Abstract.A plume rise algorithm for wildfires was included in WRF-Chem, and applied to look at the impact of intense wildfires during the 2004 Alaska wildfire season on weather simulations using model resolutions of 10 km and 2 km. Biomass burning emissions were estimated using a biomass burning emissions model. In addition, a 1-D, timedependent cloud model was used online in WRF-Chem to estimate injection heights as well as the vertical distribution of the emission rates. It was shown that with the inclusion of the intense wildfires of the 2004 fire season in the model simulations, the interaction of the aerosols with the atmospheric radiation led to significant modifications of vertical profiles of temperature and moisture in cloud-free areas. On the other hand, when clouds were present, the high concentrations of fine aerosol (PM 2.5 ) and the resulting large numbers of Cloud Condensation Nuclei (CCN) had a strong impact on clouds and cloud microphysics, with decreased precipitation coverage and precipitation amounts during the first 12 h of the integration. During the afternoon, storms were of convective nature and appeared significantly stronger, probably as a result of both the interaction of aerosols with radiation (through an increase in CAPE) as well as the interaction with cloud microphysics.

Mass balance and climate sensitivity of Glaciar Perito Moreno (GPM), one of the main outlet glaciers of Hielo Patagónico Sur (southern Patagonia icefield), were investigated. Field measurements were carried out from 1995 to 2003, including ice ablation and velocity at stakes, seismic profiling, bathymetry of the lake near the calving fronts and meteorological data. The database was complemented by satellite observations, to derive the motion field by interferometric data, map glacier boundaries and snowlines from multi-year time series of radar images, and obtain glacier topography from the Shuttle Radar Topography Mission. In September 2003, GPM started to dam the southern arm of Lago Argentino, resulting in a maximum rise of the lake level of 9.35 m before the dam burst in March 2004. The ice dam formed again in August 2005, bursting in March 2006. Analysis of mass fluxes indicates no long-term trend in mass balance. This behaviour, contrasting with most retreating glaciers in the vicinity, can be attributed to a particular glacier geometry. Monthly climate sensitivity characteristics for glacier mass balance were derived using a degree-day model, showing similar importance of both temperature and precipitation. Also, the reconstruction of the mass balance for the last 50 years from local climate data shows a near-steady-state condition for GPM, with some small fluctuations, such as a slightly positive balance after 1998, that may have triggered the minor advance leading to damming events in 2003 and 2005.

Abstract. Accumulation, ablation, calving, and flow dynamics of Moreno Glacier, one of the main outlet glaciers of the Southern Patagonia Icefield, were studied based on field campaigns and on spaceborne radar imagery acquired by SIR-C/X-SAR. Ice velocities and ablation were measured through two summers and one winter. The ice depth was sounded seismically at a transact 8 km above the calving front, showing a maximum depth of 720 m. The velocity field of the terminus was derived from SIR-C/X-SAR data by means of interferometry and amplitude correlation. The average specific annual net accumulation is 5540 + 500 mm water equivalent. The bottom topography of the lake and the high ratio of calving flux to net accumulation explain the remarkable stability of Moreno Glacier throughout this century which is in contrast to the retreat of other glaciers in this region.

Abstract. We describe a new functionality within the Weather Research and Forecasting (WRF) model with coupled Chemistry (WRF-Chem) that allows simulating emission, transport, dispersion, transformation and sedimentation of pollutants released during volcanic activities. Emissions from both an explosive eruption case and a relatively calm degassing situation are considered using the most recent volcanic emission databases. A preprocessor tool provides emission fields and additional information needed to establish the initial three-dimensional cloud umbrella/vertical distribution within the transport model grid, as well as the timing and duration of an eruption. From this source condition, the transport, dispersion and sedimentation of the ash cloud can be realistically simulated by WRF-Chem using its own dynamics and physical parameterization as well as data assimilation. Examples of model applications include a comparison of tephra fall deposits from the 1989 eruption of Mount Redoubt (Alaska) and the dispersion of ash from the 2010 Eyjafjallajökull eruption in Iceland. Both model applications show good coincidence between WRF-Chem and observations.

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