Oscar Martínez-Alvarado

• DPhil
• Researcher at University of Reading

The DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) project aims to improve forecasts of high-impact weather in extratropical cyclones through field measurements, high-resolution numerical modeling, and improved design of ensemble forecasting and data assimilation systems. This article introduces DIAMET and presents som...

Atmospheric fronts and cyclones play an important role in day‐to‐day weather variability, especially in the mid‐latitudes and during the winter season. Severe rainfall and windstorm events are often associated with the passage of a front or a cyclone. While there are many studies of individual fronts and climatologies of instantaneous fronts, there...

Sting jets have been identified in the most damaging extratropical cyclones impacting northwest Europe. Unlike the cold conveyor belt and other long-lived cyclone wind jets, sting jets can lead to regions of exceptionally strong near-surface winds and damaging gusts over just a few hours and with much smaller wind “footprints”. They descend into th...

In the mid‐latitudes extreme precipitation events are strongly associated with cold fronts. By exploring drivers across different scales and relating them to precipitation, we aim to improve our understanding of processes influencing cold frontal extremes. Using hourly ERA5 data over Europe and the North Atlantic, cold fronts are detected and the a...

The THINICE field campaign, based from Svalbard in August 2022, provided unique observations of summertime Arctic cyclones, their coupling with cloud cover, and interactions with tropopause polar vortices and sea ice conditions. THINICE was motivated by the need to advance our understanding of these processes and to improve coupled models used to f...

This study explores the mechanisms contributing to heavy precipitation associated with landfalling atmospheric rivers (ARs) and orography, focusing on a high‐profile case study of an extratropical cyclone, storm Bronagh, which caused flooding and travel disruption in the UK. While prior research has established the connection between ARs, orography...

Sting jets have been identified in the most damaging extratropical cyclones impacting northwest Europe. Unlike the cold conveyor belt and other long-lived cyclone wind jets, sting jets can lead to regions of exceptionally strong near-surface winds, and damaging gusts, over just a few hours and with much smaller wind “footprints”. They descend into...

Recent work has demonstrated that skilful hybrid statistical–dynamical forecasts of heavy rainfall events in Southeast Asia can be made by combining model forecasts of the phases and amplitudes of Kelvin, Rossby, and westward‐moving Rossby gravity waves with climatological rainfall statistics conditioned on these waves. This study explores the sens...

Precipitation efficiency refers to the amount of water that is lost from the atmosphere through precipitation compared to the available water vapor in the atmosphere. This metric plays a critical role in understanding precipitation patterns. However, calculating precipitation efficiency for extratropical cyclones can be challenging because cyclones...

Atmospheric blocking is a circulation pattern that describes the presence of large-scale, persistent anticyclones, which have the potential to bring severe impacts at the surface. However, the dynamical behaviour of blocks is still not fully understood. For example, the factors that determine the persistence of blocking events are not clear. In thi...

Storm Eunice caused severe wind impacts on the United Kingdom on 18 February 2022. This article contains the second of a two‐part study and consists of a detailed analysis of Eunice's airstream structure, confirming the presence of sting‐jet (SJ) activity during its lifecycle. By the time Eunice crossed Wales and southern England, several other air...

Storm Eunice caused severe wind impacts on the United Kingdom on 18 February 2022. This article contains the first of a two‐part study and shows how Eunice's cyclone structure was well‐forecast days in advance, but small‐scale uncertainty persisted on peak‐wind location and strength. Several indications of sting‐jet activity in observations and mod...

Billions of historical climatological observations remain unavailable to science as they exist only on paper, stored in numerous archives around the world. The conversion of these data from paper to digital could transform our understanding of historical climate variations, including extreme weather events. Here we demonstrate how the rescue of suc...

While skilful forecasts of heavy rainfall are highly desirable for weather warnings and mitigating impacts, forecasting such events is notoriously difficult, even with the most advanced numerical weather prediction models, due to the strong dependence on convective‐scale processes. The large‐scale circulation, on the other hand, is typically more p...

Atmospheric blocking is a circulation pattern that describes the presence of large-scale, persistent anticyclones, which have the potential to bring severe impacts at the surface. However, the dynamical behaviour of blocks is still not fully understood. For example, the factors that determine the persistence of blocking events are not clear. In thi...

The characterization of wind speed and its variability at a site is important for wind resource assessment. The most readily available wind measurements are at 10 m above ground level. These measurements can then be extrapolated vertically to estimate wind power production. In this work, the Monin–Obukhov similarity method was implemented to estima...

Billions of historical climatological observations remain unavailable to science as they exist only on paper, stored in numerous archives around the world. The conversion of these data from paper to digital could transform our understanding of historical climate variations, including extreme weather events. Here we demonstrate how the rescue of suc...

Understanding near-surface wind variability is crucial to support wind power penetration on national electrical grids. High-resolution numerical simulations are often proposed as the best solution to study the fluctuation of wind resources. We compare WRF and MERRA-2 bias-corrected wind speeds at hub height at different spatial resolutions and tran...

Analysis of moist airflows associated with a case study, storm Bronagh, is conducted to determine whether moisture contributing to observed precipitation near the cyclone centre is transported from the subtropics or local environment. Reanalysis data are used to identify the warm conveyor belt and dry intrusion, and an algorithm is developed to ide...

The climate crisis has led to an increased interest in renewable energy, and in wind energy in particular. Wind farms with the largest generating potential are generally located offshore. In this study we consider the case of Mexico, a sub-tropical country in North-America. Due to Mexico’s location, offshore wind farms (OWF) would be at risk of dam...

Two sets of weather patterns describing variability in 850 hPa winds in Southeast Asia are presented and compared. Patterns are calculated using EOF/k‐means clustering with and without imposing a separation between planetary‐scale and regional‐scale circulation features. The former are labelled as tiered patterns while the latter are referred to as...

Atmospheric reanalyses are widely used for understanding the past and present climate. They have become increasingly used within the renewable energy sector for assessing wind and solar resources for different regions of the globe in conjunction with observations. Mexico is a country with considerable potential for wind energy production, especiall...

Sting jets in European windstorms can cause damaging winds and gusts, but the resolution of global ensemble prediction systems is too coarse to represent them. Here we describe the development of a tool applied to outputs from these systems that forecasters can use to identify favourable conditions for sting‐jet occurrence several days ahead. Plots...

The seasonal and diurnal variability of the wind resource in Northern Mexico is examined. Fourteen weather stations were grouped according to the terrain morphology and weather systems that affect the region to evaluate the impact on wind ramps and high wind persistent events. Four areas driven by weather systems seasonality are identified. Wind po...

Based on the Van der Hoven’s seminal work, wind power industry has adopted the 10 min mean time as the proper sampling to estimate resource assessment. However, research within the literature questions the generalization of the 10 min as a standard measure of minima dispersion due to the particular geographic characteristics where the measurements...

In this study, we use a k‐mean clustering approach to investigate the weather patterns responsible for extreme wind speed events throughout Mexico using 40 years of the ERA‐5 atmospheric reanalysis. Generally, we find a large geographical split between the weather patterns that generate the strongest winds across the country. The highest wind power...

In this study, we use a k-mean clustering approach to investigate the weather patterns responsible for extreme wind speed events throughout Mexico using 40 years of the ERA-5 atmospheric reanalysis. Generally, we find a large geographical split between the weather patterns that generate the strongest winds across the country. The highest wind power...

In the fundamental stage of resource assessment, high-quality wind speed measurements are required to estimate power production. However , this high-quality data is not always available, and therefore the analysis of alternative sources becomes essential. In this work, we analyze the ability of MERRA-2 to represent wind speed characteristics at 24...

The examination of model error is fundamental to improve weather forecasts at any time‐scale. Here, model errors for two forecast lead times (12, 24 hr) at the grid‐point level are analysed using (a) the total Eulerian changes in variables, such as potential temperature and potential vorticity (PV), both conserved under adiabatic, frictionless cond...

Models are continuously developed at numerical weather prediction (NWP) centres to improve forecast skill, with new operational model configurations adopted every few years. The parametrizations of diabatic processes are probably the most frequently updated part of NWP models as they are crucial for accurate weather predictions and contain uncertai...

While contemporary numerical weather prediction models represent the large‐scale structure of moist atmospheric processes reasonably well, they often struggle to maintain accurate forecasts of small‐scale features such as convective rainfall. Even though high‐resolution models resolve more of the flow, and are therefore arguably more accurate, mois...

Extreme precipitation associated with extratropical cyclones can lead to flooding if cyclones track over land. However, the dynamical mechanisms by which moist air is transported into cyclones is poorly understood. In this paper we analyze airflows within a climatology of cyclones in order to understand how cyclones redistribute moisture stored in...

Atmospheric blocking has been shown to be a phenomenon that models struggle to predict accurately, particularly the onset of a blocked state following a more zonal flow. This struggle is, in part, due to the lack of a complete dynamical theory for block onset and maintenance. Here, we evaluate the impact cyclone representation had on the forecast o...

Weather models differ in their ability to forecast, at medium range, atmospheric blocking and the associated structure of upper‐level Rossby waves. Here, we evaluate the effect of a model’s dynamical core on such forecasts. Operational forecasts from the ensemble prediction systems (EPSs) of the European Centre for Medium‐range Weather Forecasts (E...

Extra-tropical cyclones dominate autumn and winter weather over western Europe. The strongest cyclones, often termed windstorms, have a large socio-economic impact on landfall due to strong surface winds and coastal storm surges. Climate model integrations have predicted a future increase in the frequency of, and potential damage from, European win...

Extratropical cyclones are typically weaker and less frequent in summer as a result of differences in the background state flow and diabatic processes with respect to other seasons. Two extratropical cyclones were observed in summer 2012 with a research aircraft during the DIAMET (DIAbatic influences on Mesoscale structure in ExTratropical storms)...

Recent work has shown that both the amplitude of upper-level Rossby waves and the tropopause sharpness decrease with forecast lead time for several days in some operational weather forecast systems. In this contribution, the evolution of error growth in a case study of this forecast error type is diagnosed through analysis of operational forecasts...

The term atmospheric river is used to describe corridors of strong water vapor transport in the troposphere. Filaments of enhanced water vapor, commonly observed in satellite imagery extending from the subtropics to the extratropics, are routinely used as a proxy for identifying these regions of strong water vapor transport. The precipitation assoc...

Strong winds equatorward and rearward of a cyclone core have often been associated with two phenomena: the cold conveyor belt (CCB) jet and sting jets. Here, detailed observations of the mesoscale structure in this region of an intense cyclone are analyzed. The in situ and dropsonde observations were obtained during two research flights through the...

The parametrization of diabatic processes in numerical models is critical for the accuracy of weather forecasts and for climate projections. A novel approach to the evaluation of these processes in models is introduced in this contribution. The approach combines a suite of on‐line tracer diagnostics with off‐line trajectory calculations. Each trace...

The warm conveyor belt (WCB) of an extratropical cyclone generally splits into two branches. One branch (WCB1) turns anticyclonically into the downstream upper-level tropospheric ridge, while the second branch (WCB2) wraps cyclonically around the cyclone centre. Here, the WCB split in a typical North Atlantic cold-season cyclone is analysed using t...

Strong winds equatorwards and rearwards of a cyclone core have often been associated with two phenomena, the cold conveyor belt (CCB) jet and sting jets. Here, detailed observations of the mesoscale structure in this region of an intense cyclone are analysed. The {\it in-situ} and dropsonde observations were obtained during two research flights thr...

Numerical climate models constitute the best available tools to tackle the problem of climate prediction. Two assumptions lie at the heart of their suitability: (1) a climate attractor exists, and (2) the numerical climate model's attractor lies on the actual climate attractor, or at least on the projection of the climate attractor on the model's p...

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Sting jets are transient coherent mesoscale strong wind features that can cause damaging surface wind gusts in extratropical cyclones. Currently, we have only limited knowledge of their climatological characteristics. Numerical weather prediction models require enough resolution to represent slantwise motions with horizontal scales of tens of kilom...

{DIAMET} Science Meeting, 7-8 March, Manchester

Departmental seminar, Department of Meteorology, University of Reading}

{DIAMET} Science Meeting, 7-8 March, Manchester

{DIAMET} Science Meeting, 7-8 March, Manchester

Extratropical cyclones dominate autumn and winter weather over western Europe. The strongest cyclones, often termed windstorms, have a large socio-economic impact due to the strong surface winds and associated storm surges in coastal areas. Here we show that sting jets are a common feature of windstorms; up to a third of the 100 most intense North-...

Geophysical and Nonlinear Fluid Dynamics Seminar, AOPP, 23 October, Oxford

{DIAMET} Science Meeting, 6 November, Manchester

Sting jets are transient mesoscale jets of air that descend from the tip of the cloud head towards the top of the boundary layer in severe extratropical cyclones and can lead to damaging surface wind gusts. This recently identified jet is distinct from the well-documented jets associated with the cold and warm conveyor belts. One mechanism proposed...

The existence of sting jets as a potential source of damaging surface winds during the passage of extratropical cyclones has recently been recognized However, there are still very few published studies on the subject Furthermore, although ills known that other models are capable of reproducing sting jets, in the published literature only one numeri...

Sting jets are transient, highly localized low-level jets that descend from the tip of the cloud head towards the top of the boundary layer in some rapidly deepening Shapiro-Keyser type extratropical cyclones. Sting jets have recently been recognised as clearly different from other air streams, such as the warm and cold conveyor belts, that are als...

The hypothesis of a low dimensional martian climate attractor is investigated by the application of the proper orthogonal decomposition (POD) to a simulation of martian atmospheric circulation using the UK Mars general circulation model (UK-MGCM). In this article we focus on a time series of the interval between autumn and winter in the northern he...

We use proper orthogonal decomposition (POD) to study a transient teleconnection event at the onset of the 2001 planet-encircling dust storm on Mars, in terms of empirical orthogonal functions (EOFs). There are several differences between this and previous studies of atmospheric events using EOFs. First, instead of using a single variable such as s...

The aim of this project is to determine the mechanisms that lead to sting jets in extreme windstorms and develop diagnostics for predicting their formation and development. Extratropical cyclones often produce strong surface winds, mostly associated with low-level jets along the warm and cold fronts. Some severe extratropical cyclones have been fou...

In July 2001 (Martian year 25), Mars was enshrouded by a thick veil of dust which lasted for several months and obscured the observation of its surface to spacecraft cameras and ground-based telescopes. The emergence and rapid evolution (within a few days) of multiple, isolated, regional dust storms which eventually attained planetary scale extent...

Introduction: There is considerable evidence that shows that the Martian atmosphere behaves in a more regular fashion than its terrestrial counterpart [1, 2, 3, 4]. This evidence leads to the hypothesis of theMartian climate attractor being of a relatively low dimension, which, in turn, would imply the possibility of describing the state of the atm...

Introduction: In July 2001 (Martian year 25), Mars was enshrouded by a thick veil of dust which lasted for several months and obscured the observation of its surface to spacecraft cameras and ground-based telescopes. The emergence and rapid evolution (within a few days) of multiple, isolated, regional dust storms which eventually attained planetary...

We report here on an assimilation of thermal profiles and dust optical depths from Mars Global Surveyor/Thermal Emission Spectrometer, aimed at characterizing the meteorology at the time of the 2001 global dust storm.

Not available.

In this paper we explore the possibility of deriving low-dimensional models of the dynamics of the Mar-tian atmosphere. The analysis consists of a Proper Orthogonal Decomposition (POD) of the atmospheric streamfunction after first decomposing the vertical structure with a set of eigenmodes. The vertical modes were obtained from the quasi-geostrophi...

We study systems with periodically oscillating parameters that can give way to complex periodic or nonperiodic orbits. Performing the long time limit, we can define ergodic averages such as Lyapunov exponents, where a negative maximal Lyapunov exponent corresponds to a stable periodic orbit. By this, extremely complicated periodic orbits composed o...

The effect of a harmonic variation of the feeding flow on a dripping faucet has been studied using two approaches. First, a model based on a Lagrangian point of view of the hydrodynamical system and second, a low dimension dynamical model which reproduces de essence of the first with the advantage that it requires much less computational power. In...

We analyse the classical dripping faucet problem considering that the liquid supply at the tip of the faucet is a function of time. We use the model introduced by Fuchikami et al. to describe the shape of the drops. Also, we describe the dynamics of the phenomenon at long times compared with the average interval between the departure of two subsequ...