Jorba, O.; Pérez, C.; Rocadenbosch, F.; Baldasano, J. Journal of applied meteorology Vol. 43, num. 6, p. 887-901 DOI: 10.1175/1520-0450(2004)043<0887:CAODBT>2.0.CO;2 Data de publicació: 2004-06 Article en revista
A cluster algorithm was implemented to analyze the backward trajectories arriving in the Barcelona area (BCN), located at the eastern coast of the Iberian Peninsula. Five years of 4-day kinematic back trajectories, computed with version 4 of the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), were clustered and classified in groups of similar length and curvature. To describe better the tropospheric circulations at BCN, backward trajectories arriving at 5500, 3000, and 1500 m above sea level were analyzed. The main transport patterns are identified at 5500 m: westerly flows (49% of the total situations), northwesterly flows (17%), southwesterly flows (20%), and regional recirculations over Europe and the Mediterranean Sea (15%). An annual distribution of the transport patterns is described. During the summertime, moderate westerlies (19%) and southwesterlies (13%) in the middle troposphere, slow westerlies (11%) and southwesterlies (10%) at 3000 m, and regional recirculations (29%) at 1500 m characterize the BCN long-range transport. This general pattern varies during wintertime, with more westerlies at 5500 m and an increase of northern and northwestern situations at 1500 m. A large number of situations with decoupling between the lower and middle troposphere are observed when combining 5500- and 1500-m cluster results. Interannual variability is discussed, and the influence of the North Atlantic Oscillation phase is captured by winter average regime patterns.
Structural parameters for chemisorption of atomic carbon above a Si(100) surface have been obtained through a Si35H 32
cluster model and a MINDO/3 hamiltonian. The most stable position has been found to be the bridge one when considering
the unrelaxed surface. The stability increases about 14 kcal/mol when relaxation of the surface is allowed. Further research
has been carried out using a reduced cluster model (SigH i2) at the ab initio Hartree-Fock level of calculation. Results
confirm the increase of stability of the relaxed system. At this level, the binding energy is 90 kcal/mol for the unrelaxed
surface and the stabilization when the surface is relaxed is of about 20% with respect to the non-relaxed surface.
Zawadzki, I.; Sempere-Torres, D.; Lee, G. W.; Szyrmer, W.; Uijlenhoet, R. Journal of applied meteorology Vol. 43, p. 264-281 DOI: 10.1175/1520-0450(2004)043<0264:AGATDN>2.0.CO;2 Data de publicació: 2004-02 Article en revista
Normalization of drop size distributions (DSDs) is reexamined here. First, an extension of the scaling normalization that uses one moment of the DSD as a scaling parameter to a more general scaling normalization that uses two moments as scaling parameters of the normalization is presented. In addition, the proposed formulation includes all two-parameter normalizations recently introduced in the literature. Thus, a unified vision of the question of DSD normalization and a good model representation of DSDs are given. Data analysis of some convective and stratiform DSDs shows that, from the point of view of the compact representation of DSDs, the double-moment normalization is preferred. However, in terms of physical interpretation, the scaling exponent of the single-moment normalization clearly indicates two different rain regimes, whereas in the double-moment normalization the two populations are not readily separated. It is also shown that DSD analytical models (exponential, gamma, and generalized gamma DSD) have the same scaling properties, indicating that the scaling formalism of DSDs is a very general way of describing DSDs.