ALBERT

Description: Villarrica Volcano is an active ice-covered volcano in southern Chile (2847 m a.s.l., 39°25’12’’ S, 71°56’27’’W), with a current glacier extent of 23.6 km〈sup〉2〈/sup〉. To investigate meteorological conditions and the impact of ongoing climatic warming on glacier melt, an automatic weather station (AWS) was installed at 1900 m a.s.l. on a tephra-covered surface in the glacier ablation zone in December 2019, providing continuous measurements of meteorological variables and tephra temperatures. To give further insight into the turbulent fluxes of sensible and latent heat at the glacier surface, an eddy covariance system, consisting of a parallel-mounted 3D sonic anemometer and krypton hygrometer, was deployed over tephra and snow surfaces close to the AWS between 12-16 January 2023. During the summer, snow and ice are subject to intense insolation and positive air temperatures, with high melt rates further amplified by surface darkening from windblown low-albedo tephra. In contrast, ice beneath extensive areas of tephra cover in the lower ablation zone is effectively insulated, with much lower ablation rates. Both tephra and snow exhibit predominantly negative latent heat fluxes, indicating surface water evaporation, with notably high magnitude and variable fluxes at the tephra site during the afternoon when surface temperature exceeds 35°C. The snow site is predominantly a sink of atmospheric sensible heat, due to positive air temperatures, while the tephra site alternates between positive and negative sensible heat fluxes, determined by high daytime and low night-time surface temperature, respectively. These measurements will be used to inform approaches to modelling the turbulent fluxes.

Description: We review in this work the activities carried out by our geoscience research group using historical data especially focused on the Extremadura region (SW Spain). We describe some recent works such as the use of correspondence by the Duke of Feria to create precipitation and temperature indices for the period 1750-1840 or the systematic recovery of old meteorological data (including data on unusual variables related to solar radiation). We also describe the work we are doing recovering news about events of interest in geosciences from regional newspapers (meteorological phenomena, earthquakes, fireballs, aurorae at low latitude, ...). Finally, we show a rare episode of great thunderstorms that devastated the Extremadura region in June 1925.

Description: Precipitation in the tropics is dominated by variability on seasonal, intraseasonal and diurnal scales. However, at the finest spatial scales, this variability can be strongly modulated by numerous local factors that represent a range of physical processes. One aspect of this modulation that operates across multiple scales is the orientation of coastal and inland topography relative to the background wind. This is particularly relevant where complex topography occurs in the vicinity of tropical coastlines, which can cause local changes in moisture flux convergence. Another aspect is the coupling of the diurnal cycle to changes in surface heating, surface moisture, column moisture, background wind and cloudiness. This link between clouds, radiation and diurnally forced convection forges a two-way interaction between the intraseasonal scales and mesoscale variability. Further to these modulating factors, propagating disturbances from neighbouring coastlines, and interactions between coastal processes across adjacent seas introduces a non-local mesoscale source of variability, particularly amidst the complex archipelago of the Maritime Continent. These processes also occur outside the deep tropics, where the added complexity of mid-latitude interactions contributes to the overall variation in precipitation. Multiple spatial and temporal scales are impacted by these competing sources of variability, which presents a challenge in quantifying their representation and impact in weather and climate models. This has implications for weather prediction and down-scaling of climate change projections. This talk will examine some of the local manifestations of scale-interactions in tropical Queensland (Australia) and the Maritime Continent, using diverse observational datasets and high-resolution numerical modelling.