Seasonal and continual wind speed modelling for the coastal urban city, Karachi

ABSTRACT. Variation in wind speed not only indicates the strengthening or weakening of pressure systems but its role in wind farm in the vicinity of coastal area is also crucial. Probability distributions through time series of wind speed data serves foremost basic need for the said parameters. Exploratory data analysis revealed that for coastal city Karachi, maximum wind speed (~23 m/s) occurred during monsoon with its peak during postmonsoon with maximum deviation (~3.5 m/s). Mean / trimmed mean during spring and postmonsoon (~11.5 m/s) as well as in premonsoon and monsoon (~18.5 m/s) remain almost identical while minimum wind blowing during winter and postmonsoon are also identical (~6 m/s). Autumn and winter exhibits least standard deviations. Critical and statistical values have been compared for distribution modelling, while parametric values of different seasonal and continual distributions are also estimated. The study is supported by cumulative distribution functions and probability-probability plots. It is not uncommon to use Weibull distribution for wind speed modelling. By using daily data time series of wind speed for the coastal station Karachi, it has been explored that widely accepted Weibull distribution provides comparatively poor distribution results when compared to other more complicated models (i.e., Wakeby and generalized extreme value distributions]. It is found that annual and seasonal wind comes after the Wakeby distribution except premonsoon summer which follows the generalized extreme value distribution (GEV) for the city. No continual and / or seasonal wind speed follows the Weibull distribution, ultimately and / or more appropriately. The study may give some new insights for aviation and wind engineering purposes.

Assessment of the Resources of Wind Energy in Various Regions of Algeria

Details on the wind potential during a period of about thirteen years in Algeria is given in the present work. The inspection is performed for sixteen regions covering almost all the territory of the country. The density of the mean wind power is determined for the different regions. The maps of annual and seasonal wind energy resources are also established. The characteristics of the wind velocity, as well as the potential of wind power, are determined by the Weibull distribution. From the given results, the highest values of annual mean wind speed and the annual mean wind power density are found in Adrar (P10 = 283.12 W/m2 and P50 = 646.91 W/m2), while the lowest values are observed in Skikda (P10 = 40.61 W/m2 and P50 = 115.51 W/m2, respectively).

A continuous decline of global seasonal wind speed range over land since 1980

To investigate changes in global wind speed phenomena, we constructed homogenized monthly time series (1980-2018) for 4,722 meteorological stations. Through examining monthly-averaged wind speeds (MWS), we found that seasonal wind speed range (SWSR; calculated as the difference between maximum and minimum MWS) has declined significantly by 10% since 1980 (p < 0.001). This global SWSR reduction was primarily influenced by decreases in Europe (-19%), South America (-16%), Australia (-14%), and Asia (-13%), with corresponding rate reductions of -0.13, -0.08, -0.09 and -0.06 m s-1 decade-1, respectively (p < 0.01). In contrast, the SWSR in North America rose 3%. Important is that the decrease in SWSR occurred regardless of the stilling or reversal of annual wind speed. The shrinking SWSR in Australia and South America was characterized by continuous decreases in maximum MWS and increases in the minimum. For Europe and Asia, maximum and minimum MWS declined initially after 1980, followed by substantial increases in minimum MWS (about 2000 and 2012, respectively) that preserved the long-term reduction in the range. Most reanalysis products (ERA5, ERA-Interim, and MERRA-2) and climate model simulations (AMIP6 and CMIP6) fail to reproduce the observed trends. However, some ocean-atmosphere indices (seasonality characteristics) were correlated significantly with these trends, including West Hemisphere warm pool, East Atlantic Patten, Pacific Decadal Oscillation, and others. These findings are important for increasing the understanding of mechanisms behind wind speed variations that influence a multitude of other biogeophysical processes and the development of efficient wind energy generations, now and in the future.

δ2H and δ18O in Precipitation and Water Vapor Disentangle Seasonal Wind Directions on the Loess Plateau

In many areas of the Loess Plateau, groundwater is too deep to extract, making meteoric water (snow and rain) the only viable water resource. Here we traced the rainwater and water vapor sources using the δ2H and δ18O signature of precipitation in the northern mountainous region of Yuzhong on the Loess Plateau. The local meteoric water line in 2016 and 2017 was defined as δ2H = 6.8 (±0.3)∙δ18O + 4.4 (±2.0) and δ2H = 7.1 (±0.2)∙δ18O + 1.5 (±1.6), respectively. The temperature and precipitation amount are considered to be the main factor controlling the δ2H and δ18O variation of precipitation, and consequently, relationships were first explored between δ18O and local surface air temperature and precipitation amount by linear regression analysis. The temperature effect was significant in the wet seasons but was irrelevant in the dry seasons on daily and seasonal scales. The amount effect was significant in the wet seasons on a daily scale but irrelevant in the dry seasons. However, based on the data of the Global Network of Isotopes in Precipitation (GNIP) (1985–1987, 1996–1999) of Lanzhou weather station, the amount effects were absent at seasonal scales and were not useful to discriminate either wetter or drier seasons or even wetter or drier decades. Over the whole year, the resulting air mass trajectories were consistent with the main sources of water vapor were from the Atlantic Ocean via westerlies and from the Arctic region, with 46%, 64%, and 40% of water vapor coming from the westerlies, and 54%, 36%, and 60% water vapor from the north in spring, autumn and winter, respectively. In the summer, however, the southeast monsoon (21%) was also an important water vapor source in the Loess Plateau. Concluding, using the δ2H and δ18O signatures of precipitation water, we disentangled and quantified the seasonal wind directions that are important for the prediction of water resources for local and regional land use.

State of the art of Seasonal and Subseasonal Wind and Wind Power Forecasting for the Iberian Peninsula and the Canary islands

&lt;p&gt;Renewable energy plays a key role to play in the transition towards a low-carbon society and many countries have been investing in R&amp;D and deployment of renewables over the last few decades. Despite its importance, relatively little attention has been focused on the crucial impact of weather and climate on energy demand and supply, or on the seasonal forecast generation or operational planning of renewable technologies. In particular, to improve the operation and longer-term planning of renewables it is essential to consider seasonal and subseasonal weather forecasting. Unfortunately, reports that focus on these issues are not common in the scientific literature.&lt;br&gt;Here we present a systematic review of the seasonal forecasting of wind and wind power for the Iberian peninsula and the Canary Islands, a region leading the world in the development of renewable energies (particularly wind), and thus an important illustration in global terms. To this end, we consider the scientific literature published over the last eleven years (2008-2018). An initial search of this literature produced 8355 documents, but our review suggests that only around 0.3% are actually relevant to our purposes. The results show that the teleconnection patterns (NAO, EA, and SCAND) and the stratosphere are important sources of predictability in the Iberian Peninsula and that GloSea5 is an effective model for seasonal wind forecasting for the region. We conclude that the existing literature in this crucial area is very limited, which points to the need for increased research efforts. Moreover, the approach and methods developed here could be applied to other areas for which systematic reviews might be either useful or necessary.&lt;/p&gt;

Operational Feasibility Study of High Altitude Balloon Platform based on the Wind Environment in South Korea

Naval helicopters flying at extremely low altitudes often face communication problems when the helicopter is located in the distance from the mother ship. Accordingly, new attention is being cast on the high altitude balloon (HAB) to solve this problem due to its cost-effectiveness and ability of rapid deployment to the battlefield. The balloon is one of a lighter-than-air vehicle that the blowing wind determines its speed, direction, and travel distance. Therefore, it is likely that seasonal changes in wind conditions will restrict the operation of the balloon. In this paper, the feasibility study of the balloon, which is regarded as a future communication relay platform, on the theater of operation of the Republic of Korea Navy the First Fleet was performed. The trends of the balloon trajectory for five years (2014 ~ 2018) with respect to seasonal wind variations were investigated employing the numerical trajectory prediction program. Simulated balloon trajectories of summer and winter showed considerable differences due to seasonal wind. Summer season was found that it has the most favorite flight environment for the balloon campaign. Upon reflecting on the simulation results, the HAB operating procedure, which capitalised on the Ulleungdo, was also suggested.