Small Seasonal Variations Research Articles

Uncertainties in Evapotranspiration Estimates over West Africa

An evapotranspiration (ET) ensemble composed of 36 land surface model (LSM) experiments and four diagnostic datasets (GLEAM, ALEXI, MOD16, and FLUXNET) is used to investigate uncertainties in ET estimate over five climate regions in West Africa. Diagnostic ET datasets show lower uncertainty estimates and smaller seasonal variations than the LSM-based ET values, particularly in the humid climate regions. Overall, the impact of the choice of LSMs and meteorological forcing datasets on the modeled ET rates increases from north to south. The LSM formulations and parameters have the largest impact on ET in humid regions, contributing to 90% of the ET uncertainty estimates. Precipitation contributes to the ET uncertainty primarily in arid regions. The LSM-based ET estimates are sensitive to the uncertainty of net radiation in arid region and precipitation in humid region. This study serves as support for better determining water availability for agriculture and livelihoods in Africa with earth observations and land surface models.

Evaluation of Groundwater Simulations in Benin from the ALMIP2 Project

AbstractA comprehensive estimation of water budget components, particularly groundwater storage (GWS) and fluxes, is crucial. In this study, we evaluate the terrestrial water budget of the Donga basin (Benin, West Africa), as simulated by three land surface models (LSMs) used in the African Monsoon Multidisciplinary Analysis Land Surface Model Intercomparison Project, phase 2 (ALMIP2): CLM4, Catchment LSM (CLSM), and Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO). All three models include an unconfined groundwater component and are driven by the same ALMIP2 atmospheric forcing from 2005 to 2008. Results show that all three models simulate substantially shallower water table depth (WTD) with smaller seasonal variations, approximately 1–1.5 m compared to the observed values that range between 4 and 9.6 m, while the seasonal variations of GWS are overestimated by all the models. These seemingly contradictory simulation results can be explained by the overly high specific yield prescribed in all models. All models achieve similar GWS simulations but with different fractions of precipitation partitioning into surface runoff, base flow, and evapotranspiration (ET), suggesting high uncertainty and errors in the terrestrial and groundwater budgets among models. The poor performances of models can be attributed to bias in the hydrological partitioning (base flow vs surface runoff) and sparse subsurface data. This analysis confirms the importance of subsurface hydrological processes in the current generation of LSMs and calls for substantial improvement in both surface water budget (which controls groundwater recharge) and the groundwater system (hydrodynamic parameters, vertical geometry).

Seasonal dynamics of phytoplankton morphological characters and driving factors in tropical reservoirs: A case study from Gaozhou Reservoir

体积、比表面积和最大轴性长度是浮游植物主要的形态性状，反映浮游植物资源竞争和反牧食能力.群落中物种的性状分布会随着环境条件的季节改变而变化，热带水库环境条件的季节性变化小，可能导致群落形态性状变化不显著.本文以热带大型水库——高州水库为研究对象，分析浮游植物形态性状季节动态及关键影响因子.高州水库浮游植物以丝状和单细胞藻类为主，群落水平的平均细胞体积在108.52~753.25 μm³之间，平均比表面积在0.93~2.08 μm^-1之间，平均最大轴性长度在5.21~17.44 μm之间，均有明显的季节特征.浮游植物群落平均细胞体积、最大轴性长度与总氮浓度呈负相关，与水温呈正相关；平均比表面积与硝态氮浓度呈负相关.粘质长孢藻（Dolichospermum mucosa）和光角星鼓藻（Staurastrum muticum）是高州水库浮游植物优势种，其形态性状均具有明显的时空差异，表现出明显的形态可塑性.粘质长孢藻的平均细胞体积、最大轴性长度与总氮浓度呈正相关，与水温呈负相关；平均比表面积与总氮浓度呈负相关，与水温呈正相关.光角星鼓藻的平均细胞体积、最大轴性长度与正磷酸盐浓度呈正相关.总体上高州水库浮游植物在群落和种群水平形态性状均有明显的季节差异，夏季以大细胞为主，其他季节以小细胞种类为主，水温、氮和磷的可利用性是导致浮游植物形态性状季节差异的关键因子.;Volume, specific surface area and the longest axial linear dimension are main morphological characters of phytoplankton. These characters reflect the ability of phytoplankton in competing for resources and resisting grazing. The morphological characters of cells change with the seasonal environmental conditions. It was assumed that limited seasonal changes occurred on phytoplankton cells morphological characters in community, due to the small seasonal variation of environmental conditions in tropical reservoirs. To test this assumption, the seasonal dynamic of phytoplankton morphological characters and the affecting factors in large tropical reservoir (Gaozhou Reservoir)were analyzed. The phytoplankton community was dominated by filamentous species and unicellular algae in Gaozhou Reservoir. In community level, the average cell volume was 108.52-753.25 μm³, the average cell specific surface area was 0.93-2.08 μm^-1, the average cell longest axial linear dimension was 5.21-17.44 μm, and the three morphological characters all showed seasonal dynamics. The average cell volume and the average cell longest axial linear dimension were correlated negatively with total nitrogen, and positively with temperature, the average cell specific surface area was correlated negatively with nitrate nitrogen. Dolichospermum mucosa and Staurastrum muticum were the dominant phytoplankton species in Gaozhou Reservoir, and they both showed morphological plasticity and seasonal dynamics in the morphological characters. The average cell volume and the average cell longest axial linear dimension of D. mucosa were correlated positively with total nitrogen, and negatively with temperature. The average cell specific surface area of D. mucosa was correlated negatively with total nitrogen, and positively with temperature. The average cell volume and the average cell longest axial linear dimension of S. muticum were correlated positively with soluble reactive phosphate. In conclusion, the morphological characters of phytoplankton in community and species were different with seasonal dynamics in Gaozhou Reservoir. The large cells dominated phytoplankton community in summer, but small cells in other season. Temperature, the availability of nitrogen and phosphorus were the primary factors to explain the morphological variation of phytoplankton.

On wind speed pattern and energy potential in China

To achieve sustainable socioeconomic development as part of the global community, China has set ambitious goals for developing wind power within its national energy security framework. Existing wind power density maps in China present some knowledge gaps (e.g., lack of spatiotemporal resolution/characteristics and estimates at the height of a typical wind turbine). To address them, we combine the advantages of large network of wind speed observations (2430 meteorological stations; 2006–2015) and the grid-based method in order to create the spatiotemporal distributions of wind resource at the hub height. We found that the spatiotemporal variability of wind resources in China is apparent. Nationally, the annual mean wind speed and wind power density are 4.09 m s−1 and 164.1 W m−2, respectively. Spatially, Northeast China has the highest wind potential with annual mean wind speed and power density 4.64 m s−1 and 204 W m−2, while South China has the lowest wind potential annual mean wind speed and power density 3.55 m s−1 and 97.4 W m−2. Temporally, the wind resources over the entire China are higher in the cold season (spring and winter with peaks in April) than those in the warm season (summer and autumn with bottoms in August). Specifically, the wind power output in “Three North” region (including Northeast China, North China and Northwest China) in the cold season is 1.4 times higher than that in the warm season. Some coastal regions in East China have relatively high wind power density (>500 W m−2) and small seasonal variations. These findings should help decision-makers to identify the areas suitable for utilizing wind energy, and optimizing power generation and transmission across the grid for better system performance.

Accuracy Assessment on MODIS (V006), GLASS and MuSyQ Land-Surface Albedo Products: A Case Study in the Heihe River Basin, China

This study assessed accuracies of MCD43A3, Global Land-Surface Satellite (GLASS) and forthcoming Multi-source Data Synergized Quantitative Remote Sensing Production system (MuSyQ) albedos using ground observations and Huan Jing (HJ) data over the Heihe River Basin. MCD43A3 and MuSyQ albedos show similar high accuracies with identical root mean square errors (RMSE). Nevertheless, MuSyQ albedo is better correlated with ground measurements when sufficient valid observations are available or snow-free. The opposite happens when less than seven valid observations are available. GLASS albedo presents a larger RMSE than MCD43A3 and MuSyQ albedos in comparison with ground measurements. Over surfaces with smaller seasonal variations, MCD43A3 and MuSyQ albedos show smaller RMSEs than GLASS albedo in comparison with HJ albedo. However, for surfaces with larger temporal variations, both RMSEs and R2 of GLASS albedo are comparable with MCD43A3 and MuSyQ. Generally, MCD43A3 and MuSyQ albedos featured the same RMSEs of 0.034 and similar R2 (0.920 and 0.903, respectively), which are better than GLASS albedo (RMSE = 0.043, R2 = 0.787). However, when it comes to comparison with aggregated HJ albedo, MuSyQ and GLASS albedos are with lower RMSEs of 0.027 and 0.032 and higher R2 of 0.900 and 0.898 respectively than MCD43A3 (RMSE = 0.038, R2 = 0.836). Despite the limited geographic region of the study area, they still provide an important insight into the accuracies of three albedo products.

Feasible Energy System with Electrochemical Hydrogen Energy Storage for Leveling the Received Electricity at Large-Scale Solar Cell Installation

Introduction Recently, the large-scale installation of renewable energy is required to prevent global warming problem. Especially, the production cost of solar cell has drastically decreased recently. To install large-scale unstable power sources on renewable energy, the management of the gap between electricity demand and supply is a key issue. Thus, large-scale energy storage technologies have to progress to compensate the gap. As an energy storage, chemical energy of hydrogen is a promising candidate. Particularly in urban area, both “global hydrogen” and “local hydrogen” are required to supply sufficient energy to their huge energy demand. “Global hydrogen” is produced from low-cost primary energy globally and is transported for demand with a certain cost. “Local hydrogen” is produced by distributed energy system and is directly supplied without transportation. In the paper, we proposed a cost-competitive distributed energy system with the “local hydrogen” energy storage system. We analyzed the variation of total system cost by installing electrolysis cell (EC), fuel cell (FC) and secondary battery to compensate the gap due to electricity supply from large-scale solar cells (SC). We also proposed the appropriate SC arrangement for a middle size of distributed energy system. Method We evaluated the total system cost on the basis of real data from smart energy control system “Ene-Swallow”, developed by our research group, which manages the megawatt-scale distributed power sources in Tokyo Institute of Technology, Tokyo. The system has 1400 kW-SC, 100 kW-FC, 70 kW-gas engine and 100 kWh-lithium ion battery to manage the 10000 kW-scale electricity demand, which is suitable as a model for a middle-scale society with distributed power sources. The 650 kW-SC, which is almost half of total capacity of SC, is installed on the building (shown in Fig1) located in Tokyo. This building nearly achieves electricity self-sufficiency by the SC, 100 kW-FC and 70kW-gas engine. The building is covered with the “envelope of solar cells” (445 kW at the south wall, 40 kW at the west wall and 165 kW on the roof), where the maximum altitude in winter solstice is 31°. Global solar radiation in summer and winter are 15 MJ/m2 and 8 MJ/m2, respectively. Average temperature in summer and winter are 25°C and 5°C, respectively. In the location, the SCs on the building generates maximum electric power in winter because about 68% of SCs is installed at the south walls. The SC arrangement of the building has much smaller seasonal variation than typical arrangement on the roof to get better matching with the larger energy demands in winter. We constructed the energy system model to analyze the distributed energy system with electrochemical hydrogen energy storage and large-scale SC. In our model, the energy system with SC, alkaline EC, solid oxide FC, compressor, hydrogen tank and battery was assumed. Three hourly data from Apr/1/2016 to Mar/31/2017 were used (power generation from 750 kW-SC on the roofs, 650kW-SC on the building and electricity demand in the area). Based on these data, imaginary set of SC installation was assumed, where total amount of power generation from SC is equivalent to the electricity demand. Fig2 shows the energy flow in the model. In the daytime, the surplus electricity supplied from SC was assumed to be used for the production of hydrogen or battery charge. If the capacity of each device is not sufficient, the surplus electricity was assumed to be curtailed because it is hard to sell it in the future scenario with “large amount of solar energy”. In the night, the electricity to satisfy the demand was assumed to be generated by battery or FC. When the electricity supply is not enough, electricity was assumed to be purchased from an electrical grid. We carried out the energy balance simulation in the model by setting the capacities and technological parameters of devices. Finally, we analyzed the total system cost on the basis of the simulation. The analysis was carried out with the three cases of technology parameters of devices: (1) current (2015), (2) reduced SC price and (3) reduced all device prices (Table1). Result From the series of analysis, the total system cost can be reduced by installing the appropriate-scale hydrogen energy storage in the future. To achieve self-sufficiency ratio 100%, on the other hand, hydrogen tank cost drastically increased because its capacity got larger to absorb seasonal variation in power generation from SC. Controlling seasonal variation through SC arrangement can reduce the hydrogen tank cost. The cost-competitive system was proposed with the combination of hydrogen energy storage and SC arrangement. Figure 1

Seasonal contribution of assessed sources to submicron and fine particulate matter in a Central European urban area

This study presents the air pollution findings of the submicron (PM1) and fine (PM2.5) particulate matter. The submicron particles are entirely absorbed by the human body and they cause the greatest health risk. For the PM2.5 concentration, there are yearly and/or daily limit values regulations by the European Union (EU) and World Health Organization (WHO). There are no such regulations for PM1 but for health risk reason the knowledge of its concentration is important. This paper presents the seasonal concentration contribution of PM1 and PM2.5, their chemical composition and assessed three basic sources. Daily samples of both fractions were collected from 2nd July 2016 to 27th February 2017 in Krakow, Poland. Apart from PM1 and PM2.5 the concentration of 16 elements, 8 ions and BC for each samples were measured. Based on these chemical species the positive matrix factorization (PMF) receptor modeling was used for the determination of three main sources contribution to the PM1 and PM2.5 concentrations. Daily average concentrations of PM2.5 were 12 μg/m3 in summer and 60 μg/m3 in winter. For PM1 it was 6.9 μg/m3 in summer and 17.3 μg/m3 in winter. These data show a significant difference in percentage contribution of PM1 in PM2.5 in summer (58%) and in winter (29%).For the combustion source, the concentrations calculated from PMF modeling in winter were 4.8 μg/m3 for PM1 and 31 μg/m3 for PM2.5. In summer, the concentrations were smaller than 1 μg/m3 for both fractions. Secondary aerosols' concentration for PM1 was 3.4 μg/m3 in summer and 11 μg/m3 in winter - for PM2.5 these were 7.1 μg/m3 and 17 μg/m3 respectively. The third source - soil, industry and traffic together, had small seasonal variation: for PM1 it was from 1.4 to 1.8 μg/m3 and for PM2.5 from 4.7 to 7.9 μg/m3.

Heavy metals in the finest size fractions of road-deposited sediments

The concentration of heavy metals in urban road-deposited sediments (RDS) can be used as an indicator for environmental pollution. Thus, their occurrence has been studied in whole road dust samples as well as in size fractions obtained by sieving. Because of the limitations of size separation by sieving little information is available about heavy metal concentrations in the road dust size fractions <20 μm. In this study air classification was applied for separation of dust size fractions smaller than 20 μm from RDS collected at different times during the year. The results showed only small seasonal variations in the heavy metals concentrations and size distribution. According to the Geoaccumulation Index the pollution of the road dust samples deceased in the following order: Sb » As > Cu ≈ Zn > Cr > Cd ≈ Pb ≈ Mn > Ni > Co ≈ V. For all heavy metals the concentration was higher in the fine size fractions compared to the coarse size fractions, while the concentration of Sr was size-independent. The enrichment of the heavy metals in the finest size fraction compared to the whole RDS <200 μm was up to 4.5-fold. The size dependence of the concentration decreased in the following order: Co ≈ Cd > Sb > (Cu) ≈ Zn ≈ Pb > As ≈ V » Mn. The approximation of the size dependence of the concentration as a function of the particle size by power functions worked very well. The correlation between particle size and concentration was high for all heavy metals. The increased heavy metals concentrations in the finest size fractions should be considered in the evaluation of the contribution of road dust re-suspension to the heavy metal contamination of atmospheric dust. Thereby, power functions can be used to describe the size dependence of the concentration.

EFEITO DA SAZONALIDADE SOBRE O RENDIMENTO DO ÓLEO ESSENCIAL DE &lt;i&gt;Piper gaudichaudianum &lt;/i&gt;KUNTH

Piper gaudichaudianum Kunth (Piperaceae) é uma planta com ampla distribuição no território brasileiro. Além de sua importância ecológica, é utilizada na medicina popular e muitas de suas atividades biológicas já foram comprovadas. O objetivo deste trabalho foi verificar o efeito da sazonalidade sobre o teor de óleo essencial (OE) em folhas de Piper gaudichaudianum e averiguar a possível influência do processo de secagem do material vegetal no rendimento deste extrativo. Foram coletadas aleatoriamente folhas de indivíduos de uma população nativa de Santa Maria - RS, Brasil, ao longo de um ano. O OE foi extraído de folhas frescas e secas à temperatura ambiente pelo método de hidrodestilação. Quando verificada a presença de órgãos reprodutivos, os mesmos foram extraídos, a fim de examinar a sua influência no rendimento do OE de folhas. Para determinação do teor de umidade (TU%), 20 g de folhas e 10 g de órgãos reprodutivos foram secos separadamente em estufa a 50°C até peso constante. O rendimento de OE de folhas (% m/m) foi calculado para o material fresco com base na massa seca, considerando o TU%, bem como para o material seco à temperatura ambiente. Apenas pequenas variações sazonais nos teores de OE foram detectadas para as amostras analisadas, não havendo diferença estatística entre eles. O maior rendimento foi observado na primavera, tanto para o OE de folhas (1,61±0,09%), quanto de órgãos reprodutivos (5,17%), enquanto o menor teor de OE em folhas ocorreu no verão (1,32±0,14%), a única estação em que não houve a presença de órgãos reprodutivos. A ausência de diferença significativa entre os rendimentos indica que não houve variabilidade sazonal quantitativa na produção de OE em folhas desta população. Portanto, a coleta deste órgão vegetal pode ser realizada em qualquer época do ano visando à obtenção deste extrativo. Uma vez que não foi verificada diminuição do teor de OE durante o processo de secagem à temperatura ambiente, esse processamento pós-colheita poderá ser adotado.

Analysis of seasonal characteristics of water exchange in Beibu Gulf based on a particle tracking model

The seasonal characteristics of water exchange in Beibu Gulf are investigated based on a particle tracking model. The gulf is divided into six sub-regions in order to better understand the exchange processes and water movement in the gulf. The residence time is computed for each sub-region, and the results show that the whole gulf has a small seasonal variation, with 66 days in winter and 71 days in summer, while the sub-regions exhibit a large seasonal difference with short residence times in summer. Water exchange curves indicate water movement in the gulf follows the circulation patterns. In winter, the water particles move cyclonically and accumulate near the western coast of the gulf. The current flows entering the gulf are dominated by the westward flow from the Qiongzhou Strait. The influence area of this flow can extend to the Vietnam coast. In summer, water particles from the coastal area tend to move offshore and undergo strong mixing in the center of the gulf. The northward current flow from the south opening becomes the dominant flow, with a large influence area in the eastern part of the gulf.

Drinking water salinity associated health crisis in coastal Bangladesh

Salinity intrusion in coastal Bangladesh has serious population health implications, which are yet to be clearly understood. The study was undertaken through the ‘Assessing Health, Livelihoods, Ecosystem Services and Poverty Alleviation in Populous Deltas’ project in coastal Bangladesh. Drinking water salinity and blood pressure measurements were carried out during the household survey campaign. The study explored association among Socio-Ecological Systems (SESs), drinking water salinity and blood pressure. High blood pressure (prehypertension and hypertension) was found significantly associated with drinking water salinity. People exposed to slightly saline (1000–2000 mg/l) and moderately saline (≥2000 mg/l) concentration drinking water had respectively 17% (p &amp;lt; 0.1) and 42% (p &amp;lt; 0.05) higher chance of being hypertensive than those who consumed fresh water (&amp;lt;1000 mg/l). Women had 31% higher chance of being hypertensive than men. Also, respondents of 35 years and above were about 2.4 times more likely to be hypertensive compared to below 35 years age group. For the 35 years and above age group, both prehypertension and hypertension were found higher than national rural statistics (50.1%) for saline water categories (53.8% for slightly and 62.5% for moderate saline). For moderate salinity exposure, hypertension prevalence was found respectively 21%, 60% and 48% higher than national statistics (23.6%) in consecutive survey rounds among the respondents. Though there was small seasonal variation in drinking water salinity, however blood pressure showed an increasing trend and maximum during the dry season. Mean salinity and associated hypertension prevalence were found higher for deep aquifer (21.6%) compared to shallow aquifer (20.8%). Localized increase in soil and groundwater salinity was predicted over the study area. Shallow aquifer salinity increase was projected based on modelled output of soil salinity. Rather than uniform increase, there were localized extreme values. Deep aquifer salinity was also predicted to exhibit increasing trend over the period. Study findings and recommendations are suggested for immediate and planned intervention.

Spatial variations in Titan’s atmospheric temperature: ALMA and Cassini comparisons from 2012 to 2015

Submillimeter emission lines of carbon monoxide (CO) in Titan’s atmosphere provide excellent probes of atmospheric temperature due to the molecule’s long chemical lifetime and stable, well constrained volume mixing ratio. Here we present the analysis of 4 datasets obtained with the Atacama Large Millimeter/Submillimeter Array (ALMA) in 2012, 2013, 2014, and 2015 that contain strong CO rotational transitions. Utilizing ALMA’s high spatial resolution in the 2012, 2014, and 2015 observations, we extract spectra from 3 separate regions on Titan’s disk using datasets with beam sizes ranging from 0.35 × 0.28″ to 0.39 × 0.34″. Temperature profiles retrieved by the NEMESIS radiative transfer code are compared to Cassini Composite Infrared Spectrometer (CIRS) and radio occultation science results from similar latitude regions. Disk-averaged temperature profiles stay relatively constant from year to year, while small seasonal variations in atmospheric temperature are present from 2012 to 2015 in the stratosphere and mesosphere ( ∼ 100–500 km) of spatially resolved regions. We measure the stratopause (320 km) to increase in temperature by 5 K in northern latitudes from 2012 to 2015, while temperatures rise throughout the stratosphere at lower latitudes. We observe generally cooler temperatures in the lower stratosphere ( ∼ 100 km) than those obtained through Cassini radio occultation measurements, with the notable exception of warming in the northern latitudes and the absence of previous instabilities; both of these results are indicators that Titan’s lower atmosphere responds to seasonal effects, particularly at higher latitudes. While retrieved temperature profiles cover a range of latitudes in these observations, deviations from CIRS nadir maps and radio occultation measurements convolved with the ALMA beam-footprint are not found to be statistically significant, and discrepancies are often found to be less than 5 K throughout the atmosphere. ALMA’s excellent sensitivity in the lower stratosphere (60–300 km) provides a highly complementary dataset to contemporary CIRS and radio science observations, including altitude regions where both of those measurement sets contain large uncertainties. The demonstrated utility of CO emission lines in the submillimeter as a tracer of Titan’s atmospheric temperature lays the groundwork for future studies of other molecular species – particularly those that exhibit strong polar abundance enhancements or are pressure-broadened in the lower atmosphere, as temperature profiles are found to consistently vary with latitude in all three years by up to 15 K.

The Climate Range Expansion of Aedes albopictus (Diptera: Culicidae) in Asia Inferred From the Distribution of Albopictus Subgroup Species of Aedes (Stegomyia).

We compared climatic distribution ranges between Aedes albopictus (Skuse) (Diptera: Culicidae) and the five wild (nondomesticated) species of Albopictus Subgroup of Scutellaris Group of Aedes (Stegomyia) in southern Asia. Distribution sites of the wild species concentrate in seasonal forest and savannah climate zones in India, Indochina, and southern China. The distribution of Ae. albopictus is broader than the wild species under 1) tropical rain-forest climate, 2) steppe and temperate savannah climate, and 3) continental climate with large seasonal temperature variation (hot summer and cold winter) at temperate lowlands (northernmost sites 40°N in Ae. albopictus vs 32°N in the wild species). However, the distribution of Ae. albopictus is more limited at tropical and subtropical highlands where the climate is cool but less continental (small seasonal variation, mild summer, and winter). We discuss a possibility that the broader climate ranges of Ae. albopictus are ecological or eco-evolutionary consequences of adaptation to human habitats. We also propose a general scenario for the origin, dispersal, and adaptation of Ae. albopictus in Asia as a hypothesis for future research.

Dependence of the muon intensity on the atmospheric temperature measured by the GRAPES-3 experiment

The large area (560 m2) GRAPES-3 tracking muon telescope has been operating uninterruptedly at Ooty, India since 2001. Every day, it records 4 × 109 muons of ≥ 1 GeV with an angular resolution of ∼ 4°. The variation of atmospheric temperature affects the rate of decay of muons produced by the galactic cosmic rays (GCRs), which in turn modulates the muon intensity. By analyzing the GRAPES-3 data of six years (2005–2010), a small (amplitude ∼ 0.2%) seasonal variation (1 year (Yr) period) in the intensity of muons could be measured. The effective temperature ‘Teff’ of the upper atmosphere also displays a periodic variation with an amplitude of ∼ 1 K which was responsible for the observed seasonal variation in the muon intensity. At GeV energies, the muons detected by the GRAPES-3 are expected to be anti-correlated with Teff. The anti-correlation between the seasonal variation of Teff, and the muon intensity was used to measure the temperature coefficient αT by fast Fourier transform (FFT) technique. The magnitude of αT was found to scale with the assumed attenuation length ‘λ’ of the hadrons in the range λ = 80–180 g cm−2. However, the magnitude of the correction in the muon intensity was found to be almost independent of the value of λ used. For λ = 120 g cm−2 the value of temperature coefficient αT was found to be (−0.17±0.02)% K−1.

Comparison of Turbulence Indicators Obtained from In Situ Flight Data

AbstractTwo indicators of turbulence—the eddy dissipation rate (EDR) and derived equivalent vertical gust velocity (DEVG)—are calculated using aircraft observations from Hong Kong–based airlines, whose aircraft included Boeing and Airbus models, for 39 months from February 2011 to April 2014. Characteristics of the two turbulence indicators that were calculated at 1-min intervals from the flight data are investigated. For Boeing and Airbus aircraft, there are large seasonal variations in the 90th and 99th percentiles of EDR and DEVG, whereas there are relatively small seasonal variations in the medians of EDR and DEVG. For the turbulence encounters estimated from EDR and DEVG, the authors compute their correlations for each level of turbulence and each type of aircraft. Strong correlations (larger than 0.7) occurred for all levels of turbulence encounters for Boeing aircraft, whereas relatively weak correlations (less than 0.5) occurred for Airbus aircraft. This difference is due to the different characteristics of recorded Boeing and Airbus aircraft data (the number of decimals and data sampling frequency). Based on correlation analyses, the authors construct the best-fit curves using mean EDR values for each DEVG bin and mean DEVG values for each EDR bin and obtain relationships between EDR and DEVG for Boeing and Airbus aircraft. The EDR and DEVG-derived EDR for moderate-or-greater-level turbulence are generally similar for Boeing aircraft.

Phytoplankton composition and biomass in tropical soda Lake Shala: seasonal changes in response to environmental drivers

AbstractAlthough soda lakes are valuable, sensitive aquatic resources where phytoplankton play a decisive role for the entire ecological functions, they are among the least‐studied ecosystems. Seasonal variations in phytoplankton composition, abundance and biomass in relation to some environmental parameters of the little known, deep, large, volcanic and saline–alkaline Lake Shala were investigated over an annual cycle. The lake phytoplankton community consisted of relatively diverse taxa (23) belonging to Bacillariophyceae, Cryptophyta, Cyanoprokaryota and Dinophyta. Bacillariophyceae and Cryptophyta were the dominant groups throughout the annual cycle, accounting for about 57% and 22% of the total number of species, and 28% and 69% of the total abundance of the phytoplankton community, respectively. Cryptomonas spp. were most abundant throughout nearly all months, contributing about 59%–95% of total phytoplankton abundance, followed by Thalassiosira sp. (1%–35%). The chlorophyll‐a concentration, as a proxy for algal biomass, was generally low (mean 17 μg L−1), exhibiting only small seasonal variation. The strong, inverse relation of chlorophyll‐a with water transparency (r = −0.69; n = 11) and the persistent dominance of species adapted to low‐light conditions and mixing suggest the overriding importance of these factors in controlling the lake's phytoplankton. The results of the present study generally suggest the phytoplankton composition and biomass in Lake Shala exhibited muted seasonal changes, despite the environmental perturbations, probably because of the lake's high buffering capacity against allochthonous impacts because of its voluminous nature.

Upper water mass variability in the Anegada–Jungfern Passage, NE Caribbean, during the last 11,100 cal. yr

Using qualitative and quantitative analyses of planktonic foraminifera assemblages, δ18O measurements, Mg/Ca–temperature relationship ( Globigerinoides ruber pink sensu stricto) data and sea-surface temperatures (SSTs) derived from artificial neural network (ANN) transfer functions, a reconstruction was made of upper water mass variability in the Anegada–Jungfern Passage (AJP), northeastern Caribbean Sea, over the last c. 11,100 years. Our record is based on the study of two marine sediment cores and reveals three main circulation stages during the Holocene. In the early-Holocene (11,100–6300 cal. yr BP), ANN-based SST estimations indicate moderately cooler than present winter condition in the NE Caribbean with SSTs of ~25.5°C. These conditions presumably reflect advection of well-mixed upper water masses from the Guyana upwelling area associated with a strong Atlantic Meridional Overturning Circulation (AMOC) and enhanced trade wind activity, linked to a more northerly location of the inter-tropical convergence zone (ITCZ). Between 6300 and 3700 cal. yr BP, a relative warming of winter SSTs (~26.5°C) was probably related to a weaker circulation and upper water mass mixing because of less intense trade wind activity, as the ITCZ moved southwards. From 3700 cal. yr BP to the present, the region was characterised by small seasonal SST variations and generally stable winter and summer SSTs. The data suggest a minor shift in the (sub)surface inflow pattern during the last 2000 years, possibly related to changes in Northern Hemisphere large-scale atmospheric circulation also observed at higher latitude. The ANN-based temperature pattern is supported by fluctuations in the Mg/Ca-derived temperature record, although temperature maxima derived from the Mg/Ca ratio appear anomalously high. On a Holocene timescale, we conclude that the northeastern Caribbean SST and circulation regime have been mainly dependent on the position of the ITCZ, which, in turn, is controlled by changes in hemispheric solar insolation.

The relationship between vitamin D status and muscle strength in young healthy adults from sunny climate countries currently living in the northeast of Scotland.

Vitamin D has been suggested to play a role in muscle health and function, but studies so far have been primarily in older populations for falls prevention and subsequent risk of fractures. Vitamin D status was assessed in a healthy young adults from sunny climate countries (n=71, aged 19-42years) with 56% seen within 3months of arriving in Aberdeen [newcomers; median (range) time living in the UK=2months (9-105days)] and the remainder resident for >6months [residents; 23months (6-121months)]. Participants attended visits every 3months for 15months. At each visit, fasted blood samples were collected for analysis of serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type I collagen (P1NP). Maximal voluntary contractions (MVC) were performed for grip strength (both arms) and for maximal isometric strength of the knee extensors (right knee). There were small seasonal variations in 25(OH)D concentrations within the newcomers and residents, but no seasonal variation in bone turnover markers. There was a positive, albeit small, association between 25(OH)D and knee extensor maximal isometric strength. Mixed modelling predicted that for each 1nmol/L increase in 25(OH)D, peak torque would increase by 1Nm (p=0.04). This study suggests that vitamin D may be important for muscle health in young adults migrating from sunnier climates to high latitudes, yet the potential effect is small.

Remote sensing and ground-based measurements of evapotranspiration in an extreme cold Patagonian desert

Accurate estimates of seasonal evapotranspiration (ET) at different temporal and spatial scales are essential for understanding the biological and environmental determinants of ecosystem water balance in arid regions and the patterns of water utilization by the vegetation. For this purpose, remote sensing ET estimates of a Patagonian desert in Southern Argentina were verified with field measurements of soil evaporation and plant transpiration using an open top chamber. Root distribution and seasonal variation in soil volumetric water content were also analysed. There was a high correlation between remote sensing and field measurements of ecosystem water fluxes. A substantial amount of the annual ET occurred in spring and early summer (73.4 mm) using winter rain stored in the soil profile and resulting in water content depletion of the upper soil layers. A smaller amount of annual ET was derived from few rainfall events occurring during the mid or late summer (41.4 mm). According to remote sensing, the 92.9% of the mean annual precipitation returns to the atmosphere by transpiration or evaporation from the bare soil and by canopy interception. Only 7.1% infiltrates to soil layers deeper than 200 cm contributing to the water table recharge. Fourier time series analysis, cross-correlation methods and multiple linear regression models were used to analyse 11 years of remote sensing data to assess determinants of water fluxes. A linear model predicts well the variables that drive complex ecosystem processes such as ET. Leaf area index and air temperature were not linearly correlated to ET because of the multiple interaction among variables resulting in time lags with ET variations and thus these two variables were not included in the linear model. Soil water content, the fraction of photosynthetic active radiation and precipitation explained 86% of the ET monthly variations. The high volumetric water content and the small seasonal variations at 200-cm depth were probably the result of little water uptake from deeper soil horizons by roots with low hydraulic conductivity. Copyright © 2016 John Wiley & Sons, Ltd.

Validation of a national hydrological model

Nationwide predictions of flow time-series are valuable for development of policies relating to environmental flows, calculating reliability of supply to water users, or assessing risk of floods or droughts. This breadth of model utility is possible because various hydrological signatures can be derived from simulated flow time-series. However, producing national hydrological simulations can be challenging due to strong environmental diversity across catchments and a lack of data available to aid model parameterisation. A comprehensive and consistent suite of test procedures to quantify spatial and temporal patterns in performance across various parts of the hydrograph is described and applied to quantify the performance of an uncalibrated national rainfall-runoff model of New Zealand. Flow time-series observed at 485 gauging stations were used to calculate Nash-Sutcliffe efficiency and percent bias when simulating between-site differences in daily series, between-year differences in annual series, and between-site differences in hydrological signatures. The procedures were used to assess the benefit of applying a correction to the modelled flow duration curve based on an independent statistical analysis. They were used to aid understanding of climatological, hydrological and model-based causes of differences in predictive performance by assessing multiple hypotheses that describe where and when the model was expected to perform best. As the procedures produce quantitative measures of performance, they provide an objective basis for model assessment that could be applied when comparing observed daily flow series with competing simulated flow series from any region-wide or nationwide hydrological model. Model performance varied in space and time with better scores in larger and medium-wet catchments, and in catchments with smaller seasonal variations. Surprisingly, model performance was not sensitive to aquifer fraction or rain gauge density.