0000000000060076
AUTHOR
Jörg Trentmann
Small-scale mixing processes enhancing troposphere-to-stratosphere transport by pyro-cumulonimbus storms
Abstract. Deep convection induced by large forest fires is an efficient mechanism for transport of aerosol particles and trace gases into the upper troposphere and lower stratosphere (UT/LS). For many pyro-cumulonimbus clouds (pyroCbs) as well as other cases of severe convection without fire forcing, radiometric observations of cloud tops in the thermal infrared (IR) reveal characteristic structures, featuring a region of relatively high brightness temperatures (warm center) surrounded by a U-shaped region of low brightness temperatures. We performed a numerical simulation of a specific case study of pyroCb using a non-hydrostatic cloud resolving model with a two-moment cloud microphysics p…
Simulation of a biomass-burning plume: Comparison of model results with observations
[1] We have simulated the dynamical evolution of the plume from a prescribed biomass fire, using the active tracer high- resolution atmospheric model (ATHAM). Initialization parameters were set to reflect the conditions during the fire. The model results are compared with airborne remote-sensing and in situ measurements of the plume. ATHAM reproduces the injection height (250-600 m) and the horizontal extent of the plume (similar to4 km) with good accuracy. The aerosol mass concentrations are underestimated but still in the range of the observations. Remaining differences between the model results and the measurements are attributed to limited meteorological and fire emission information. A…
On the determination of coherent solar climates over a tropical island with a complex topography
Abstract Many tropical islands aim at developing a greener self-sufficient energy production systems based on renewable energy, notably solar-generated electricity. This work explores the mean diurnal and annual solar cycles over La Reunion island (southwest Indian Ocean: 21°S, 55.5°E), and their spatial behavior, using the Solar surfAce RAdiation Heliosat – East (SARAH-E) satellite-derived data at high spatial ( 0.05 ° × 0.05 ° ) and time (hourly) resolutions over period 1999–2016. Comparisons of the SARAH-E data with ground-based measurements over the period 2011–2015 show differences of ~ 15 % for diurnal-seasonal variations. The solar resource over the island displays strong spatial var…
High‐resolution simulations of convective cold pools over the northwestern Sahara
[1] Cooling by evaporation of convective precipitation in the deep and dry subcloud layer over desert regions can generate intense downdrafts and long-lived and extensive atmospheric density currents. The strong gusts at their leading edges can cause so-called haboob dust storms. Despite their importance for the dust cycle, the ability of state-of-the-art numerical weather prediction models to realistically simulate the associated convective cold pools has been investigated very little to date. During the first field campaign of the Saharan Mineral Dust Experiment in southern Morocco in May/June 2006, several density currents were observed. They were triggered by deep moist convection over …
Three-dimensional solar radiation effects on the actinic flux field in a biomass-burning plume
[1] Three-dimensional (3-D) solar radiative transfer models describe radiative transfer under inhomogeneous atmospheric conditions more accurately than the commonly used one-dimensional (1-D) radiative transfer models that assume horizontal homogeneity of the atmosphere. Here results of 3-D radiative transfer simulations for a biomass-burning plume are presented and compared with local one-dimensional (l-1-D) simulations, i.e., 1-D simulations in every column of the model domain. The spatial distribution of the aerosol particles was derived from a 3-D atmospheric transport simulation. We studied the impact of 3-D radiative effects on the actinic flux within the plume center. The differences…