坊中间层和低热层大气平均风观测模拟

利用中国廊坊站（39.4°N,116.7°E）流星雷达在2012年4月1日至2013年3月31日的水平风场观测数据,分析廊坊上空80~100km的中间层与低热层（Mesosphere and Lower Thermosphere,MLT）大气平均纬向风和经向风的季节变化特征.结果表明平均纬向风和经向风都表现出明显的季节变化特征.平均纬向风在冬季MLT盛行西风,极大值位于中间层顶,随高度增加西风减弱;在夏季中间层为东风,低热层为强西风,风向转换高度约为82km.平均经向风在冬季以南风为主,在夏季盛行北风.纬向风和经向风在春秋两季主要表现为过渡阶段.流星雷达观测结果与WACCM4模式和HWM93模式模拟的气候变化特点基本一致,但WACCM4模式纬向风和经向风风速偏大,而HWM93模式纬向风和经向风风速偏小.      

The 16-day waves in the mesosphere and lower thermosphere over Wuhan (30.6°N, 114.5°E) and Adelaide (35°S, 138°E)

Winds from a meteor radar at Wuhan (30.6°N, 114.5°E) and a MF radar at Adelaide (35°S, 138°E) are used to study the 16-day waves in the mesosphere and lower thermosphere (MLT). The height range is 78–98 km at Wuhan and 70–98 km at Adelaide. By comparison, it is found that the zonal components at both sites are generally larger than the meridional ones, and eastward motion of the zonal background winds is favorable for the 16-day waves penetration to the MLT region. The zonal maximum amplitude appears in the autumn (September–October) around 86–98 km at Wuhan and in the winter months and early spring (July–October) around 72–82 km at Adelaide. Differences are found in wave amplitudes and time of appearance between the two years of 2002 and 2003. In 2003, the intensity of the wave amplitudes is relatively smaller than that for 2002 at both sites. The summer 16-day waves are comparatively weaker at Adelaide in both years, but stronger in 2002 at Wuhan near the mesopause and the lower thermosphere (86–98 km). The strong summer waves at Wuhan may come from the winter southern hemisphere.     

激光雷达观测的武汉上空对流边界层高度与夹卷层厚度

基于地基偏振激光雷达2011年1月至2017年12月对武汉中心城区的观测资料，研究了超大城市对流边界层高度与夹卷层厚度的变化特征.采用Fernald方法进行数据反演获得了1min时间分辨率、30m空间分辨率的后散比剖面，通过方差法确定了对流边界层高度和夹卷层厚度.结果表明，武汉上空对流边界层高度和夹卷层厚度具有明显的季节变化特征.对流边界层顶的均值最大处在春季为1.14km，夏季为1.25km，秋季为1.06km，冬季为0.74km；夹卷层厚度均值最大处在春季为0.40km，夏季为0.51km，秋季为0.34km，冬季为0.26km.这些特征与武汉地区地表温度的周年变化特征具有很强的相关性.      

Microgravity experiment system utilizing a balloon

A system for microgravity experiments by using a stratospheric balloon has been planned and developed in ISAS since 1978. A rocket-shaped chamber mounting the experiment apparatus is released from the balloon around 30 km altitude. The microgravity duration is from the release to opening of parachute, controlled by an on-board sequential timer. Test flights were performed in 1980 and in 1981. In September 1983 the first scientific experiment, observing behaviors and brain activities of fishes in the microgravity circumstance, have been successfully carried out. The chamber is specially equipped with movie cameras and subtransmitters, and its release altitude is about 32 km. The microgravity observed inside the chamber is less than 2.9 × 10^?3 G during 10 sec. Engineering aspects of the system used in the 1983 experiment are presented.     

The parameters of shock acoustic waves generated during rocket launches

We investigate the form and dynamics of shock acoustic waves (SAW) generated during the launching of rockets Proton and Soyuz from the Baikonur cosmodrome in 1998–2000. In spite of the difference of geophysical conditions, the ionospheric response for all launchings had the character of an N-wave with a period of about 300 s and with an amplitude far exceeding background fluctuations. The angle of elevation of the SAW wave vector varies from 30° to 65°, and the SAW phase velocity (800–1200 m/s) approaches the sound velocity at heights of the ionospheric F region maximum. The position of the SAW source, inferred by neglecting refraction corrections, corresponds to the segment of the rocket path at a distance no less than 700–900 km from the launch pad, which is consistent with the estimated delay time of SAW source triggering (250–300 s).     

Positive ion composition and electron density in a combined auroral and NLC event

The positive ion composition and electron density were measured in the lower ionosphere above Kiruna in salvo A of CAMP (Cold Arctic Mesopause Project). The CAMP/P (S37/P) payload carrying a magnetic ion spectrometer, positive ion and electron probes, and propagation experiments was launched on 3 August 1982 2332 UT during extended Noctilucent Clouds (NLC) and auroral activities over Kiruna. The measured electron density was 5×10³cm^?3 at 80 km and 2.5×10⁵cm^?3 at 90 km. The increase of ion and electron densities in the D- and E-region during twilight was caused by precipitating auroral particles. The height distribution of the positive ions measured by the mass spectrometer in the mass range 19–280 amu is different from a winter flight with similar auroral conditions. Below 85.5 km proton hydrates H⁺(H₂O)₃ ? H⁺(H₂O)₈ were the dominant ions. The heaviest proton hydrates H⁺(H₂O)₇ and H⁺(H₂O)₈ were most abundant at 82–85.5 km, the altitude of visible NLC. Above 85.5 km O₂⁺ and NO⁺ became dominant. A small metal ion layer was observed between 90.5–93 km with a maximum ion density of 10% of the total positive ion density at 91 km altitude. The metal ion density disappeared within about a km below 90.5 km.