Wind Speed Trends Research Articles

Attributing near-surface atmospheric trends in the Fram Strait region to regional sea ice conditions

Abstract. Arctic sea ice has declined in all seasons accompanied by rapid atmospheric warming. Here, the focus lies on the wider Fram Strait region where the connection between trends in observed near-surface variables (temperature, humidity, wind speed) and local sea ice conditions are analyzed. Reanalysis data from ERA5 and MERRA-2 and Special Sensor Microwave/Imager ARTIST Sea Ice (SSM/I-ASI) sea ice concentrations for the winters of 1992 to 2022 are used for the analyses. Two focus regions are identified for which trends are largest. In the western Nansen Basin (WNB), sea ice cover decreased by −10 % per decade with especially large open water areas in 2022, and temperature and humidity increased by up to 3.7 K and 0.29 g kg−1 per decade, respectively. In the Greenland sea region (GRL), trends were slightly smaller, with −4.7 % per decade for sea ice and up to 1.3 K and 0.15 g kg−1 per decade for temperature and humidity. Trends for wind speed were mostly not significant. As a next step, two typical flow directions for this region were studied: cold-air outbreaks with northerly winds originating from ice covered areas (off-ice flow) and warm-air intrusions with southerly winds from open ocean regions (on-ice flow). To identify possible relationships between sea ice changes and atmospheric trends, correlation maps were calculated, and the results for off- and on-ice flow were compared. Up to two thirds of the observed temperature and humidity variability in both regions are related to upstream sea ice variability and an influence of sea ice cover is still present up to 500 km downstream of the ice edge. In the marginal sea ice zone the impact of a decreasing sea ice cover in this region is largest for off-ice flow conditions during cold-air outbreaks.

Impact of Surface Roughness Changes on Surface Wind Speed Over Western Europe: A Study With the Regional Climate Model RACMO

AbstractThe temporal trend of wind speed near the surface over land has been investigated over recent decades. A prevailing trend of decline was found in several studies for most areas in the Northern hemisphere, denoted as terrestrial stilling, with multiple causes being discussed. In this study, we focus on the impact of changes of surface roughness due to changes in land‐use and vegetation cover on this variable for western Europe using the regional climate model RACMO driven by ERA5 reanalysis. We conduct two simulations at climate scale, with and without changes in land‐use and vegetation on a yearly basis. We find that upper level large‐scale circulation slowing down results in declining near surface mean wind speed, and that increases in surface roughness due to changes in land use and vegetation cover play an important role in intensifying this declining trend from our simulations with RACMO. However, the trends inferred from the model simulations and ERA5 are not consistent with trends derived from gridded observations database E‐OBS. This could come from the complexity of integrating in‐situ measurements with uncorrectable inhomogeneity to derive E‐OBS.

Spatio-Temporal Trend Analysis of Reference Evapotranspiration in Central Luzon, Philippines

Understanding trends in reference evapotranspiration (ETₒ) and their influencing factors is crucial for calculations of irrigation requirements and water management. Meteorological data in Central Luzon (1985–2019) were used to estimate ETₒ using the FAO Penman-Monteith method. Spatial and temporal ETₒ trends were analyzed using the Mann-Kendall test and Sen’s slope estimator. Correlation and sensitivity analyses were conducted to analyze the impact of weather variables on ETₒ. Positive correlations were observed for maximum temperature, solar radiation, and wind speed whereas negative correlations were observed for relative humidity and minimum temperature. In general, ETₒ was statistically dependent and most sensitive to solar radiation, maximum temperature, and relative humidity. ETₒ in the stations surrounded by mountains was consistently lower than the stations in the agricultural areas by 197 and 207 mm for the dry season and annual basis, respectively. The increasing trends with a magnitude of 3.98 mm/yr in annual ETₒ were caused by the rising trend in solar radiation and maximum temperature and a decreasing trend in relative humidity. The decreasing ETₒ trend (–2.6 to –4.63 mm/yr) predominant in the study area was mainly attributed to the decreasing trend of solar radiation and wind speed. Areas with increasing ETₒ trends indicate the need for supplemental irrigation. Decreasing ETₒ trends may indicate climate change, land-use change, or human-related factors.

Trend analysis and inter-annual variability in wind speed in South Africa

Reliable forecasts of long-term longitudinal wind speed patterns may help predict air circulation changes. They are also essential for the planning and financing of wind projects for Independent Power Producers (IPPs). Long-term wind speed trends and variations in historical mean wind speed data were examined using Mann Kendall’s test and calculating inter-annual variability (IAV). The Wind Atlas for South Africa (WASA) provides high resolution quality wind data for research and applications locally. WASA has 19 meteorological stations in South Africa. The WASA project began in 2009 with the aim of mapping South Africa's wind resource, allowing stakeholders in the wind energy sector and industry to explore and prepare for utility-scale wind power generation. For the past ten years, WASA has been measuring and providing data.The results showed an increasing trend at WM01 and a decreasing trend at WM08. There was no clear trend at other wind masts. Satellite data was used to validate results and no trends were observed at most of the stations. IAV values for this study ranged between 1.088% and 3.353% which is relatively low compared to the commonly found IAV values of 5-6%, implying that mean annual wind speed variation at these stations is low. To confirm a clear trend in wind speed, it is recommended that further work be done with long term periods and substantiate our finding with the use of historical simulation and climate change scenarios.

Dependence of daily precipitation and wind speed over coastal areas: evidence from China's coastline

AbstractRainfall and wind speed are two important meteorological variables that have a significant impact on agriculture, human health, and socio-economic development. While individual rainfall or wind events have been widely studied, little attention has been devoted to studying the lead–lag relationship between rainfall and wind speed, particularly in coastal regions where strong dependence between rainfall and wind speed is expected. Taking China's coastline as the case study, this paper aims to explore the variation trends of wind speed and rainfall and reveal the relationships between rainfall events and wind speeds on days before and after rainfall occurrence, by using meteorological station data from 1960 to 2018. The results show that wind speed tended to decrease while rainfall showed a slight increase for most stations. The daily wind speed increased 2 days before rainfall occurrence and decreased after then, with the highest wind speed observed during rainfall onset regardless of rainfall amount. Moreover, heavier rainfall events are more likely to occur with higher wind speeds. The findings of this study potentially improve the understanding of the dependence of rainfall and wind speed, which could help rainfall or wind-related disaster mitigation.

Analysis of Rainfall, Wind Speed and Streamflow Trends and Their Relationships in the Klip River Catchment, Alfred Duma Municipality, South Africa

Analysis of Rainfall, Wind Speed and Streamflow Trends and Their Relationships in the Klip River Catchment, Alfred Duma Municipality, South Africa

Analysis of Heat and Humidity in Single-Slope Greenhouses with Natural Ventilation

A single-slope greenhouse (SSG) is the general name of a kind of agricultural greenhouse facility widely used in China. Microclimate studies for SSGs in Weifang, Shandong Province, are relatively scarce. This paper mainly discusses the test data of nine SSGs including temperature, humidity, solar global radiation intensity, CO2 concentration, wind speed, and vapor pressure deficit (VPD) trend. Moreover, the conservation of quality method is used to estimate the ventilation volume and humidity growth after opening the top vent in the greenhouse. Through the analysis in this paper, for local SSGs, the internal environmental change has commonality but its internal environment is still influenced by many factors, such as plant planting density, internal cover, plant growth height, and vent opening time. In addition, the method in this paper can provide a quantitative tool for calculating and controlling humidity for researchers and greenhouse workers and provide a basis for greenhouse ventilation strategies.

Changes in Meteorological Elements and Its Impacts on Yunnan Plateau Lakes

In this study, we analyzed the main climatic factors influencing nine plateau lakes in Yunnan Province over the past 40 years (from 1980 to 2019) based on trend and mutation analyses. The results revealed that the air temperatures of these plateau lakes have increased, with an annual average air temperature increase of 0.18 °C per decade, during this 40-year period. From 2000 to 2005, there was an abrupt change in the air temperature increase, the rate of which was 0.20 °C per decade, and there were reductions in long-wave radiation, relative humidity, wind speed, precipitation, and snowfall. In addition, the rising trend in the air temperature of these lakes located in northwest Yunnan (temperate climate, higher elevation) was found to be significantly higher than that of the lakes in central Yunnan (subtropical climate, lower elevation), whereas in contrast, the declining trends in long-wave radiation, relative humidity, wind speed, and precipitation were more pronounced in central than in northwestern Yunnan.

Investigating recent changes in the wind speed trends over Turkey

Investigating recent changes in the wind speed trends over Turkey

Preliminary assessment on climatological conditions in Royal Belum-Temenggor Rainforest Complex, Malaysia using MERRA-2 reanalysis datasets

Royal Belum-Temenggor Rainforest Complex (RBTRC) is renowned as one of the world’s oldest tropical rainforests and biodiversity hotspots. Its extensive forest coverage serves as a crucial carbon sink that stock more than 185 Mg ha-1 carbon, thereby playing a crucial role in regulating Earth’s temperature. Despite its significance as a major carbon sink and biodiversity ecosystem, studies on RBTRC have been limited primarily to biological and ecological studies. Baseline climate studies for this region are non-existent to-date. Baseline climate assessment is crucial for assessments of future climate change impact in this region. This study fills this critical research gap by investigating the climatological trends of annual-averaged temperature, surface pressure, specific humidity, wind speed and rainfall in RBTRC from 1991 to 2020 using the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) reanalysis dataset. All atmospheric variables exhibit a normal distribution, and increasing trends are observed for all variables except for windspeed. Pearson’s correlations indicate positive correlation between pressure and temperature (0.5), specific humidity and rainfall (0.45), and negative correlation in pressure and rainfall (-0.59), specific humidity and windspeed (-0.55), and temperature and windspeed (-0.42). This complements the fundamental physical laws, indicating the reliability of the MERRA-2 reanalysis datasets for further climatological evaluation.

Comparison of Spring Forecasting Ability between GY-WRF and GRAPES in Danghe South Mountain

The Plateau Numerical Weather Forecast System (GY-WRF) was evaluated for its ability to forecast spring weather in Danghe South Mountain. The forecasted temperature, relative humidity, and wind were compared with GRAPES using data from four automatic weather stations in March and April 2022. The results showed that GY-WRF had the smallest mean absolute error (MAE) for each factor at station 4, and a small MAE for temperature, relative humidity, and wind speed at station 2, but a slightly larger MAE for wind direction. GRAPES had a small MAE for wind direction, and a similar trend in wind speed MAE to GY-WRF. GY-WRF was better at predicting the diurnal variation trend of temperature, while GRAPES had a better effect on forecasting the minimum temperature. Both GY-WRF and GRAPES were capable of pre-dicting the trend of wind direction conversion at each station, with GY-WRF being better at predicting the diurnal variation trend of wind speed.

Subsurface heat conduction along the CHINARE traverse route, East Antarctica

AbstractUsing data from three automatic weather stations (LGB69, Eagle and Dome A) from distinctly different climatological zones along the CHINARE (Chinese National Antarctic Research Expedition) traverse route from Zhongshan Station to Dome A, we investigated the characteristics of meteorological conditions and subsurface heat conduction. Spatial analysis indicated decreasing trends in air temperature, relative humidity and wind speed from the coastal katabatic wind zone to the inland plateau region, and air temperatures clearly showed a strong daily variability in winter, suggesting the effect from the fluctuation in the Antarctic atmospheric system. We also analyzed the optimal response time of the 1 and 3 m depth snow temperatures to the 0.1 m depth snow temperature for each site under clear/overcast and day/night situations. This showed an important enhancement to the heat transfer from shortwave radiation penetration. Using an iterative optimization method, we estimated the subsurface heat conduction variations along the transect. This was ~3–5 W m–2. Multiple maxima in daily mean subsurface fluxes were found in winter, with a typical value above 2 W m–2, while a single minimum value under –2 W m–2was found in summer. On an annual scale, a larger mean loss of subsurface heat conduction was observed in the inland plateau compared to in the coastal katabatic area. Finally, we discussed the possible influences of turbulent and radiant transport on the vertical heat response and confirmed the wind enhancement on the growth of thermal conductivity. This preliminary study provides a brief perspective and an important reference for studying subsurface heat conduction in inland areas of Antarctica.

Increases in China’s wind energy production from the recovery of wind speed since 2012

China has realized a 56-fold increase in installed wind capacity, from 5.9 GW in 2007 to 328 GW in 2021. In addition to increasing installed capacity, plans to substantially increase wind energy production for climate change mitigation also depend on future wind speeds, which strongly influences the efficiencies of installed turbines within individual wind farms. A reversal in globally decreasing wind speeds over several decades has been reported previously. However, subsequent studies using other data sources reported only a slight increase or no reversal in China. These uncertainties regarding China’s wind energy production hamper estimates of wind energy production potential. Here, our analysis of quality-controlled wind speed measurements from in-situ stations shows that the wind speed decline in China reversed significantly since 2012 (P < 0.001), but with substantial spatio-temporal variability. We further estimated the capacity factor (CF) growth and the wind power gain solely associated with the changes in wind speed ranges from 31.6 to 56.5 TWh yr−1 based on the 2019 installed capacity. This estimate explains 22.0%–39.3% of the rapid increase in wind generation CF in China during 2012–2019. The result implies that the site selection of wind farms should consider both current wind situation and future wind speed trends. Further studies are needed to understand the driving factor of wind speed recovery in support of the wind energy industry.

Future wind speed trends in the Indian offshore region

Climate models help assess the future availability of wind speeds to extract wind power; however, these climate models are mathematical models that include uncertainty in wind forecasts. Finding an appropriate climate model for analyzing future wind power generation is critical. Therefore, in the present work, six Coordinated Regional Climate Downscaling Experiment-South Asia (CORDEX-SA) climate models and their ensembles were statistically examined in the Indian offshore region using in-situ buoy readings and ERA5 reanalysis data. Statistical parameters like correlation coefficient, bias, RMSD, and standard deviation are computed to examine the applicable model at buoy locations. With ERA5 wind speeds, the overlapping percentage of climate models is later analyzed for the Indian offshore regions. The ensemble model statistically outperforms individual climate models at buoy sites, with 77% overlap with ERA5 wind speeds in the offshore region. Further, the trends and cumulative variations in wind speeds are calculated for ensemble models under two emission scenarios RCP (Representative Concentration Pathway) 4.5 and RCP 8.5. In the future, the North-East (NE) zone will have the most advantageous change in wind speeds (0.21 to 8.68%), whereas the North-West (NW) area will have a negative cumulative change in wind speeds.

Projected Changes in Wind Speed over the Korean Peninsula in the 21st Century Based on Climate Change Scenarios

In this study, the spatio-temporal characteristics of long-term variability of wind speed over the Korean Peninsula in the 21st century were analyzed using RCP and SSP climate change scenario data. The spatial distribution of the average wind speed in the 21st century showed that the wind speed in the sea area was about twice that of the land area, and the SSP scenario showed a stronger overall wind speed distribution compared to the RCP scenario. The anomaly distributions of the multi-decadal wind speed showed various patterns depending on the target scenario and space-time, and showed relatively large anomaly variability in the sea area than in the land. In the 21st century, the long-term trend of wind speed over the Korean Peninsula was dominated by negative variability indicating a decreasing trend overall. Compared to the RCP scenario, the variability of wind speed was evaluated to be relatively large in the SSP scenario. It was also found that the variability of wind speed in the high greenhouse gas emission scenarios(RCP8.5 and SSP5- 8.5) was slightly greater than the medium greenhouse gas emission scenarios(RCP4.5 and SSP2-4.5). In conclusion, the projected changes in wind speed over the Korean Peninsula in the 21st century may vary depending on climate change scenarios, and the spatio-temporal complexity of winds must be considered.

Analysis and Prediction of Wind Speed Effects in East Asia and the Western Pacific Based on Multi-Source Data

With the increasing problem of global warming caused by the massive use of fossil fuels, biomass energy as a renewable energy source has attracted widespread attention throughout the globe. In this paper, we analyzed the spatial and temporal variation in wind energy in the East Asia and Western Pacific areas using IGRA site data, ERA5, and NCEP/NCAR reanalysis data from 2000 to 2021, and multi-variate empirical orthogonal function (MV-EOF) decomposition with the Pettitt mutation test, and the seasonal autoregression integrated moving average (SARIMA) model was used to predict the trend of wind speed. The spatial and temporal variations in wind energy in East Asia and Western Pacific areas were analyzed, and it was found that the richer wind-energy resources were mainly concentrated in the “Three Norths” (North China, Northwest China, and Northeast China) and Mongolia, followed by the Western Pacific areas. In addition, the T’ai-hang Mountains and the Qinghai-Tibet Plateau in China block the wind resources in the eastern and southern regions of East Asia, resulting in a shortage of wind resources in this region. In addition, the summer wind speed is significantly lower than in the other three seasons. The first-mode contributions of the MV-EOF wind field and geopotential heights, respectively, are 29.47% and 37.75%. The results show that: (1) There are significant seasonal differences in wind-energy resources in the study area, with the lowest wind speed in summer and the highest wind speed in winter. (2) The wind energy in the study area has significant regional characteristics. For example, China’s Qinghai-Tibet Plateau, Inner Mongolia, Xinjiang region, and Mongolia are rich in wind-energy resources. (3) Wind-energy resources in the study area have gradually increased since 2010, mainly due to changes in large-scale oceanic and atmospheric circulation patterns caused by global warming.

An Analysis of Meteorological Conditions in Relation to Occurrence of the Mucilage Outbreaks in Sea of Marmara, March-June 2021

A severe mucilage problem appeared as a major environmental disaster in the Marmara Sea, Turkey, during March-May 2021 period, imposing significant implications for the fishing industry, marine life and tourism. This study aimed to provide an insight into the mucilage outbreak observed in the Marmara Sea during March-May 2021 period by establishing some links between meteorological factors including SST anomalies and changes in wind speed and mucilage occurrence and puts some emphasis on the importance of monitoring variability of such parameters to assess mucilage outbreaks. For this purpose, mean and maximum SSTs and wind speed variability at a number of locations along the shores of Marmara and Black Seas are analysed for the April-June period, when the mucilage problem peaked. Both surface and satellite data are used to identify the spatial and temporal extent of the SST anomalies. Furthermore, the relationship between turbidity in the Marmara Sea and the SSTs is sought as a contributing factor to mucilage formation and enhancement. The findings indicate that most of the stations are characterized by warming trends and positive SST anomalies, with a few stations indicating periodic warming and cooling. Moreover, the NOAA NCEP Optimum Interpolation SST (OISST) data supported the warming event especially in central and eastern parts of the Marmara Sea. The wind observations at different locations along the shores of Marmara and Black Seas indicate decreasing trends in the mean wind speed. It is the view taken in this paper that both the increased SSTs and reduced wind speed generate a favourable environment both for the formation and enhancement of the mucilage episode over the Marmara Sea during the March-June 2021 period. Therefore, analysis of such meteorological parameters can provide a better understanding of mucilage aggregation in addition to other causative factors involved. The study also concluded that the modest turbidity conditions caused to increase in the SSTs to some extent in addition to the climate change-related warming.

Spatiotemporal Variations in Reference Evapotranspiration and Its Contributing Climatic Variables at Various Spatial Scales across China for 1984–2019

Reference evapotranspiration (ET0) is of great significance in studies of hydrological cycle, agricultural water resources, and hydrometeorology. The present study collected daily meteorological data at 536 meteorological stations in China from 1984 to 2019, calculated daily ET0 using the FAO Penman–Monteith equation, analyzed the spatial distribution and temporal variation characteristics of ET0 and meteorological variables at four different spatial scales (continental, regional, provincial, and local), and discussed the sensitivity of ET0 to the meteorological variables and the contribution rates of the meteorological variables to the ET0 variations. The results showed that ET0 increased at 406 out of the 536 stations (75.7%), with the trends being significant at 65 stations at the 5% significance level, and 147 at the 1% significance level. The slope calculated using Sen’s method and linear trend method showed that the annual ET0 at the continental scale increased by approximately 12 mm/decade. Most of the stations showed decreasing trends in relative humidity (Hm), sunshine duration (SD), and wind speed at 2 m height (U2) while increasing trends in the maximum air temperature (Tmax) and minimum air temperature (Tmin). ET0 was most sensitive to Hm (sensitivity coefficient, St = −0.66), followed by Tmax (St = 0.29), SD (St = 0.18), U2 (St = 0.16), and Tmin (St = 0.07). Most of the stations showed increasing trends in St for Hm (56.16%), Tmax (72.95%), Tmin (87.31%), and U2 (90.49%), and decreasing trends for SD (69.78%). The variations in Hm, Tmax, and Tmin increased the ET0 at most of the stations (82.28%, 98.13%, and 69.03%, respectively). The variations in SD and U2 decreased ET0 at most of the stations (66.04% and 56.34%, respectively). Some ET0 characteristics in a few regions can be well described using a single spatial scale. However, most regions exhibited significantly different ET0 characteristics across spatial scales. The results of this project can provide reference for hydrological analysis and agricultural water management under climate change conditions and provide data and information for other hydrology-related applications.

Interannual variabilities, long-term trends, and regulating factors of low-oxygen conditions in the coastal waters off Hong Kong

Abstract. The summertime low-oxygen conditions in the Pearl River Estuary (PRE) have experienced a significant spatial expansion associated with notable deoxygenation in recent decades. Nevertheless, there is still a lack of quantitative data on the long-term trends and interannual variabilities in oxygen conditions in the PRE as well as on the driving factors. Therefore, the long-term deoxygenation in a subregion of the PRE (the coastal waters off Hong Kong) was comprehensively investigated in this study using monthly observations during 1994–2018. To evaluate the changes in scope and intensity of oxygen conditions, an indicator (defined as the low-oxygen index, LOI) that integrates several metrics related to low-oxygen conditions was introduced as the result of a principal component analysis (PCA). Moreover, primary physical and biogeochemical factors controlling the interannual variabilities and long-term trends in oxygen conditions were discerned, and their relative contributions were quantified by multiple regression analysis. Results showed that the regression models explained over 60 % of the interannual variations in LOI. Both the wind speeds and concentrations of dissolved inorganic nitrogen (DIN) played a significant role in determining the interannual variations (by 39 % and 49 %, respectively) and long-term trends (by 39 % and 56 %, respectively) in LOI. Due to the increasing nutrient loads and alterations in physical conditions (e.g., the long-term decreasing trend in wind speeds), coastal eutrophication was exaggerated and massive marine-sourced organic matter was subsequently produced, thereby resulting in an expansion of intensified low-oxygen conditions. The deteriorating eutrophication has also driven a shift in the dominant source of organic matter from terrestrial inputs to in situ primary production, which has probably led to an earlier onset of hypoxia in summer. In summary, the Hong Kong waters have undergone considerable deterioration of low-oxygen conditions driven by substantial changes in anthropogenic eutrophication and external physical factors.

Impact of Climate Change on Food Security in Kazakhstan

Global food production faces immense pressure, much of which can be attributed to climate change. A detailed evaluation of the impact of climate change on the yield of staple crops in Kazakhstan, a major food exporter, is required for more scientific planting management. In this study, the Mann–Kendall test and Theil–Sen Median slope were used to determine climate trends and staple food yields over the past 30 years; random forest was used to analyze the importance of monthly climatic factors; states were classified according to climatic factors through systematic clustering method; and lastly, the influence of climate on yield was analyzed using panel regression models. The upward trend in wind speed and potato yield throughout Kazakhstan was apparent. Furthermore, barley and wheat yields had increased in the southeast. We determined that for wheat, frostbite should be prevented after the warmer winters in the high-latitude areas. Except for July–August in the low-latitude areas, irrigation water should be provided in the other growth periods and regions. As similar effects were reported for barley, the same preventive measures would apply. For potatoes, tuber rot, caused by frost or excessive precipitation in May, should be prevented in high-latitude areas; soil dryness should be alleviated during the germination and seedling stages in low-latitude areas; and irrigation and cooling should be maintained during tuber formation and maturation. Furthermore, hot dry air in March and April could damage the crops.