Modeling the dust life cycle and its associated meteorological processes from global to regional scales
- Autores: Lluís Vendrell Miguel
- Directores de la Tesis: Oriol Jorba Casella (dir. tes.), Sara Basart Alpuente (codir. tes.), María Gonçalves Ageitos (tut. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Emilio Cuevas Agulló (presid.), Jorge Pey Betrán (secret.), Carlos Pérez García-Pando (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Ambiental por la Universidad Politécnica de Catalunya
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
This thesis aims to test the ability of a non-hydrostatic multiscale mineral dust model to reproduce the physical processes associated with the dust cycle at meteorological scales ranging from synoptic to mesoscale (~100-1 km spatial resolution) over Northern Africa, the Middle East and Europe (NAMEE). The NMMB/BSC-Dust model, the mineral dust module of the NMMB-MONARCHv1.0 model, is the main tool used. To reach this objective, three specific modeling studies investigate the model¿s ability to reproduce mineral dust processes in a wide range of spatial scales.
The first study aims to address the consistency of the model in reproducing the dust cycle and its major involved processes, from synoptic to mesoscale (~100-10 km spatial resolution), for a year (2011) in NAMEE. For that purpose, three model runs are used: one at a global scale and two at the regional scale, which are compared to ground-based observations (weather sites, in-situ PM10 stations and sun-photometers) and aerosol satellite products (MISR and MODIS). The model reproduces the large-scale processes involved in the seasonality of the dust transport in line with MISR and MODIS, and remains consistent between the studied meteorological scales. In comparison with surface observations, the model shows a great ability to resolve long-range dust transport. The model underestimates dust concentrations in the Western and Central Sahara-Sahel in summer, which are associated with wind speed underestimations, low emissions from Mali-Mauritania and omitting haboobs. Otherwise, dust overestimations in the central Sahara-Sahel from October to March are linked to an overestimation of the Harmattan winds. In the Middle East, the model underestimates dust concentrations, which is partly linked to its topography and meteorological small-scale processes that are not well resolved in these configurations. The regional configurations better represented the dust fields¿ spatiotemporal variability over the region and the finer scales by, for example, enhancing the development of low-level jets and topographic effects on meteorology and dust fields. This analysis demonstrates the model¿s consistency between global and regional scales.
The second study addresses how the model reproduces topographic effects on dust transport over complex topography. For that purpose, two regional model runs (30 and 3 km spatial resolution) covered two synoptic dust storms that occurred on 17¿20/03/2012 in the Middle East. In comparison with observations from surface weather stations, sun-photometers, and satellite aerosol products (MODIS and MSG), the model successfully reproduces these dust storms despite differences in the magnitude of the simulated dust fields. Differences between both simulations arise in Southwestern Saudi Arabia, Yemen and Oman where the topography alters the meteorology and the transported dust fields by channeling the dust flow through valleys or by blocking on the windward side of the mountain ranges. In this sense, the dust simulation using a higher horizontal resolution reproduced the dust transport better in the vicinity of complex terrain.
The third study investigates the model¿s ability to resolve haboobs with five model runs at different spatial resolutions and for both parameterized and explicit convection, under a convective situation on 14/07/2011 in West Africa. Parameterized runs are limited in resolving haboobs because they tend to remove atmospheric instability, especially under orographic convective events. This results in an earlier and more abundant rainfall than compared to explicit runs. Haboobs and their associated processes, such as moist convection, cold pools and density currents, are well-developed in the explicit runs at 3 km, but at coarser resolutions (e.g. 10 km) those processes are less intense, and the vertical development of the haboob¿s front edge is poorly resolved.
