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Based on data from the Gurbantunggut Desert, the largest fixed/semi-fixed desert in China, and ERA5-Land reanalysis data, the long-term variations and spatial surface heat source (SHS) differences in the Gurbantunggut Desert are discussed herein. The results show the following: (1) The hourly SHS at the Kelameili station during the 2013–2021 period was a weak heat source at night; contrastingly, it was a strong heat source during the day. The duration of the hourly SHS increased gradually from January to July, but it decreased gradually from July to December. The daily SHS showed obvious seasonal variation, reaching the maximum in summer and the minimum in winter. The ERA5-Land reanalysis can reproduce all the variation characteristics of the SHS well. (2) The climatology (i.e., multi-year mean) of the monthly SHS intensity was lower than 50 W/m2 during the January–March and September–December periods in the Gurbantunggut Desert, indicating a weak heat source. On the other hand, the climatology recorded in April–August was higher than 50 W/m2, with a strong heat source. From the perspective of spatial distribution, the eastern and western regions of the Gurbantunggut Desert show strong heat sources, while the central region shows weak heat sources. The spatial distribution of the first and second modes of the empirical orthogonal function (EOF) decomposition reflected the consistent spatial variability and a north–south (or east–west) polarity variation of the monthly SHS in the Gurbantunggut Desert, respectively. (3) The yearly SHS showed negative anomalies during the 1950–1954, 1964–1982 and 2004–2015 periods, and positive anomalies during the 1955–1963, 1983–2003 and 2016–2021 periods in the Gurbantunggut Desert. Additionally, the time series of the SHS anomalies was positively correlated with the Interdecadal Pacific Oscillation (IPO) index. During the negative IPO phase, the yearly SHS showed a negative anomaly in the Gurbantunggut Desert, while the yearly SHS showed a positive anomaly during the positive IPO phase in most regions of the Gurbantunggut Desert. [ABSTRACT FROM AUTHOR]

Long-term variations in precipitation during the major rainy periods in Japan--the Baiu (June-July) and Akisame (September-October) seasons--are investigated using precipitation records from 44 weather stations in western to eastern Japan over the past 120 years (1901 - 2020). The total amount of Baiu precipitation has increased over the 1901 - 2020 period, mainly during the mid-late stages of the season (late June-July) over regions on the Sea of Japan side of the country. Conversely, the precipitation amount during the Akisame season has decreased, mainly during the mid-stage (late September-early October) over all regions. The frequency and intensity of heavy precipitation have generally increased in both seasons, but the trends are much stronger for the Baiu season than for the Akisame season. A prominent positive trend, 23.5 % (100 yr)-1 (18.1 % °C-1), which is much higher than the Clausius-Clapeyron rate (approximately 7 % °C-1), is observed for the Sea of Japan side of western Japan for the seasonal maximum one-day precipitation total during the Baiu season. It may be noteworthy that the observed long-term trends differ greatly between the Baiu and Akisame seasons even though the statistical significances of the trends are not so high, because similar differences between the two rainy seasons are found in the results of global warming simulations. [ABSTRACT FROM AUTHOR]

Study of Air Quality Objectives (AQOs) and long-term changes of air pollution plays a decisive role in formulating and refining pollution control strategies. In this study, 10-year variations of six major air pollutants were analyzed at seven monitoring sites in Hong Kong. The continuous decrease of annual averaged concentrations of NO 2 , SO 2 , CO, PM 2.5 and PM 10 and numbers of days with severe pollution conditions validated the efficiency of the series of air pollution control schemes implemented by the Hong Kong government. However, there is still a big gap to meet the ultimate targets described by the World Health Organization. Besides, the concentration of O 3 at roadside and urban stations increased by 135% ± 25% and 37% ± 18% from 2011 to 2020, respectively, meanwhile the highest 8 hr averaged O 3 concentration was observed as 294 µg/m3 at background station in 2020, which pointed out the increasing ozone pollution in Hong Kong. There was a great decrease in the annual times of air quality health index (AQHI) laying in "high", "very high" and "serious" categories from 2011 to 2020 with the decrease rate of 89.70%, 91.30% and 89.74% at roadside stations, and 79.03%, 95.98% and 72.73% at urban stations, respectively. Nevertheless, the number of days categorized as "high" or above at roadside station was twice more than that in the urban station during the past ten years. Thus, more policies and attentions should be given to the roadside air quality and its adverse health effect to pedestrians on street. [Display omitted] [ABSTRACT FROM AUTHOR]

Vulnerability of each stock in the catches from trawl fisheries in the Gulf of Thailand was assessed by productivity susceptibility analysis. Separate assessments were made based on type of trawler (otter-board, pair and beam) and vessel size (SS, S, M, L and XL, according to gross tonnage). Catches were distinctly different among trawler types and were dominated by demersal fishes, pelagic fishes and shrimps in the otter-board, pair and beam trawlers, respectively. The stocks of over 200 taxa were included in the study; high-vulnerability taxa were found for all trawl types and sizes, except the beam trawler size S. Only seven (7) taxa were classified as high vulnerability, including four (4) teleost taxa, namely Saurida elongata, Plotosus spp., Gymnothorax spp. and Sphyraena spp., and three (3) elasmobranch taxa, namely Carcharhinus spp., Brevitrygon heterura and Neotrygon kuhlii. Meanwhile, as many as 26 high-medium vulnerability taxa were found in catches by otter-board trawler size L, which included not only fishes but also cephalopods. Trends and variation in fish landings of 20 high and high-medium vulnerability taxa were analyzed. Eighteen (18) taxa showed monotonic trends, both continuous and discontinuous, in their time series of annual landings, but not Muraenesox spp. nor Uroteuthis spp. The long-term variations in fish landings ranged mostly between 40% and 50%. The short-term variations showed positive absolute and relative skewness, i.e., mostly between 10% and 20%. Results of this study highlight the taxa that require a precautionary approach for fishery management and warrant comprehensive fish stock assessment. Such data will allow more accurate determination of their status compared to the reference points and facilitate better management of trawl fisheries in the Gulf of Thailand. [ABSTRACT FROM AUTHOR]

• Enhanced Kuroshio looping path across the Luzon Strait is observed during 1993–2020. • Eddy Kinetic Energy shows long-term increasing in the Northeastern South China Sea. • Energy from baroclinic instability is dominant for the EKE long-term increasing. The seasonal to interannual variability of eddy kinetic energy (EKE) in the Northeastern South China Sea (NE-SCS) has been widely studied and it is recognized that they are strongly related to the state of the Kuroshio pathway in the Luzon Strait. While, due to the lack of long-term observations and high-resolution simulations, the decadal change of EKE in NE-SCS remains unexplored. In this study, we show the EKE trend in the past ∼ 30 years in the NE-SCS by using satellite observation and global HYbrid Coordinate Ocean Model reanalysis with the Navy Coupled Ocean Data Assimilation. It is found that due to the weakening of the Kuroshio in the Luzon Strait since 1990 s, the Kuroshio shows an enhanced looping path in the NE-SCS, inducing stronger EKE in this region. Further analysis confirms that the energy transfer by baroclinic instability is dominant for the increasing of EKE, when the Kuroshio intrudes into the NE-SCS and brings more potential energy inside the circulation. The Kuroshio state along the Luzon Strait is the key for modulating the EKE in the NE-SCS. Furthermore, the long-term weakening of Kuroshio current along the Luzon strait during 1993–2020 is determined by the decreasing of subtropical mode water, corresponding to the positive phase of the Atlantic Multidecadal Oscillation. This study provides insight into the interaction between marginal sea (i.e., the SCS) and the open ocean (i.e., the western Pacific Ocean), finally linking to the global climate change. [ABSTRACT FROM AUTHOR]

Sandstorm is a disastrous weather phenomenon that often occurs in arid and semi-arid areas, endangering the ecological environment and affecting people's lives and property safety seriously. Since the 21st century, the sandstorm weather in the Yellow River Basin has ameliorated obviously. However, the causes of the long-term trends in sandstorms during 21st century were still unknown. In this study, fifteen influencing factors from five aspects: ecology, meteorology, hydrology, geography and man-made were selected to comprehensively analyze the driving mechanism of sandstorm activities in the Yellow River Basin since the 21st century, and the effect of each influencing factor on sandstorm weather was quantified. The results indicated that ecological, meteorological and geographical factors had dominant impacts on the spatio-temporal variation of sandstorms during 2000–2021, while hydrological and human factors played little role in the long-term variation of sandstorms. Sandstorms frequently occurred in semi-desert or grassland or non-high vegetation covered areas in spring. Vegetation coverage, precipitation, surface pressure, surface roughness, and soil moisture content were negatively correlated with sandstorms, while wind speed, friction velocity, evaporation, and soil temperature were positively correlated with sandstorms. Precipitation, runoff, evaporation, soil moisture content, soil temperature, and surface temperature indirectly acted on normalized brightness temperature dust index (NBTDI) and sandstorms by changing soil texture. Normalized Vegetation Index (NDVI) had direct negative effects on NBTDI, while wind speed 10 m (WS10m), slope of sub-gridscale orography (SOSGO), and forecast surface roughness (FSR) had direct positive effects on NBTDI. This study comprehensively revealed the dominant factors and their driving mechanism of sandstorm weather in the Yellow River Basin since the 21st century, which had practical application value for the prevention of sandstorms. [Display omitted] • Spatial heterogeneity existed in sandstorms drives across different regions during 2000–2021. • Precipitation, runoff, evaporation, soil moisture, and temperature indirectly affect sandstorms through soil texture. • SP, NDVI, ST, E, R and WS10m on the long-term change of sandstorm were more important. • Vegetation, evaporation, runoff, slope negatively affect sandstorms; wind, temperature positively. [ABSTRACT FROM AUTHOR]

Regional variations in atmospheric moisture residence time (RT) highlight the need to obtain independent observation indexes to constrain different model-based estimates. Stable isotopes of oxygen and hydrogen naturally exist in water molecules that can provide such observational constraints. We analyzed the relationship between RT and precipitation isotopes (δ2H and δ18O) across different climatic zones in Eurasia from 1980 to 2020. Our analysis reveals that: (1) Both precipitation isotopes and RT showed significant increasing trends during 1980–2020. The increase in RT corresponds to weakened net isotopic distillation over Eurasia, suggesting reduced atmospheric circulation intensity under warming conditions. (2) The spatial patterns of RT and precipitation isotopes vary significantly among different moisture source regions, reflecting distinct moisture transport and precipitation formation processes. (3) On long-term scales, RT generally shows positive correlations with precipitation isotopes, except in plateau regions. The RT-δ18O relationship exhibits latitude-dependent variations, with similar slopes in regions sharing common moisture sources. These findings enhance our understanding of the long-term controls on precipitation isotopic composition and atmospheric moisture cycling patterns across Eurasia. • The relationship between RT and δ18O varies obviously with latitude. • RT and precipitation isotopes vary with moisture source regions rather than simple inland-monsoon division. • Long-term increases in RT indicate weakening atmospheric circulation over Eurasia. [ABSTRACT FROM AUTHOR]

To examine how compositional changes in a community vary depending on time scales, we estimated temporal β-diversity of zooplankton in Lake Hataya Ohnuma, a small lake in Yamagata, Japan. The zooplankton community was monitored for 9 years with monthly samplings. We estimated the inter-annual, inter-seasonal, intra-seasonal, and inter-month β-diversity with the magnitude of sampling errors, and examined relative contributions of these time scales on changes in the zooplankton community structure. The temporal β-diversity was high at the inter-seasonal scale than at the intra-seasonal and inter-annual time scales, suggesting that taxonomic turnover in the zooplankton community was regulated by seasonally changing parameters such as water temperature. Indeed, the temporal β-diversity is related significantly to water temperature, although no significant relationship was detected between the temporal β-diversity and chlorophyll-a concentrations. In addition, the large inter-month β-diversity with significant inter-annual β-diversity indicated that the phenology of the zooplankton community changed depending on years, especially before and after 2012. These results indicate that temporal β-diversity is a useful gauge for detecting phenological changes and for quantifying the temporal stability of plankton communities at various time scales. [ABSTRACT FROM AUTHOR]

A tidal shear front (TSF) can be defined as an obvious horizontal gradient of flow velocity formed by opposing tidal currents (reversed TSF) or same-direction tidal currents (homogenous TSF) on both sides of the front with limited impact by river runoff. Observational and modeling studies have been conducted to investigate the impact of a reversed TSF on the transport of freshwater and sediment in the Yellow River Mouth (YRM). The reversed TSF existence period is only about 40% of a tidal cycle (around slack of flood and ebb); however, when this front disappears (around maximum flood and ebb), sediment transport across the frontal zone is still rare. This suggests that the dynamic mechanism of cross-frontal sediment transport in a tidal cycle remains unclear. In this study, synchronous observations of sea current and suspended sediment concentrations along the river mouth profiles at the YRM in 1995, 2003, and 2019 were used to investigate the long-term variation characteristics, mechanisms, and impacts of the TSF on cross-frontal sediment transport. The results indicate that in addition to the reversed TSF, there are also homogenous TSF during flood and ebb tides, with the ebb homogenous TSF being more significant due to tidal asymmetry in the YRM. The ebb homogenous TSF is located between shallow shoals and the slopes of the subaqueous delta front and lasts for about 3 h around the maximum ebb. Its maximum shear strength is similar to that of the reversed TSF, and the formation mechanism is also similar. The presence of the ebb homogenous TSF reduces the efficiency of cross-frontal sediment transport during the ebb. The reversed and homogenous TSFs alternately block sediment moving towards the sea. Thus, terrigenous sediment is difficult to cross the frontal zone to the central Bohai Sea by tidal currents solely. Over the past two decades of low discharge, with the Yellow River implementing artificial water and sediment regulation, the homogenous TSF during the ebb tide has become more and more important and cannot be neglected for cross-frontal sediment transport under normal conditions. Furthermore, from a long-term perspective, the shear strength of the TSF is positively correlated with the distance of river mouth siltation into the sea. Additionally, salinity and turbidity gradients are also positively correlated with the shear strength in the estuary. This indicates that the blocking of cross-frontal sediment transport by the TSF is a key process in river-sea interaction in the YRM. • The tidal shear fronts (TSFs) evolution and their impact on cross-frontal sediment transport are revisited. • The homogenous TSFs are found as one of the key sedimentary dynamic factors too. • Fluvial sediment seaward transport is hindered not only by reverse TSFs, but also ebb homogeneous TSFs. • Interaction between topography, TSFs, and sediment transport is a key process in long-term river-estuary-sea interaction. [ABSTRACT FROM AUTHOR]

When investigating the long-term variation of wave characteristics as associated with storm surges in the Bohai Sea, the Simulating Waves Nearshore (SWAN) model and ADvanced CIRCulation (ADCIRC) model were coupled to simulate 32 storm surges between 1985 and 2014. This simulation was validated by reproducing three actual wave processes, showing that the simulated significant wave height (SWH) and mean wave period agreed well with the actual measurements. In addition, the long-term variations in SWH, patterns in SWH extremes along the Bohai Sea coast, the 100-year return period SWH extreme distribution, and waves conditional probability distribution were calculated and analyzed. We find that the trend of SWH extremes in most of the coastal stations was negative, among which the largest trend was −0.03 m/a in the western part of Liaodong Bay. From the 100-year return period of the SWH distribution calculated in the Gumbel method, we find that the SWH extremes associated with storm surges decreased gradually from the center of the Bohai Sea to the coast. In addition, the joint probability of wave and surge for the entire Bohai Sea in 100-year return period was determined by the Gumbel logistic method. We therefore, assuming a minimum surge of one meter across the entire Bohai Sea, obtained the spatial SWH distribution. The conclusions of this study are significant for offshore and coastal engineering design. [ABSTRACT FROM AUTHOR]

Plenty of dust aerosols are emitted into the atmosphere in East Asian regions and significantly impact the regional environment and climate. In the past decade, the frequency of dust storm outbreaks has largely declined in the sources of Asian dust. However, it is still rarely reported how the dust properties after long-range transport in the downstream regions respond to this downtrend. Here we report on the long-term characteristics of dust aerosols over central China with the observations of a polarization lidar at Wuhan (30.5°N, 114.4°E) during 2010–2020. The dust optical depths (DOD) exhibit a decrease trend with a rate of −0.011 yr−1, accounting for 22% of the decrease rate for total aerosol optical depths (AOD) in Wuhan. The mass concentration and columnar mass density of dust also decline with a rate of −2.03 μg·m−3·yr−1 and -1.97 mg·m−2·yr−1, respectively. Spring and winter are the most active seasons for dust intrusion, with seasonal mean DOD of 0.21 and 0.15, respectively. Compared with spring, dust aerosols in winter generally concentrate at lower levels below 1.0 km with a slightly smaller particle depolarization ratio of 0.11 (0.14 in spring), attributing to the weakened nonspherical shape of dust particles under wintertime high-level moisture/polluted conditions. Both the surface PM 10 concentration and lidar-derived dust mass concentration at 0.3 km present a downtrend with a rate of −8.0 μg·m−3·yr−1 and -20.1 μg·m−3·yr−1, respectively. This study provides a comprehensive long-term and seasonal analysis of dust properties in central China, which can supplement our understanding of the feedback in the downstream regions to the reduction of dust emissions in the deserts of East Asia. • Dust aerosols are observed in central China during 2010–2020 with ground-based polarization lidar. • Dust optical depths (DOD) exhibit a decrease of −0.011 yr−1, accounting for 22% decrease rate for total AOD. • Dust frequently intrudes into Wuhan in spring and winter, with DOD of 0.21 and 0.15. • Dust in winter concentrates at lower levels (<1.0 km) with a smaller PDR (0.11) than in spring (0.14). [ABSTRACT FROM AUTHOR]

Abstract Concentrations of atmospheric pollutants over East China have varied considerably during the past decades. These variations are partly due to variations of human activities, e.g., increasing energy consumption and implementation of government emission control policies, and partly to natural fluctuations. This study aims to separate the effects of natural processes and anthropogenic activities on the increase/decrease of the concentrations of some of the most important pollutants (SO 2 , NO 2 , CO and aerosols) over East China in the last decade. This was achieved by the comparison of the temporal variations in long-term time series of satellite-retrieved aerosol optical depth (AOD) and vertical column densities (VCDs) of SO 2 , NO 2 , and CO, with those in model-simulated time series of the natural variations only. The latter were created by the use of the same anthropogenic emissions throughout the whole simulation, while using re-analysis data (MERRA) to describe meteorological processes and natural emissions. Thus, the comparison between observed and simulated temporal variations reveals the effects due to anthropogenic emissions only, assuming that the atmospheric processes affect natural and anthropogenic species in the same way. In the analysis, a Kolmogorov–Zurbenko (KZ) filter is used to extract long-term components from both the observed and simulated data and normalization to the situation at a certain reference point is used to eliminate bias between observations and simulations. By this new method, natural and anthropogenic contributions to long-term variations of trace gases and AOD are quantitatively estimated. The results show that NO 2 VCDs increased from 2004 to 2011 by 76% and of the overall increase in this period only 1% ± 1% was attributed to natural factors, 99% ± 1% attributed to anthropogenic factors. AOD increased by 24% between 2001 and 2011 and of the overall increase 24% ± 32% was due to natural factors and 76% ± 32% was due to anthropogenic factors. SO 2 VCDs decreased by 15% from 2007 to 2013, natural and anthropogenic factors contributed respectively 16% ± 14% and 84% ± 14% to the overall decrease in this period. CO decreased since 2003 with 13% and of the overall decrease 6% ± 6% was due to natural factors and 94% ± 6% was due to anthropogenic factors. Highlights • A new method to separate natural and anthropogenic contributions to long-term variations of SO 2 , NO 2 , CO, and AOD. • Quantified natural and anthropogenic contributions. • Variations of trace gases and AOD are mostly attributed to anthropogenic activities. [ABSTRACT FROM AUTHOR]

This study examines the temporal variations and spatial distributions of annual precipitation over Central Asia during the periods of 1901-2013, 1951-2013, and 1979-2013 using the latest version of Global Precipitation Climatology Centre (GPCC) full data reanalysis version 7 (GPCC V7) data set. The linear trend and multiperiods of the precipitation over the entire region and plain and mountainous area separately are analysed by linear least square method and ensemble empirical mode decomposition method. An overall increasing trend [0.66mm(10 years)-1] is found for the entire region during 1901-2013, which is smaller than that of 1951-2013. The regional annual precipitation exhibits multi-decadal variations, with a sharp decline during 1901-1944, followed by an increase until 1980s, and a fluctuation thereafter. During 1979-2013, the mountainous area shows a greater increasing trend than the entire region. Furthermore, the regional annual precipitation has exhibited high-frequency variations with 3-year and 6-year quasiperiods and a low-frequency variation with 28-year quasiperiods. In terms of the spatial distribution, increasing trend in the annual precipitation is found in Xinjiang and decreasing trends appear over the five countries of Central Asia during 1951-2013. Empirical orthogonal function results show that the mountainous area is the large variability centre of the annual precipitation. The dominant mode of interannual variability in Central Asia annual precipitation is related to El Niño-Southern Oscillation, which explains about 17% of the interannual variance during 1951-2013. The results of this study describe the long-term variation in the annual precipitation over Central Asia as well as its relationship with some key climate indices in great detail, which will benefit the understanding and the prediction of the climate variations in this region. [ABSTRACT FROM AUTHOR]

ABSTRACT This study examines the temporal variations and spatial distributions of annual precipitation over Central Asia during the periods of 1901-2013, 1951-2013, and 1979-2013 using the latest version of Global Precipitation Climatology Centre (GPCC) full data reanalysis version 7 ( GPCC V7) data set. The linear trend and multiperiods of the precipitation over the entire region and plain and mountainous area separately are analysed by linear least square method and ensemble empirical mode decomposition method. An overall increasing trend [0.66 mm (10 years)−1] is found for the entire region during 1901-2013, which is smaller than that of 1951-2013. The regional annual precipitation exhibits multi-decadal variations, with a sharp decline during 1901-1944, followed by an increase until 1980s, and a fluctuation thereafter. During 1979-2013, the mountainous area shows a greater increasing trend than the entire region. Furthermore, the regional annual precipitation has exhibited high-frequency variations with 3-year and 6-year quasiperiods and a low-frequency variation with 28-year quasiperiods. In terms of the spatial distribution, increasing trend in the annual precipitation is found in Xinjiang and decreasing trends appear over the five countries of Central Asia during 1951-2013. Empirical orthogonal function results show that the mountainous area is the large variability centre of the annual precipitation. The dominant mode of interannual variability in Central Asia annual precipitation is related to El Niño-Southern Oscillation, which explains about 17% of the interannual variance during 1951-2013. The results of this study describe the long-term variation in the annual precipitation over Central Asia as well as its relationship with some key climate indices in great detail, which will benefit the understanding and the prediction of the climate variations in this region. [ABSTRACT FROM AUTHOR]

We use five test data series to search for, and quantify, putative discontinuities around 1946 in five different annual-mean sunspot-number or sunspot-group-number data sequences. The data series tested are the original and new versions of the Wolf/Zürich/International sunspot number composite [ $R_{\text{ISNv1}}$ and $R_{\text{ISNv2}}$ ] (respectively Clette et al. in Adv. Space Res. 40, 919, 2007 and Clette et al. in The Solar Activity Cycle 35, Springer, New York, 2015); the corrected version of $R$ proposed by Lockwood, Owens, and Barnard ( J. Geophys. Res. 119, 5193, 2014a) [ $R _{\mathrm{C}}$ ]; the new 'backbone' group-number composite proposed by Svalgaard and Schatten ( Solar Phys. 291, 2016) [ $R_{\text{BB}}$ ]; and the new group-number composite derived by Usoskin et al. ( Solar Phys. 291, 2016) [ $R_{\text{UEA}}$ ]. The test data series used are the group-number [ $N_{\mathrm{G}}$ ] and total sunspot area [ $A _{\mathrm{G}}$ ] from the Royal Observatory, Greenwich/Royal Greenwich Observatory (RGO) photoheliographic data; the Ca K index from the recent re-analysis of Mount Wilson Observatory (MWO) spectroheliograms in the Calcium ii K ion line; the sunspot-group-number from the MWO sunspot drawings [ $N_{\text{MWO}}$ ]; and the dayside ionospheric F2-region critical frequencies measured by the Slough ionosonde [foF2]. These test data all vary in close association with sunspot numbers, in some cases non-linearly. The tests are carried out using both the before-and-after fit-residual comparison method and the correlation method of Lockwood, Owens, and Barnard, applied to annual mean data for intervals iterated to minimise errors and to eliminate uncertainties associated with the precise date of the putative discontinuity. It is not assumed that the correction required is by a constant factor, nor even linear in sunspot number. It is shown that a non-linear correction is required by $R_{\mathrm{C}}$ , $R_{\mathrm{BB}}$ , and $R_{\text{ISNv1}}$ , but not by $R_{\text{ISNv2}}$ or $R_{\text{UEA}}$ . The five test datasets give very similar results in all cases. By multiplying the probability distribution functions together, we obtain the optimum correction for each sunspot dataset that must be applied to pre-discontinuity data to make them consistent with the post-discontinuity data. It is shown that, on average, values for 1932 - 1943 are too low (relative to later values) by about 12.3 % for $R_{\text{ISNv1}}$ but are too high for $R_{\text{ISNv2}}$ and $R_{\mathrm{BB}}$ by 3.8 % and 5.2 %, respectively. The correction that was applied to generate $R_{\mathrm{C}}$ from $R$ reduces this average factor to 0.5 % but does not remove the non-linear variation with the test data, and other errors remain uncorrected. A valuable test of the procedures used is provided by $R_{\text{UEA}}$ , which is identical to the RGO $N_{\mathrm{G}}$ values over the interval employed. [ABSTRACT FROM AUTHOR]

We reviewed the long-term trends and inter-annual variations in the surface shortwave irradiance in China and Japan. Pyranometer observations revealed decreases followed by increases in the shortwave irradiance in China and Japan between the 1960s and 2000s, while obvious long-term trends were not evident in the satellite observations after 1983. In China, surface shortwave irradiance decreased from 1961 until around 1990, but then began to increase. In Japan, on the contrary, the decreasing trend stopped in the 1960s, with little inter-annual variation during the 1970s and 1980s, and an increase began around 1990. The causes of the differences between the shortwave irradiance trends in China and Japan were ascribed to an increase in light-absorbing aerosols in China that began in the 1960s and a decrease in absorbing aerosols in Japan that began in the late 1970s. Absorbing aerosols decrease both direct and diffuse radiation, while non-absorbing aerosols decrease direct radiation but increase diffuse radiation. Although these aerosol influences are generally found under clear sky conditions, absorbing aerosols could have direct effects even under cloudy sky conditions. The trends of surface shortwave irradiance in China and Japan are in line with the so-called global dimming and brightening dimming processes, although the phases of the minimum periods in the two regions slightly differed. An increase in anthropogenic aerosol was responsible for the variation in the shortwave irradiance through the direct radiative effect of aerosol in the polluted area, while indirect radiative effects, i.e., changes in cloud cover due to an increase in cloud condensation nuclei, dominated in pristine areas. The effects of other factors, such as variations in water vapor and natural aerosol levels, appear to be small compared to the effects of cloud and anthropogenic aerosols. [ABSTRACT FROM AUTHOR]

Coastal environment has been disturbed by human activities for a long time, especially in the rapidly urbanizing and industrializing areas. Although the surrounding area has achieved great economic success in the past 30 years, Western Xiamen Bay (China) is seriously affected by pollutants and is facing increasing ecological pressure. Because of this, Xiamen was selected in 1994 as a demonstration site for implementing an integrated coastal management program, which included a series of measures for protecting the coastal environment. However, coastal environment is dynamic, complex and site-specific, and thus a scientific quantitative evaluation framework is necessary for environment quality analysis and effective coastal management. In this study, we used oceanographic knowledge together with quantitative methods (Bai-Perron's structural break test) to analyze the long-term variations of water quality indices (pH, DO, COD, DIN, PO 4 -P and Oil) in Western Xiamen Bay. In addition, we compared with other coastal areas to identify the effectiveness of phosphorus-based nutrient management measures and predicted the probable variation trend in the future. The results show that in Western Xiamen Bay: (1) the concentrations of DO and Oil in seawater are effectively controlled by local coastal management measures; (2) seawater acidification will continue to worsen based on the present situation; and (3) the P-limitation treatment strategies are effective and PO 4 -P concentration starts to fall according to the multiple statistical analysis and Environmental Kuznets Curve. This paper hopes to provide an epitome of the conflicts and consolations between socioeconomic development and environmental quality in the past, and hints for coastal management in the future. [ABSTRACT FROM AUTHOR]

Rainwater samples were collected monthly from Fukushima, Japan, in 2012–2014 and analysed for 127 I and 129 I. These are combined with previously reported data to investigate atmospheric levels and behaviour of Fukushima-derived 129 I before and after the 2011 nuclear accident. In the new datasets, 127 I and 129 I concentrations between October 2012 and October 2014 varied from 0.5 to 10 μg/L and from 1.2 × 10 8 to 6.9 × 10 9 atoms/L respectively, resulting in 129 I/ 127 I atomic ratio ranges from 3 × 10 −8 to 2 × 10 −7 . The 127 I concentrations were in good agreement with those in the previous period from March 2011 to September 2012, whereas the 129 I concentrations and 129 I/ 127 I ratios followed declining trends since the accident. Although 129 I concentrations in five samples during the period of 2013–2014 have approached the pre-accident levels, 129 I concentrations in most samples remained higher values in winter and spring-summer. The high 129 I levels in winter and spring-summer are most likely attributed to local resuspension of the Fukushima-derived radionuclide-bearing fine soil particles deposited on land surfaces, and re-emission through vegetation taking up 129 I from contaminated soil and water, respectively. Long-term declining rate suggests that contribution of the Fukushima-derived 129 I to the atmosphere would become less since 2014. [ABSTRACT FROM AUTHOR]

Continuous measurements of ozone (O 3) and nitrogen oxides (NO x = NO + NO 2) were conducted from 2007 to 2019 in Hong Kong in order to evaluate the effectiveness of control strategies for NO x emission from diesel commercial vehicles (DCV). DCV control programs were periodically applied in three phases starting from 2007, 2010 and 2014. It was found that NO and NO 2 levels decreased during the study period but more dramatically after the implementation of DCV Phase III than pre-DCV Phase III. Source apportionment analysis confirmed that the ambient NO and NO 2 in Hong Kong attributed to the regulated DCV emissions in Phase III reduced at rates of 5.1–14.4 ppbv/yr in roadside environment and 1.6–3.1 ppbv/yr in suburban area. Despite overall NO x reduction, increased NO 2 /NO x ratios were recorded during the study period possibly due to the application of diesel particulate filter (DPF) in DCVs. However, after introducing DCV Phase III, observed O 3 values experienced more dramatic increasing trends in most areas of Hong Kong than pre-DCV Phase III. Model simulations revealed that O 3 production rate kept increasing and turned to be less sensitive to NO x from 2014 to 2019. On the roadside, net O 3 production rate was more than doubled during 2014–2019 owing to NO x reduction. Moreover, the levels of oxidants (OH, HO 2 and RO 2) were 1.5–5 times those before 2014. In suburban environment, NO x reduction also facilitated O 3 production and radical cycling, but made smaller contributions than those on the roadside during 2014–2019. This study unraveled that NO x reductions benefited from DCV regulations caused increase in surface O 3 and fueled O 3 photochemistry in various environments. More stringent control measures on emissions of VOCs, especially those with high OH reactivity, might help to better mitigate O 3 pollution. [Display omitted] • DCV control programs, especially Phase III led to NO x decrease in urban Hong Kong. • O 3 production rate increased and became less sensitive to NO x after DCV Phase III. • Roadside O 3 production rate was more than doubled owing to NO x reduction. • More stringent control measures on VOC emissions are suggested for O 3 mitigation. [ABSTRACT FROM AUTHOR]

ADCP current data and sea level data from tide gauges and satellite altimetry were used in order to analyze long-term variation of the Tsushima Warm Current (TWC) volume transport passing through the Korea/Tsushima Strait. The annual mean transport of the TWC estimated from ADCP current measurement for about 17 years (1997–2013) is 2.64 ± 0.41 Sv (Sv = 106 m3s−1) in the Korea/Tsushima Strait, 1.53 ± 0.36 Sv (about 58% of the total transport) in the western channel, and 1.11 ± 0.14 Sv (about 42%) in the eastern channel. The TWC shows the minimum transport (1.74 Sv) in January and the maximum transport (3.10 Sv) in October, with seasonal variation of up to 1.36 Sv (51.5% of the annual mean transport). The seasonal variation of the total TWC transport in the Korea/Tsushima Strait is mainly similar to that in the western channel. The annual mean transport of the TWC and its seasonal variation in the Korea/Tsushima Strait, the western and eastern channels are all similar in three datasets (ADCP, tide gauge, satellite altimetry). The annual mean volume transport of the TWC estimated from long-term tide gauge data was 2.57 ± 0.37 Sv (total volume transport) for 44 years (1975–2018) in the Korea/Tsushima Strait, 1.51 ± 0.32 Sv in the western channel and 1.06 ± 0.14 Sv in the eastern channel. Long-term variation of the TWC transport shows a decreasing trend for 1975 to 1988, and an increasing trend from 1989 to 2018. For the latter period (1989 to 2018), monthly transport tends to increase in all months throughout the years, showing a greater increase, especially in spring and summer months. The increase of the transport in the eastern channel was about 2.8 times larger than that in the western channel. It is suggested that the increasing trend of the TWC transport since 1989 is related to the Pacific Decadal Oscillation (PDO), which has been changed to negative direction since mid-1980s. During the period when the negative PDO index is strong, the negative wind stress curl weakens in the mid-latitudes of the North Pacific, and the Kuroshio in the East China Sea also weakens. As a result, the flow is strengthened toward the Korea/Tsushima Strait, increasing the TWC transport. • Long-term variation of the TWC transport in the Korea/Tsushima Strait was studied. • The annual mean of the TWC transport was 2.57 ± 0.37 Sv for 44 years (1975–2018). • The TWC transport shows a decreasing trend for 1975–1988 and an increasing trend thereafter. • Its increase since 1989 is closely related to the PDO and weakening of the Kuroshio. [ABSTRACT FROM AUTHOR]

Numerical simulations on oceanic 134Cs and 137Cs dispersions were intensively conducted in order to assess an effect of the radioactive cesium on the North Pacific environment with a focus on the long-term variation of the radioactive cesium concentration after the Fukushima disaster that occurred in March 2011. The amounts of 134Cs and 137Cs released into the ocean were estimated using oceanic monitoring data, whereas the atmospheric deposition was calculated through atmospheric dispersion simulations. The highly accurate ocean current reanalyzed through a three-dimensional variational data assimilation enabled us to clarify the time series of the 134Cs and 137Cs concentrations in the North Pacific. It was suggested that the main radioactive cesium cloud due to the direct oceanic release reached the central part of the North Pacific, crossing 170°W one year after the Fukushima disaster. The radioactive cesium was efficiently diluted by meso-scale eddies in the Kuroshio Extension region and its concentration in the surface, intermediate, and deep layers had already been reduced to the pre-Fukushima background value in the wide area within the North Pacific 2.5 years after the Fukushima disaster. [ABSTRACT FROM AUTHOR]

While there is growing interest in clinical applications of handwriting grip kinetics, the consistency of these forces over time is not well-understood at present. In this study, we investigated the short- and long-term intra-participant consistency and inter-participant differences in grip kinetics associated with adult signature writing. Grip data were collected from 20 adult participants using a digitizing tablet and an instrumented pen. The first phase of data collection occurred over 10 separate days within a three week period. To ascertain long-term consistency, a second phase of data collection followed, one day per month over several months. In both phases, data were collected three times a day. After pre-processing and feature extraction, nonparametric statistical tests were used to compare the within-participant grip force variation between the two phases. Participant classification based on grip force features was used to determine the relative magnitude of inter-participant versus intra-participant differences. The misclassification rate for the longitudinal data were used as an indication of long term kinetic consistency. Intraparticipant analysis revealed significant changes in grip kinetic features between the two phases for many participants. However, the misclassification rate, on average, remained stable, despite different demarcations of training, and testing data. This finding suggests that while signature writing grip forces may evolve over time, inter-participant kinetic differences consistently exceeds within-participant force changes in the long-term. These results bear implications on the collection, modeling and interpretation of grip kinetics in clinical applications. [ABSTRACT FROM AUTHOR]

The effects of meteorological conditions controlled by specific synoptic patterns on regional surface ozone episodes have been widely discussed. However, the impacts of synoptic climate systems and their interaction on long-term variation of ozone are less known. In this study, we use the daily meteorological data and hourly surface ozone concentrations in the summer of 1950–2014 from CMIP6 to investigate the relationship between ozone variations and synoptic climate types (SCTs). Eight SCTs are identified by an objective circulation classification method of an R package called synoptReg. Our results show that the mainland of China is controlled by the low-pressure system for SCT1–5, while dominated by Siberian high for SCT6–8. During SCT1–5 days, the interactions of Asian continental low, Western Pacific Subtropical High (WPSH), warm ridge at 700 hPa, high-level shallow Asian trough, westerly belt, and topography lead to high surface temperature, low relative humidity, and poor diffusion over Northern China with frequent ozone exceedance days. However, the low-level ozone concentrations over Northern China are shown under SCT6–8, affected by the weakened Asian continental low, enhanced Siberian high, stronger WPSH, and denser westerly belt. While over Southern China, ozone concentrations are higher for SCT6–8 than SCT1–5, due to the significantly reduced cloud and precipitation affected by the delivery of cold dry air mass from high latitudes to the South. The interdecadal variabilities of ozone during all SCTs may be controlled by the large-scale climate system of the East Asian monsoon. • Relationships of synoptic climate types and spatiotemporal variations of historical ozone are investigated. • The impacts of synoptic climate system interaction on meteorological conditions and ozone are analyzed. • The interdecadal ozone variation is controlled by the East Asian monsoon. [ABSTRACT FROM AUTHOR]

We present observations of CH4 concentrations from the lower to upper troposphere (LT and UT) over Japan during 1988-2010 based on aircraft measurements from the Tohoku University (TU). The analysis is aided by simulation results using an atmospheric chemistry transport model (i.e. ACTM). Tropospheric CH4 over Japan shows interannual and seasonal variations that are dependent on altitudes, primarily reflecting differences in air mass origins at different altitudes. The long-term trend and interannual variation of CH4 in the LT are consistent with previous reports of measurements at surface baseline stations in the northern hemisphere. However, those in the UT show slightly different features from those in the LT. In the UT, CH4 concentrations show a seasonal maximum in August due to efficient transport of air masses influenced by continental CH4 sources, while LT CH4 reaches its seasonal minimum during summer due to enhanced chemical loss. Vertical profiles of the CH4 concentrations also vary with season, reflecting the seasonal cycles at the respective altitudes. In summer, transport of CH4-rich air from Asian regions elevates UT CH4 levels, forming a uniform vertical profile above the mid-troposphere. On the other hand, CH4 decreases nearly monotonically with altitude in winter-spring. The ACTM simulations with different emission scenarios reproduce general features of the tropospheric CH4 variations over Japan. Tagged tracer simulations using the ACTM indicate substantial contributions of CH4 sources in South Asia and East Asia to the summertime high CH4 values observed in the UT. This suggests that our observations over Japan are highly sensitive to CH4 emission signals particularly from Asia. [ABSTRACT FROM AUTHOR]

The paper focuses on the frequency, annual pattern and long-term variability of thermal specific days in Warsaw during the period 1951 - 2010. The following were distinguished : days with frost ( tmax ≥ 0.0 °C, tmin < 0.0 °C ), cold days ( tmax -0.1 - -10.0°C ), very cold days ( tmax - 10.1- - 20.0 °C ), extremely cold days ( tmax < -20.0°C ), hot days ( tmax 25.1-30.0 °C ), very hot days ( tmax 30.1-35.0 °C ) and extremely hot days ( tmax > 35.0 °C ) as well as warm nights ( tmin 15.1 - 18.0 °C ), very warm nights ( tmin 18.1 - 20.0 °C ) and tropical nights ( tmin > 20.0 °C ). The following average numbers of days/nights per year were found during the period 1951 - 2010 : 109 days with tmin < 0.0°C, including 37 days with tmax < 0.0°C, 38 days with tmax > 25°C, and 21 nights with tmin > 15.0 °C. The minimum temperature ranged from -30.7 °C to 21.8 °C and the maximum temperature from -20.4 °C to 36.4 °C. The number of days with tmax ≥ 0.0 °C and tmin < 0.0 °C dropped by 1.8 day/10 years, days with tmax < 0.0 °C also by 1.8 day / 10 years; the number of days with tmax > 25.0 °C rose by 2.2 day / 10 years, while the number of days with tmin > 15.0 °C rose by 2.4 day / 10 years. The results are based the on data collected at the Okęcie airport station, which is located outside the town and therefore they are not representative of the Warsaw urban area, but rather of the eastern part of the Warsaw basin. [ABSTRACT FROM AUTHOR]

Highlights: [•] Investigate effectiveness of pavement preservation on friction. [•] Consider four preservation treatments (thin overlay, chip seal, crack seal, and slurry seal). [•] Investigate variation of friction subject to material, traffic, and environmental factors. [•] Aid state agencies making better pavement maintenance decisions. [ABSTRACT FROM AUTHOR]

Fog is an important indicator of weather. Long-term variations of fog and mist were studied by analyzing the meteorological data from 743 surface weather stations in mainland China during 1951-2005. In climatology, there are more foggy days in the southeast than in the northwest China and more in the winter half of the year than in the summer half. The decadal change of foggy days shows regional variation. Southwest China is the region with the most foggy days, and more than 20 foggy days occur in Sichuan Basin in one year. Persistent heavy fog usually appears in winter and spring over the North China Plain and Northeast China Plain. Misty days are much more frequent in the provinces south of the Yangtze River than in the regions north of it, and there is an obvious increase of misty days after the 1980s. Southwest China is the area with the most number of misty days, and more than 100 misty days occur in Sichuan Basin in a year. [ABSTRACT FROM AUTHOR]

Background and Aims Functional groups of species interact and coevolve in space and time, forming complex networks of interacting species. A long-term study of temporal variation of an ant–plant network is presented with the aims of: (1) depicting its structural changes over a 20-year period; (2) detailing temporal variation in network topology, as revealed by nestedness and modularity analysis and other parameters (i.e. connectance, niche overlap); and (3) identifying long-term turnover in taxonomic structure (i.e. switches in ant resource use or plant visitor assemblages according to taxa). Methods Fieldwork was carried out at La Mancha, Mexico, and ant–plant interactions were observed between 1989 and 1991, between 1998 and 2000, and between May 2010 and 2011. Occurrences of ants on extrafloral nectaries (EFNs) were recorded. The resulting ant–plant networks were constructed from qualitative presence–absence data determined by a species–species matrix defined by the frequency of occurrence of each pairwise ant–plant interaction. Key Results Network variation across time was stable and a persistent nested structure may have contributed to the maintenance of resilient and species-rich communities. Modularity was lower than expected, especially in the most recent networks, indicating that the community exhibited high overlap among interacting species (e.g. few species were hubs in the more recent network, being partly responsible for the nested pattern). Structurally, the connections created among modules by super-generalists gave cohesion to subsets of species that otherwise would remain unconnected. This may have allowed an increasing cascade-effect of evolutionary events among modules. Mutualistic ant–plant interactions were structured 20 years ago mainly by the subdominant nectarivorous ant species Camponotus planatus and Crematogaster brevispinosa, which monopolized the best extrafloral nectar resources and out-competed other species with broader feeding habits. Through time, these ants, which are still present, lost their position as network hubs and diminished in their importance in structuring the network; simultaneously, plants gained in importance. Conclusions The long-term network analysis reveals a decrease in attended plant species richness, a notable increase in plant species participation from 1990 to 2010 (sustained by less plant taxonomic similarity in the older 1990 network), an increase in the number of ant species and a diminishing dominance of super-generalist ants. The structure of the community has remained highly nested and connected with low modularity, suggesting overall a more participative, homogeneous, cohesive interaction network. Although previous studies have suggested that interactions between ants and EFN-bearing plants are susceptible to seasonality, abiotic factors and perturbation, this cohesive structure appears to be the key for biodiversity and community maintenance. [ABSTRACT FROM PUBLISHER]

El Niño and La Niña exhibit significant asymmetry in their duration. El Niño tends to turn rapidly into La Niña after the mature, while La Niña tends to persist for up to 2 years. Reconstructed historical sea surface temperatures (SST) show a significantly increase in the intensity of El Niño-Southern Oscillation (ENSO) asymmetry, particularly El Niño transitivity, during the last six decades. Atmospheric observational data have shown that the relationship between El Niño and surface zonal wind anomalies over the equatorial Western Pacific (WP) has strengthened, and anomalous WP easterlies have appeared after the 1970s climate regime shift. To investigate the dependency of ENSO transitivity on its amplitude, a suite of idealized experiments using an atmospheric general circulation model (AGCM) is performed by imposing 12 different ENSO-related SST anomalies exhibiting equal spatiotemporal distribution but different amplitude. Our AGCM experiments show strong nonlinearity in the WP zonal wind against the amplitude of the warm phase. In the strong (weak) El Niño state, the WP response tends to accelerate (prevent) the transition from El Niño to La Niña; however, this relationship is not applicable to the La Niña phase. The asymmetry in transitivity/persistency is found to differ in terms of their sensitivity to the ENSO amplitude; this difference is also detected in the long-term control simulation of Geophysical Fluid Dynamics Laboratory-Climate Model version 2.1. The long-term variation in El Niño transitivity in this model correlates strongly with the decadal variation in the ENSO amplitude and Indo-Pacific interbasin coupling. However, this result is not apparent in the opposite phase. The results of this study indicate that the decadal change in ENSO amplitude and Indian Ocean feedback could be significantly related to the decadal change in the cyclic nature of ENSO and should be discussed separately for El Niño and La Niña. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Abstract: The average absorbed dose and dose equivalent rates from space radiation were observed using passive dosimeters with same material and configuration at the same location onboard the International Space Station (ISS) over four different occasions (I–IV) between 2007 and 2008. The passive dosimeters consisted of a combination of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs). Total average absorbed dose rate increased by 68 ± 9% over two years. The observed increase was due to the incremental increase in the altitude of the ISS over the course of the experiment and the corresponding increase in trapped proton flux encountered during passage of the ISS through the SAA (South Atlantic Anomaly), which was confirmed with the results monitored by DB-8 active dosimeter on the ISS. The PNTD data showed that the average absorbed dose and dose equivalent rates from particles of LET∞H2O ≥ 100 keV/μm were 28 ± 2% and 51 ± 3% of ≥10 keV/μm during Periods I–III, while the dose contributions of particles ≥100 keV/μm during Period IV were 36 ± 5% and 59 ± 10%, respectively. The integral dose equivalent distribution during Period IV shows significant enhancement from particles ≥100 keV/μm. These facts suggest that a significant fraction of the high LET component is due to short-range recoil nuclei produced in target fragmentation reactions between primary protons and the nuclei of the passive dosimeters and surrounding materials. [Copyright &y& Elsevier]

Abstract: Spatial and interannual variations of phytoplankton diversity were characterized along the French Atlantic Coast in relation to physical factors and large-scale climatic indices using phytoplankton surveys conducted from 1993 to 2010 in four geographical areas. This study relates phytoplankton diversity to oyster recruitment success by comparing a ‘specific’versus a ‘functional’ diversity approach. Functional diversity was represented by functional groups of different phytoplanktonic functional traits (size, shape, toxicity), relevant for oyster feeding during growth, reproduction and larval development. Phytoplankton diversity patterns along the French Atlantic coast corresponded to a geographical distribution mainly driven by a latitudinal gradient and hydrodynamic features as confirmed by the functional characteristics of the indicator species recorded for each geographical area (C-S-R strategies of Reynolds, specific habitat). This geographical typology was less clear for functional diversity. Only few functional groups were explained by physical factors: the non-toxic small and solitary cells were in particular related to temperature, with high densities observed in the southern areas. Even if temporal variation was less important in explaining the phytoplankton diversity patterns, the main drivers explaining the interannual pattern were the large-scale climatic indices, mainly the Atlantic Multidecennal Oscillation. Functional groups were readily explained by climatic indices than species even if the relationships cannot be applied generally because of the non-linearity of the correlations (local and temporal variations). However, the potentially toxic, small and linear phytoplankton were anticorrelated to NAO. The functional approach thus brings constructive elements concerning the relationships between the prey assemblage of oysters and their physical drivers. Redundancy and co-inertia analyses appeared as complementary analyses in investigating phytoplankton pattern of variation, being particularly useful in analyzing geographical and temporal diversity fluctuation, respectively. [Copyright &y& Elsevier]

Abstract: Strong positive correlation between sporadic E layers and the solar activity and the long-term declining trend of Es were found in this paper. Then the feed-forward back propagation neural networks (NNs) were used to simulate the long-term variation of Es at four stations and predict foEs yearly average values. The inputs used for NNs are the yearly mean values of foEs in the daytime of the past ten years and the yearly averaged data of solar 10.7cm radio flux (F107) of the present year, and the output is the present yearly mean value of daytime foEs. The outputs of trained NNs have high correlation with the desired values and the foEs yearly mean values predicted by NNs have good agreement with the observed data. The results indicate that NNs can make full use of the observed data to simulate the long variation rule of Es. Also, the results confirm the effect of solar activity on Es. [Copyright &y& Elsevier]

Abstract: In order to investigate the continuous volcanic tremor of Aso Volcano in Japan, we performed a series of temporary short-period seismic array observations near the Nakadake first crater (the active crater) during five years from 1999 to 2003. We deployed in all of the temporary observations a seismic array at the same location about 700 m west of the active crater, in order to investigate long-term changes in the tremor activity. In 1999 and 2003, another array was simultaneously deployed at a different location 700 m north of the crater to help locate the tremor sources. We developed a frequency domain semblance method and applied it to the waveform data of the frequency range where the continuous tremor is dominant (3–6 Hz). We measured arrival azimuths and slownesses of the continuous tremor signals as functions of frequency, which are then used to locate the epicenters of the tremor signals corresponding to the principal peaks of the power spectra. For the observations in 1999 and 2002, the continuous tremor amplitudes are relatively small, and the slowness of the tremor signal observed at the west array takes a local minimum (0.5 to 0.6 s/km) near the frequency (∼4.7 Hz for 1999 and ∼4.8 Hz for 2002) which corresponds to the highest spectral peak. This implies that body waves dominate the tremor signals at the west array around the frequency. The tremor epicenters corresponding to 4.7 Hz for the observation in 1999 are located at the west rim of the currently active crater. While the surface crater activity of Aso remains low and the tremor activity is not clearly linked with the surface activity until early 2003, a close link between the tremor and crater activity appears in the middle of 2003, when a small phreatic eruption occurred a month before the array observation (July 10, 2003). Tremor signals of the observation in 2003 show a large spectral peak (4.2 Hz) where the slowness measured for the west array is very large (1.1 s/km), clearly suggesting that surface waves are dominant. The epicenter is again located at the western rim of the active crater. We interpret these observations as follows: in 1999 and 2002 when the surface activities of Aso were low, the continuous tremor excitation was deep and inactive. In the middle of 2003 when Aso Volcano became active with a series of phreatic eruptions a shallower tremor source was activated, possibly masking the deeper sources. This shallowing of the dominant tremor source could be due to the increase in the volcanic gas flow rate triggered by the phreatic eruptions. [Copyright &y& Elsevier]

Nitrous oxide (N2O) is a potent and long-lived greenhouse gas that contributes to global warming with a global warming potential (GWP) 298 times that of carbon dioxide (CO2). In this paper, we analyzed the trend of N2O concentration in vertical layers of the stratosphere from 2005 to 2020 using the N2O observed from the Microwave Limb Sounder (MLS) that is on board the Aura satellite. We found that the local N2O concentration showed a downward trend in the lower stratosphere but rose or fluctuated in the upper stratosphere. The reduction reached −5 ppb/yr at pressure levels of 31.62 hPa and 68.13 hPa, with a confidence level of over 90%. The growth was around 1–2 ppb/yr in the upper stratosphere. In addition, a concentration anomaly was observed in the tropical stratosphere in 2013. After the appearance of this anomaly, the N2O concentration in the middle and lower layers of the tropical stratosphere was lower than before 2013. We speculated that the enhancement of the Brewer–Dobson circulation (BDC) upwelling before and after stratospheric sudden warming (SSW) is the main reason for the abnormal concentration distribution in 2013. Stratospheric N2O has changed significantly in the past 16 years with the mutual coupling effect of BDC and SSW and such changes can have further impact on the chemical equilibrium and radiation balance in the stratosphere, as well as on the persistent climate-warming trend. [ABSTRACT FROM AUTHOR]

We studied the relationship between the food habits of Japanese macaques (Macaca fuscata) and the availability of nuts (Fagus crenata, Zelkova serrata, Carpinus spp., and Torreya nucifera) on Kinkazan Island, northern Japan, from 1997 to 2005 to examine the long-term variations in both food habits and availability. The food habits of the monkeys showed clear seasonal changes: the staple foods were woody leaves and flowers in spring (May and June), woody leaves and seeds or fruits other than nuts in summer (July and August), nuts and seeds or fruits other than nuts in fall (September–November), and herbaceous plants in winter (December–April). The availability of nuts, combinations of masting species, and energy production varied among years. Food habits varied among years, but the magnitude of variability of food habits differed among seasons, with large variability during summer and winter, and small variability in spring. Food availability was poor in summer and winter, but in several years the monkeys were able to consume nuts during those seasons. We emphasize the importance of conducting long-term studies on both food availability and the food habits of animals in the temperate zone. Am. J. Primatol. 68:1068–1080, 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The source strength of volatile organic compounds (VOCs) emitted by vegetation is of great interest for the understanding of processes in atmospheric chemistry and climate change. In this study terpene emissions from branches of European beech ( Fagus sylvatica L.) were studied in a deciduous forest. Using the branch enclosure technique changes in the emission pattern and the variation of emission rates over the year were investigated over two consecutive vegetation periods. More than 10 monoterpene compounds were found in the emissions, among which sabinene dominates. For most compounds the emission pattern changed only slightly over the year. Interestingly, two compounds tentatively identified as para-cymene and cis-ocimene showed differences in the emission behaviour in late summer compared to the other terpenes. In contrast to previous studies our investigation characterise European beech as a strong emitter. For the main compounds the emission rates changed up to two orders of magnitude as a function of temperature and light over the day. In general, highest emission rates were observed in summer and lowest in fall. A seasonality was characterized by a temperature independent decline of emissions in late summer, resulting in changes of the standard emission rate on the order of one magnitude. A standard emission factor of up to 3.5 nmol m−2s−1 for the sum of measured terpenes was calculated. No emissions were found in early spring even though leaves were fully developed and temperature and light conditions were moderate. The results underline the importance of characterising the annual variation of the emission behaviour. Especially for the up-scaling to global VOC emissions, seasonal influences have to be considered to achieve realistic emission inventories. [ABSTRACT FROM AUTHOR]

Abstract: Recent research pointed out the question of missing OH reactivity in a forest system and the question for unknown highly reactive biogenic emissions. In this study we show that coniferous forests are an important source of highly reactive hydrocarbons, the sesquiterpenes. We investigated the seasonality of terpene emissions from Scots pine to work out influences on atmospheric chemistry in different seasons for both mono- and sesquiterpenes. Especially sesquiterpenes (C15) change dramatically in their contribution to the terpene emissions of Scots pine. Fourteen sesquiterpenes and oxygenated compounds were found in the emissions. In spring, the pattern was most complex with all 14 compounds being emitted, whereas in summer and fall it was reduced to 1,8-cineol and camphor. The emission pattern of the monoterpenes varied only slightly. The main compounds emitted were α-pinene, β-pinene, and 3-carene representing up to 90% of the total terpene emission. The total monoterpene emission rates varied from below detection limit to 460pmolm−2 s−1 with highest emission rates found in June. Standard emission rates of the main compounds calculated from the monthly measured diurnal emission courses varied considerably over the year. Highest values were found in spring and early summer with up to 700pmolm−2 s−1. [Copyright &y& Elsevier]

Abstract: In this paper, we investigate properties long-term variations in galactic cosmic ray intensity as an important possible link in the connection between solar activity variation and global climate change. There are two main aims of the paper: (1) to estimate how solar activity influences on galactic CR long-term variations, what are the relative role in this influence of convection-diffusion modulation and drift modulation and (2) to estimate the expected part of global climate change which may be caused by the influence of solar activity cycle on climate through 11- and 22-year cosmic ray variations. [Copyright &y& Elsevier]

Abstract: On the basis of results obtained in our paper [Dorman, L.I. Long-term cosmic ray intensity variation and part of global climate change, controlled by solar activity through cosmic rays, Paper D2.1/C2.2/E3.1-0097-04. Adv. Space Res., 2004 (accepted)], we determine: the dimension of the Heliosphere (modulation region), radial diffusion coefficient and other parameters of convection–diffusion; drift mechanisms of long-term variations of cosmic ray (CR) dependence on particle energy; level of solar activity (SA); and generally, the solar magnetic field. We obtain this important information on the basis of CR and SA data in the past, taking into account the theory of convection–diffusion and global drift modulation of galactic CR in the Heliosphere. By using these results and other regularly published predictions of expected SA variation in the near future, as well as predictions of the next SA cycle, we may make predictions of long-term cosmic ray intensity variation expected in the near future (up to 10–12 years). In [Dorman, L.I. Long-term cosmic ray intensity variation and part of global climate change, controlled by solar activity through cosmic rays, Paper D2.1/C2.2/E3.1-0097-04. Adv. Space Res., 2004 (accepted)], properties of connections between long-term variation in CR intensity and some part of a global climate change were estimated, controlled by solar activity through CR. We show that in this way we may make predictions of some part of a global climate change expected in the near future (up to 10–12 years and maybe more, depending upon the period during which definite predictions of SA can be made), controlled by solar activity through CR. In this case, estimations of expected long-term changes in the planetary distribution of cutoff rigidities, which also influence CR intensity, as well as CR-influenced effects on global climate variation, become important. [Copyright &y& Elsevier]

Evidence supports the hypothesis that two climatic regime shifts in the North Pacific and the Japan/East Sea, have affected the dynamics of the marine ecosystem and fisheries resources from 1960 to 2000. Changes in both mixed layer depth (MLD) and primary production were detected in the Japan/East Sea after 1976. The 1976 regime shift appears to have caused the biomass replacement with changes in catch production of major exploited fisheries resources, including Pacific saury, Pacific sardine and filefish. Both fisheries yield and fish distribution are reflected in these decadal fluctuations. In the 1960s and 1990s, common squid dominated the catches whereas in the 1970s and 1980s, it was replaced by walleye pollock. In the post-1988 regime shift, the distribution of horse mackerel shifted westward and southward and its distributional overlap with common mackerel decreased. The habitat of Pacific sardine also shifted away from mackerel habitats during this period. To evaluate changes in the organization and structure of the ecosystem in the Japan/East Sea, a mass-balanced model, Ecopath, was employed. Based on two mass-balanced models, representing before (1970–75) and after (1978–84) the 1976 regime shift, the weighted mean trophic level of catch increased from 3.09 before to 3.28 after. Total biomass of species groups in the Japan/East Sea ecosystem increased by 15% and total catch production increased by 48% due to the 1976 regime shift. The largest changes occurred at mid-trophic levels, occupied by fishes and cephalopods. The dominant predatory species shifted from cephalopods to walleye pollock due to the 1976 regime shift. It is concluded that the climatic regime shifts caused changes in the structure of the ecosystem and the roles of major species, as well as, large variations in biomass and production of fisheries resources. [Copyright &y& Elsevier]

90Sr is useful for tracing water mass movement in oceans. We collected a suit of seawater samples from the East China Sea (ECS) in the May 2011 to investigate the spatial and vertical distribution of 90Sr and to understand its transportation and fate. To understand the sources and transportation of 90Sr more clearly, published 137Cs data from the same cruise were used to obtain the 90Sr/137Cs activity ratios. The results showed that 90Sr activities were controlled by the circulation system of the ECS, with high values in coastal regions and low values in oceanic waters. The plume with a high 90Sr/137Cs ratio showed that in late spring, the Changjiang Diluted Water could flow southeastward and extend to 126–127° E, which is farther than the previously known value of 124° E. The high 90Sr/137Cs ratios (1.35 ± 0.62) and a long effective half-life of 90Sr (20.0 ± 0.3 y) in the ECS surface water revealed that 90Sr is surplus in comparison with 137Cs. However, historical variations in the 90Sr/137Cs ratio seem to preclude the simple explanation that riverine input causes a 90Sr surplus in the ECS. Groundwater discharge with a high 90Sr but very low 137Cs may be a new potential source. However, it is difficult to quantify the contribution of groundwater discharge at present, and more detailed studies are required in this regard. Additionally, we compiled 90Sr and 137Cs water column inventory data in the western North Pacific and found that the cumulative fallout onto the ocean was different from that on land in the 20–40° N band. Unlabelled Image • 90Sr/137Cs ratios show that Changjiang Diluted Water can extend to 126°E in spring. • 90Sr/137Cs ratios in coastal waters are higher than the global fallout ratio. • The effective half-life of 90Sr in the East China Sea is 20.0 ± 0.3 y. • Groundwater input may be a new potential source of 90Sr surplus in coastal waters. • The cumulative fallout of 90Sr and 137Cs onto the ocean differs from that on land. [ABSTRACT FROM AUTHOR]

A long-term dataset, including physicochemical, nutrient, and phytoplankton assemblages from 1994 to 2016, was analyzed to investigate the response of the algal community to variations in environmental factors in Deep Bay and Mirs Bay in southern China. These bays differ in their overall nutrient loadings, as well as in physical factors. The results showed that diatoms were numerically dominant in Mirs Bay, while other minor phytoplankton groups, including eutrophication-tolerant species, constituted the majority in Deep Bay. Phytoplankton community composition tended to be less complex in Deep Bay, suggesting a stressed, unstable and unbalanced ecosystem compared to that in Mirs Bay. Algal blooms occurred more frequently in Mirs Bay, whereas fewer but larger-scale blooms occurred in Deep Bay. Statistically, the combination of all explanatory variables accounted for approximately 55% of the variation in Chlorophyll-a (Chl-a) concentration and less than 20% of the total phytoplankton variation over the 23-year period in the two bays. The high level of nutrients caused by urbanization was not the driving force in the formation of blooms but presumably provided a nutrient base that resulted in blooms with longer durations and covering larger areas. Unlabelled Image • A 23-year phytoplankton dynamics and water quality data set was present. • Deep Bay and Mirs Bay significantly differ in nutrients and physical factors. • Phytoplankton community was less diverse with higher biomass in Deep Bay. • Significant variables were identified to explain part of phytoplankton dynamics. • Organic nutrients may be a potential factor to influence phytoplankton dynamics. [ABSTRACT FROM AUTHOR]

Using high-resolution satellite-derived sea surface temperature (SST) data from September 1981 to December 2015, the present study develops a new index to detect the long-term variation in mesoscale eddy activity over the Kuroshio Extension (KE) region. This eddy activity index (EAI) highlights the strength of eddy-induced poleward heat transport and has obvious advantages over the other existing KE indices in depicting the low-frequency changes in KE eddy activity. An analysis of the EAI shows that over the long term, the KE eddy activity variability presents a significant spectral peak of about 8 years and is not directly modulated by wind-driven oceanic Rossby waves generated in the central North Pacific. When the EAI is positive, the strengthened KE eddy activity significantly enhances the heat release from ocean to atmosphere over the Kuroshio–Oyashio confluence region (KOCR). This induces an anomalous dipole pattern of near-surface baroclinicity over this region that can persist for up to 6 months, favoring a weakened and northward-moving East Asian jet, and vice versa. It is believed that the new EAI will facilitate future studies focusing on the climatic effects of the KE eddy activity variation. [ABSTRACT FROM AUTHOR]

In recent decades, freshwater ecosystems have been threatened worldwide by multiple simultaneous stressors, including eutrophication, climate change and competing demands for water sources. However, understanding of the long-term variation of zooplankton communities remains limited because long-term observations are lacking. Here, using a long-term (19 year) monitoring dataset, we demonstrate the spatio-temporal variation of zooplankton communities in Lake Taihu, a large, shallow, heterogenous lake in China. With the development of eutrophication, the abundance and biomass of zooplankton first increased from 1998 to 2004, and then exhibited a decreasing trend thereafter. Specifically, the population of rotifer dramatically declined after 2001, while the abundance of copepod and cladoceran showed an increasing trend even though their biomass decreased significantly after 2008. The dominance of small cladocerans (Bosmina coregoni and Ceriodaphnia cornuta) and copepod (Limnothora sinensis) significantly increased with decreasing rotifer density after 2014. Moreover, the zooplankton community structure exhibited heterogenous spatial population dynamics. Cladoceran and rotifer were predominant in cyanobacteria-dominated regions, while a higher proportion of copepod were found in macrophyte-dominated regions. Analyses revealed that zooplankton communities were strongly affected by climate warming and nutrients. These results reinforce previous work demonstrating that the development of eutrophication and climate warming could change the structure of zooplankton community and increase the dominance of small-bodied crustacean. Our findings address the recognized gap in understanding the variation of the zooplankton community in Lake Taihu, and provide an opportunity to evaluate ongoing changes in the zooplankton community related to future environmental change scenarios. • Long-term datasets for zooplankton communities in lakes are few, especially in China. • Spatial heterogeneity of zooplankton communities is less investigated in a single lake. • The dominance of smaller crustaceans increased with warming and eutrophication. • Environmental heterogeneity controls the spatial dynamics of zooplankton communities. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) has been experiencing warming and wetting since the 1980s. Under such circumstances, we estimated the summer latent heat flux (LE) using the maximum entropy production model driven by the net radiation, surface temperature, and soil moisture of three reanalysis datasets (ERA5, JRA-55, and MERRA-2) at the Ali site over the western TP during 1980–2018. Compared with the observed LE of the Third Tibetan Plateau Atmospheric Scientific Experiment, the coefficient of determination, root-mean-square error, and mean bias error of the estimated summer LE are 0.57, 9.3 W m−2, and −2.25 W m−2 during 2014–2016, respectively, which are better than those of LE of the reanalysis datasets. The estimated long-term summer LE presents a decreasing (an increasing) trend of −7.4 (1.8) W m−2 decade−1 during 1980–1991 (1992–2018). The LE variation is closely associated with the local soil moisture influenced by precipitation, glacier, and near-surface water conditions at the Ali site. The summer soil moisture also presents a decreasing (an increasing) trend of −0.082 (0.022) decade−1 during 1980–1991 (1992–2018). The normalized difference vegetation index generally shows the consistent trend with LE at the Ali site. [ABSTRACT FROM AUTHOR]

Turbidity, relating to underwater light attenuation, is an important optical parameter for water quality evaluation. Satellite estimation of turbidity in alpine rivers is challenging for common ocean color retrieval models due to the differences in optical properties of the water bodies. In this study, we present a simple two-band semi-analytical turbidity (2BSAT) retrieval model for estimating turbidity in five alpine rivers with varying turbidity from 1.01 to 284 NTU. The model was calibrated and validated, respectively, while using one calibration dataset that was obtained from the Three Parallel Rivers basin and two independent validation datasets that were obtained from the Kaidu River basin and the Yarlung Zangbo River basin. The results show that the model has excellent performance in deriving turbidity in alpine rivers. We verified the consistency of the simulated reflectance and satellite-based reflectance and calibrated the 2BSAT model for the specified bands of high spatial resolution satellites in order to achieve the goal of remote sensing monitoring. It is concluded that the model can be used for the quantitative monitoring of turbidity in alpine rivers using satellite images. Based on the model, we used the Sentinel-2 images from one year to identify the seasonal patterns of turbidity of five alpine rivers and the Landsat series images from 1989 to 2018 to analyze the turbidity variation trends of these rivers. The results indicate that the turbidity of these alpine rivers usually presents the highest level in summer, followed by spring and autumn, and the lowest in winter. Meanwhile, the variation trends of turbidity over the past 30 years present distinctly different characteristics in the five rivers. [ABSTRACT FROM AUTHOR]

• Seasonal variations of the DN, POM and SOM sources were identified. • Low discharge was favorable for vertical mixing and sedimentation. • The δ15N value of the sediment core could record historic flooding event. • 65-years isotope record of C and N reveals the impact of human activities. Knowledge about the origin and transformation of nutrients at different temporal scales in river ecosystems can provide a better understanding of carbon (C) and nitrogen (N) cycles in rivers and bear important implications for regional and global C and N cycling. In this study, stable isotopes of C and N (δ13C and δ15N) and a radioactive isotope of 210Pb were used to investigate the factors affecting seasonal and long-term changes in N source apportionment and C and N biogeochemical processes in the Beijiang River located in the Pearl River basin, China. Source apportionment by a Bayesian model (stable isotopic analysis in R, SIAR) showed significant seasonal variations. During the flood season, the dominant origins were non-point sources, such as soil N for dissolved nitrogen (DN, accounting for 38%), soil organic matter for particulate organic matter (POM, 58%) and sedimentary organic matter (SOM, 31%), due to intense precipitation. During the non-flood season, fertilizer became the dominant nitrate source (48%), and effluent detritus prevailed in the POM (47%) and SOM (32%) pools. N transformation between the DN, POM and SOM was influenced by seasonally variable hydrology. Our data suggested that low discharge was more favorable for the vertical mixing of the water column and sedimentation, which was supported by similar δ15N values in the DN, POM and SOM in the non-flood season. A sedimentary history record of 65 years (1951–2015) showed that the variation of N in the sediment was mainly affected by human activities. From 1999 to 2005, a decreasing trend in the δ15N values was observed due to the promotion of aquatic plant cultivation after reservoir impoundment. From 2005 to 2011, the enrichment in the δ15N values was caused by increases in manure and sewage due to the development of the tourism industry. From 2011 to 2015, the increase in pollution treatment funds from the government improved the water environment, resulting in δ15N depletion in the sediment. At the 65-year temporal scale, increased temperature and CO 2 concentration had less impact on the C and N cycles in river ecosystems, however, high discharge could increase the C and N contents, and flood events might increase the δ15N values in the sediment. This study provided more detailed information regarding the nutrient sources and improved our understanding of the C and N cycling processes at different temporal scales in river ecosystems. [ABSTRACT FROM AUTHOR]