Gerhard Held

In this paper we compare water vapor mixing ratio measurements from two quasi-parallel flights of the Pico-SDLA H<sub>2</sub>O and FLASH-B hygrometers. The measurements were made on 10 February 2013 and 13 March 2012, respectively, in the tropics near Bauru, Sao Paulo St., Brazil during an intense convective period. Both flights were performed as part of a French scientific project, TRO-Pico, to study the impact of the deep-convection overshoot on the water budget. Only a few instruments that permit the frequent sounding of stratospheric water vapor can be flown within a small volume weather balloons. Technical difficulties preclude the accurate measurement of stratospheric water vapor with conventional in situ techniques. The instruments described here are simple and lightweight, which permits their low-cost deployment by non-specialists aboard a small weather balloon. We obtain mixing ratio retrievals which agree above the cold-point tropopause to within 1.9 and 0.5 % ...

Two processes are competing in the control of water vapor concentration in the tropical stratosphere: i) The so-called cold trap that is the slow ascent of water vapour in the TTL (Tropical Tropopause Layer) followed by ice crystal freezing and sedimentation leading to the drying of air entering the stratosphere and ii) convective overshooting that injects ice crystals sublimating in the stratosphere, eventually followed by further condensation and sedimentation. In contrast with the large-scale cold trap mechanism, overshooting towers are small in size and fast, but relatively frequent processes. Even if the first is frequently thought to be the main process controlling the amount of water in the stratosphere, the importance of overshooting, highly dependent on the frequency of the events, is still unknown. The aim of the TRO-pico project, funded by the French ANR, is to characterize the variability and frequency of convective water injections, its contribution at the regional wet ...

The tropical region is the main entry point of tropospheric chemical species lifted by convection and transported into the stratosphere across the tropopause. It is therefore the most sensitive region to dynamical and chemical changes. Long series of NO2 columns have become available in the tropics from two SAOZ uv-visible spectrometer stations, in Bauru (Brazil, 22˚ S, 49˚ W) since

3), and Thiago Ramires (4) (1) Instituto de Pesquisas Meteorológicas, Universidade Estadual Paulista, Bauru, S.P., Brazil (gerhard@ipmet.unesp.br, +55 14 3203-3649), (2) Departamento de Ciências Florestais, Universidade Federal de Paraná/Capes, Curitiba, PR, Brazil, (3) Instituto de Pesquisas Energéticas e Nucleares, Universidade de São Paulo, São Paulo, S.P., Brazil, (4) Campus Experimental de Ourinhos, Universidade Estadual Paulista, Ourinhos, S.P., Brazil The S-band radars of the Meteorological Research Institute (IPMet) in Bauru and Presidente Prudente are situated within major sugar cane producing regions in the State of São Paulo, where the sugar cane is harvested from April until November, generally by burning sectors of the plantations prior to manual harvesting, resulting in large quantities of aerosols being emitted into the atmosphere, not only negatively affecting local towns, but also regions much further away. In the absence of rain during the dry winter season, the ac...

ABSTRACT The main objective of this work is to obtain methods that automatically allow qualitative detections of Atmospheric Boundary Layer heights from LIDAR data. Case studies will be used to describe the more relevant days of a campaign carried out in July of 2012 in Vitória, Espírito Santo, Brazil. The data analysis compares three mathematical algorithms that automatically provide the ABL height: Gradient Method (GM), using the derivative of the Range Corrected Signal (RCS) logarithm, WCT (Wavelet Covariance Transform), and Bulk Richardson's Number, which was used to validate the methods mentioned above. The comparison between the methods has shown that as the presence of clouds and the aerosol sublayer increased, the more sensitive was the refinement needed to choose the "right" parameters, whereas even Richardson's method had ambiguities in finding a good estimate of the ABL top.

The TroCCiBras (Tropical Convection and Cirrus experiment Brasil) campaign was conducted jointly with the European HIBISCUS and TROCCINOX projects from 21 January to 11 March 2004. The general objective of TroCCiBras, coordinated by IPMet/UNESP, is to obtain a set of special measurements throughout the troposphere and the lower stratosphere, to meet specific research needs of Brazilian research institutions, through the

ABSTRACT Optical remote sensing techniques have obvious advantages for monitoring gas and aerosol emissions, since they enable the operation over large distances, far from hostile environments, and fast processing of the measured signal. In this study two remote sensing devices, namely a Lidar (Light Detection and Ranging) for monitoring the vertical profile of backscattered light intensity, and a Sodar (Acoustic Radar, Sound Detection and Ranging) for monitoring the vertical profile of the wind vector were operated during specific periods. The acquired data were processed and compared with data of air quality obtained from ground level monitoring stations, in order to verify the possibility of using the remote sensing techniques to monitor industrial emissions. The campaigns were carried out in the area of the Environmental Research Center (Cepema) of the University of Sao Paulo, in the city of Cubatao, Brazil, a large industrial site, where numerous different industries are located, including an oil refinery, a steel plant, as well as fertilizer, cement and chemical/petrochemical plants. The local environmental problems caused by the industrial activities are aggravated by the climate and topography of the site, unfavorable to pollutant dispersion. Results of a campaign are presented for a 24- hour period, showing data of a Lidar, an air quality monitoring station and a Sodar.

The goal of this paper is to analyze the performance of the Meso-Eta Model (non- hydrostatic) with a grid resolution of 10km X 10km, centered in Bauru, State of São Paulo, during the field experiment of the TroCCiBras, TROCCINOX and HIBISCUS projects. The vertical temperature and humidity profiles, as well as the wind speed and velocity at 10m, generated by

This overview paper summarizes the objectives of the Tropical Convection and Cirrus Brasil (TroCCiBras) project, as well as those of the European Commission sponsored TROCCINOX (Tropical Convection, Cirrus and Nitrogen Oxides) and HIBISCUS (Impact of tropical convection on the upper troposphere and lower stratosphere) projects, which conducted a joint field campaign in the State of São Paulo from January to March 2004. The general objective of the TroCCiBras project is to obtain a set of special measurements throughout the troposphere and the lower stratosphere, to meet specific research needs of Brazilian research institutions, through the realization of the TROCCINOX and HIBISCUS projects in Brazil. Besides introducing TroCCiBras and its partner projects, the emphasis of this paper is on lightning-related observations and preliminary results, such as the relation- ship between the structure of tropical thunderstorms and lightning, as well as the production of NOx by lightning disc...

ABSTRACT Low-level jets (LLJ) over various regions of southern Africa are shown to occur mostly as a result of a thermal gradient established over gently sloping terrain and have been observed to overlie the nocturnal temperature inversions. Strong low-level winds associated with plain-mountain and mountain-plain circulations have also been observed over the central Namib desert and Natal interior. With the exception of the Namib and Natal, where no temperature profiles accompanied wind profile observations, the LLJ is seen to increase in strength as the nocturnal surface temperature inversion intensifies through the night. The height of the LLJ above the surface also increases as the inversion deepens. Wind speeds in all regions exceed 10 ms-1 in the jet core, which typically is located between 200 and 300 m above ground level (agl). Over the central Namib, the summertime plain-mountain wind reaches similar wind speeds in a jetlike core located about 200 to 600 m agl. The Natal mountain-plain winds may exceed 10 ms-1 in a layer of up to 1000 m deep. It is suggested that all these regional-scale wind systems transport pyrogenic products in excess of 400 km during a single night. Subsequent daytime convective lifting of these ozone precursors, coupled with synoptic-scale anticyclonic circulation, provides a transport mechanism for pyrogenic products over southern Africa toward the Atlantic and Indian Oceans.

... The balloons flown include: - two 10 000 m3 (ZL) for the remote measurement of NOx, in the UTLS from 30 km altitude; ... Backscatter ratio in situ. Aerosol size distribution. O 3. ... lidar looking downward for the remote measurement of aerosols, high-level clouds and polarization. ...

ABSTRACT Optical remote sensing techniques have obvious advantages for monitoring gas and aerosol emissions, since they enable the operation over large distances, far from hostile environments, and fast processing of the measured signal. In this study two remote sensing devices, namely a Lidar (Light Detection and Ranging) for monitoring the vertical profile of backscattered light intensity, and a Sodar (Acoustic Radar, Sound Detection and Ranging) for monitoring the vertical profile of the wind vector were operated during specific periods. The acquired data were processed and compared with data of air quality obtained from ground level monitoring stations, in order to verify the possibility of using the remote sensing techniques to monitor industrial emissions. The campaigns were carried out in the area of the Environmental Research Center (Cepema) of the University of Sao Paulo, in the city of Cubatao, Brazil, a large industrial site, where numerous different industries are located, including an oil refinery, a steel plant, as well as fertilizer, cement and chemical/petrochemical plants. The local environmental problems caused by the industrial activities are aggravated by the climate and topography of the site, unfavorable to pollutant dispersion. Results of a campaign are presented for a 24- hour period, showing data of a Lidar, an air quality monitoring station and a Sodar.

ABSTRACT The experimental phase of SAFARI-92 in the Kruger National Park took place from September 7 to 26, 1992. Eskom's Environmental Sciences was committed to provide meteorological support during the experimental burns in the Pretoriuskop area of the KNP and to characterize the boundary layer during the field campaign. Surface temperature inversions were found during most nights when vertical soundings were available. The inversion strength was generally ≤3.5° with a depth of ≤270 m above ground level (agl). Low-level elevated inversions with a base height of 350 to 500 m agl and a strength of ≤3.6°C were found on four occasions. The base height of the subsidence inversion, when observed, varied between 1500 and 2500 m agl. Significant superadiabatic temperature gradients, impacting directly on the vertical dispersion of pyrogenic products, have been observed to reach as high as several hundred meters above ground level. Vertical profiles of wind speed and direction varied greatly from day to day in response to the changes in the synoptic pattern. However, weak low-level wind maxima just above the surface inversion were observed during most nights, generally with speeds of

... et al., 1986; Ayers et al., 1988; Likens et al., 1987; Andreae et al., 1988, 1990; Sanhueza et al., 1992; Williams et al., 1997; Ayers et al ... They have the effect of inhibit-ing vertical transfer of trace gases and aerosols and of trapping them in between (Cosijn and Tyson, 1996; D ...

ABSTRACT In the State of São Paulo, located in the south-east of Brazil, severe convective storms frequently cause local flooding in towns and/or devastation of crops and property due to hail or wind storms (microbursts), resulting in many millions of US Dollar damage annually, loss of lives and leave many persons injured (Gomes et al., 2000; Held et al., 2001). Therefore, it is of prime importance to develop an effective alert system for the occurrence of these severe storms, ranging from a couple of days (based on model outputs) to one to three hours ahead (nowcasting, using radar information) of these events. The Meteorological Research Institute (IPMet) of the University of the State of São Paulo (UNESP), based in the geographic center of the State in the town of Bauru, operates a network of two S-band Doppler radars for continuous precipitation monitoring in the State of São Paulo (Figure 4), which provided the ideal tools for such a pilot study.

Detailed climatological studies of hailstorms on the South African plateau have been made using a dense network of voluntary observers. Hailstone structures have been investigated and, since 1971, radar observations have been used to study storm characteristics. Results are given for the frequency of hailstorm occurrence, characteristics of hailfalls at a point, hail paths, types of storms, radar characteristics and hailstone trajectories. Practically all features showed great variability, the magnitude of which is given whenever possible. Application of the results to the design of a hail suppression experiment is briefly discussed.

This study aims to give a contribution to improving the overall skill of the warnings of storms, enabling the mitigation of potential risks associated with these events in the central area of São Paulo and adjacent regions within the operating range of 240 km from the radar Doppler Bauru of the Meteorological Research Institute (IPMet). For setting alert thresholds was performed using descriptive statistics using volumetric data collected with the Bauru radar. From these data we obtained the distribution of VIL, top of echoes and VIL density relative to storms. For the selection of potentially severe storms cells it was defined a threshold of 40 dBZ for reflectivity, yielding thereafter the average magnitudes of which these events occur in the area. The climatological bulletins of the Center for Weather Forecasting and Climate (CPTEC) provided an understanding and analysis of the mesoscale systems that has traversed the state of São Paulo during the period. We selected the event of ...

The Meteorological Research Institute (IPMet), of the São Paulo State University (UNESP), which pioneered weather radar surveillance for general purposes in Brazil, presently operates two S-Band Doppler radars in a round-the-clock routine, backed by an R&D ...

This overview paper summarizes the objectives of the Tropical Convection and Cirrus Brasil (TroCCiBras) project, as well as those of the European Commission sponsored TROCCINOX (Tropical Convection, Cirrus and Nitrogen Oxides) and HIBISCUS (Impact of tropical convection on the upper troposphere and lower stratosphere) projects, which conducted a joint field campaign in the State of São Paulo from January to March 2004. The general objective of the TroCCiBras project is to obtain a set of special measurements throughout the troposphere and the lower stratosphere, to meet specific research needs of Brazilian research institutions, through the realization of the TROCCINOX and HIBISCUS projects in Brazil. Besides introducing TroCCiBras and its partner projects, the emphasis of this paper is on lightning-related observations and preliminary results, such as the relation- ship between the structure of tropical thunderstorms and lightning, as well as the production of NOx by lightning disc...

ABSTRACT Three chemical species related to biomass burning, levoglucosan, potassium and water-soluble organic carbon (WSOC), were measured in aerosol samples collected in a rural area on the outskirts of the municipality of Ourinhos (São Paulo State, Brazil). This region is representative of the rural interior of the State, where the economy is based on agro-industrial production, and the most important crop is sugar cane. The manual harvesting process requires that the cane be first burned to remove excess foliage, leading to large emissions of particulate materials to the atmosphere. Most of the levoglucosan (68–89%) was present in small particles (<1.5 μm), and its concentration in total aerosol ranged from 25 to 1186 ng m−3. The highest values were found at night, when most of the biomass burning occurs. In contrast, WSOC showed no diurnal pattern, with an average concentration of 5.38 ± 2.97 μg m−3 (n = 27). A significant linear correlation between levoglucosan and WSOC (r = 0.54; n = 26; p < 0.0001) confirmed that biomass burning was in fact an important source of WSOC in the study region. A moderate (but significant) linear correlation between levoglucosan and potassium concentrations (r = 0.62; n = 40; p < 0.0001) was indicative of the influence of other sources of potassium in the study region, such as soil resuspension and fertilizers. When only the fine particles (<1.5 μm; typical of biomass burning) were considered, the linear coefficient increased to 0.91 (n = 9). In this case, the average levoglucosan/K+ ratio was 0.24, which may be typical of biomass burning in the study region. This ratio is about 5 times lower than that previously found for Amazon aerosol collected during the day, when flaming combustion prevails. This suggests that the levoglucosan/K+ ratio may be especially helpful for characterization of the type of vegetation burned (such as crops or forest), when biomass-burning is the dominant source of potassium. The relatively high concentrations of WSOC (and inorganic ions) suggest an important influence on the formation of cloud condensation nuclei, which is likely to affect cloud formation and precipitation patterns.