Four distinct meteorological regimes in the Amazon basin have been examined to distinguish the contributions from boundary layer aerosol and convective available potential energy (CAPE) to continental cloud structure and electrification. The lack of distinction in the electrical parameters (peak flash rate, lightning yield per unit rainfall) between aerosol‐rich October and aerosol‐poor November in the premonsoon regime casts doubt on a primary role for the aerosol in enhancing cloud electrification. Evidence for a substantial role for the aerosol in suppressing warm rain coalescence is identified in the most highly polluted period in early October. The electrical activity in this stage is qualitatively peculiar. During the easterly and westerly wind regimes of the wet season, the lightning yield per unit of rainfall is positively correlated with the aerosol concentration, but the electrical parameters are also correlated with CAPE, with a similar degree of scatter. Here cause and effect are difficult to establish with available observations. This ambiguity extends to the “green ocean” westerly regime, a distinctly maritime regime over a major continent with minimum aerosol concentration, minimum CAPE, and little if any lightning.

Drought threatens the world's food production, particularly in Sub Saharan Africa low external input and rain fed agricultural systems, where cowpea (Vigna unguiculata (L.) Walp.) is an important food crop. In the context of growing concerns regarding climate changes implications on water availability, this study aimed at 1) to evaluate the drought responses in cowpea landraces with contrasting drought tolerance levels (A55high sensitivity; A80 -mild sensitivity; A116 -tolerant), 2) using an integrated physiological (leaf gas exchanges; chlorophyll a fluorescence) and biochemical (photoprotective pigments; RuBisCO activity; primary metabolite profiling) analysis to identify drought tolerance probes, in plants submitted to three water availability levels (well-watered, WW; mild drought, MD; severe drought, SD). A116 plants maintained a better water status under drought, what could justify the higher P n and P nmax values in MD, as well as higher photochemical use of energy (reflected in the photochemical quenching (q L ) and in the quantum yield of non-cyclic electron transport (Y (II) )), and the lower need of photoprotective thermal dissipation mechanisms (given by the non-photochemical quenching (q N ), and the quantum yield of regulated energy dissipation at photosystem PSII (Y (NPQ) )), in MD and SD plants. Greater declines of net (P n ) and potential (P nmax ) photosynthesis were observed in A55 plants, which frequently showed significant impacts already under MD conditions in most parameters, whereas A80 usually displayed and intermediate behaviour. Still, even A55 showed some acclimation response, regarding photoprotective mechanisms associated with high contents of zeaxanthin, lutein, and carotenes, and high Y (NPQ) , and q N values, supporting the absence of an increase in the non-regulated energy dissipation at PSII (Y (NO) did not increased) even in SD plants. Additionally, A55 was not significantly affected in RuBisCO activity, which showed to be quite resilient in cowpea. A primary metabolite profiling, complemented with a partial least square discrimination analysis (PLS-DA), allowed a better separation of A116 and A55 plants according to their degree of drought tolerance. In response to drought, A116 showed the greatest accumulation of most responsive metabolites, 14 in total, with sucrose, fucose, urea, alanine and putrescine being exclusively increased in this genotype, suggesting that they can be candidates as drought tolerance proxies. Other compounds, as proline, valine, isoleucine (among amino acids), and rhamnose and raffinose (among sugars) showed close increase patterns

Abstract. The EU HIBISCUS project consisted of a series of field campaigns during the intense convective summers in 2001, 2003 and 2004 in the State of São Paulo in Brazil. Its objective was to investigate the impact of deep convection on the Tropical Tropopause Layer (TTL) and the lower stratosphere by providing a new set of observational data on meteorology, tracers of horizontal and vertical transport, water vapour, clouds, and chemistry in the tropical Upper Troposphere/Lower Stratosphere (UT/LS). This was achieved using short duration research balloons to study local phenomena associated with convection over land, and long-durationCorrespondence to: J.-P. Pommereau (jean-pierre.pommereau@latmos.ipsl.fr) balloons circumnavigating the globe to study the contrast between land and oceans.Analyses of observations of short-lived tracers, ozone and ice particles show strong episodic local updraughts of cold air across the lapse rate tropopause up to 18 or 19 km (420-440 K) in the lower stratosphere by overshooting towers. The long duration balloon and satellite measurements reveal a contrast between the composition of the lower stratosphere over land and oceanic areas, suggesting significant global impact of such events. The overshoots are shown to be well captured by non-hydrostatic meso-scale Cloud Re- Weather Forecast Models (NWP) underestimating the overshooting process. Finally, the data collected by the HIBIS-CUS balloons have allowed a thorough evaluation of temperature NWP analyses and reanalyses, as well as satellite ozone, nitrogen oxide, water vapour and bromine oxide measurements in the tropics.