Vertically resolved precipitation intensity retrieved through a synergy between the ground-based NASA MPLNET lidar network measurements, surface disdrometer datasets and an analytical model solution

In this paper, we illustrate a new, simple and complementary ground-based methodology to retrieve the vertically resolved atmospheric precipitation intensity through a synergy between measurements from the National Aeronautics and Space Administration (NASA) Micropulse Lidar network (MPLNET), an analytical model solution and ground-based disdrometer measurements. The presented results are obtained at two mid-latitude MPLNET permanent observational sites, located respectively at NASA Goddard Space Flight Center, USA, and at the Universitat Politècnica de Catalunya, Barcelona, Spain. The methodology is suitable to be applied to existing and/or future lidar/ceilometer networks with the main objective of either providing near real-time (3 h latency) rainfall intensity measurements and/or to validate satellite missions, especially for critical light precipitation (< 3 mm h-1).Peer ReviewedPostprint (published version

Precipitation type classification of micro rain radar data using an improved doppler spectral processing methodology

This research was funded by the Spanish Government through projects CGL2015-65627-C3-1-R, CGL2015-65627-C3-2-R (MINECO/FEDER), CGL2016-81828-REDT and RTI2018-098693-B-C32 (AEI/FEDER).This paper describes a methodology for processing spectral raw data from Micro Rain Radar (MRR), a K-band vertically pointing Doppler radar designed to observe precipitation profiles. The objective is to provide a set of radar integral parameters and derived variables, including a precipitation type classification. The methodology first includes an improved noise level determination, peak signal detection and Doppler dealiasing, allowing us to consider the upward movements of precipitation particles. A second step computes for each of the height bin radar moments, such as equivalent reflectivity (Ze), average Doppler vertical speed (W), spectral width (σ), the skewness and kurtosis. A third step performs a precipitation type classification for each bin height, considering snow, drizzle, rain, hail, and mixed (rain and snow or graupel). For liquid precipitation types, additional variables are computed, such as liquid water content (LWC), rain rate (RR), or gamma distribution parameters, such as the liquid water content normalized intercept (Nw) or the mean mass-weighted raindrop diameter (Dm) to classify stratiform or convective rainfall regimes. The methodology is applied to data recorded at the Eastern Pyrenees mountains (NE Spain), first with a detailed case study where results are compared with different instruments and, finally, with a 32-day analysis where the hydrometeor classification is compared with co-located Parsivel disdrometer precipitation-type present weather observations. The hydrometeor classification is evaluated with contingency table scores, including Probability of Detection (POD), False Alarm Rate (FAR), and Odds Ratio Skill Score (ORSS). The results indicate a very good capacity of Method3 to distinguish rainfall and snow (PODs equal or greater than 0.97), satisfactory results for mixed and drizzle (PODs of 0.79 and 0.69) and acceptable for a reduced number of hail cases (0.55), with relatively low rate of false alarms and good skill compared to random chance in all cases (FAR 0.70). The methodology is available as a Python language program called RaProM at the public github repository

Vertically resolved precipitation intensity retrieved through a synergy between the ground-based NASA MPLNET lidar network measurements, surface disdrometer datasets and an analytical model solution

In this paper, we illustrate a new, simple and complementary ground-based methodologyto retrieve the vertically resolved atmospheric precipitation intensity through a synergy betweenmeasurements from the National Aeronautics and Space Administration (NASA) Micropulse Lidarnetwork (MPLNET), an analytical model solution and ground-based disdrometer measurements.The presented results are obtained at two mid-latitude MPLNET permanent observational sites,located respectively at NASA Goddard Space Flight Center, USA, and at the Universitat Politècnicade Catalunya, Barcelona, Spain. The methodology is suitable to be applied to existing and/or futurelidar/ceilometer networks with the main objective of either providing near real-time (3 h latency)rainfall intensity measurements and/or to validate satellite missions, especially for critical lightprecipitation (<3 mm h−1)

Vertically resolved precipitation intensity retrieved through a synergy between the ground-based NASA MPLNET lidar network measurements, surface disdrometer datasets and an analytical model solution

In this paper, we illustrate a new, simple and complementary ground-based methodology to retrieve the vertically resolved atmospheric precipitation intensity through a synergy between measurements from the National Aeronautics and Space Administration (NASA) Micropulse Lidar network (MPLNET), an analytical model solution and ground-based disdrometer measurements. The presented results are obtained at two mid-latitude MPLNET permanent observational sites, located respectively at NASA Goddard Space Flight Center, USA, and at the Universitat Politècnica de Catalunya, Barcelona, Spain. The methodology is suitable to be applied to existing and/or future lidar/ceilometer networks with the main objective of either providing near real-time (3 h latency) rainfall intensity measurements and/or to validate satellite missions, especially for critical light precipitation (< 3 mm h-1).Peer Reviewe

Vertically resolved precipitation intensity retrieved through a synergy between the ground-based NASA MPLNET lidar network measurements, surface disdrometer datasets and an analytical model solution

In this paper, we illustrate a new, simple and complementary ground-based methodologyto retrieve the vertically resolved atmospheric precipitation intensity through a synergy betweenmeasurements from the National Aeronautics and Space Administration (NASA) Micropulse Lidarnetwork (MPLNET), an analytical model solution and ground-based disdrometer measurements.The presented results are obtained at two mid-latitude MPLNET permanent observational sites,located respectively at NASA Goddard Space Flight Center, USA, and at the Universitat Politècnicade Catalunya, Barcelona, Spain. The methodology is suitable to be applied to existing and/or futurelidar/ceilometer networks with the main objective of either providing near real-time (3 h latency)rainfall intensity measurements and/or to validate satellite missions, especially for critical lightprecipitation (<3 mm h−1)

Precipitació i circulacions mesoescalars en zones d’orografia complexa

[cat] L’orografia té un impacte molt important en la circulació del vent i en la precipitació a totes les escales, des de la microescala fins a la macroescala. La complexitat i la singularitat de les interaccions entre el relleu i l’atmosfera fan que el seu estudi sigui complicat. En aquesta tesi es pretén aportar nous coneixements sobre aquestes interaccions, posant èmfasi en l’estudi de la microescala i la mesoescala. En la primera part s’ha realitzat una caracterització dels extrems absoluts de precipitació a Espanya a diverses escales temporals. S’ha estudiat que l’escalat d’aquestes dades és compatible amb una llei potencial del tipus R = a Db on R és la precipitació per a una pluja extrema de durada D. Els resultats mostren que la proximitat al mar i la influència orogràfica són elements claus en la localització d’aquests extrems a Espanya. En la segona part s’ha estudiat la precipitació hivernal i les circulacions de muntanya a la vall de la Cerdanya (Pirineus Orientals) des del punt de vista microfísic, utilitzant dades de sensors no convencionals, tant remots com in-situ. En concret, s’ha analitzat les mesures del disdròmetre Parsivel i del Micro Rain Radar (MRR) obtingudes durant la campanya experimental Cerdanya-2017, i s’han desenvolupat i aplicat noves metodologies per a l’anàlisi d’aquest tipus de dades descrivint i examinant els episodis de precipitació ocorreguts durant la campanya, tant de la neu com de la pluja des del punt de vista microfísic. En la tercera part s’ha estudiat com interacciona la circulació atmosfèrica a nivells baixos davant l’orografia costanera del litoral català. En concret, s’ha identificat i analitzat la resposta ageostròfica mesoescalar de l’aire en forma de corrents de densitat atrapades per la costa (CTDs en les seves sigles en anglès). Aquests estudis pretenen contribuir en l’aprofundiment del coneixement de les interaccions orogràfiques tant en la precipitació com en les circulacions mesoescalars induïdes pel relleu, de forma que a la llarga puguin contribuir a la millora les estimacions de precipitació en zones d’orografia complexa així com els models conceptuals i numèrics de predicció.[eng] The orography of a region has a large impact on the precipitation and the circulation of the wind at all scales, from the microscale to the macroscale. However, the study the interactions between the relief and the atmosphere is difficult due to their singularity and complexity. This thesis intends to improve the knowledge of those interactions, with emphasis on microscale and mesoscale. The first part characterizes the absolute extreme precipitation records in Spain on different temporal scales. It has been stablished that these data are compatible with a power-law scaling R = a Db where R is the maximum rainfall record achieved during duration D. The results of this analysis show that the proximity to the sea and the orographic influence are key elements to achieve a record in Spain. Winter microphysical precipitation and mountain circulations in the Cerdanya valley (Eastern Pyrenees) have been studied in the second part of this thesis using non-conventional instrumentation both remote sensing and in-situ measurements. In particular, data from a Parsivel disdrometer and from a Micro Rain Radar (MRR) measured during the experimental campaign Cerdanya-2017 has been analyzed. New methodologies for the analysis of this kind of data have been developed and applied describing and analyzing the precipitation events occurred during the campaign for both the snow and rain have been analyzed from the microphysical perspective. The third part studies the interaction of the low-level atmospheric circulation and the coastal orography on the Catalan coast. Specifically, the mesoscale ageostrophic reaction of the air have been identified as Coastally Trapped Disturbances (CTDs). The results of these studies aim to contribute to a better understanding of the orographic interactions for both the precipitation and the mesoscale circulations in such a way they serve to eventually improve the precipitation estimates in complex orography areas and to make progress in the conceptual models and the numerical weather prediction

Producció científica de l'ETSEIB a Futur. Articles publicats per investigadors de l'ETSEIB l'any 2018

Postprint (author's final draft

Lidar remote sensing and co-operative observations: Processing methods and aerosol radiative transfer

This Ph.D. thesis focuses on: (i) the design and integration of a polarimetric channel for the multi-spectral Raman lidar station of the Universitat Politècnica de Catalunya (UPC), Remote Sensing, Antennas, Microwaves and Superconductivity Group (CommSensLab), (ii) the study of the temporal and spatial evolution of atmospheric aerosol optical, microphysical and radiative properties by means of active and passive remote sensing in the context of ACTRIS and Spanish National projects, and (iii) rainfall rate retrieval by means of a vertically-pointed ceilometer in the context of the Verification of the Origins of Rotation in Tornadoes Experiment Southeast (VORTEX-SE). The first goal of this Ph.D., tested on the UPC multi-spectral Raman lidar station, consists of developing a secondary optical receiving chain, installed next to the laser source. The secondary telescope, mounted in the optical chain, allows retrieving the cross-polarized return signal separately from the total-power signal, avoiding the need of a very precise characterization of the crosstalk parameters of the beam-splitters. The first experimental results, corresponding to a collection of atmospheric conditions over the city of Barcelona, are also presented. The second goal of this Ph.D. deals first with the GAME (Global Atmospheric Model) code, necessary to retrieve the aerosol radiative properties. The radiative fluxes estimated in the short-wave and long-wave spectral ranges at the bottom and the top of the atmosphere by GAME are compared to the ones retrieved by a different radiative transfer model, namely Two-Stream, in order to know the importance of the spectral parameterization of a radiative transfer code. Then, GAME code, in both configurations, is fed by means of three different datasets to evaluate the parameterization of the vertically-resolved properties and to assess the uncertainty of GAME when is tuned with input parameters from different sources. Afterwards, an evaluation of the seasonal variability of the aerosol background optical and radiative properties in the Western Mediterranean Basin (WMB) is performed by means of AERONET (Aerosol Robotic Network) sun-photometers data from two background sites, Ersa (Corsica Island, France) and Palma de Mallorca (Mallorca Island, Spain). In addition, in order to detect possible northeast-southwest gradients in the aerosol properties, a third site located at Abolrán (Alborán Island, Spain) is considered. Finally, during 15-24 June 2013 a moderate Saharan dust multi-intrusion was detected by some EARLINET/ACTRIS (Granada, Barcelona, Naples, Potenza and Serra la Nave (Italy)) and ADRIMED/ChArMEx (Cap d’en Font, (Minorca Island, Spain) and Ersa) stations. This Ph.D. uses this event to study the spatio-temporal evolution of the mineral dust properties, since the lidar stations were supported during the multi-intrusion by collocated AERONET sun-photometers and the Falcon 20 aircraft. Also the GAME code is used to estimate the aerosol radiaite effect during the Saharan dust event. Besides, air- and space-borne lidar measurements, satellite images and back-trajectories are used to confirm the multi-intrusion aspect of the event. The last goal of this Ph.D. pursues estimation of the rain rate (RR) from ceilometer measurements. In VORTEX-SE, a Vaisala CL-31 ceilometer, a S-band radar, and a disdrometer were deployed in Alabama during March-April 2016. First, rain-extinction coefficients from ceilometer attenuated backscatter measurements are derived by means of a modified form of the well-known slope-method. These coefficients are compared with the RRs measured by a collocated S-band radar and a disdrometer in order to get the RR-to-extinction models. Advanced covariance-weighted techniques are used to best assess and validate the estimated models. These models can be used to estimate the RR from the ceilometer in similar situations without need to have a collocated cooperative instrument permanently deployed.Este Ph.D. se centra en: (i) en el diseño e integración de un canal polarimétrico para la estación lidar multi espectral del grupo de teledetección, antenas, microondas y superconductividad (CommSensLab) de la Universitat Politècnica de Catalunya (UPC), (ii) en el estudio de la evolución temporal y espacial de las propiedades ópticas, microfísicas y radiativas de los aerosoles por medio de teledetección activa y pasiva en el contexto de ACTRIS y proyectos estatales, y (iii) en la recuperación de intensidad de lluvia por medio de un ceilómetro en configuración vertical en el contexto del proyecto Verification of the Origins of Rotation in Tornadoes Experiment Southeast (VORTEX-SE). El primer objetivo, realizado en la estación lidar de UPC, consiste en el desarrollo de una cadena óptica secundaria instalada junto al láser. El telescopio secundario, montado en la cadena óptica, permite recuperar la componente cross-polarized de la señal total por separado, evitando la necesidad de conocer con precisión los parámetros de los beam-splitters. Se presentan también los primeros resultados obtenidos en Barcelona durante diferentes situaciones atmosféricas. El segundo objetivo de este Ph.D. se centra en el código GAME (Global Atmospheric Model), necesario para recuperar las propiedades radiativas de los aerosoles. Los flujos radiativos estimados tanto en onda larga como en onda corta en la base y en la parte superior de la atmósfera son comparados con los estimados por otro código de transferencia radiativa, Two-Stream, para conocer la importancia de la parametrización espectral. Después, el código GAME es alimentado con 3 bases de datos diferentes para evaluar la parametrización de las propiedades resueltas en altura y conocer la incertidumbre de GAME cuando es alimentado con parámetros con diferentes orígenes. Por otro lado, se presenta una evaluación de la variabilidad estacional de las propiedades ópticas y radiativas del aerosol de fondo en la cuenca oeste mediterránea (WMB) realizada con datos de fotómetros solares de la red AERONET (Aerosol Robotic Network) situados en dos puntos considerados libres de contaminación: Ersa (isla de Córcega, Francia) y Palma de Mallorca. Además, para detectar posibles gradientes noreste-suroeste en las propiedades delos aerosoles, se considera un tercer punto ubicado en la isla de Alborán. Por último, en este Ph.D. se aprovecha una multi intrusión moderada de polvo sahariano, detectada entre los días 15 y 24 de junio de 2013 por algunas estaciones EARLINET/ACTRIS (Granada, Barcelona, Nápoles, Potenza y Serra la Nave (Italia)) y ADRIMED/ChArMEx (Cap d'en Font (Menorca) y Ersa), para estudiar la evolución espacio-temporal de las propiedades del polvo mineral, ya que las estaciones lidar estaban apoyadas durante el evento por fotómetros solares pertenecientes a la red AERONET, situados junto a las estaciones lidar, y por vuelos del Falcon 20. GAME es usado para obtener también el efecto radiativo de los aerosoles durante el evento de polvo sahariano. Para confirmar el aspecto de multi intrusión se utilizan medidas lidar tomadas a bordo de aviones y satélites, imágenes satelitales y retro trayectorias. El último objetivo del Ph.D. persigue la estimación de la RR utilizando medidas de un ceilómetro. En VORTEX-SE, se desplegaron (Alabama, marzo-abril 2016) un ceilómetro Vaisala CL-31, un radar de banda S y un disdrómetro. Se han estimado los coeficientes de extinción debida a la lluvia a partir del retorno atenuado medido por el ceilómetro, utilizando una versión modificada del método de la pendiente. Estos coeficientes se comparan con las intensidades de lluvia (RR) estimadas con el radar y el disdrómetro para obtener modelos de RR-extinción. Para validarlos se utilizan técnicas avanzadas de covarianza ponderada. Dichos modelos pueden usarse para estimar la RR con un ceilómetro, en situaciones similares, sin necesidad de tener desplegado permanentemente un instrumento cooperativo.Postprint (published version