Search

The results of studying the influence of internal gravity waves (IGWs) on the spatiotemporal variability of atmospheric pressure and wind velocity in the lower troposphere using a triangular network of three microbarographs and an antihail acoustic cannon installed in Talin (Armenia) are presented. By coherent analysis of pressure fluctuations measured at different points, IGWs generated by thunderstorm fronts about 5–6 h before the passage of the fronts over the network of microbarographs have been detected. The regularities of changes in phase speeds and propagation directions of IGWs as thunderstorm precursors with time are studied. The possibility of IGW monitoring in the troposphere by measuring temporal fluctuations of the travel time of acoustic pulses along the ray-paths connecting the antihail cannon with spatially separated acoustic receivers has been demonstrated. Vertical profiles of wind velocity fluctuations in certain layers of the lower troposphere up to a height of 800 m have been retrieved from the shapes and travel times of acoustic pulses having a shock front and scattered by anisotropic fluctuations of wind velocity and temperature in the stably stratified lower troposphere. Owing to the high vertical resolution (on the order of 1 m) of the method of pulsed acoustic sounding of the lower troposphere used here, the vertical spectra of anisotropic fluctuations of wind velocity in the range of short vertical scales, from one to tens of meters, are obtained for the first time and theoretically interpreted. [ABSTRACT FROM AUTHOR]

Despite lower‐troposphere wind flow being a major control of rainfall in equatorial Africa, no studies have systematically compared winds from multiple reanalyses nor have attempted to validate the wind directions. Therefore, the objectives of this study are to assess differences in wind directions among multiple reanalysis products and compare reanalysis winds with wind measurements made at weather stations. The study region is western Uganda, part of the transition region between western equatorial Africa (WEA) and eastern equatorial Africa (EEA). Four‐times daily (i.e., 0Z, 6Z, 12Z and 18Z) 10‐m and 850‐hPa winds from 1980 to 2021 are obtained for ECMWF Reanalysis v5 (ERA5), Japan Meteorological Agency 55‐year Reanalysis (JRA55), Modern‐Era Retrospective analysis for Research and Applications Version 2 (MERRA2), NCEP‐NCAR Reanalysis 1 (R1) and NCEP/DOE Reanalysis II (R2). Wind measurements at 10 m and 850 hPa are obtained for six weather stations and two weather stations, respectively. Agreements between pairs of products and between measurements and reanalysis estimates are determined. In addition, differences between reanalyses and measurements with respect to wind vectors are calculated. Results show that the majority of reanalyses have western Uganda within the prevailing easterly flow over EEA and east of the prevailing westerly flow over WEA. Ten‐meter wind measurements also show easterly flow being prevalent throughout western Uganda. R1 is unique among the products due to a relatively large number of westerly days. However, much of the westerly flow is likely artificial, based on station data. MERRA2 has large easterly biases. JRA55 is much more accurate than the other products at reproducing the intra‐annual frequencies of wind directions. JRA55 and ERA5 are the least biased products based on the magnitudes of difference vectors. Therefore, it is recommended that JRA55 and ERA5 continue to be used in examinations of winds in western Uganda. [ABSTRACT FROM AUTHOR]

Aircraft observations made off the coast of northern Chile in the Southeastern Pacific (20 degrees S, 72 degrees W; named Point Alpha) from 16 October to 13 November 2008 during the VAMOS Ocean-Cloud-Atmosphere-Land Study-Regional Experiment (VOCALS-REx), combined with meteorological reanalysis, satellite measurements, and radiosonde data, are used to investigate the boundary layer (BL) and aerosol-cloud-drizzle variations in this region. On days without predominately synoptic and meso-scale influences, the BL at Point Alpha was typical of a non-drizzling stratocumulus-topped BL. Entrainment rates calculated from the near cloud-top fluxes and turbulence in the BL at Point Alpha appeared to be weaker than those in the BL over the open ocean west of Point Alpha and the BL near the coast of the northeast Pacific. The cloud liquid water path (LWP) varied between 15 gm(-2) and 160 gm(-2). The BL had a depth of 1140 +/- 120 m, was generally well-mixed and capped by a sharp inversion without predominately synoptic and mesoscale influences. The wind direction generally switched from southerly within the BL to northerly above the inversion. On days when a synoptic system and related mesoscale costal circulations affected conditions at Point Alpha (29 October-4 November), a moist layer above the inversion moved over Point Alpha, and the total-water mixing ratio above the inversion was larger than that within the BL. The accumulation mode aerosol varied from 250 to 700 cm(-3) within the BL, and CCN at 0.2% supersaturation within the BL ranged between 150 and 550 cm(-3). The main aerosol source at Point Alpha was horizontal advection within the BL from south. The average cloud droplet number concentration ranged between 80 and 400 cm(-3). While the mean LWP retrieved from GOES was in good agreement with the in situ measurements, the GOES-derived cloud droplet effective radius tended to be larger than that from the aircraft in situ observations near cloud top. The aerosol and cloud LWP relationship reveals that during the typical well-mixed BL days the cloud LWP increased with the CCN concentrations. On the other hand, meteorological factors and the decoupling processes have large influences on the cloud LWP variation as well.

The effect of the aerosol vertical distribution on photolysis frequencies of O3 and NO2 is studied. Aerosol measurements in Raciborz (50.08° N, 18.19° E), Poland, made using the CIMEL Sun photometer and collocated CHM-15k “Nimbus” ceilometer are analyzed for the period 2015–2020. Vertical profiles of the aerosol extinction are derived from the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm combining the ceilometer measurements of the aerosol backscattering coefficient with the collocated CIMEL measurements of the columnar characteristics of aerosols. The photolysis frequencies are calculated at the three levels in the lower troposphere (the surface and 0.5 and 2 km above the surface) using a radiative transfer model, Tropospheric Ultraviolet and Visible (TUV), for various settings of aerosol optical properties in the model input. The importance of the aerosol vertical distribution on photolysis frequencies is inferred by analyzing statistics of the differences between the output of the model, including the extinction profile from the GRASP algorithm, and the default TUV model (based on columnar aerosol characteristics by the CIMEL Sun photometer and Elterman’s extinction profile). For model levels above the surface, standard deviation, 2.5th percentile, 97.5th percentile, and the extremes, calculated from relative differences between these input settings, are comparable with the pertaining statistical values for the input pair providing changes of photolysis frequencies only due to the variability of the columnar aerosol characteristics. This indicates that the vertical properties of aerosols affect the distribution of the photolysis frequencies in the lower troposphere on a similar scale to that due to variations in columnar aerosol characteristics.

The role of cyclones in atmospheric mixing and troposphere–stratosphere exchange of ozone and relative humidity (RH) is investigated for two severe cyclones PHAILIN and HUDHUD over the Bay of Bengal. Ozone concentration from Microwave Limb Sounder along with RH profiles obtained from Sounder for Probing Vertical Profiles of Humidity instrument aboard Meghatropiques platform, upon analysis at different pressure levels, revealed a rapid increase in RH and ozone concentration from lower troposphere to upper troposphere one day prior to landfall for both cyclones. The Weather Research and Forecasting model based simulations of convergence and divergence were used to estimate mass and momentum exchanges between troposphere and stratosphere which suggest the drastic increase in RH and ozone concentrations in UT due to high convective activity. Variations in the vertical profiles of ozone and RH during cyclonic period acts as a tracer for stratosphere–troposphere exchanges during peak cyclone intensity period.

Abstract This study analyzes the variability of winter haze days and visibility in the Beijing-Tianjin-Hebei (BTH) region, in relation to the regional average wind speed changes in the lower troposphere and emissions for 1961–2014. Winter mean surface meteorological data, NCEP/NCAR atmospheric reanalysis data, and fossil fuel emission data are used. The results reveal a significant increase in the haze days of +0.8 days decade−1 (p <.01), and a subsequent decline in visibility of −1.56 km decade−1 (p <.01). Most interestingly, an accelerated increase in the number of haze days was observed for the last 11-year period (+8.3 days decade−1, p <.01) of the study period (2004–2014). Regression analysis indicates that the increase of haze occurrence and decrease in visibility are partly due to the significant (p <.01) declining trend of the mean wind speed in the lower troposphere (−0.19 m s−1 decade−1 at 10 m, (−0.23 m s−1 decade−1 at 925 hPa), and − 0.21 m s−1 decade−1 at 850 hPa), and partly due to the declining (dust storm frequency as a proxy, −0.41 days dec−1) surrounding particulate sources and increasing fossil fuel emissions (total carbon emission as a proxy, +48,206.8 thousand metric tons dec−1). Specifically, wind speed changes in the lower troposphere explain 41.3% of the interannual varation of the winter haze days and 71.2% of the visibility variance. These are extended to 51.7% and 81.6% respectively when combined with information about the natural (dust storm frequency) and anthropogenic (fossil fuel emissions) particulate sources. Therefore, the analyses show that wind speed changes in the lower troposphere, together with the varied natural and anthropogenic sources of particulates, play a key role in modulating winter haze and visibility conditions in the BTH area. Highlights • A significant increase in winter haze days and a decline in visibility in the Beijing-Tianjin-Hebei region was observed. • Weakened wind speed in the lower troposphere was adverse to the ventilation and long distance transport of haze particles. • The varied particles source from natural and human activity caused the increase of winter haze occurrence. [ABSTRACT FROM AUTHOR]

Seasonal and spatial characterizations of wind and stability in the lower troposphere below 1500 m are investigated using 1 s high-resolution operational radiosonde data observed at five stations (Baengnyeongdo, Heuksando, National Typhoon Center (NTC), Bukgangneung, and Pohang) in South Korea for 4 years (July 2016–June 2020), concentrating on four variables: horizontal wind speed (HWS), vertical wind shear (VWS), squared Brunt–Väisälä frequency (N2), and Richardson number (Ri). Significant seasonal variations are identified in these variables due to the heterogeneity of the geographical locations as well as seasonal variations in the synoptic patterns. VWS is high in spring and summer at two island stations on the west of the Korean Peninsula, Baengnyeongdo, and Heuksando, whereas it is high in winter at NTC, Bukgangneung, and Pohang, leading to frequent Kelvin–Helmholtz (KH) instability (KHI; 0 ≤ Ri < 1/4). Below z = 1000 m, static stability is lower in winter than in summer at all stations, resulting in a higher convective instability (Ri < 0) in winter, which is attributed to the inflow of the marine boundary layer. The frequent convective instability observed in spring at Bukgangneung suggests a potential relationship with mountain wave breaking and downslope windstorms. The microstructures of the lower tropospheric instabilities revealed in the current radiosonde observations are not properly represented in the high-resolution local numerical weather prediction and analysis system, namely local Data Assimilation and Prediction System (LDAPS) of Korea Meteorological Administration. In particular, the observed convective and KH instabilities, which are approximately 45% for the whole period, are rarely (approximately 15%) represented in LDAPS. The synoptic patterns favorable for the convective and KH instabilities cases are identified based on a self-organizing map clustering algorithm: (1) west-high and east-low patterns with extended Siberian high in winter, (2) strong low-pressure systems susceptible to KHI from spring to fall, (3) weak high-pressure systems with potential convective instability, accompanying northerly or north-westerly flows with cold advection at 925 hPa. • Seasonal and vertical variations of the lower troposphere are investigated. • Instability occurrences link to the marine boundary layer and local dynamics. • Local model underestimates vertical gradients, hindering instability representation. • Synoptic patterns for convective and Kelvin–Helmholtz instabilities are identified. • Cold advection with northerly flows at 925 hPa is crucial for instability generation. [ABSTRACT FROM AUTHOR]

This paper uses the comparative method in order to highlight the thermal anomalies, the impact of atmospheric circulation and the air masses through specific situations. Our preliminary study employs radio sounding data from Bucharest-Băneasa weather station, and this method is applied for an altitude interval bounded by Earth’s surface and the geopotential surface of 900hPa. Thus, the results have been obtained from radio soundings up to the 900 hPa level, which corresponds to an altitude of 1000 meters, because above this level, there is a tendency towards generalization due to the decreased influence of the subjacent active surface and the impact of the particularities of the general atmospheric circulation above Bucharest. The aim of the study was to explain the temperature distribution through statistical shape/form indices and to measure their degree of flattening and asymmetry. Processing the radio – soundings data complemented, when not measured, by the remote sensing data available after 2007, involved the statistical modeling of time series for the cold season (October to March), which meant analyzing the temporal variations and the prognosis for the evolution of meteorological and climatic elements. A comparison of the values taken by different parameters of the analyzed thermal regime could not be achieved without a more detailed presentation of the thermal regime up to 900 hPa, by entirely taking into account thermal anomalies, exceptional thermal gradients and the altitude/height of isotherms directly involved in the analyzed phenomenon, and also by directly correlating these elements with the characteristic synoptic situations.

Modern climatic changes for 1991-2013 in the lower 4-km layer of the atmosphere in the Moscow region are discussed based on long-term measurements using radiosondes in Dolgoprudny near Moscow and sensors installed on a high mast in Obninsk and on a television tower in Ostankino in Moscow. It is shown that at the end of the 20th century and the beginning of the 21st century the mean-annual air temperature at all heights from 2 to 4000 m increased by an average of 0.1°C per year. In recent years, the warming has slowed. Over the last two decades, long-term changes were multidirectional, depending on the season: warming in May-December, cooling in January-February, and no statistically significant changes in March and April. The probable reason for the temperature decrease in the middle of the cold period is changes in the large-scale atmospheric circulation during recent years (the negative phase of the North Atlantic Oscillation in early 2010s). In recent years, the Moscow region climate continentality has increased because of warming in summer and cooling in winter, despite the secular decreasing trend, which was noted before. Mean daily and annual warming rates in Dolgoprudny were higher than in Obninsk. The probable reason is the northward construction expansion and the strengthening of the Moscow heat island. The highest annual temperature amplitude is recorded at heights of 200-300 m. [ABSTRACT FROM AUTHOR]

Results of acoustic sounding of the lower troposphere with the aid of detonation generators of acoustic pulses are given. This sounding method is based on a partial reflection of acoustic pulses with shock fronts from vertical wind-velocity and temperature gradients continuously varying with height in the troposphere and on the penetration of reflected signals into the region of acoustic shadow. Experiments on tropospheric sounding were carried out on the ground of the Barva Innovation Scientific and Technical Center (Talin, Armenia) in September 2015. In these experiments, an antihail acoustic system was first used as a generator of acoustic pulses. Experimental results have been compared with data obtained earlier in similar experiments carried out in the vicinity of Zvenigorod with the use of a special detonation generator of acoustic pulses. Due to the high resolution (in height) of the sounding method, which reaches 1 m in the stably stratified lower troposphere within a height range of 250-600 m, the vertical profiles of layered effective sound speed inhomogeneities with vertical scales from a few to a few tens of meters have been retrieved. The influence of these fluctuations on the form and amplitude of acoustic signals at a long distance from their pulsed source has been studied. [ABSTRACT FROM AUTHOR]

We used a lower tropospheric ozone column (LTOC) and column-averaged dry-air mole fraction of carbon monoxide (XCO) data observed in the area around Saga, which is located in western Japan and is close to the Asian continent, with an aim to investigate whether these data can characterize the seasonal variation of the photochemical ozone (O 3 ) formation in the northeast Asian Pacific rim region. The LTOC data after April 2009 were retrieved from thermal infrared spectra measured by the Thermal and Near Infrared Sensor for Carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) onboard the Greenhouse Gases Observing Satellite (GOSAT). The XCO data after July 2011 were obtained from ground-based high-resolution FTS measurements at Saga. The retrieved LTOCs were validated with those derived from a differential absorption lidar for O 3 at Saga. The LTOCs showed a distinct seasonal variation that reached a maximum in late spring (May or June) and a local minimum in winter. In addition to the general seasonal pattern, we observed pronounced minimums in July or August. The XCO concentrations showed a maximum in spring and a minimum in summer. These seasonal patterns are consistent with those observed from mountainous sites in Japan. The origins of the air masses reaching Saga were characterized for each season according to backward trajectories, and the factors causing the temporal variations of the LTOCs and the XCO were identified based on the transport paths of the air masses. The enhancement of the LTOC relative to the XCO (ΔO 3 /ΔCO ratio) reveals significant positive correlations in the spring and summer seasons with slopes of 0.21 and 0.45 ppb/ppb, respectively. The effects of stratospheric air intrusion on the observed ΔO 3 /ΔCO ratio in spring were investigated using meteorological data (backward trajectory and potential vorticity) and column-averaged hydrogen fluoride data derived from the ground-based FTS measurements. It was found that there was little contribution of the stratospheric intrusion. This suggests that the positive correlations of the ΔO 3 /ΔCO ratio are likely to be a result of photochemical O 3 production in the troposphere. [ABSTRACT FROM AUTHOR]

The role of cyclones in atmospheric mixing and troposphere–stratosphere exchange of ozone and relative humidity (RH) is investigated for two severe cyclones PHAILIN and HUDHUD over the Bay of Bengal. Ozone concentration from Microwave Limb Sounder along with RH profiles obtained from Sounder for Probing Vertical Profiles of Humidity instrument aboard Meghatropiques platform, upon analysis at different pressure levels, revealed a rapid increase in RH and ozone concentration from lower troposphere to upper troposphere one day prior to landfall for both cyclones. The Weather Research and Forecasting model based simulations of convergence and divergence were used to estimate mass and momentum exchanges between troposphere and stratosphere which suggest the drastic increase in RH and ozone concentrations in UT due to high convective activity. Variations in the vertical profiles of ozone and RH during cyclonic period acts as a tracer for stratosphere–troposphere exchanges during peak cyclone intensity period. [ABSTRACT FROM AUTHOR]

Analyses of 60 years (1949-2008) of monthly energetics of the zonal waves derived from NCEP/NCAR data indicate that ultra-long waves (waves 1 and 2) dominate the spectrum of lower tropospheric zonal waves during monsoon season (June-September). Westerlies over the Indian subcontinent are a source of energy to wave 1. Two oceanic anticyclones, one over Pacific and the other over Atlantic are sources of energy to wave 2. These two waves are inversely correlated. Climatology of the energetics of ultra-long waves for the two epochs 1949-1978 (CLP1) and 1979-2008 (CLP2) of 30 years indicates that the intensity of wave 1 has decreased by about 33% whereas the intensity of wave 2 has increased by about 27%. Northward transport of sensible heat during CLP1 changes to southward during CLP2. Larger generation of zonal mean Available Potential Energy (APE) during CLP2 indicates more heating. A larger conversion of kinetic energy (KE) of wave 1 into APE of wave 1 leads to weakening of wave 1 during CLP2. In case of wave 2, lower rate of conversion of KE to APE leads to stronger wave 2 during CLP2. [ABSTRACT FROM AUTHOR]

Estimates of methane (CH4) concentrations in the lower troposphere over the land surfaces of the world, and in more detail for China, were derived from data from the Atmospheric Infrared Sounder (AIRS). Derivation of CH4 estimates is described, and these were validated with reference to CH4 concentrations analyzed for air samples in three regions of China and the observations from three global baseline sites. The values of sample points and three global baseline sites were extracted from remotely sensed images. The correlation coefficients between remotely sensed geographical point estimates of CH4 and observations were equal to 0.779 and 0.763. Seasonal and monthly variation of CH4 concentrations for the 2010–2011 year and the spatial variation of these concentrations for the troposphere over China derived from remotely sensed data were mapped and interpreted with reference to possible sources of CH4 emission. Methane concentrations were about 15 ppb higher in winter than summer. The changes in concentrations were about 50 ppb in Inner Mongolian Plateau between September and October 2010, northwest China between February and March 2011. Variations of CH4 concentration are considered with reference to mixing of atmospheric gases by oceanic influences and to sources of CH4 emissions including vegetation cover particularly wetland, crop, and pastoral land use. [ABSTRACT FROM PUBLISHER]

Abstract: Four years (April 2003 – July 2007) of ozonesonde observations over Ahmedabad have been studied for the first time using ten days backward trajectories in the boundary layer (lower 2 km) and lower troposphere (2.5–4 km). Ozone data are classified according to the residence times of air-masses over the North-Western India (NWI), marine and Northern Africa/Southern Europe (NASE) regions. Ozone increases linearly with increasing residence days over the NWI region for about six days with maximum increase rate (boundary layer ∼4.5 ± 1.1 ppbv/day, lower troposphere ∼3.4 ± 0.8 ppbv/day) during spring and minimum during winter (boundary layer ∼0.7 ± 0.8 ppbv/day, lower troposphere ∼0.8 ± 0.7 ppbv/day). The analysis of surface ozone over Ahmedabad confirms that ozone increase with residence days is largely due to photochemical build up. The estimated background ozone corresponding to zeroth residence day is found to be significantly lower during summer-monsoon (∼26.3 ± 3.3 ppbv) than winter (∼47.7 ± 3.2 ppbv) within the boundary layer. The air masses mainly influenced by NWI region, marine and NASE regions are termed as regionally polluted, marine and long range transport (LRT) respectively. The regionally polluted ozone is found to be higher than the average ozone during spring and summer-monsoon by 22–41% within the boundary layer and by 9–12% in the lower troposphere. The marine air shows lower ozone by 38% and 10% during spring and summer seasons respectively in the boundary layer. LRT plays a significant role in the lower troposphere during spring and summer seasons with an ozone enhancement of 9% and 27% respectively. The present work suggests that regional pollution and long range transport have significant influence on the seasonal distribution of ozone in the lower troposphere whereas the background ozone levels in summer-monsoon are mainly influenced by marine air mass over this region. [Copyright &y& Elsevier]

The article discusses the behaviour of surface ozone to determine temporal variations in the industrial-urban region Iberian Peninsula. It notes that photochemical ozone pollution significantly affects human health, vegetation and forest ecosystems. Moreover, it cites that urban emissions and specific weather conditions cause high ozone levels that exceed the normal threshold levels.

The effect of the aerosol vertical distribution on photolysis frequencies of O3 and NO2 is studied. Aerosol measurements in Raciborz (50.08° N, 18.19° E), Poland, made using the CIMEL Sun photometer and collocated CHM-15k "Nimbus" ceilometer are analyzed for the period 2015–2020. Vertical profiles of the aerosol extinction are derived from the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm combining the ceilometer measurements of the aerosol backscattering coefficient with the collocated CIMEL measurements of the columnar characteristics of aerosols. The photolysis frequencies are calculated at the three levels in the lower troposphere (the surface and 0.5 and 2 km above the surface) using a radiative transfer model, Tropospheric Ultraviolet and Visible (TUV), for various settings of aerosol optical properties in the model input. The importance of the aerosol vertical distribution on photolysis frequencies is inferred by analyzing statistics of the differences between the output of the model, including the extinction profile from the GRASP algorithm, and the default TUV model (based on columnar aerosol characteristics by the CIMEL Sun photometer and Elterman's extinction profile). For model levels above the surface, standard deviation, 2.5th percentile, 97.5th percentile, and the extremes, calculated from relative differences between these input settings, are comparable with the pertaining statistical values for the input pair providing changes of photolysis frequencies only due to the variability of the columnar aerosol characteristics. This indicates that the vertical properties of aerosols affect the distribution of the photolysis frequencies in the lower troposphere on a similar scale to that due to variations in columnar aerosol characteristics. [ABSTRACT FROM AUTHOR]

Abstract: The potential resources on the ion-stimulated syntheses effects of aerosol particles of lower troposphere in test sites in the arctic, mountain, arid and forest areas as the function of irradiation time and gas-precursor concentration were experimentally and theoretically evaluated. The dust-free outdoor air was irradiated with an ionization current of 10−6 A by α-rays from isotope 239Pu. The total output of radiolytic aerosols (RA) with a diameter of 3–1000 nm was found to be 0.05–0.1 molecules per 1 eV of absorbed radiation, while the physical upper limit is 0.25–0.4 molecules/eV. In an interval of exposition time from 6 to 800 s (adsorbed energy is 3·1012–1014 eV/cm3) the RA mass concentration at different sites was increased from 1–10 to 50–500 μg/m3. According to the liquid chromatography data the major RA material is the H2O/HNO3 solution with acid concentration ∼ 25%. The used physical model presents new aerosols as a product from small and intermediate ion association through formation of neutral clusters and describes adequately some of the peculiarities in field experiment data. Introducing SO2, NH3, and also hydrochloric, nitric and sulphuric acid vapours with concentration 0.1–1 mg/m3 in the irradiated air stimulated an increase of mass aerosol concentration by a factor of 8–30. The mean size also decreased by a factor of 3–5. These facts allowed us to expect that the chemical composition of radiolytic aerosols generated in outdoor air would noticeably differ after addition of the gas-precursors. [Copyright &y& Elsevier]

We analyzed vertical distributions of ozone (O3) in the lower troposphere (< 5 km above ground) at Lin’an (119.75°E, 30.30°N), Zhejiang Province using electrochemical concentration cell (ECC) ozonesonde data obtained from February 21 to April 13, 2001. The results showed that the vertical O3 distributions are controlled by metrological conditions and the characteristics of O3 profiles are related to those of wet bulb potential temperature and wind field. O3 below 2 km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta (YRD) region. Vertical O3 profiles below 5 km can be grouped into 5 categories: (1) peak mixing ratio type, (2) well-mixed type, (3) layered-structure type, (4) episodic pollution type and (5) altitudinal increasing type. Vertical distributions of O3 affected by regional transport of polluted air masses were investigated. Transport of polluted air from high latitudes of northern China, accompanying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at Lin’an. The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and central-eastern China also lead to regional accumulation of O3 and high O3 mixing ratio at Lin’an. Long-range transport of O3 and pollutants from the Pearl River Delta in South China and insitu O3 formation also resulted in elevated O3 mixing ratios at around 1 km altitudes and layered O3 distribution in the lower troposphere. [ABSTRACT FROM AUTHOR]

This paper includes a discussion of the validity of theobjections which are usuallyraised against the physical plausibility of the correlationsbetween extraterrestrialphenomena and changes in circulation in the lower atmosphere.The behaviour of the winterlower troposphere in the Northern Hemisphere was analysed bothon a month-to-month timescale and on a day-to-day time scale. The mechanisms which cansatisfactorily explainthe behaviour of the winter lower troposphere on these timescales have been described.The basic features of the results presented were explained bymeans of a mechanism basedon the propagation of planetary waves. Attention was focussedon studying the connectionsamong the changes in the pressure and temperature fields, thechanges in solar/geomagnetic activity and QBO phases by the method of composites. It hasbeen found that the compositeswithout considering QBO phases are similar to the QBO-eastpatterns under the highestactivities. Pressure deviations during QBO-west high solaractivity or low geomagneticactivity and temperature deviations during QBO-east/west lowgeomagnetic activity provedto be of negligible statistical significance. [ABSTRACT FROM AUTHOR]

The changes of pressure and temperature fields in the winter lower troposphere observed in association with changes in solar and/or geomagnetic activity are compared. It is shown that the fact whether it was solar or geomagnetic activity was not so important as whether the levels of the two activities were high or low. The differences between the effects of solar/geomagnetic activity, however, are revealed, the pressure and temperature data being stratified according to the QBO phase. The relationship obtained are discussed from the viewpoint of mechanisms resting upon both the planetary wave propagation and the changes of atmospheric air currents in the global electric circuit. [ABSTRACT FROM AUTHOR]