Analysis Of Wind Field Research Articles

The Temporal-Spatial Variations and Potential Causes of Dust Events in Xinjiang Basin During 1960–2015

Dust events not only cause local ecosystem degradation and desertification, but also have profound impacts on regional and global climate system, as well as air quality and human health. Dust events in Xinjiang Basin, as the important dust source of Eastern Asia, have undergone a significant change under the global warming background and may be in a new active period after 2000, which is worthy of study. This study provides the temporal and spatial variations of dust events in the Xinjiang Basin based on surface meteorological station observation data during 1960–2015. The results show that Southern Xinjiang is the main dust occurrence region where dust events are significantly more than that in the Northern Xinjiang, and each year more than 73% of dust events occurred in spring and summer. The dust index (DI), which is defined to represent the large-scale variation of dust event, shows a significant downward trend during the past 56 years with a linear decreasing rate −8.2 years−1in Southern Xinjiang. The DI is positively correlated to surface wind speed with a mean correlation coefficient of 0.79. The declining trend of surface wind speed could explain dust events variation during 1960–2000. But in the new active period after 2000, the increase of DI is not consistent with the rising wind speed with the correlation coefficient decreasing to 0.34. It is found that, compared with 1960–1999, the average annual precipitation and frequency increased by 17.4 and 13% during 2000–2015, respectively, and the NDVI also increased at the same time, which indicates that the surface condition changes induced by the increase of precipitation might suppress the occurrence of dust. Moreover, the analysis of high-altitude wind field shows that the variation of the East Asian general circulation’s intensity, dominating the upper-level wind fields in the Xinjiang basin, will change the surface wind speed and precipitation, and further affect the occurrence of dust events.

Water exchange in Van Phong bay, Khanh Hoa province by hydrodynamic model

The analysis of the average wind field from 1979 to 2018 showed that in the Van Phong bay area, the hydrodynamic process is mainly influenced by tidal currents when the frequency of weak wind accounts for a high proportion and the wind regime is controlled entirely by locality and less likely to alter tidal currents significantly. Based on the shallow water hydrodynamic finite element model (FEM), a two-dimensional hydrodynamic model has been developed for Van Phong bay to study hydrodynamic features, especially exchange capacity of seawater with the open sea. The results show that the daily average daily exchange of water in Van Phong bay is about 1,845.46 × 106 m3/day, equivalent to 34.7% water volume in the bay. In the rainy season, the typical daily average water exchange in Van Phong bay is about 2,136.04 × 106 m3/day, equivalent to 43.19% of the volume of water in the bay. In the dry season, the typical daily average total water exchange in Van Phong bay is about 1,825.56 × 106 m3/day, corresponding to 34.35% of water volume in the bay.

The potential for geostationary remote sensing of NO<sub>2</sub> to improve weather prediction

Abstract. Observations of winds in the planetary boundary layer remain sparse making it challenging to simulate and predict atmospheric conditions that are most important for describing and predicting urban air quality. Short-lived chemicals are observed as plumes whose location is affected by boundary layer winds and whose lifetime is affected by boundary layer height and mixing. Here we investigate the application of data assimilation of NO2 columns as will be observed from geostationary orbit to improve predictions and retrospective analysis of wind fields in the boundary layer.

Spatio-temporal Variations of Sea Surface Wind in Coral Reef Regions over the South China Sea from 1988 to 2017

The seasonal and interannual variabilities of sea surface wind (SSW) in the South China Sea (SCS), especially in coral reef regions such as Nansha Islands, Xisha Islands, Zhongsha Islands and Dongsha Islands were investigated in detail using the Blended Sea Winds dataset (1988–2017). Annual and monthly variations of SSW and sea surface temperature (SST) in the four zones were investigated. Empirical Orthogonal Function (EOF) analysis of wind field was performed to aid in better understanding the different spatial patterns. The results indicate that, as observed in the spatial distribution of the first mode of monthly mean wind speed anomaly, the magnitudes in the four island zones are all negative and are similar to each other, showing that the variations of SSW in the four island zones are consistent. In the second mode, the magnitudes in Nansha Islands are opposite to those in the other three zones. The spatial distribution of the third mode reflects regional differences. The maximum annual SSW appears in Dongsha Islands, and the minimum appears in Nansha Islands. The interannual variations of SSW in all island zones are basically concurrent. The island zones with high SSW mostly have low SST, and vice versa. There may be an inverse relationship between SSW and SST in coral reef regions in the SCS. The multi-year monthly variations of SSW in the island zones present a ‘W’-shaped structural variation. Each island undergoes two months of minimum SSW every year, one during March–May (MAM) and the other during September–November (SON). Both months are in monsoon transition periods. During the months with low SSW, high SST appears. The SST peaks almost correspond to the SSW troughs. This further indicates that SSW and SST may have opposite changes in coral reef regions. Coral bleaching events often correspond to years of high SST and low SSW.

Analysis of a turbulent wind field in a street canyon: Good agreement between LES model results and data from a mobile platform

Analysis of a turbulent wind field in a street canyon: Good agreement between LES model results and data from a mobile platform

Elevated Ducts and Low Clouds over the Central Western Pacific Ocean in Winter Based on GPS Soundings and Satellite Observation

Both low clouds and elevated ducts are common phenomena in the oceanic atmosphere. Low clouds affect elevated ducts by changing the structure of atmospheric temperature and humidity. However, due to the limitation of met-ocean measurements, research on them is still scattered. This paper presents the distribution of elevated ducts and clouds over the central Western Pacific Ocean (WPO) based on Global Position System (GPS) sounding data and Himawari-8 satellite products from November 2015 to January 2016. Results show that the frequency of elevated ducts detected by ship-based GPS soundings was as high as 77% over the central WPO. The height and frequency of elevated ducts are closely related to the low clouds. If there are no clouds, the occurrence probability and mean base height of the elevated ducts are 14% and 730 m, respectively. By comparison, the occurrence probability and mean base height increase up to 24% and 1471 m, respectively, in the presence of cumulus (Cu) clouds, and 22% and 1511 m, respectively, in the presence of stratocumulus (Sc) clouds. Elevated ducts occur near the cloud top. The analysis of geopotential height and wind fields from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis dataset (ERA-interim) shows that the study area is covered by a strong and stable subtropical high, and slowly sinking dry air masses inside the subtropical high are above the moist boundary-layer air mass. The appearance and evolution of low clouds will adjust the temperature and humidity structure of the lower troposphere. If there are no clouds, the marine boundary layer (MBL) is the classic mixed boundary layer. Humidity gradient and subsidence inversion are formed atop the mixed layer. When low clouds are present, long wave radiation and entrainment atop clouds form a strong temperature inversion and humidity gradient, which strengthen elevated ducts. However, when Sc clouds are decoupled, a weaker temperature inversion and humidity gradient may occur between the surface mixed layer and subcloud layer, leading to a weak elevated duct atop the mixed layer.

Study on Urban Wind Patterns for Developments in Wuhan China

This paper reports a project with the purpose to develop design guidance on urban wind fields for the Chinese city. The project assesses “super-block” developments in Wuhan China at first, then redesigns a super-block using Transit-Oriented Development (TOD) guidelines and draws wind performance comparisons. The project addresses wind Patterns for three major criteria: pedestrian comfort, air quality, and building ventilation potential. Computational Fluid Dynamics (CFD) software was used to model velocity, PMV comfort, pressure and air age patterns for summer and winter conditions. Super-blocks with isolated towers have poor urban quality on many measures, while residents drive more and use much more energy than in traditional housing. TOD guidelines solve these problems but no discussion of urban wind patterns, air pollution, pedestrian comfort, or building ventilation which have been found important during the period of Corona Virus Disease 2019 (COVID-19) in Wuhan China. Our target was to generate TOD urban form that equaled or exceeded super-block wind performance. Results were inconclusive for pedestrian comfort and other indices and modeling are needed. Other parameters depend significantly on orientation and wind direction. Therefore, sometimes TOD was better than towers and sometimes not. The general method of the project is in six parts: 1) Assess five existing super-block designs for wind performance and characterize three performance metrics; 2) Draw conclusions about performance. Select one site for redesign; 3) Using TOD guidelines, design a new neighborhood at the same density on the selected site; 4) Evaluate wind performance of the new design; 5) Select wind design strategies to improve performance and redesign the TOD neighborhood; 6) Compare wind performance of TOD neighborhood and super-block. The study indicates the value of wind field analysis for improving urban designs for multi-building sites or for development rules. We were generally able to make performance improvements for development schemes, even during the special period.

A long-term (2005–2019) eddy covariance data set of CO<sub>2</sub> and H<sub>2</sub>O fluxes from the Tibetan alpine steppe

Abstract. The Tibetan alpine steppe ecosystem covers an area of roughly 800 000 km2 and contains up to 3.3 % soil organic carbon in the uppermost 30 cm, summing up to 1.93 Pg C for the Tibet Autonomous Region only (472 037 km2). With temperatures rising 2 to 3 times faster than the global average, these carbon stocks are at risk of loss due to enhanced soil respiration. The remote location and the harsh environmental conditions on the Tibetan Plateau (TP) make it challenging to derive accurate data on the ecosystem–atmosphere exchange of carbon dioxide (CO2) and water vapor (H2O). Here, we provide the first multiyear data set of CO2 and H2O fluxes from the central Tibetan alpine steppe ecosystem, measured in situ using the eddy covariance technique. The calculated fluxes were rigorously quality checked and carefully corrected for a drift in concentration measurements. The gas analyzer self-heating effect during cold conditions was evaluated using the standard correction procedure and newly revised formulations (Burba et al., 2008; Frank and Massman, 2020). A wind field analysis was conducted to identify influences of adjacent buildings on the turbulence regime and to exclude the disturbed fluxes from subsequent computations. The presented CO2 fluxes were additionally gap filled using a standardized approach. The very low net carbon uptake across the 15-year data set highlights the special vulnerability of the Tibetan alpine steppe ecosystem to become a source of CO2 due to global warming. The data are freely available at https://doi.org/10.5281/zenodo.3733202 (Nieberding et al., 2020a) and https://doi.org/10.11888/Meteoro.tpdc.270333 (Nieberding et al., 2020b) and may help us to better understand the role of the Tibetan alpine steppe in the global carbon–climate feedback.

Interdecadal Change in the Relationship between Northern and Southern Hemisphere Meridional Circulation over the Western Pacific Ocean

The western North Pacific monsoon in the Northern Hemisphere (NH) and the local Hadley circulation in the Southern Hemisphere (SH) are important components of the vertical meridional circulation over the western Pacific Ocean. Here, we define the SH meridional circulation (SHMC) and NH meridional circulation (NHMC) and investigate their relationship over the western Pacific Ocean. Although they are consistent integrally in the climatological circulation, the NHMC and SHMC do not have a positive change relationship but a significantly negative relationship. In addition, this negative correlation experiences an interdecadal change, with one closely related period during 1989–2003 (Period 2, P2) and two weakened related periods during 1979–1988 (Period 1, P1) and 2004–2017 (Period 3, P3). Through the analysis of the meridional wind field at lower and upper levels, we found that the SHMC moves northward during P2, which can result in a close relationship with the NHMC. The possible mechanism is as follows: The Walker circulation strengthened in P2, which strengthened the ascending motion over the western Pacific Ocean, thus inducing the SHMC to strengthen and move northward, resulting in a significantly stronger relationship with the NHMC.

In Situ Observations of Light‐Absorbing Carbonaceous Aerosols at Himalaya: Analysis of the South Asian Sources and Trans‐Himalayan Valleys Transport Pathways

AbstractThe mountain‐valleys along the south margin of the Himalaya‐Tibetan Plateau (HTP), referred to as trans‐Himalayan valleys, are transport pathways of atmospheric pollutants from the South Asia lifting to the HTP based on atmospheric models and satellite detections. However, few field studies can be conducted to confirm the aerosol transport along these valleys due to the harsh environment and limited power supply. Individual particle collection instruments offer the unique advantage of collecting samples and tracing particle sources in remote areas due to their portability and efficiency. In this study, transmission electron microscopy was used to study individual particles collected in two trans‐Himalayan valleys. We found that 49–70% of thousands of particles were light‐absorbing carbonaceous aerosols including soot‐bearing and tarball‐bearing particles in December of 2017. The dominant sizes of soot‐bearing and tarball‐bearing particles were 151–370 and 198–255 nm, respectively. The WRF‐Chem model and wind field analyses show that the intense regional air pollution with high mass concentrations of light‐absorbing carbonaceous aerosol occurred in the South Asia and southwest wind normally prevailed along the trans‐Himalayan valleys in the afternoon of each day during wintertime. Backward trajectory and CALIPSO data further confirm that these light‐absorbing carbonaceous aerosols from the South Asia were transported to the southern HTP. These carbonaceous aerosols exhibited significantly internally mixing with secondary sulfates. Here individual particle analysis coupled with the WRF‐Chem model, the meteorological observation data, and satellite data confirm the trans‐Himalayan valleys as the direct channels for abundant carbonaceous aerosols lifting from the South Asia to the HTP.

The spatio-temporal evolution of black carbon in the North-West European ‘air pollution hotspot’

Particulate black carbon has a range of negative impacts on health, the environment and climate, however despite this there are relatively few long-term studies on its ambient distribution as a tropospheric air pollutant. In order to address this lack of data, to help to provide greater insight into the spatio-temporal distribution of particulate black carbon and to assess potential influencing factors, a new, permanent suburban monitoring network was established with sites in four northwest European cities: London (UK), Leicester (UK), Amsterdam (the Netherlands) and Antwerp (Belgium). We report here an analysis of the first measurements made by the network over a twenty-seven-month period (January 01, 2013–April 01, 2015), alongside data from pre-existing comparator urban roadside (AURN Marylebone Road, London, UK) and rural background (AURN Auchencorth Moss, Scotland) sites. The temporal evolution of black carbon was investigated at each site, as were associations with other commonly monitored pollutants (e.g. O3, NOx, PM2.5, PM10) and wind fields. Results showed clear anthropogenic signatures across the diurnal, weekly and annual timeframes, and positive correlations were obtained between black carbon measurements and other common traffic-related pollutants, highlighting the importance of vehicle emissions as a major contributor to ambient black carbon concentration in northwest Europe. Average black carbon concentrations varied from 6.6 μg m−3 at the urban roadside, to 0.2 μg m−3 in the rural background, with suburban and urban background sites having average concentrations in the range of 1.0–2.4 μg m−3. Wind field analysis further highlighted the importance of road traffic as a source of black carbon and demonstrated the importance of local emission sources at the various receptor locations. Statistical analysis of data between sites generally indicated a weak correlation (rs = −0.03 to 0.68, COD = 0.32–0.91), further highlighting the importance of local emissions in determining ambient black carbon concentration. It was also found that black carbon comprised a significant portion of total ambient particulate matter (PM), particularly at sites with the larger traffic volumes and during rush-hour (e.g. ~45% of PM2.5 at Marylebone Road), however, its contribution to total PM was found to decrease on days of high pollution, indicating the importance of other PM components when air quality is particularly poor.

Migration sources and pathways of the pest species Sogatella furcifera in Yunnan, China, and across the border inferred from DNA and wind analyses.

The migration sources and pathways of Sogatella furcifera (Horváth) in topologically complex regions like Yunnan, China, and adjacent montane areas have long been a challenging task and a bottleneck in effective pest forecast and control. The present research reinvestigated this issue using a combination of mtDNA and long‐term historical wind field data in an attempt to provide new insights. Genetic analyses showed that the 60 populations of S. furcufera collected across Myanmar, Thailand, Laos, Vietnam, Yunnan, Guizhou, and Sichuan lack genetic structure and geographic isolation, while spatial analysis of haplotype and diversity indices discovered geographic relevance between populations. Migration rate analysis combined with high‐resolution 10‐year wind field analysis detected the following migration sources, pathways, and impacted areas which could explain the outbreak pattern in Yunnan. (a) Dominating stepwise northward migrations originated from northern Indochina, southern Yunnan, and central‐eastern Yunnan, impacting their northern areas. (b) Concurring summer–autumn southward (return) migration originated from nearly all latitude belts of Sichuan and Yunnan mainly impacting central and southern Yunnan. (c) Regular eastward and summer–autumn westward migrations across Yunnan. The northward migration reflects the temporal rhythm of gradual outbreaks from the south to the north in a year, while the return migration may explain the repeated or very severe outbreaks in the impacted areas. To form a better pest forecast and control network, attention must also be paid to the northern part of Yunnan to suppress the impact of return migration in summers and autumns.

Wind Field Reconstruction and Analysis of Super Typhoon Mangkhut (1822)

Liu, X.; Wang, Q.; Liu, C.; He, C.; Wang, S.; Hou, P.; Zhu, X., and Wu, Z., 2020. Wind field reconstruction and analysis of super typhoon Mangkhut (1822). In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 151–157. Coconut Creek (Florida), ISSN 0749-0208.This paper reports the research conducted on wind field reconstruction for super typhoon Mangkhut (1822), which occurred in 2018/09. The performances of two common methods, i.e., the parametric typhoon model and CCMP reanalysis data, for the hindcasting of typhoon wind fields are examined, and an improved method is then proposed, which avoids the radius effect in the traditional superposition method. The proposed method relies on a combination of CCMP reanalysis data and parametric wind field results and directly evaluates the maximum wind speed. Moreover, the central difference method is employed to smooth the transitional area. This method notably improves the hindcasting of typhoon wind fields, and its capability is calibrated by field data from buoy platforms in the Pearl River Estuary. Finally, certain typical parameters, such as the wind field, wind speed and wind stress curl, during super typhoon Mangkhut are determined and analyzed.

Columbus: aportes de la teledetección y análisis de coste anisotrópico a un debate histórico

La ruta seguida por la primera expedición de Cristóbal Colón es incierta debido a la ausencia o poca fiabilidad de esta información en el diario del almirante. Los actuales datos procedentes de teledetección y su análisis mediante SIG pueden aportar nueva información mediante análisis de los campos de viento estacionales en la zona. Los resultados del análisis de seis años muestran que el régimen de vientos es homogéneo y que configura dos corredores o pasillos de bajo coste relativo para la navegación a vela con las condiciones de los barcos del siglo XV. De estos dos corredores uno conduce con exactitud al destino al que se cree que llegó Colón el 12 de octubre de 1492 y se presenta como la ruta más probable, algo más al Sur que la propuesta hasta el presente en la bibliografía. Los SIG se muestran como una herramienta capaz de aportar información inédita a partir de datos globales, tomados en este caso por el escaterómetro QuikSCAT, aplicando métodos de análisis espacial poco usados en la literatura científica.

Error Analysis of Multivariate Wind Field Simulated by Interpolation-Enhanced Spectral Representation Method

AbstractAn interpolation-based technique can effectively reduce the computational demand involved in a traditional simulation of the multivariate wind field utilizing the spectral representation me...

The wind load prediction and comparative study of asmmetric semi-submersible lifting platform based on CFD

In order to accurately predict the wind load of asymmetric offshore structures, this paper studied the wind load of an asymmetric semi-submersible lifting platform based on the CFD software FINE/MARINE, and calculated the wind load of operation state, lifting state and survival state respectively, and compared the results with those of China Classification Society(CCS) specification. The results show that under the same wind speed, the change of wind direction angle has a great influence on the distribution of wind field around the platform. The specification calculation can not fully consider the influence of the shielding effect between the components of the superstructure, therefore, the results are larger than the numerical simulation value. In addition, the wind field distribution near the platform can be used to analyze the variation of wind load, which provides an effective method for wind load prediction and wind field analysis of asymmetric offshore structures.

Temporal variation of dust aerosol pollution in northern China

By employing the sandstorm dataset from meteorological station observations, the temporal and spatial variations in dust outbreak duration in the source regions and visibility variations over the downwind regions of northern China were analyzed over the past four decades. The statistics and wind field analyses reveal that after the early 2000s, the duration of dust outbreaks over the potential source areas of northern China had decreased by 63% compared with that in the 1970s, which suggests that the dust aerosol emission intensities in the region were significantly reduced. However, although the potential dust aerosol emission intensities were significantly reduced, the visibility during dust aerosol emission periods increased by only 25%. The emerging potential source areas in the eastern regions, variations in the wind field, increases in up-air winds, and decreases in surface winds all contribute to the observed continued high dust aerosol pollution in northern China since the early 2000s.

Wind Speed and Altitude Dependent AMDAR Observational Error and Its Impacts on Data Assimilation and Forecasting

Aircraft Meteorological Data Relay (AMDAR) observations have been widely used in numerical weather prediction (NWP) because of its high spatiotemporal resolution. The observational error of AMDAR is influenced by aircraft flight altitude and atmospheric condition. In this study, the wind speed and altitude dependent observational error of AMDAR is estimated. The statistical results show that the temperature and the observational error in wind speeds slightly decrease as altitude increases, and the observational error in wind speed increases as wind speed increases. Pseudo single AMDAR observation assimilation tests demonstrate that the wind speed and altitude dependent observational error can provide more reasonable analysis increment. Furthermore, to assess the performance of wind speed and altitude dependent observational error on data assimilation and forecasting, two-month 3-hourly cycling data assimilation and forecast experiments based on the Weather Research and Forecasting Model (WRF) and its Data Assimilation system (WRFDA) are performed for the period during 1 September-31 October, 2017. The results of the two-month 3-hourly cycling experiments indicate that new observational error improves analysis and forecast of wind field and geo-potential height, and has slight improvements on temperature. The Fractions Skill Score (FSS) of the 6-h accumulated precipitation shows that new wind speed and altitude dependent observational error leads to better precipitation forecast skill than the default observational error in the WRFDA does.

Long-term Analysis of Sea Surface wind field over the Persian Gulf Basin, Using reanalysis data, NCDC-BSW and in situ observations during a 23-year period

Long-term Analysis of Sea Surface wind field over the Persian Gulf Basin, Using reanalysis data, NCDC-BSW and in situ observations during a 23-year period

A spatial evaluation of high-resolution wind fields from empirical and dynamical modeling in hilly and mountainous terrain

Abstract. Empirical high-resolution surface wind fields, automatically generated by a weather diagnostic application, the WegenerNet Wind Product Generator (WPG), were intercompared with wind field analysis data from the Integrated Nowcasting through Comprehensive Analysis (INCA) system and with regional climate model wind field data from the Consortium for Small Scale Modeling Model in Climate Mode (CCLM). The INCA analysis fields are available at a horizontal grid spacing of 1 km × 1 km, whereas the CCLM fields are from simulations at a 3 km × 3 km grid. The WPG, developed by Schlager et al. (2017, 2018), generates diagnostic fields on a high-resolution grid of 100 m × 100 m, using observations from two dense meteorological station networks: the WegenerNet Feldbach Region (FBR), located in a region predominated by a hilly terrain, and its Alpine sister network, the WegenerNet Johnsbachtal (JBT), located in a mountainous region. The wind fields of these different empirical–dynamical modeling approaches were intercompared for thermally induced and strong wind events, using hourly temporal resolutions as supplied by the WPG, with the focus on evaluating spatial differences and displacements between the different datasets. For this comparison, a novel neighborhood-based spatial wind verification methodology based on fractions skill scores (FSSs) is used to estimate the modeling performances. All comparisons show an increasing FSS with increasing neighborhood size. In general, the spatial verification indicates a better statistical agreement for the hilly WegenerNet FBR than for the mountainous WegenerNet JBT. The results for the WegenerNet FBR show a better agreement between INCA and WegenerNet than between CCLM and WegenerNet wind fields, especially for large scales (neighborhoods). In particular, CCLM clearly underperforms in the case of thermally induced wind events. For the JBT region, all spatial comparisons indicate little overlap at small neighborhood sizes, and in general large biases of wind vectors occur between the regional climate model (CCLM) and analysis (INCA) fields and the diagnostic (WegenerNet) reference dataset. Furthermore, grid-point-based error measures were calculated for the same evaluation cases. The statistical agreement, estimated for the vector-mean wind speed and wind directions again show better agreement for the WegenerNet FBR than for the WegenerNet JBT region. A combined examination of all spatial and grid-point-based error measures shows that CCLM with its limited horizontal resolution of 3 km × 3 km, and hence too smoothed an orography, is not able to represent small-scale wind patterns. The results for the JBT region indicate significant biases in the INCA analysis fields, especially for strong wind speed events. Regarding the WegenerNet diagnostic wind fields, the statistics show acceptable performance in the FBR and somewhat overestimated wind speeds for strong wind speed events in the Enns valley of the JBT region.