Vertical Wind Profiles Research Articles

Improvement of the all-weather profiler

The article considers the issues of improving the quality of vertical wind profile measurements. In order to make these measurements under any meteorological conditions, data from profilometers operating in different wave ranges, from optical to centimetre, are combined. At the same time, the resolving power of the latter is considerably inferior to that of the former. We propose a way to improve the quality of measurements in the radio band by applying a new method of information processing, using estimates of the width of the spectrum and the peculiarities of their spatial distribution.

Combinational Optimization of the WRF Physical Parameterization Schemes to Improve Numerical Sea Breeze Prediction Using Micro-Genetic Algorithm

This study aims to improve the performance of the Weather Research and Forecasting (WRF) model in the sea breeze circulation using the micro-Genetic Algorithm (micro-GA). We found the optimal combination of four physical parameterization schemes related to the sea breeze system, including planetary boundary layer (PBL), land surface, shortwave radiation, and longwave radiation, in the WRF model coupled with the micro-GA (WRF-μGA system). The optimization was performed with respect to surface meteorological variables (2 m temperature, 2 m relative humidity, 10 m wind speed and direction) and a vertical wind profile (wind speed and direction), simultaneously for three sea breeze cases over the northeastern coast of South Korea. The optimized set of parameterization schemes out of the WRF-μGA system includes the Mellor–Yamada–Nakanishi–Niino level-2.5 (MYNN2) for PBL, the Noah land surface model with multiple parameterization options (Noah-MP) for land surface, and the Rapid Radiative Transfer Model for GCMs (RRTMG) for both shortwave and longwave radiation. The optimized set compared with the various other sets of parameterization schemes for the sea breeze circulations showed up to 29 % for the improvement ratio in terms of the normalized RMSE considering all meteorological variables.

Large eddy simulation of the atmospheric boundary layer to investigate the Coriolis effect on wind and turbulence characteristics over different terrains

The wind veering phenomenon caused by the Coriolis force is frequently observed in the atmospheric boundary layer (ABL) and may affect the wind and turbulence characteristics of the ABL, thus influencing the wind effects on structures, especially high-rise structures. To investigate the Coriolis effect, this study firstly reproduces a realistic thousand-meter height ABL with a wind veering phenomenon by large eddy simulation. The simulated vertical profiles of mean wind speed and twist angle are validated against field observations. Three typical terrain types are considered in the simulation and the corresponding vertical profiles of wind and turbulence characteristics are presented and discussed. Furthermore, an additional group of reference cases not considering the Coriolis force is also considered for comparison to quantify the Coriolis effects on the wind and turbulence characteristics. The results show that both the Coriolis force and terrain type significantly affect the vertical profiles of mean wind speed and turbulence intensity in three orthogonal directions. The Coriolis effect on the turbulence integral length scale is more appreciable in the streamwise direction than in the other two orthogonal directions. The vertical profiles of wind speed and turbulence properties in the ABL simulated with consideration of the Coriolis force may serve as a crucial reference for the more reliable wind-resistant design of high-rise structures.

Characteristics and Vertical Profiles of Mean Wind and Turbulence for Typhoon, Monsoon, and Thunderstorm Winds

AbstractThe vast majority of current structural design codes and standards do not separately consider the wind and turbulence profiles for different storm types. Based on the 356-m-high Shenzhen Me...

Improvement of wind power prediction from meteorological characterization with machine learning models

To mitigate uncertainties in wind resource assessments and to improve the estimation of energy production of a wind project, this work uses a decision tree machine learning model to assess the effectiveness of hub-height wind speed, rotor-equivalent wind speed, and lapse rate as variables in power prediction. Atmospheric data is used to train regression trees and correlate the power outputs to wind profiles and meteorological characteristics to be able to predict power responses according to physical patterns. The decision tree model was trained for four vertical wind profile classifications to showcase the need for multiple calculations of wind speed at various levels of the rotor layer. Results indicate that when compared to traditional power curve methods, the decision tree combining rotor-equivalent wind speed and lapse rate improves prediction accuracy by 22% for the given data-set, while also proving to be the most effective method in power prediction for all classified vertical wind profile types. Models incorporating lapse rate into predictions performed better than those without it, showing the importance of considering atmospheric criteria in wind power prediction analyses.

Sensitivity analysis of planetary boundary layer schemes using the WRF model in Northern Colombia during 2016 dry season

This study conducted meteorological simulations in northern Colombia by analyzing different planetary boundary layer (PBL) schemes available in the numerical Weather Research and Forecasting (WRF) model. The study area included three nested domains with horizontal resolutions of 18 km, 6 km, and 2 km, with 38 vertical levels. The evolution and structure of the PBL were analyzed during the driest months (March, April, and May 2016) and in regions with the highest particulate matter concentrations. Sensitivity analysis of the WRF model was performed with two local and two non-local PBL schemes. The results were validated using observations of the surface air temperature, relative humidity, and surface wind speed collected from three meteorological stations in the area. The PBL heights were experimentally determined using radiosonde data provided by a station located in the center of the study area. Variations in PBL heights were estimated using linear regression methods and minimization of statistical errors for the bulk Richardson number, as well as analysis of vertical temperature and wind profiles. The WRF model reliably reproduced the daily values and diurnal cycles of temperature, relative humidity, and wind speed within the PBL and accounted for the influence of topography and sea breezes. Horizontal heat advection dominates the upwelling of air masses when sea breezes are active. The onshore wind direction starts to change from east to northwest, implying a decay in the land breeze regime. All schemes overestimate the mixing height and tend to underestimate surface air temperature values at night. All show wetter conditions and underestimate wind speed. Although the non-local Yonsei University (YSU) scheme shows the best performance, it also shows the largest sources of errors when determining the behavior of the surface layer during stable conditions. Relative humidity and wind speed estimates provided by the local Mellor‐Yamada‐Nakanishi‐Niino (MYNN) scheme were closer to those recorded at the meteorological stations.

Southern Great Plains Wildfire Outbreaks

Destructive wildfire outbreaks are a preeminent natural hazard on the grass-dominated landscape of the southern Great Plains. These southern Great Plains wildfire outbreaks (SGPWOs) are characterized by tens of wildfires that evolve on spatial and temporal scales closely tied to the passage of midlatitude cyclones when dormant herbaceous vegetation is particularly dry and abundant. Ten SGPWOs inflicted tragic losses of life and property across eastern New Mexico, west Texas, and Oklahoma between December 2005 and April 2009. This study reviews the conditions that promoted these dangerous phenomena. Texas A&M; Forest Service records reveal that enhanced seasonal wildfire activity and increased potential for SGPWOs typically occurs during El Niño Southern Oscillation cold phases (La Niña), especially when preceded by positive growing-season rainfall anomalies. The antecedent state of predominately fine grassland vegetative fuels associated with SGPWOs is quantified per Energy Release Component (ERC, fuel model G). Average ERC values >50 (>70th percentile) supported the 2005-2009 SGPWOs on the Great Plains of Texas. Meteorological composites that quantify mean synoptic patterns during SGPWOs are generated via Rapid Update Cycle analyses, and averaged vertical temperature, moisture, and wind profiles are presented. Further analyses of subsynoptic low and midlevel tropospheric temperatures and winds illustrate a tendency for wildfires to occur near 2-m and 850-hPa thermal ridges when overspread by 500-hPa wind maxima. The juxtaposition of these atmospheric features appears to be a useful meso-α-scale predictor of heightened wildfire risks. Recognition of the presented seasonal indicators toward a fire-prone regime influenced strategic preparations for the historic 2011 Texas wildfires. Operational use of composite pattern recognition-based forecasts in tactical decision support is demonstrated for the 27 February 2011 “firestorm”, a particularly damaging SGPWO during an unprecedented fire season. Average ERC values >75 (>95th percentile) additionally supported prolonged burn periods with the passage of subsequent fire outbreak-bearing weather systems during the spring of 2011. Lastly, seasonal trends and the chronology of climatic and environmental signals prior to SGPWOs are highlighted, per a summary of conditions that preceded all of the 2005-2011 episodes.

Environments of Significant Tornadoes Occurring within the Warm Sector versus those Occurring along Surface Baroclinic Boundaries

Archived, hourly-analysis proximity soundings from the operational Rapid Update Cycle (RUC) model are used to examine the vertical wind profiles and thermodynamic parameter space associated with significant tornadoes (rated F2+/EF2+) occurring in the warm sector (33 events) of synoptic cyclones, as well as those occurring along surface baroclinic boundaries (52 events), during the period 1999-2010 over the central and eastern United States. These tornadoes were associated with either the warm sector or a surface baroclinic boundary through the use of subjective surface analyses, supplemented by visible satellite and WSR-88D imagery. A key finding is that measures of ground-relative wind speed, storm-relative helicity, and bulk wind difference are much stronger for warm-sector significant tornado events. In contrast, thermodynamic parameters did not distinguish between the two regimes. Among all of the parameters examined, the observed and predicted speed of the parent supercell showed the most substantial differences between warm-sector and boundary significant tornado environments.

Environmental sensitivities of shallow-cumulus dilution – Part 2: Vertical wind profile

Abstract. This second part of a numerical study on shallow-cumulus dilution focuses on the sensitivity of cloud dilution to changes in the vertical wind profile. Insights are obtained through large-eddy simulations of maritime and continental cloud fields. In these simulations, the speed of the initially uniform geostrophic wind and the strength of geostrophic vertical wind shear in the cloud and subcloud layer are varied. Increases in the cloud-layer vertical wind shear (up to 9 ms-1km-1) lead to 40 %–50 % larger cloud-core dilution rates compared to their respective unsheared counterparts. When the background wind speed, on the other hand, is enhanced by up to 10 m s−1 and subcloud-layer vertical wind shear develops or is initially prescribed, the dilution rate decreases by up to 25 %. The sensitivities of the dilution rate are linked to the updraft strength and the properties of the entrained air. Increases in the wind speed or vertical wind shear result in lower vertical velocities across all sets of experiments with stronger reductions in the cloud-layer wind shear simulation (27 %–47 %). Weaker updrafts are exposed to mixing with the drier surrounding air for a longer time period, allowing more entrainment to occur (i.e., the “core-exposure effect”). However, reduced vertical velocities, in concert with increased cloud-layer turbulence, also assist in widening the humid shell surrounding the cloud cores, leading to entrainment of more humid air (i.e., the “core–shell dilution effect”). In the experiments with cloud-layer vertical wind shear, the core-exposure effect dominates and the cloud-core dilution increases with increasing shear. Conversely, when the wind speed is increased and subcloud-layer vertical wind shear develops or is imposed, the core–shell dilution effect dominates to induce a buffering effect. The sensitivities are generally stronger in the maritime simulations, where weaker sensible heat fluxes lead to narrower, more tilted, and, therefore, more suppressed cumuli when cloud-layer shear is imposed. Moreover, in the experiments with subcloud wind shear, the weaker baseline turbulence in the maritime case allows for a larger turbulence enhancement, resulting in a widening of the transition zones between the cores and their environment, leading to the entrainment of more humid air.

Field measurement and numerical simulation of the relationship between the vertical wind environment and building morphology in residential areas in Xi'an, China.

The inadequate consideration of the impact of building morphology on ventilation efficiency in many urban residential areas has resulted in a series of environmental problems that threaten human health. The purpose of this paper is to establish a predictive model between ventilation efficiency and building forms in residential areas. First, the characteristics of the vertical wind profile in residential areas were measured using unmanned aerial vehicle (UAV). Second, the wind speed ratio (WSR) at different height levels under the impact of morphological index (floor area ratio, building density, average building height, enclosure degree, height fall, and maximum building height) in the residential area was simulated by ENVI-met. Two kinds of prediction formulas were finally obtained: (1) the average ventilation efficiency at the pedestrian level and (2) the prediction formula of WSR at different heights. The results show that the wind speed (WS) in residential area below 35 m is about 0.6 m/s lower than that in green park. The numerical simulation shows that the mean WSR at the pedestrian level is negatively correlated with each index, and the height fall morphological index has the largest impact on the WSR at different heights. The research provides a reference for the optimal planning and design of ventilation efficiency of residential buildings, especially those in static wind areas.

Vertical Structure of Air Pollutant Transport Flux as Determined by Ground-Based Remote Sensing Observations in Fen-Wei Plain, China

Air pollutant transport plays an important role in local air quality, but field observations of transport fluxes, especially their vertical distributions, are very limited. We characterized the vertical structures of transport fluxes in central Luoyang, Fen-Wei Plain, China, in winter based on observations of vertical air pollutant and wind profiles using multi-axis differential optical absorption spectroscopy (MAX-DOAS) and Doppler wind lidar, respectively. The northwest and the northeast are the two privileged wind directions. The wind direction and total transport scenarios were dominantly the northwest during clear days, turning to the northeast during the polluted days. Increased transport flux intensities of aerosol were found at altitudes below 400 m on heavily polluted days from the northeast to the southwest over the city. Considering pollution dependence on wind directions and speeds, surface-dominated northeast transport may contribute to local haze events. Northwest winds transporting clean air masses were dominant during clean periods and flux profiles characterized by high altitudes between 200 and 600 m in Luoyang. During the COVID-19 lockdown period in late January and February, clear reductions in transport flux were found for NO2 from the northeast and for HCHO from the northwest, while the corresponding main transport altitude remained unchanged. Our findings provide better understandings of regional transport characteristics, especially at different altitudes.

An observational and modeling study of a sea fog event over the yellow and east China seas on 17 March 2014

The Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery, weather charts, objectively reanalyzed data, the observational data and station sounding data were analyzed to investigate a sea fog event occurred over the Yellow and East China Seas on March 17, 2014. The sounding profiles, weather situations and the related meteorological factors during the development and dissipation stages of this sea fog event were documented. Weather Research Forecast (WRF) model was applied to simulate this sea fog case. The simulated horizontal atmospheric visibility, cloud water, humidity, and vertical wind profile during the different stages of this fog event were analyzed. During the development stage of this sea fog, a southerly lower-jet with 16–18 ms-1, an inversion layer and a cold center over the Yellow Sea were detected. The relative humidity in the fog area was above 95%. The specific humidity over the East China Sea was higher than that over the Yellow Sea. Southerly was dominated in fog area. However, during the dissipation stage of this sea fog, westerly replaced the southerly and at the lower level, southerly jet disappeared. A dry air area formed over the Shandong Peninsula and moved eastwards. Moreover, the WRF modeling result showed that the simulated atmospheric horizontal visibility and cloud water were approximately consistent with the MODIS satellite imagery. Most of cloud water concentrated below 200–400 m, and the cloud water in the southern part of fog area extended to a higher height than the northern part. While both of air temperature and dew-point temperature were close to sea surface temperature.

Simulating the storm environment responsible for Nepal's first observed tornado

A high-resolution numerical forecast model was used to simulate the meteorological conditions leading up to the March 31st, 2019 severe weather event that produced Nepal's first-ever observed tornado. The sparse meteorologic observations in the region capturing the storm environment limit the ability to anticipate another similar situation should the particular set of conditions present themselves again. This study presents a multifaced view of the storm environment through 1) a synoptic perspective provided by the Global Data Assimilation System (GDAS) reanalysis dataset and 2) a trio of progressively higher resolution one-way nested simulations (12 km–4km–1km) driven by GDAS boundary conditions to more closely examine the storm-scale environment. GDAS data and numerical simulations revealed moderately strong instability throughout the region with CAPE values between 1000 and 2000 J kg−1 K−1 and lifted index values between −4 and −7. Vertical wind profiles featuring little directional shear and moderate velocity shear yielded shear-based convective indices that suggested slight potential for rotating supercell thunderstorms. Within this environment, the 1-km simulation produced strong, rotating convection in nearly the same location and at nearly the same time as the observed tornadic storm. Lastly, an assessment of the limited number of observed historical tornadic events in the region showed that with amply convective available potential energy, the 2019 Nepal tornado environment stood out for the limited vertical directional wind shear present.

Effects of different stagnant meteorological conditions on aerosol chemistry and regional transport changes in Beijing, China

To study the aerosol chemistry and regional transport changes in Beijing under different stagnant meteorological conditions, a simultaneous combined observation of the nonrefractory submicron aerosol (NR-PM1) chemical compositions and vertical wind profiles was conducted at an urban site (Beijing) and a regional background site (Xinglong) in the North China Plain (NCP) from November 2018 to January 2019. The backward trajectories of PM1 species in Beijing under different pollution stages were calculated. The results showed that the proportion of backward trajectories from southern regions increased from 0% in the clean stage (PM1 < 35 μg m−3) to 47% in the pollution stage (PM1 > 75 μg m−3), suggesting the aerosol pollution in winter Beijing was greatly affected by regional transport from southern regions. Although the proportion of trajectories from the northwestern regions of Beijing decreased from the clean stage to the pollution stage, the trajectories still comprised a large proportion (53%), which indicates that the northwestern air mass can also cause heavy pollution in winter. Therefore, two typical episodes with air masses from the southwest (episode 1) and northwest (episode 2) regions were selected for further study. The results showed that episode 1 in Beijing lasted for several days and was initiated by regional transport and dominated by heterogeneous reactions, while episode 2 was dominated by rapid regional transport in a short time. Both water vapor and pollutants were transported from southern regions in episode 1, while only pollutants were transported in episode 2. Because of the stronger heterogeneous reactions in episode 1, inorganic aerosols in Beijing accounted for 71% of PM1 in episode 1, which was higher than that in episode 2 (56%). In addition, the transport of water vapor from southern China enhanced the secondary aerosol formation in Xinglong and expanded the scope of regional pollution. In comparison, the systematic south wind did not reach the background area in episode 2. Correspondingly, the PM1 concentration in Beijing was 62% higher than that in Xinglong in episode 2, which was much higher than that in episode 1 (11%). Our results showed that in addition to the enhancement of heterogeneous reactions caused by the increase in humidity, the rapid transport of pollutants because of the sudden change of wind field from north to south can also dominant heavy haze episodes in winter Beijing.

Spatial and temporal variability of ozone along the Colorado Front Range occurring over 2 days with contrasting wind flow

Transport of pollution into pristine wilderness areas is of concern for both federal and state agencies. Assessing such transport in complex terrain is a challenge when relying solely on data from standard federal or state air quality monitoring networks because of the sparsity of network monitors beyond urban areas. During the Front Range air quality study, conducted in the summer of 2008 in the vicinity of Denver, CO, research-grade surface air quality data, vertical wind profiles and mixing heights obtained by radar wind profilers, and ozone profile data obtained by an airborne ozone differential absorption lidar augmented the local regulatory monitoring networks. Measurements from this study were taken on 2 successive days at the end of July 2008. On the first day, the prevailing winds were downslope westerly, advecting pollution to the east of the Front Range metropolitan areas. On this day, chemistry measurements at the mountain and foothills surface stations showed seasonal background ozone levels of approximately 55–68 ppbv (nmol mol–1 by volume). The next day, upslope winds prevailed, advecting pollution from the Plains into the Rocky Mountains and across the Continental Divide. Mountain stations measured ozone values greater than 90 ppbv, comparable to, or greater than, nearby urban measurements. The measurements show the progression of the ozone-enriched air into the mountains and tie the westward intrusion into high-elevation mountain sites to the growth of the afternoon boundary layer. Thus, under deep upslope flow conditions, ozone-enriched air can be advected into wilderness areas of the Rocky Mountains. Our findings highlight a process that is likely to be an important ozone transport mechanism in mountainous terrain adjacent to ozone source areas when the right circumstances come together, namely a deep layer of light winds toward a mountain barrier coincident with a deep regional boundary layer.

Microphysical processes producing high ice water contents (HIWCs) in tropical convective clouds during the HAIC-HIWC field campaign: evaluation of simulations using bulk microphysical schemes

Abstract. Regions with high ice water content (HIWC), composed of mainly small ice crystals, frequently occur over convective clouds in the tropics. Such regions can have median mass diameters (MMDs) &lt;300 µm and equivalent radar reflectivities &lt;20 dBZ. To explore formation mechanisms for these HIWCs, high-resolution simulations of tropical convective clouds observed on 26 May 2015 during the High Altitude Ice Crystals – High Ice Water Content (HAIC-HIWC) international field campaign based out of Cayenne, French Guiana, are conducted using the Weather Research and Forecasting (WRF) model with four different bulk microphysics schemes: the WRF single‐moment 6‐class microphysics scheme (WSM6), the Morrison scheme, and the Predicted Particle Properties (P3) scheme with one- and two-ice options. The simulations are evaluated against data from airborne radar and multiple cloud microphysics probes installed on the French Falcon 20 and Canadian National Research Council (NRC) Convair 580 sampling clouds at different heights. WRF simulations with different microphysics schemes generally reproduce the vertical profiles of temperature, dew-point temperature, and winds during this event compared with radiosonde data, and the coverage and evolution of this tropical convective system compared to satellite retrievals. All of the simulations overestimate the intensity and spatial extent of radar reflectivity by over 30 % above the melting layer compared to the airborne X-band radar reflectivity data. They also miss the peak of the observed ice number distribution function for 0.1&lt;Dmax&lt;1 mm. Even though the P3 scheme has a very different approach representing ice, it does not produce greatly different total condensed water content or better comparison to other observations in this tropical convective system. Mixed-phase microphysical processes at −10 ∘C are associated with the overprediction of liquid water content in the simulations with the Morrison and P3 schemes. The ice water content at −10 ∘C increases mainly due to the collection of liquid water by ice particles, which does not increase ice particle number but increases the mass/size of ice particles and contributes to greater simulated radar reflectivity.

Wind Energy Assessment during High-Impact Winter Storms in Southwestern Europe

The electricity produced through renewable resources is dependent on the variability of weather conditions and, thus, on the availability of the resource, as is the case with wind energy. This study aims to assess the wind resource available and the wind energy potential (WEP) during the December months for the three years 2017, 2018, and 2019, in southwestern Europe, when several high-impact storms affected the region. Additionally, a comparison of Prandtl’s logarithmic law and Power-law equations for extrapolation of the vertical wind profile is performed for onshore conditions, to evaluate the differences in terms of energy production, with the use of different equations. To assess the effect of the strong winds associated with the storms, 10 m wind components are used, with a 6-hourly temporal resolution, for the December months over the southwestern Europe region (30° N–65° N; 40° W–25° E). Results are compared to the climatology (1981–2010) and show an increase of wind intensity of 1.86 m·s−1 in southwestern Europe during December 2019, and a decrease up to 2.72 m·s−1 in December 2018. WEP is calculated for the selected wind turbine, 4 MW E-126 EP3—ENERCON, as well as the values following the wind resource record, that is, (i) higher values in December 2019 in the offshore and onshore regions, reaching 35 MWh and 20 MWh per day, respectively, and (ii) lower values in December 2018, with 35 MWh and 15 MWh per day for offshore and onshore. Differences in WEP when using the two equations for extrapolation of wind vertical profile reached 60% (40%) in offshore (onshore) regions, except for the Alps, where differences of up to 80% were reached. An additional analysis was made to understand the influence of the coefficients of soil roughness and friction used in each equation (Prandtl’s logarithmic law and Power-law), for the different conditions of onshore and offshore. Finally, it is notable that the highest values of wind energy production occurred on the stormy days affecting southwestern Europe. Therefore, we conclude that these high-impact storms had a positive effect on the wind energy production in this region.

Evaluation of global reanalysis winds and high‐resolution regional model outputs with the 205 MHz stratosphere–troposphere wind profiler radar observations

AbstractA stratosphere–troposphere (ST) wind profiler radar operating at a high VHF range (205 MHz) installed at Cochin (10.03°N, 76.33°E), India, provides high‐resolution winds in time and altitude extending from 315 m to 20 km. We evaluated the horizontal and vertical winds obtained from atmospheric global reanalyses (ERA5, ERA‐Interim, MERRA‐2 and NCEP) data and the high‐resolution regional model (WRF) output winds with the ST radar (STR) wind observations at Cochin. The data for one whole year, from 1 August 2018 to 31 July 2019, for 0600 UTC and 1200 UTC were used. Wind data appraisal has been carried out at 24 levels from 315 m to 18.5 km altitude for the reanalyses datasets and 29 levels for model‐simulated winds in different seasons. Vertical profiles of horizontal winds from reanalysis and model‐simulated data somewhat catch the major changes observed from STR. The zonal winds match very well with the STR, whereas meridional winds show moderate similarity. Higher correlations in zonal winds are found during the summer monsoon, whereas meridional winds show apparent likeness during winter. The ERA5, ERA‐Interim, and model‐simulated winds have better agreement with the STR winds. Observed vertical winds from STR displays large fluctuations, while the estimated vertical winds in reanalysis are highly smoothed. Vertical profiles of vertical winds from the reanalysis datasets are not uniform. The reliability of vertical winds in reanalysis and WRF model output values are dubious compared to that of the directly observed winds from STR. The study indicates that improved quality of vertical and meridional winds in reanalysis data is needed by assimilating directly observed data from the available advanced facilities.

A Study of Extrapolation Nowcasting Based on IVAP-Retrieved Wind

AbstractIn this study, we propose a new way to obtain motion vectors using the integrating velocity–azimuth process (IVAP) method for extrapolation nowcasting. Traditional tracking methods rely on tracking radar echoes of a few time slices. In contrast, the IVAP method does not depend on the past variation of radar echoes; it only needs the radar echo and radial velocity observations at the latest time. To demonstrate it is practical to use IVAP-retrieved winds to extrapolate radar echoes, we carried out nowcasting experiments using the IVAP method, and compared these results with the results using a traditional method, namely, the tracking radar echoes by correlation (TREC) method. Comparison based on a series of large-scale mature rainfall cases showed that the IVAP method has similar accuracy to that of the TREC method. In addition, the IVAP method provides the vertical wind profile that can be used to anticipate storm type and motion deviations.

In Situ, Rotor-Based Drone Measurement of Wind Vector and Aerosol Concentration in Volcanic Areas

Unmanned aerial vehicles (UAVs), represented by rotor-based drones, are suitable for volcanic observations owing to the advantages of mobility and safety. In this study, vertical profiles of wind and aerosol concentrations at altitudes up to 1000 m around Mt. Sakurajima, one of the most active volcanoes in Japan, were measured in situ using a drone equipped with an ultrasonic anemometer and aerosol sensor. The drone-measured wind profiles were compared with Doppler LiDAR data and analysis values derived from a meteorological model. Drone-measured vertical profiles collected at a vertical speed of 1 m·s−1 (upward and downward) showed strong agreement with the LiDAR observations, as did the averaged values of hovering drone measurements. Obvious vertical wind shear was found by the drone in the vicinity of Mt. Sakurajima. An aerosol sensor was installed on the drone with the capability to measure fine (PM2.5) and coarse particles (PM10) simultaneously; in this manner, volcanic ash and aerosol pollutants around the volcano could be distinguished. Thus, it was proven that drones could be applied to investigate wind conditions and aerosols in situ, even at dangerous locations near active volcanoes.