Seasonal Variation Characteristics Research Articles

Temporal characteristics of urban heat island and its response to heat waves and energy consumption in the mountainous Chongqing, China

In this study, the time series of temperature in Chongqing, China, from 1979 to 2018 was statistically analyzed, and both the interdecadal and seasonal variation characteristics of urban heat island intensity (UHII) were studied. The results show that the temperature in Chongqing has risen significantly in the past 40 years and that the temperature of the Chongqing urban area is approximately 1.6 times higher than the global warming trend. During the study period, the annual average UHII at urban and rural stations increased significantly at a rate of +1.3 °C/century. The seasonal variation in the nighttime UHII was higher in summer, while the seasonal variation in the daytime UHII was higher in winter. In addition, the annual average UHII was found to be related to the heat wave (HW) days, cooling degree days (CDD), and heating degree days (HDD). With an increase of 1 °C in the UHII, the HW days in urban area increased by approximately 10 d, the average difference of the CDD increased by approximately 72 °C•d, and the average difference of the HDD decreased by approximately 86 °C•d.

Raindrop size distribution characteristic differences during the dry and wet seasons in South China

Raindrop size distribution (DSD) is a basic feature of precipitation microphysics, and it plays a vital role in improving radar quantitative precipitation estimation and forecast accuracy. In South China, due to the influence of atmospheric circulation and weather systems, precipitation is frequent, and the types of precipitation and their temporal and spatial distributions are complex. It has become essential to study the types of precipitation in this area and their seasonal variation characteristics. Therefore, in this study, the DSDs in the dry and wet seasons of southern China are analyzed using measurements from seven ground-based two-dimensional video disdrometers (2DVDs) over the course of four years (2016–2019). The dynamic and microphysical characteristics of precipitation in the dry and wet seasons are established for South China, combined with the Moderate Resolution Imaging Spectroradiometer (MODIS) and the European Centre for Medium-Range Weather Forecasts (ECMWF) Fifth-generation Reanalysis (ERA5) data. Compared to the dry season results, the concentration of small raindrops (diameters <1 mm) in wet season is similar, while the concentration of midsized raindrops (diameters between 1 and 3 mm) and large raindrops (diameters >3 mm) in the wet season are significantly greater. Furthermore, taking the contributions to precipitation into account, the rainfall in the dry season is dominated by stratiform rain, which accounts for 59.3% of the total rainfall. Considering precipitation in the wet season, convective rain accounts for 77.9% of total the rainfall. The obtained relations of the shape parameter (μ) versus the slope parameter (Λ) (μ-Λ) and the radar reflectivity factor (Z) versus the rainfall rate (R) (Z-R) have obvious differences for different type rainfall in the two seasons. In the wet season, the water vapor is sufficient and the upward convection activity is intense in South China, causing the frequent occurrence of raindrop collisions and coalescence. This is also the reason that the Dm and R values in the wet season are greater than those in the dry season, while the wet season log10Nw is relatively small. This not only deepens the understanding of the seasonal DSD variation in South China, but also provides theoretical support for improving numerical weather prediction models.

Short and Medium-Term Prediction of Winter Wheat NDVI Based on the DTW–LSTM Combination Method and MODIS Time Series Data

The normalized difference vegetation index (NDVI) is an important agricultural parameter that is closely correlated with crop growth. In this study, a novel method combining the dynamic time warping (DTW) model and the long short-term memory (LSTM) deep recurrent neural network model was developed to predict the short and medium-term winter wheat NDVI. LSTM is well-suited for modelling long-term dependencies, but this method may be susceptible to overfitting. In contrast, DTW possesses good predictive ability and is less susceptible to overfitting. Therefore, by utilizing the combination of these two models, the prediction error caused by overfitting is reduced, thus improving the final prediction accuracy. The combined method proposed here utilizes the historical MODIS time series data with an 8-day time resolution from 2015 to 2020. First, fast Fourier transform (FFT) is used to decompose the time series into two parts. The first part reflects the inter-annual and seasonal variation characteristics of winter wheat NDVI, and the DTW model is applied for prediction. The second part reflects the short-term change characteristics of winter wheat NDVI, and the LSTM model is applied for prediction. Next, the results from both models are combined to produce a final prediction. A case study in Hebei Province that predicts the NDVI of winter wheat at five prediction horizons in the future indicates that the DTW–LSTM model proposed here outperforms the LSTM model according to multiple evaluation indicators. The results of this study suggest that the DTW–LSTM model is highly promising for short and medium-term NDVI prediction.

Abstract 11434: Emergency Department Disposition for Patients with Low-Risk Acute Pulmonary Embolism: A Nationwide Analysis

Background: Outpatient management has been shown to be safe and effective for patients presenting to the emergency department (ED) with low-risk acute pulmonary embolism (PE). The degree to which outpatient management for PE has evolved in contemporary clinical practice is uncertain, as is an understanding of whether certain patient or hospital factors are associated with outpatient PE management. Methods: Using the Nationwide Emergency Department Sample, we identified hospitalizations with primary or secondary PE between 2006-2018. We excluded patients who were &lt;18 years old, died during ED visit, received systemic or catheter-directed thrombolysis, or had any of the following: acute coronary syndrome, heart failure, atrial fibrillation, chronic kidney/lung disease, gastrointestinal bleeding, or respiratory failure. Multivariable regression models were utilized to identify patient and hospital factors that predicted discharge to home from the ED. Results: Among 516,670 ED visits with acute PE, 92,108 (17.8%) patients were discharged to home. As compared to those admitted, patients who were managed as an outpatient were younger (median 52, interquartile range (IQR) 26-78 vs 61 IQR (35-87) years, P&lt;0.001), and more female (57.9% vs 53.1%, P&lt;0.001). In more recent years there was a significant increase in discharge from ED to home (9.2% in 2016 to 29.7% in 2018 (relative increase 69.0%, P&lt;0.001)) Panel A. In a sensitivity analysis, when PE was only a primary diagnosis, the rate of home disposition increased from 4.8% to 27.7%, P&lt;0.001. Patient and hospital factors associated with an increased likelihood of home discharge are listed Panel B . Conclusion: Outpatient management of patients with low-risk PE has become increasingly common, with more than one-quarter of patients evaluated in the ED now discharged to home. Patient demographics, seasonal variation, and hospital characteristics were associated with a differential effect on the home disposition.

Measurement report: Regional characteristics of seasonal and long-term variations in greenhouse gases at Nainital, India, and Comilla, Bangladesh

Abstract. Emissions of greenhouse gases (GHGs) from the Indian subcontinent have increased during the last 20 years along with rapid economic growth; however, there remains a paucity of GHG measurements for policy-relevant research. In northern India and Bangladesh, agricultural activities are considered to play an important role in GHG concentrations in the atmosphere. We performed weekly air sampling at Nainital (NTL) in northern India and Comilla (CLA) in Bangladesh from 2006 and 2012, respectively. Air samples were analyzed for dry-air gas mole fractions of CO2, CH4, CO, H2, N2O, and SF6 and carbon and oxygen isotopic ratios of CO2 (δ13C-CO2 and δ18O-CO2). Regional characteristics of these components over the Indo-Gangetic Plain are discussed compared to data from other Indian sites and Mauna Loa, Hawaii (MLO), which is representative of marine background air. We found that the CO2 mole fraction at CLA had two seasonal minima in February–March and September, corresponding to crop cultivation activities that depend on regional climatic conditions. Although NTL had only one clear minimum in September, the carbon isotopic signature suggested that photosynthetic CO2 absorption by crops cultivated in each season contributes differently to lower CO2 mole fractions at both sites. The CH4 mole fraction of NTL and CLA in August–October showed high values (i.e., sometimes over 4000 ppb at CLA), mainly due to the influence of CH4 emissions from the paddy fields. High CH4 mole fractions sustained over months at CLA were a characteristic feature on the Indo-Gangetic Plain, which were affected by both the local emission and air mass transport. The CO mole fractions at NTL were also high and showed peaks in May and October, while CLA had much higher peaks in October–March due to the influence of human activities such as emissions from biomass burning and brick production. The N2O mole fractions at NTL and CLA increased in June–August and November–February, which coincided with the application of nitrogen fertilizer and the burning of biomass such as the harvest residues and dung for domestic cooking. Based on H2 seasonal variation at both sites, it appeared that the emissions in this region were related to biomass burning in addition to production from the reaction of OH and CH4. The SF6 mole fraction was similar to that at MLO, suggesting that there were few anthropogenic SF6 emission sources in the district. The variability of the CO2 growth rate at NTL was different from the variability in the CO2 growth rate at MLO, which is more closely linked to the El Niño–Southern Oscillation (ENSO). In addition, the growth rates of the CH4 and SF6 mole fractions at NTL showed an anticorrelation with those at MLO, indicating that the frequency of southerly air masses strongly influenced these mole fractions. These findings showed that rather large regional climatic conditions considerably controlled interannual variations in GHGs, δ13C-CO2, and δ18O-CO2 through changes in precipitation and air mass.

Retraction Note: Ocean surface circulation based on video features and swimmer training monitoring

This paper aims at efficient recognition and video features and then studies the ocean surface circulation and swimmer training monitoring. Firstly, a method based on video feature extraction is proposed to describe the ocean surface circulation movement, and then a fusion method based on video dynamic and static features is designed for swimmer training monitoring, Finally, a video feature classification method based on dual stream improved C3d is designed to complete the recognition and classification. Then the characteristics of seasonal variation of tropical ocean surface circulation are analyzed, and the possible mode of seasonal water exchange between bay and ocean is discussed. Next, we analyze the temperature and salinity structure of the upper part of the ocean, the spatial distribution of the Arabian Sea and the Gulf, and the characteristics of seasonal variation. The expansion path and scope of the two water masses in the study area are clarified. Finally, the Bay Estuary 6° N segment, the net salt flux, and freshwater transport formula are used to quantitatively analyze the water exchange process of the tropical ocean surface circulation. Next, we will analyze the blood lactic acid level of the best Chinese swimmers, and note that Chinese swimmers are slightly insufficient in the case of high-intensity exercise. The lactic acid in the blood of the competition will be affected by the way of swimming, the gender of the athletes, and the venue of the competition. The purpose of training monitoring is to timely understand the athletes’ body reaction to sports training, prevent excessive fatigue and sports injury, maximize sports performance in a short period of time, and achieve good results in the next ten games swimming competition. Based on the research of ocean surface circulation and swimmer training monitoring, this paper applies it to the video features, so as to improve the performance of swimmers.

Seasonal variation in the total alkalinity and δ13CDIC values of cave drip water in a ventilated cave in response to the regional climatology, southwest China

The simulation and monitoring of environmental proxies in cave systems is of great significance for understanding the controlling factors of stalagmite geochemistry and for further analysing the signal transmission process and mechanism in cave systems. In this study, we collected samples from three drip points in Liangfeng Cave from 2015 to 2020, Guilin City, Southwest China. The δ13CDIC values, total alkalinity and modern calcite deposition rates at the drip points in the cave were measured during the monitoring period. Comparison of these data with atmospheric temperature and rainfall data from the study area revealed that (1) the δ13CDIC and total alkalinity values of cave drip water show a seasonal pattern involving low values that increase in summer and autumn and high values that decrease in winter and spring, which is synchronized with the changes in the regional rainfall and temperature. (2) The modern calcite deposition rate also shows characteristics of significant seasonal variation. In addition, modern calcite deposition rate of drip water (site LF-4) decreased year by year. On an interannual time scale, the recharge regime of this drip water is likely to be the main control on the modern calcite deposition rate. (3) The δ13CDIC values of the drip water in Liangfeng Cave (well ventilated) are generally higher than those of another cave (weakly ventilated) in the study area for winter and spring. The cave ventilation effect leads to a higher δ13CDIC value in the drip water during times of low cave pCO2. (4) Because Liangfeng Cave is a well-ventilated cave, the drip water could record the seasonal regional climatology variation. Observations from the well-ventilated Liangfeng Cave provide a reference point for the interpretation of regional climatology signals from speleothem proxy records.

Long-term and seasonal variation in groundwater storage in the North China Plain based on GRACE

The over exploitation of groundwater has seriously restricted the healthy development of social economy in North China Plain (NCP). The study of the change in the groundwater storage at different time scales is helpful to understand the characteristics of groundwater dynamic changes and real-time groundwater management. Based on Gravity Recovery and Climate Experiment (GRACE) satellite products and Global Land Data Assimilation System (GLDAS) data, this paper analyses the seasonal and long-term trend changes of NCP groundwater storage from June 2003 to June 2017 by using adaptive Ensemble Empirical Mode Decomposition (EEMD) algorithm. Moreover, their relationships with precipitation and the South-to-North Water Diversion Middle Route Project (SWDP) are analysed. The main conclusions are as follows: (1) The change of groundwater storage in NCP mainly shows a long-term downward trend and the downward trend gradually increases from northeast to southwest, and the maximum decline rate appears in Handan, reaching 26.44 mm/yr; (2) The main spatial pattern in the seasonal variation of groundwater storage in the NCP has a good consistency and the response of seasonal groundwater variation to seasonal precipitation variation lags by 3–4 months; and (3) After implementing the SWDP, the long-term decline rate of groundwater storage is reduced and the average contribution rate of seasonal variation characteristics of groundwater storage increases from 20% to 28%. The research results of this paper are helpful to understand the dynamic change process of groundwater storage and lay a foundation for further exploring the reasons for the change of groundwater storage.

The epidemiological characteristics of rash and fever syndrome in Gansu Province from 2009 to 2019

Objective To understand the compositions of pathogens and seasonal distribution characteristics of rash and fever syndrome (RFS) in Gansu Province from 2009 to 2019, so as to provide references for further disease surveillance and scientific prevention and control. Methods Descriptive epidemiological methods were used to analyze the composition of pathogens of RFS in Gansu Province from 2009 to 2019 and the seasonal variation characteristics of the main pathogens. Results The compositions of pathogens of RFS in Gansu Province were dominated by viruses, mainly enterovirus (56.04%), measles virus (19.14%), varicella-zoster virus (16.85%) and rubella virus (7.33%). The differences of positive rate of the main pathogens in different age groups and different seasons were statistically significant (all P Conclusions From 2009 to 2019, the compositions of pathogens of RFS in Gansu Province were mainly viruses and the main pathogens have obvious seasonal characteristics. Seasonal and targeted proventive methods should be adopted for high-risk populations.

Spatial and temporal characteristics of annual and seasonal precipitation variation in Shijiazhuang region, north China

Spatial and temporal characteristics of annual and seasonal precipitation variation in Shijiazhuang region, north China

RETRACTED ARTICLE: Ocean surface circulation based on video features and swimmer training monitoring

This paper aims at efficient recognition and video features and then studies the ocean surface circulation and swimmer training monitoring. Firstly, a method based on video feature extraction is proposed to describe the ocean surface circulation movement, and then a fusion method based on video dynamic and static features is designed for swimmer training monitoring, Finally, a video feature classification method based on dual stream improved C3d is designed to complete the recognition and classification. Then the characteristics of seasonal variation of tropical ocean surface circulation are analyzed, and the possible mode of seasonal water exchange between bay and ocean is discussed. Next, we analyze the temperature and salinity structure of the upper part of the ocean, the spatial distribution of the Arabian Sea and the Gulf, and the characteristics of seasonal variation. The expansion path and scope of the two water masses in the study area are clarified. Finally, the Bay Estuary 6° N segment, the net salt flux, and freshwater transport formula are used to quantitatively analyze the water exchange process of the tropical ocean surface circulation. Next, we will analyze the blood lactic acid level of the best Chinese swimmers, and note that Chinese swimmers are slightly insufficient in the case of high-intensity exercise. The lactic acid in the blood of the competition will be affected by the way of swimming, the gender of the athletes, and the venue of the competition. The purpose of training monitoring is to timely understand the athletes’ body reaction to sports training, prevent excessive fatigue and sports injury, maximize sports performance in a short period of time, and achieve good results in the next ten games swimming competition. Based on the research of ocean surface circulation and swimmer training monitoring, this paper applies it to the video features, so as to improve the performance of swimmers.

Hydro-chemical Characteristics and Ion Origin Analysis of Surface Groundwater at the Shengjin Lake and Yangtze River Interface

The interface between Shengjin Lake and Yangtze River was selected as the study area. The water chemical composition and hydrogen and oxygen isotope values of different types of water bodies were tested, and their seasonal variation characteristics were analyzed to explore the sources of chemical ions in the surface and groundwater. Finally, the contribution of mixed water sources to chemical ions in groundwater was estimated. The results show the following ① The concentration of chemical ions in the surface and groundwater of the study area is higher than that of atmospheric precipitation, and the physical and chemical parameters exhibit seasonal variation. ② Surface water mainly belongs to the Ca-HCO3 type, but the proportion of the Ca-SO4 type in summer is significantly lower than that in other seasons; Groundwater primarily belongs to Ca-HCO3 and Ca-SO4 types, with proportions of 46% and 27%, respectively, and the seasonal difference is not significant. ③ Ca2+ and Mg2+ in the surface and groundwater mainly come from the dissolution of carbonate rocks, carbonic acid and sulfate ions participate in the dissolving process of carbonate minerals. Na+and Cl- are partly derived from atmospheric precipitation and partly sourced from agricultural fertilization and manure sewage. ④ Mixed water sources is also an important source of chemical ions in groundwater, with the average contribution 28% to Cl-, showing a seasonal trend.

Comparative study on the influene factors of chlorophyll-a and nutrient structure between winter and summer in the central Bohai Sea

Based on the data of chlorophyll a (Chl a), nutrients, and hydrological environment parameters of the central Bohai Sea in January(winter) and June(summer) of 2016, we studied spatial and temporal variations of Chl a, nutrient structure, analyzed the influence factors for the phytoplankton growth and the changing trend of the phytoplankton community structure over long-time scale. The results showed that nutrient structure and Chl a had significant seasonal variation characteristics (<italic>P</italic><0.01). In winter, the concentrations of dissolved inorganic nitrogen (DIN), active phosphate (PO^3-₄-P) and silicate (SiO^2-₃-Si) were (10.51±4.52)μmol·L^-1, (0.28±0.14)μmol·L^-1, and (10.63±2.09)μmol·L^-1, respectively, and NO^-₃-N (92%) was the main form of DIN, and all nutrient contents were above the threshold, meanwhile the nutrient ratios of N/P, Si/P, and Si/N were 69.30±86.80, 64.50±68.80, and 1.20±0.50, respectively, the N and Si limitations were not obvious except that some stations showed P potential limitations because of input of the Northern Yellow Sea cold flow, the sediment resuspension, and the release by the mineralization of organic matters. Affected by seawater temperature (<italic>T</italic><8℃), the phytoplankton reproduction and growth were restricted and the content of Chl a (0.99±0.25) mg·m^-3 was low. In summer, influenced by the Yellow River dilute water, the Northern Yellow Sea cold flow, and phytoplankton uptake. The concentrations of DIN, PO^3-₄-P and SiO^2-₃-Si were (4.72±4.20) μmol·L^-1, (0.04±0.04) μmol·L^-1, and (3.81±1.72) μmol·L^-1, and decreased by 55.0%, 85.7% and 64.1%, respectively, NH⁴⁺-N (48%) and NO^-₃-N (45%) became the main forms of DIN, compared to those in the winter. The nutrient ratios of N/P, Si/P and Si/N were 274.19±328.06, 202.18±182.07 and 1.39±1.00, respectively, increased significantly compared with that of winter. The nutrient limitations showed obvious P limitation, and the contents were below the threshold of DIN and Si in some stations, which would limit the growth of phytoplankton, especially the diatoms. The content of Chl a was (4.58±5.51) mg·m^-3 with the seawater temperature of (22.1±1.88)℃, 4.6 times higher than that in winter, there were some stations in the Yellow River Estuary, the content was beyond 10 mg·m^-3 and showed an outbreak risk of alage bloom.

Seasonal Variation Characteristics of Chlorophyll and Spectrum in Leaves of Populus euphratica Under Water Stress

Seasonal Variation Characteristics of Chlorophyll and Spectrum in Leaves of Populus euphratica Under Water Stress

Seasonal Variation Characteristics of Bacteria and Fungi in PM2.5 in Typical Basin Cities of Xi’an and Linfen, China

Microorganisms existing in airborne fine particulate matter (PM2.5) have key implications in biogeochemical cycling and human health. In this study, PM2.5 samples, collected in the typical basin cities of Xi’an and Linfen, China, were analyzed through high-throughput sequencing to understand microbial seasonal variation characteristics and ecological functions. For bacteria, the highest richness and diversity were identified in autumn. The bacterial phyla were dominated by Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes. Metabolism was the most abundant pathway, with the highest relative abundance found in autumn. Pathogenic bacteria (Pseudomonas, Acinetobacter, Serratia, and Delftia) were positively correlated with most disease-related pathways. Besides, C cycling dominated in spring and summer, while N cycling dominated in autumn and winter. The relative abundance of S cycling was highest during winter in Linfen. For fungi, the highest richness was found in summer. Basidiomycota and Ascomycota mainly constituted the fungal phyla. Moreover, temperature (T) and sulfur dioxide (SO2) in Xi’an, and T, SO2, and nitrogen dioxide (NO2) in Linfen were the key factors affecting microbial community structures, which were associated with different pollution characteristics in Xi’an and Linfen. Overall, these results provide an important reference for the research into airborne microbial seasonal variations, along with their ecological functions and health impacts.

Spatiotemporal changes of terrestrial water storage and possible causes in the closed Qaidam Basin, China using GRACE and GRACE Follow-On data

Terrestrial water storage (TWS) is a crucial indicator of regional water balance and water resources changes. Due to limited hydrological observations, we combined the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) products using the Long Short-Term Memory (LSTM) neural network to monitor the TWS changes from April 2002 to March 2020 over the closed Qaidam Basin in northwest China and examined the impacts of climate and meteorological changes on TWS variations. The results indicated that the LSTM model, driven by the cumulative precipitation, temperature, and Global Land Data Assimilation System datasets, was reliable for use in reconstruction of the GRACE products in the closed basin. The TWS variations featured seasonal variation characteristics and a significant upward trend at internal-annual scales, which were tested via linear statistics and a modified Mann–Kendall method. The increasing trend is likely to remain strongly sustainable in the near future with a Hurst index over 0.75 in most regions. Moreover, the TWS oscillation has a periodicity and nonlinearity increase trend of 0.43 mm/month as observed using ensemble empirical mode decomposition analysis, and the TWS components (including snow water equivalent, soil moisture, and groundwater) demonstrate discordant increasing trends in the basin. Under climate change conditions, teleconnection factors have strong impacts on TWS variability, particularly for the Pacific Decadal Oscillation index with a significant negative correlation by cross wavelet transform technology. Nonetheless, the increase in TWS is primarily influenced by precipitation increases and is more sensitive to the accumulated precipitation in this region. In this study, the GRACE products in combination with GRACE-FO data may help us to better understand the spatiotemporal characterization of TWS in Qaidam Basin, which will provide an important support for the water resource management and ecological environment protection in such data-scarce regions.

Aerosol characteristics at the three poles of the Earth as characterized by Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations

Abstract. To better understand the aerosol properties over the Arctic, Antarctic and Tibetan Plateau (TP), the aerosol optical properties were investigated using 13 years of CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations) L3 data, and the back trajectories for air masses were also simulated using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results show that the aerosol optical depth (AOD) has obvious spatial- and seasonal-variation characteristics, and the aerosol loading over Eurasia, Ross Sea and South Asia is relatively large. The annual-average AODs over the Arctic, Antarctic and TP are 0.046, 0.024 and 0.098, respectively. Seasonally, the AOD values are larger from late autumn to early spring in the Arctic, in winter and spring in the Antarctic, and in spring and summer over the TP. There are no significant temporal trends of AOD anomalies in the three study regions. Clean marine and dust-related aerosols are the dominant types over ocean and land, respectively, in both the Arctic and Antarctic, while dust-related aerosol types have greater occurrence frequency (OF) over the TP. The OF of dust-related and elevated smoke is large for a broad range of heights, indicating that they are likely transported aerosols, while other types of aerosols mainly occurred at heights below 2 km in the Antarctic and Arctic. The maximum OF of dust-related aerosols mainly occurs at 6 km altitude over the TP. The analysis of back trajectories of the air masses shows large differences among different regions and seasons. The Arctic region is more vulnerable to mid-latitude pollutants than the Antarctic region, especially in winter and spring, while the air masses in the TP are mainly from the Iranian Plateau, Tarim Basin and South Asia.

Two decades of distributed global radiation time series across a mountainous semiarid area (Sierra Nevada, Spain)

Abstract. The main drawback of the reconstruction of high-resolution distributed global radiation (Rg) time series in mountainous semiarid environments is the common lack of station-based solar radiation registers. This work presents 19 years (2000–2018) of high-spatial-resolution (30 m) daily, monthly, and annual global radiation maps derived using the GIS-based model proposed by Aguilar et al. (2010) in a mountainous area in southern Europe: Sierra Nevada (SN) mountain range (Spain). The model was driven by in situ daily global radiation measurements, from 16 weather stations with historical records in the area; a 30 m digital elevation model; and 240 cloud-free Landsat images. The applicability of the modeling scheme was validated against daily global radiation records at the weather stations. Mean RMSE values of 2.63 MJ m−2 d−1 and best estimations on clear-sky days were obtained. Daily Rg at weather stations revealed greater variations in the maximum values but no clear trends with altitude in any of the statistics. However, at the monthly and annual scales, there is an increase in the high extreme statistics with the altitude of the weather station, especially above 1500 m a.s.l. Monthly Rg maps showed significant spatial differences of up to 200 MJ m−2 per month that clearly followed the terrain configuration. July and December were clearly the months with the highest and lowest values of Rg received, and the highest scatter in the monthly Rg values was found in the spring and fall months. The monthly Rg distribution was highly variable along the study period (2000–2018). Such variability, especially in the wet season (October–May), determined the interannual differences of up to 800 MJ m−2 yr−1 in the incoming global radiation in SN. The time series of the surface global radiation datasets here provided can be used to analyze interannual and seasonal variation characteristics of the global radiation received in SN with high spatial detail (30 m). They can also be used as cross-validation reference data for other global radiation distributed datasets generated in SN with different spatiotemporal interpolation techniques. Daily, monthly, and annual datasets in this study are available at https://doi.org/10.1594/PANGAEA.921012 (Aguilar et al., 2021).

Future forecast of global land wind and light resources in the context of climate change

Based on the multi-model ensemble average results of the CMIP5 program, we predict the changes of global terrestrial wind and solar energy resources from 2020 to 2030 under different future climate change scenarios. The results show that the multi-mode ensemble average results have high confidence in the simulation of global wind and solar energy resources. Under different climate scenarios (RCPs), the changes in global terrestrial wind and solar energy resources in the next 2020-2030 (relative to 1986-2005) will have significant regional differences. Among them, wind resources in the Americas, Africa and Australia increased, while European wind-rich areas decreased; those in Asia (e.g., Northwest China and Central Asia) increased in RCP2.6, but decreased in RCP4.5 and RCP8.5. Global terrestrial solar energy resources are increasing in different RCPs scenarios in the future, especially in European solar energy-rich areas. Wind energy and solar energy resources on the global land have obvious seasonal variation characteristics, and the seasonal variation rate varies greatly in different regions. The change trend and change range of wind energy and solar energy resources in different rich areas are different. There are some differences in the RCPs scenario. It shows the complexity of future changes in wind and solar energy resources in response to global climate change.

Assessment of size distribution of aerosols at kitchen environments in Delhi, India

The present study was carried out for size distribution of aerosols at indoor environments covering six different locations in the Jawaharlal Nehru University campus using TSI AeroTrak Portable Particle Counter (APPC), during the year 2014–15. The instrument provides the particle counts in the ranges from 0.3 μm to 20 μm. After the investigation, total suspended particulate matters (TSPM) were observed in the following order: winter > monsoon > summer. The fine mode particles contributed more than 96% in comparison to coarse modes of particles. In number size distribution, a unimodal trend but with no characteristic seasonal variation was observed, however, a clear seasonal variation of modalities in surface area and volume size distributions was obtained. Both the unimodal and bimodal size distributions in surface area were observed. A slight shift in peak was also observed in the surface area and volume size distributions, which was attributed to be related to different characteristics in the kitchens and canteens of the indoor environment.