A statistical model for isolated convective precipitation events

To study the diurnal evolution of the convective cloud field, we develop a precipitation cell tracking algorithm which records the merging and fragmentation of convective cells during their life cycles, and apply it on large eddy simulation (LES) data. Conditioning on the area covered by each cell, our algorithm is capable of analyzing an arbitrary number of auxiliary fields, such as the anomalies of temperature and moisture, convective available potential energy (CAPE) and convective inhibition (CIN). For tracks that do not merge or split (termed "solitary"), many of these quantities show generic, often nearly linear relations that hardly depend on the forcing conditions of the simulations, such as surface temperature. This finding allows us to propose a highly idealized model of rain events, where the surface precipitation area is circular and a cell's precipitation intensity falls off linearly with the distance from the respective cell center. The drop-off gradient is nearly independent of track duration and cell size, which allows for a generic description of such solitary tracks, with the only remaining parameter the peak intensity. In contrast to the simple and robust behavior of solitary tracks, tracks that result from merging of two or more cells show a much more complicated behavior. The most intense, long lasting and largest tracks indeed stem from multi-mergers - tracks involved in repeated merging. Another interesting finding is that the precipitation intensity of tracks does not strongly depend on the absolute amount of local initial CAPE, which is only partially consumed by most rain events. Rather, our results speak to boundary layer cooling, induced by rain re-evaporation, as the cause for CAPE reduction, CIN increase and shutdown of precipitation cells.Comment: Manuscript under review in Journal of Advances in Modeling Earth System

Assessing the uncertainty of soil moisture impacts on convective precipitation using a new ensemble approach

Soil moisture amount and distribution control evapotranspiration and thus impact the occurrence of convective precipitation. Many recent model studies demonstrate that changes in initial soil moisture content result in modified convective precipitation. However, to quantify the resulting precipitation changes, the chaotic behavior of the atmospheric system needs to be considered. Slight changes in the simulation setup, such as the chosen model domain, also result in modifications to the simulated precipitation field. This causes an uncertainty due to stochastic variability, which can be large compared to effects caused by soil moisture variations. By shifting the model domain, we estimate the uncertainty of the model results. Our novel uncertainty estimate includes 10 simulations with shifted model boundaries and is compared to the effects on precipitation caused by variations in soil moisture amount and local distribution. With this approach, the influence of soil moisture amount and distribution on convective precipitation is quantified. Deviations in simulated precipitation can only be attributed to soil moisture impacts if the systematic effects of soil moisture modifications are larger than the inherent simulation uncertainty at the convection-resolving scale.</p><p>We performed seven experiments with modified soil moisture amount or distribution to address the effect of soil moisture on precipitation. Each of the experiments consists of 10 ensemble members using the deep convection-resolving COSMO model with a grid spacing of 2.8 km. Only in experiments with very strong modification in soil moisture do precipitation changes exceed the model spread in amplitude, location or structure. These changes are caused by a 50 % soil moisture increase in either the whole or part of the model domain or by drying the whole model domain. Increasing or decreasing soil moisture both predominantly results in reduced precipitation rates. Replacing the soil moisture with realistic fields from different days has an insignificant influence on precipitation. The findings of this study underline the need for uncertainty estimates in soil moisture studies based on convection-resolving models

Circling in on convective organization

Cold pools (CPs) contribute to convective organization. However, it is unclear by which mechanisms organization occurs. By using a particle method to track CP gust fronts in large eddy simulations, we characterize the basic collision modes between CPs. Our results show that CP interactions, where three expanding gust fronts force an updraft, are key at triggering new convection. Using this, we conceptualize CP dynamics into a parameter‐free mathematical model: circles expand from initially random points in space. Where two expanding circles collide, a stationary front is formed. However, where three expanding circles enclose a single point, a new expanding circle is seeded. This simple model supports three fundamental features of CP dynamics: precipitation cells constitute a spatially interacting system; CPs come in generations; and scales steadily increase throughout the diurnal cycle. Finally, this model provides a framework for how CPs act to cause convective self‐organization, clustering, and extremes

Electronic catalogue of urban contemporary cartography in Spain, 1800-1950

El campo de la cartografía histórica ha hecho muchos avances en los últimos años, no solo por el esfuerzo de los investigadores, sino también por la continua labor de digitalización, puesta en valor y difusión de los documentos disponibles en los diferentes archivos institucionales y privados, que en muchos casos ya están disponibles en repositorios digitales. Este proyecto se enmarca en esta voluntad de facilitación de la labor del investigador, a partir de la creación de un catálogo de cartografía urbana histórica entre el año 1800 y el 1950, que pretende ser un punto de partida y de encuentro para la creación de un directorio centralizado en el que se pueda tener disponible toda aquella cartografía que permita el estudio histórico de la ciudad en España. Este catálogo aúna casi 1.000 mapas de 131 ciudades, esperando poder ir ampliándose en un futuro cercano.The contemporary cartography field has made many advances in the last few years, not only because of the researchers' efforts, but also because of the digitalisation work. As a result of this task, many documents in private and institutional archives are now available in digital repositories. This project is framed in this will to ease researcher's work by the launch of an electronic catalogue of urban contemporary cartography in Spain between the years 1800 and 1950. The catalogue is aimed to be a starting and encounter point for the creation of a centralised directory to approach the historical study of the city in Spain. It combines more than 1.000 maps from 131 cities, waiting to be increased in a near future

Catálogo digital de cartografía urbana contemporánea en España (1800-1950)

El campo de la cartografía contemporánea ha hecho muchos avances en los últimos años, no solo por el esfuerzo de los investigadores, sino también por la continua labor de digitalización, puesta en valor y difusión de los documentos disponibles en los diferentes archivos institucionales y privados, que en muchos casos ya están disponibles en repositorios digitales. Este proyecto se enmarca en lla voluntad de facilitar la labor del investigador, a partir de la creación de un catálogo de cartografía urbana contemporánea entre los años 1800 y 1950, que pretende ser un punto de partida y de encuentro para la creación de un directorio centralizado en el que se pueda tener disponible toda aquella cartografía que permita el estudio histórico de la ciudad en España. Este catálogo aúna más de 1.000 mapas de 131 ciudades, esperando poder ir ampliándose en un futuro cercano

El factor ferroviario en el crecimiento urbano. España, 1850-1960

Peer-reviewedEl ferrocarril aseguró una rápida interconexión entre las principales ciudades españolas en un periodo en el que se estaban liberando del confinamiento al que las habían sometido los recintos amurallados. Las estaciones se instalaron en su exterior y las compañías trazaron su tendido ferroviario de tal forma que condicionaron enormemente la expansión urbana posterior. En esta comunicación se presentan los avances de una línea de investigación que tiene por objetivo identificar las pautas de crecimiento urbano con relación al ferrocarril en un periodo que iniciamos hacia 1850, antes de que dicho impacto se hubiera podido manifestar. El análisis finaliza en torno a 1960, momento en el que en España se había optado por potenciar el transporte por carretera.El ferrocarril va assegurar una ràpida interconnexió entre les principals ciutats espanyoles en un període en el qual s'estaven alliberant del confinament al que les havien sotmès els recintes emmurallats. Les estacions es van instal·lar en el seu exterior i les companyies van traçar la seva estesa ferroviària de tal forma que van condicionar enormement l'expansió urbana posterior. En aquesta comunicació es presenten els avanços d'una línia de recerca que té per objectiu identificar les pautes de creixement urbà en relació amb el ferrocarril en un període que iniciem cap a 1850, abans que aquest impacte s'hagués pogut manifestar. L'anàlisi finalitza entorn de 1960, moment en el qual a Espanya s'havia optat per potenciar el transport per carretera.The railway ensured a rapid interconnection between the main Spanish cities in a period when they were liberating themselves from the confinement to which the walled enclosures had subjected them. The stations were installed on the outside and the companies traced their railway lines in such a way that they greatly conditioned the subsequent urban expansion. This communication presents the advances of a line of research that aims to to identify the patterns of urban growth in relation to the railroad in a period that began around 1850, before that impact could have manifested itself. The analysis ends around 1960, when Spain had opted to boost road transport

El factor ferroviario en el crecimiento urbano. España, 1850-1960

Peer-reviewedEl ferrocarril aseguró una rápida interconexión entre las principales ciudades españolas en un periodo en el que se estaban liberando del confinamiento al que las habían sometido los recintos amurallados. Las estaciones se instalaron en su exterior y las compañías trazaron su tendido ferroviario de tal forma que condicionaron enormemente la expansión urbana posterior. En esta comunicación se presentan los avances de una línea de investigación que tiene por objetivo identificar las pautas de crecimiento urbano con relación al ferrocarril en un periodo que iniciamos hacia 1850, antes de que dicho impacto se hubiera podido manifestar. El análisis finaliza en torno a 1960, momento en el que en España se había optado por potenciar el transporte por carretera.El ferrocarril va assegurar una ràpida interconnexió entre les principals ciutats espanyoles en un període en el qual s'estaven alliberant del confinament al que les havien sotmès els recintes emmurallats. Les estacions es van instal·lar en el seu exterior i les companyies van traçar la seva estesa ferroviària de tal forma que van condicionar enormement l'expansió urbana posterior. En aquesta comunicació es presenten els avanços d'una línia de recerca que té per objectiu identificar les pautes de creixement urbà en relació amb el ferrocarril en un període que iniciem cap a 1850, abans que aquest impacte s'hagués pogut manifestar. L'anàlisi finalitza entorn de 1960, moment en el qual a Espanya s'havia optat per potenciar el transport per carretera.The railway ensured a rapid interconnection between the main Spanish cities in a period when they were liberating themselves from the confinement to which the walled enclosures had subjected them. The stations were installed on the outside and the companies traced their railway lines in such a way that they greatly conditioned the subsequent urban expansion. This communication presents the advances of a line of research that aims to to identify the patterns of urban growth in relation to the railroad in a period that began around 1850, before that impact could have manifested itself. The analysis ends around 1960, when Spain had opted to boost road transport