Distribution of Articles published per year
(2015 - 2018)
(2015 - 2018)
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Article 0 Reads 0 Citations Tagging moisture sources with Lagrangian and inertial tracers: Application to intense atmospheric river events Published: 16 February 2018
Earth System Dynamics Discussions, doi: 10.5194/esd-2018-8
Two Lagrangian tracers tools are evaluated for studies on atmospheric moisture sources and pathways. In these methods, a moisture volume is assigned to each particle which is then advected by the wind flow. Usual Lagrangian methods consider this volume to remain constant and the particle follows flow path lines exactly. In a different approach, the initial moisture volume can be considered to depend on time as it is advected by the flow, due to thermodynamic processes. In this case, the tracer volume drag must be taken into account. Equations have been implemented and moisture convection was taken into account for both Lagrangian and inertial models. We apply these methods to evaluate the intense atmospheric rivers that devastated (i) the Pacific North West region of the United States, and (ii) the Western of the Iberian Peninsula, with flooding rains and intense winds in early November 2006, and May 20, 1994, respectively. We note that the usual Lagrangian method underestimates moisture availability in the continent while active tracers achieve more realistic results.
Article 0 Reads 3 Citations Evaluation of the moisture sources in two extreme landfalling atmospheric river events using an Eulerian WRF tracers too... Published: 22 December 2017
Earth System Dynamics, doi: 10.5194/esd-8-1247-2017
A new 3-D tracer tool is coupled to the WRF model to analyze the origin of the moisture in two extreme atmospheric river (AR) events: the so-called Great Coastal Gale of 2007 in the Pacific Ocean and the Great Storm of 1987 in the North Atlantic. Results show that between 80 and 90 % of moisture advected by the ARs, and a high percentage of the total precipitation produced by the systems have a tropical origin. The tropical contribution to precipitation is in general above 50 % and largely exceeds this value in the most affected areas. Local convergence transport is responsible for the remaining moisture and precipitation. The ratio of tropical moisture to total moisture is maximized as the cold front arrives on land. Vertical cross sections of the moisture content suggest that the maximum in tropical humidity does not necessarily coincide with the low-level jet (LLJ) of the extratropical cyclone. Instead, the amount of tropical humidity is maximized in the lowest atmospheric level in southern latitudes and can be located above, below or ahead of the LLJ in northern latitudes in both analyzed cases.
Conference 5 Reads 0 Citations Tagging moisture sources with Eulerian and Lagrangian tracers: Application to an intense atmospheric river event. Published: 08 November 2017
First International Electronic Conference on the Hydrological Cycle, doi: 10.3390/chycle-2017-04864
Article 0 Reads 0 Citations Climatology of Lyapunov exponents: the link between atmospheric rivers and large-scale mixing variability Published: 26 September 2017
Earth System Dynamics, doi: 10.5194/esd-8-865-2017
Large-scale tropospheric mixing and Lagrangian transport properties have been analyzed for the long-term period 1979–2014 in terms of the finite-time Lyapunov exponents (FTLEs). Wind field reanalyses from the European Centre for Medium-Range Weather Forecasts were used to calculate the Lagrangian trajectories of large ensembles of particles. Larger values of the interannual and intra-annual mixing variabilities highlight the El Niño Southern Oscillation, the storm track, or the Intertropical Convergence Zone among other large-scale structures. The mean baroclinic instability growth rate and the mean atmospheric river occurrence show large correlation values with the FTLE climatology as an indication of their influence on tropospheric mixing in the midlatitudes. As a case study, the role that land-falling atmospheric rivers have on large-scale tropospheric mixing and the precipitation rates observed in Saharan Morocco and the British Isles has been analyzed. The atmospheric river contribution to tropospheric mixing is found to decrease from 15 % in Saharan Morocco to less than 5 % for the UK and Ireland regions, in agreement with their contribution to precipitation that is 40 % larger in the former than in the latter region.
Article 0 Reads 1 Citation Influence of finite-time Lyapunov exponents on winter precipitation over the Iberian Peninsula Published: 24 May 2017
Nonlinear Processes in Geophysics, doi: 10.5194/npg-24-227-2017
Seasonal forecasts have improved during the last decades, mostly due to an increase in understanding of the coupled ocean–atmosphere dynamics, and the development of models able to predict the atmosphere variability. Correlations between different teleconnection patterns and severe weather in different parts of the world are constantly evolving and changing. This paper evaluates the connection between winter precipitation over the Iberian Peninsula and the large-scale tropospheric mixing over the eastern Atlantic Ocean. Finite-time Lyapunov exponents (FTLEs) have been calculated from 1979 to 2008 to evaluate this mixing. Our study suggests that significant negative correlations exist between summer FTLE anomalies and winter precipitation over Portugal and Spain. To understand the mechanisms behind this correlation, summer anomalies of the FTLE have also been correlated with other climatic variables such as the sea surface temperature (SST), the sea level pressure (SLP) or the geopotential. The East Atlantic (EA) teleconnection index correlates with the summer FTLE anomalies, confirming their role as a seasonal predictor for winter precipitation over the Iberian Peninsula.
Article 0 Reads 0 Citations Climatology of Lyapunov exponents: The influence of atmospheric rivers on large-scale mixing variability Published: 26 January 2017
Earth System Dynamics Discussions, doi: 10.5194/esd-2017-1
Large-scale tropospheric mixing and Lagrangian transport properties have been analyzed for a long-term period 1979–2014 in terms of the finite-time Lyapunov exponents (FTLE). Wind fields reanalysis from the European Centre for Medium-Range Weather Forecasts were used to calculate Lagrangian trajectories of large ensembles of particles. The FTLE climatology shows large correlation values with the baroclinic instability growth rate. Larger values of the inter and intra-annual mixing variabilities highlight El Niño Southern Oscillation, the storm track or the Intertropical Convergence Zone among other large-scale structures. As a case study, the role that atmospheric rivers have on the large-scale atmospheric mixing and the precipitation rates observed in the Sahara-Morocco and British Isles regions have been analyzed. Atmospheric rivers contribution to tropospheric mixing is found to decrease from 15 % in Sahara-Morocco to less than 5 % for UK-Ireland regions, in agreement to their contribution to precipitation that is 40 % larger in the former than for the latter region.