scholarly journals Detection of convective systems through surface wind gust estimation based on Sentinel-1 images: A new approach

2018 ◽  
Vol 19 (12) ◽  
pp. e863 ◽  
Author(s):  
Tran Vu La ◽  
Christophe Messager ◽  
Marc Honnorat ◽  
Claire Channelliere
Keyword(s):  
Surface Wind ◽  
Wind Gust ◽  
New Approach ◽  
Convective Systems

scholarly journals Doppler Radar Observations of a Wintertime Anticyclonic Misocyclone Associated with Surface Wind Gust on the Coast of the Sea of Japan

SOLA ◽  
2019 ◽  
Vol 15 (0) ◽  
pp. 234-237
Author(s):  
Kenichi Kusunoki ◽  
Ken-ichiro Arai ◽  
Hanako Y. Inoue ◽  
Chusei Fujiwara
Keyword(s):  
Sea Of Japan ◽  
Doppler Radar ◽  
Surface Wind ◽  
The Sea Of Japan ◽  
Wind Gust ◽  
Radar Observations

scholarly journals Using two-stream theory to capture fluctuations of satellite-perceived TOA SW radiances reflected from clouds over ocean

2020 ◽  
Vol 13 (7) ◽  
pp. 3909-3922
Author(s):  
Florian Tornow ◽  
Carlos Domenech ◽  
Howard W. Barker ◽  
René Preusker ◽  
Jürgen Fischer
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
State Of The Art ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Cloud Water ◽  
Effective Radius ◽  
The State ◽  
Distribution Models ◽  
New Approach

Abstract. Shortwave (SW) fluxes estimated from broadband radiometry rely on empirically gathered and hemispherically resolved fields of outgoing top-of-atmosphere (TOA) radiances. This study aims to provide more accurate and precise fields of TOA SW radiances reflected from clouds over ocean by introducing a novel semiphysical model predicting radiances per narrow sun-observer geometry. This model was statistically trained using CERES-measured radiances paired with MODIS-retrieved cloud parameters as well as reanalysis-based geophysical parameters. By using radiative transfer approximations as a framework to ingest the above parameters, the new approach incorporates cloud-top effective radius and above-cloud water vapor in addition to traditionally used cloud optical depth, cloud fraction, cloud phase, and surface wind speed. A two-stream cloud albedo – serving to statistically incorporate cloud optical thickness and cloud-top effective radius – and Cox–Munk ocean reflectance were used to describe an albedo over each CERES footprint. Effective-radius-dependent asymmetry parameters were obtained empirically and separately for each viewing-illumination geometry. A simple equation of radiative transfer, with this albedo and attenuating above-cloud water vapor as inputs, was used in its log-linear form to allow for statistical optimization. We identified the two-stream functional form that minimized radiance residuals calculated against CERES observations and outperformed the state-of-the-art approach for most observer geometries outside the sun-glint and solar zenith angles between 20 and 70∘, reducing the median SD of radiance residuals per solar geometry by up to 13.2 % for liquid clouds, 1.9 % for ice clouds, and 35.8 % for footprints containing both cloud phases. Geometries affected by sun glint (constituting between 10 % and 1 % of the discretized upward hemisphere for solar zenith angles of 20 and 70∘, respectively), however, often showed weaker performance when handled with the new approach and had increased residuals by as much as 60 % compared to the state-of-the-art approach. Overall, uncertainties were reduced for liquid-phase and mixed-phase footprints by 5.76 % and 10.81 %, respectively, while uncertainties for ice-phase footprints increased by 0.34 %. Tested for a variety of scenes, we further demonstrated the plausibility of scene-wise predicted radiance fields. This new approach may prove useful when employed in angular distribution models and may result in improved flux estimates, in particular dealing with clouds characterized by small or large droplet/crystal sizes.

Surface wind gust prediction over Incheon international airport using the unified model

2020 ◽  
Vol 103 (1) ◽  
pp. 1499-1535
Author(s):  
Venkatraman Prasanna ◽  
Hee Wook Choi ◽  
Seon O. K. Hong ◽  
Geun Hoi Kim ◽  
Young Gon Lee ◽  
...  
Keyword(s):  
Surface Wind ◽  
Unified Model ◽  
Wind Gust ◽  
International Airport

Radar-Based Comparison of Thunderstorm Outflow Boundary Speeds versus Peak Wind Gusts from Automated Stations

2021 ◽  
Author(s):  
Keith D. Sherburn ◽  
Matthew J. Bunkers ◽  
Angela J. Mose
Keyword(s):  
Surface Wind ◽  
Thermodynamic Characteristics ◽  
Time Of Day ◽  
Wind Gust ◽  
Severe Thunderstorm ◽  
Wind Gusts ◽  
Thunderstorm Outflow ◽  
Versus Peak ◽  
Outflow Boundary ◽  
Lapse Rates

AbstractStraight-line winds are arguably the most challenging element considered by operational forecasters when issuing severe thunderstorm warnings. Determining the potential maximum surface wind gust prior to an observed, measured gust is very difficult. This work builds upon prior research that quantified a relationship between the observed outflow boundary speed and corresponding measured wind gusts. Though this prior study was limited to a 30-case dataset over eastern Colorado, the current study comprises 943 cases across the contiguous United States and encompasses all times of day, seasons, and regions while representing various convective modes and associated near-storm environments.The wind gust ratios (WGRs), or the ratio between a measured wind gust and the associated outflow boundary speed, had a nationwide median of 1.44, mean of 1.68, and 25th–75th percentiles of 1.19–1.91, respectively. WGRs varied considerably by region, season, time of day, convective mode, near-storm environment, and outflow boundary speed. WGRs tended to be higher in the plains, Intermountain West, and southern coastal regions, lower in the cool season and during the morning and overnight, and lower in linear convective modes compared to supercell and disorganized modes. Environments with stronger mean winds and low-to-midlevel shear vector magnitudes tended to have lower WGRs, while those with steeper low-level lapse rates and other thermodynamic characteristics favorable for momentum transfer and evaporative cooling tended to have higher WGRs. As outflow boundary speed increases, WGRs—and their variability—decreases. Applying these findings may help operational meteorologists provide more accurate severe thunderstorm warnings.

scholarly journals Characterising the relationship between weather extremes in Europe and synoptic circulation features

2014 ◽  
Vol 2 (2) ◽  
pp. 1867-1911 ◽  
Author(s):  
S. Pfahl
Keyword(s):  
Central Europe ◽  
Extreme Events ◽  
Radiative Forcing ◽  
Surface Wind ◽  
Extreme Weather Events ◽  
Temperature Extremes ◽  
Wind Gust ◽  
Weather Extremes ◽  
Near Surface ◽  
The North

Abstract. Extreme weather events in Europe are closely linked to anomalies of the atmospheric circulation and in particular to circulation features like cyclones and atmospheric blocking. In this study, this linkage is systematically characterised with the help of conditional cyclone and blocking frequencies during precipitation, wind gust and temperature extremes at various locations in Europe. Such conditional frequency fields can serve as a dynamical fingerprint of the extreme events and yield insights into their most important physical driving mechanisms. Precipitation extremes over the ocean and over flat terrain are shown to be closely related to cyclones in the vicinity and the associated dynamical lifting. For extreme precipitation over complex terrain, cyclone anomalies are found at more remote locations, favouring the flow of moist air towards the topography. Wind gust extremes are associated with cyclone and blocking anomalies in opposite directions, with the cyclones occurring mostly over the North and Baltic Seas for extreme events in central Europe. This setting is associated with pronounced surface pressure gradients and thus high near-surface wind velocities. Hot temperature extremes in northern and central Europe typically occur in the vicinity of a blocking anticyclone, where subsidence and radiative forcing are strong. Over southern Europe, blocking anomalies are shifted more to the north or northeast, indicating a more important role of warm air advection. Large-scale flow conditions for cold extremes are similar at many locations in Europe, with blocking anomalies over the North Atlantic and northern Europe and cyclone anomalies southeast of the cold extreme, both contributing to the advection of cold air masses. This characterisation of synoptic-scale forcing mechanisms can be helpful for better understanding and anticipating weather extremes and their long-term changes.

Recent reversal of mean wind speed and gusts across the Iberian Peninsula and its relationship with modes of climate variability, 1961-2019

2021 ◽  
Author(s):  
Eduardo Utrabo-Carazo ◽  
Cesar Azorin-Molina ◽  
Encarna Serrano ◽  
Enric Aguilar ◽  
Manola Brunet
Keyword(s):  
Wind Speed ◽  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
Weather Forecasting ◽  
Surface Wind ◽  
Wind Gust ◽  
Near Surface ◽  
Modes Of Variability ◽  
Mean Wind Speed ◽  
Mediterranean Oscillation

<p>In a context of climate change, near-surface wind speed (SWS) has received less attention than other variables such as air temperature or precipitation, despite its undeniable environmental and socio-economic impacts. Studies suggest a generalized decrease of SWS in continental surfaces located in the middle latitudes from 1979 to 2010, the so-called stilling phenomenon, and an increase in it thereafter, which has been termed reversal or recovery phenomenon. Recent studies indicate that multidecade oscillations produced by the internal variability of the climate system are responsible for both phenomena. The aim of this work is to advance in the evaluation of the multidecadal variability and causes of the stilling and reversal in the observed SWS, covering the complete 2010s decade and focusing on the Iberian Peninsula region (IP). More specifically, the particular objectives of this study are: (i) to determine for the first time the occurrence of the reversal phenomenon in the IP over the last decade(s), identifying its onset year and its magnitude; (ii) to deepen into the relation between atmospheric teleconnection indices and observed trends in SWS; and (iii) to link atmospheric circulation changes to observed SWS variability. For that purpose, homogenized series of mean wind speed and gusts will be used, as well as data from the ERA5 reanalysis (European Centre for Medium-Range Weather Forecasting). Three SWS parameters will be analysed: monthly mean SWS anomaly; monthly mean daily peak wind gust (DPWG) anomaly; and number of days in which the value of DPWG exceeds the 90th percentile of the series considered. Trends of these parameters will be calculated, as well as the correlation between them and the modes of variability that govern in the region: North Atlantic Oscillation (NAO), Mediterranean Oscillation (MO) and Western Mediterranean Oscillation. Finally, trends of these modes of variability and of other parameters dependent on atmospheric circulation (e.g., geostrophic wind) will be calculated to try to clarify the drivers of the observed changes in the SWS.</p>

New approach to sea surface wind retrieval from GNSS-R measurements

2011 ◽  
Author(s):  
Hyuk Park ◽  
Enric Valencia ◽  
Nereida Rodriguez-Alvarez ◽  
Xavier Bosch-Lluis ◽  
Isaac Ramos-Perez ◽  
...  
Keyword(s):  
Surface Wind ◽  
Sea Surface ◽  
New Approach ◽  
Wind Retrieval ◽  
Sea Surface Wind ◽  
Sea Surface Wind Retrieval

scholarly journals Characterising the relationship between weather extremes in Europe and synoptic circulation features

2014 ◽  
Vol 14 (6) ◽  
pp. 1461-1475 ◽  
Author(s):  
S. Pfahl
Keyword(s):  
Central Europe ◽  
Extreme Events ◽  
Radiative Forcing ◽  
Surface Wind ◽  
Extreme Weather Events ◽  
Temperature Extremes ◽  
Wind Gust ◽  
Weather Extremes ◽  
Near Surface ◽  
The North

Abstract. Extreme weather events in Europe are closely linked to anomalies of the atmospheric circulation and in particular to circulation features like cyclones and atmospheric blocking. In this study, this linkage is systematically characterised with the help of conditional cyclone and blocking frequencies during precipitation, wind gust and temperature extremes at various locations in Europe. Such conditional frequency fields can serve as a dynamical fingerprint of the extreme events and yield insights into their most important physical driving mechanisms. Precipitation extremes over the ocean and over flat terrain are shown to be closely related to cyclones in the vicinity and the associated dynamical lifting. For extreme precipitation over complex terrain, cyclone anomalies are found at more remote locations, favouring the flow of moist air towards the topography. Wind gust extremes are associated with cyclone and blocking anomalies in opposite directions, with the cyclones occurring mostly over the North and Baltic seas for extreme events in central Europe. This setting is associated with pronounced surface pressure gradients and thus high near-surface wind velocities. Hot temperature extremes in northern and central Europe typically occur in the vicinity of a blocking anticyclone, where subsidence and radiative forcing are strong. Over southern Europe, blocking anomalies are shifted more to the north or northeast, indicating a more important role of warm air advection. Large-scale flow conditions for cold extremes are similar at many locations in Europe, with blocking anomalies over the North Atlantic and northern Europe and cyclone anomalies southeast of the cold extreme, both contributing to the advection of cold air masses. This characterisation of synoptic-scale forcing mechanisms can be helpful for better understanding and anticipating weather extremes and their long-term changes.

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