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Individuals vary in their ability to taste, and some individuals are more sensitive to certain tastes than others. Taste sensitivity is a predictor of various factors, such as diet, eating behavior, appetite regulation, and overall health. Furthermore, taste sensitivity can fluctuate within an individual over short to long periods of time: for example, in daily (diurnal) cycles, monthly (menstrual) cycles (in females), and yearly (seasonal) cycles. Understanding these temporal patterns is important for understanding individual eating habits and food preferences, particularly in the context of personalized and precision nutrition. This review provides a summary of the literature on taste sensitivity patterns across 3 temporal dimensions: daily, monthly, and yearly. Good evidence for diurnal patterns has been observed for sweet taste and fat taste, although the evidence is limited to rodent studies for the latter. Obese populations showed limited variation to sweet and fat taste sensitivities over a day, with limited variation in sweet taste sensitivity being linked to insulin resistance. There were mixed observations of temporal variation in sensitivity to sour and umami tastes, and there were no patterns in sensitivity to bitter taste. Menstrual patterns in sweet taste sensitivity were consistent with patterns in food intake. Other taste modality investigations had mixed findings that had little agreement across studies. Hormonal changes in females influence taste sensitivity to some degree, although the overall patterns are unclear. Seasonal patterns have been less well studied, but there is weak evidence that sweet, salty, and bitter taste sensitivities change across seasons. Differences in seasonal taste patterns have been observed in subgroups susceptible to mental health disorders, requiring further investigation. Patterns of taste sensitivity are evident across multiple temporal dimensions, and more research is needed to determine the influence of these patterns on food intake. Dysregulation of these patterns may also be a marker of certain diseases or health conditions, warranting further investigation. Notably, the alimentary tastes (umami, fat, and carbohydrate) are underrepresented in this research area and require additional investigation. [ABSTRACT FROM AUTHOR]

The rise of urbanization has led to many critical issues like increased air pollution, emission of more greenhouse gases, sudden climate change, and a rise in temperature of an urban area compared to surrounding rural regions known as urban heat islands (UHI). It becomes crucial to understand the effect of climatic conditions in those areas. In this present research, we have chosen two different cities: Bhopal and Guwahati, situated over different climatic conditions. The study examines the diurnal, seasonal and inter annual variability of surface UHI (SUHI), using MODIS LST (MOD11A2 and MYD11A2) product of 1 km spatial resolution from 2003 to 2018. The temporal trend of LST is estimated using Mann–Kendall and Sen's slope estimator test. This study also evaluates the land use land cover (LULC) change over the two cities using the LULC data. The present research also incorporates the determination of six different driving factors of SUHI starting from built-up area, urban–rural difference in evapotranspiration, black sky albedo, enhanced vegetation index, thermal inertia, and population. Pearson's correlation criteria are used to determine the correlation of SUHI with each of the determinant parameters. The results reveal the presence of a cool urban island during the summer daytime in Bhopal, while Guwahati shows a positive SUHI. The nighttime shows clear evidence and higher SUHI magnitude than the daytime for Bhopal city. Contrary, a reverse phenomenon is evident in Guwahati with higher SUHI magnitude during the daytime compared to nighttime. The negative SUHI variation can be ascribed to rural area dynamics with the majority of cropland cover. The evapotranspiration shows reasonable control of SUHI's daytime variation. Thermal inertia was found to be an influential parameter in explaining the diurnal variation of SUHI. [ABSTRACT FROM AUTHOR]

Gurugram is emerging as one of India's most advanced cities. The combined impact of industrial and vehicular emissions makes the environment toxic. Recently, Gurugram has experienced severe air quality. In the present work, an assessment of seasonal, monthly, and diurnal variations of ambient air quality was carried out in Gurugram during the period of March 2021 to 2022 February. Seasonal and monthly concentrations of key air pollutants like particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3) were examined at Vikas sadan, Gwal Pahari and Teri Gram in Gurugram city to study the most polluted seasons and months. Significantly higher mean concentrations of Particulate matter PM2.5 (406.94 μgm-3) and NO2 (353.96ppb) were seen during the colder months and seasons. O3 showed a consistent trend with variations during the year, with the highest concentration in winter (106.35µg/m³). PM2.5 and NO2 concentrations during the night were greater for all seasons when compared to diurnal values. O3 concentrations displayed diurnal tendencies that were the opposite of those of NO2 concentrations. The highest concentrations of ambient PM2.5, NO2, and CO were observed at the Vikas Sadan Monitoring Station. While the NISE Gwal Pahari station showed greater O3 values. The findings highlight the necessity of efficient air pollution control in Gurugram. To prevent public exposure to air pollutants, preventive measures like green spaces, using public transport, etc. must be adopted. The study contributes to a better understanding of air pollution by seasonal, monthly and diurnal assessment in the city of Gurugram. [ABSTRACT FROM AUTHOR]

• Model predicts diurnal, seasonal and geomagnetic activity dependence of variability. • Ionospheric variability is mainly explained by atmospheric and geomagnetic activity. • Some features of nighttime variability have not received a proper explanation. The paper presents an analysis of the ionospheric variability as a function of local time, month, and geomagnetic activity level. The 2003–2020 dataset of peak electron densities (NmF2) from the Irkutsk DPS-4 Digisonde (52.3°N, 104.3°E) was converted into the dataset of the NmF2 disturbances (ΔNmF2) representing the relative (percentage) deviations of the NmF2 from the 27-day running median. The ΔNmF2 dataset was used to calculate root mean square values of ΔNmF2 (σNmF2) by 27-day running averaging. These σNmF2 values were considered as a measure of ionospheric variability. The σNmF2 as function of local time, day of year, and year was the input for building the local empirical model of ionospheric variability based on the linear regression of σNmF2 on the 27-day average daily Ap-index of geomagnetic activity. The paper demonstrates the diurnal-seasonal variations in σNmF2 under low geomagnetic activity (linear regression intercept) as well as the rate of increase/decrease in σNmF2 with increasing Ap (linear regression slope). The obtained diurnal, seasonal, and geomagnetic activity behavior of σNmF2 is compared with previous studies of ionospheric variability. [ABSTRACT FROM AUTHOR]

Abstract Background Pinus tabuliformis adapts to cold climate with dry winter in northern China, serving as important commercial tree species. The TEOSINTE BRANCHED 1, CYCLOIDEA, and PROLIFERATING CELL FACTOR family(TCP)transcription factors were found to play a role in the circadian clock system in Arabidopsis. However, the role of TCP transcription factors in P. tabuliformis remains little understood. Results In the present study, 43 TCP genes were identified from P. tabuliformis genome database. Based on the phylogeny tree and sequence similarity, the 43 TCP genes were classified into four groups. The motif results showed that different subfamilies indeed contained different motifs. Clade II genes contain motif 1, clade I genes contain motif 1, 8, 10 and clade III and IV contain more motifs, which is consistent with our grouping results. The structural analysis of PtTCP genes showed that most PtTCPs lacked introns. The distribution of clade I and clade II on the chromosome is relatively scattered, while clade III and clade IV is relatively concentrated. Co-expression network indicated that PtTCP2, PtTCP12, PtTCP36, PtTCP37, PtTCP38, PtTCP41 and PtTCP43 were co-expressed with clock genes in annual cycle and their annual cycle expression profiles both showed obvious seasonal oscillations. PtTCP2, PtTCP12, PtTCP37, PtTCP38, PtTCP40, PtTCP41, PtTCP42 and PtTCP43 were co-expressed with clock genes in diurnal cycle. Only the expression of PtTCP42 showed diurnal oscillation. Conclusions The TCP gene family, especially clade II, may play an important role in the regulation of the season and circadian rhythm of P. tabuliformis. In addition, the low temperature in winter may affect the diurnal oscillations.

Background: Pinus tabuliformis adapts to cold climate with dry winter in northern China, serving as important commercial tree species. The TEOSINTE BRANCHED 1, CYCLOIDEA, and PROLIFERATING CELL FACTOR family(TCP)transcription factors were found to play a role in the circadian clock system in Arabidopsis. However, the role of TCP transcription factors in P. tabuliformis remains little understood. Results: In the present study, 43 TCP genes were identified from P. tabuliformis genome database. Based on the phylogeny tree and sequence similarity, the 43 TCP genes were classified into four groups. The motif results showed that different subfamilies indeed contained different motifs. Clade II genes contain motif 1, clade I genes contain motif 1, 8, 10 and clade III and IV contain more motifs, which is consistent with our grouping results. The structural analysis of PtTCP genes showed that most PtTCPs lacked introns. The distribution of clade I and clade II on the chromosome is relatively scattered, while clade III and clade IV is relatively concentrated. Co-expression network indicated that PtTCP2, PtTCP12, PtTCP36, PtTCP37, PtTCP38, PtTCP41 and PtTCP43 were co-expressed with clock genes in annual cycle and their annual cycle expression profiles both showed obvious seasonal oscillations. PtTCP2, PtTCP12, PtTCP37, PtTCP38, PtTCP40, PtTCP41, PtTCP42 and PtTCP43 were co-expressed with clock genes in diurnal cycle. Only the expression of PtTCP42 showed diurnal oscillation. Conclusions: The TCP gene family, especially clade II, may play an important role in the regulation of the season and circadian rhythm of P. tabuliformis. In addition, the low temperature in winter may affect the diurnal oscillations. [ABSTRACT FROM AUTHOR]

Odor concentrations (OC) and emissions (OE) were measured for a commercial broiler barn and a cage-layer barn in a cold region (the Canadian Prairies). Seasonal OC and OE profiles were plotted by monthly measurements over the course of a year from March 2015 to February 2016, and diurnal profiles were generated by 2-day measurements in cold, mild, and warm seasons, respectively. Seasonal OC and OE varied for both barns; OC was higher in the cold season, but OE was higher in the mild and warm seasons. The broiler barn had higher annual average OC (718 OU m−3) but slightly lower annual average OE (127 OU s−1 AU−1; AU is per 500 kg of body mass) than the layer barn (574 OU m−3 and 140 OU s−1 AU−1). For the layer barn, OC and OE were reduced by 31% and 33% in the cold season and by 30% and 26% in the mild season after manure removal compared with before manure removal. Statistical results showed increased outdoor temperature and ventilation rate (VR) were associated with decreased OC but increased OE for both barns. Finally, both single linear and multi-linear regression models of OE were developed. [ABSTRACT FROM AUTHOR]

Background: Previous studies show that myocardial infarctions (MIs) occur most frequently in the morning.Objectives: We hypothesized that there no longer is a morning predominance of MI, and that the timing of ST-elevation myocardial infarction (STEMI) vs. non-ST-elevation myocardial infarction (NSTEMI) presentation differs.Methods: We reviewed MI, STEMI, and NSTEMI patients (2013-2017) from a multiple-hospital system, identified by diagnostic codes. Daily emergency department arrival times were categorized into variable time intervals for count and proportional analysis, then examined for differences.Results: There were 18,663 MI patients from 12 hospitals included in the analysis. Most MIs occurred between 12:00 pm and 5:59 pm (35.7%), and least between 12:00 am-5:59 am (16.3%). After subdividing all MIs into STEMIs and NSTEMIs, both groups continued to have the greatest presentation between 12:00 pm and 5:59 pm (33.1% and 36.0%, respectively). STEMIs (17.2%) and NSTEMIs (16.2%) were least frequent between 12:00 am and 5:59 am. We found the second most common presentation time for MIs was in the 6 pm-11:59 pm time period, which held true for both subtypes (MI 26.7%, STEMI 26.4%, NSTEMI 26.7%).Conclusions: These data suggest a potential shift in the circadian pattern of MI, revealing an afternoon predominance for both STEMI and NSTEMI subtypes. [ABSTRACT FROM AUTHOR]

The behaviour of the CRI-MECH chemistry scheme was investigated over North-West Europe for the first week of each month for the year of 2015 using the mesoscale non-hydrostatic 3-D meteorological model, WRF-Chem. The model simulations of the distribution of important trace gas species (e.g. ozone, CO, NO, NO 2 and SO 2) were compared with ground-based measurements of selected rural and urban areas in UK. The model validation using the UK Defra Automatic Urban and Rural Network (AURN) measured data from sites across the UK showed a reasonable agreement between model-measurement for ozone (R = 0.45 for rural sites and R = 0.34 for urban sites), for NO 2 (R = 0.65 for rural sites and R = 0.45 for urban sites) and for NO (R = 0.35 for rural sites and R = 0.22 for urban sites). However, a poor correlation between model-measurement is found for CO (R = 0.15 for urban sites) and for SO 2 (R = 0.1 for rural sites and R = 0.27 for urban sites). Further investigations showed a poorer performance of the model ozone, CO, NO and NO 2 during summer and autumn months compared with winter months. The differences in model performance were most noticeable for ozone with the other species having more variance between sites and months. The possible causes for the deviations between the modelled and the measured data are discussed. • Investigating the behavior of the CRI-MECH over North-West Europe for ozone, NOx, CO and SO 2 for different seasons. • Validating the model using UK Defra Automatic Urban and Rural Network measured data across the UK. • A better model performance is found in rural sites compared to urban sites and during winter compared to summer and autumn. [ABSTRACT FROM AUTHOR]

The cambial activity and radial growth of three tropical species, Tetrameles nudiflora, Hopea pierrei and Cleidion spiciflorum at Chang Island were measured monthly from December 2011 to May 2012 and bi-monthly from June to November 2012. We installed electronic dendrometers to analyse stem diameter variation. Cambial activity was quantified by counting the layers of undifferentiated cells in the cambial zone at 10 randomly chosen positions. The relationships between the cambial activity and climatic factors, i.e. rainfall, temperature, relative humidity and soil moisture were investigated by Pearson's correlation. The number of cambial layers was significantly correlated with relative humidity. Growth dynamics of the three species differed considerably. The cambium of T. nudiflora appeared active year-long and was most active at the end of August. Cambial activity for H. pierrei and C. spiciflorum was highest at the end of June and July respectively, but was not significantly correlated with climate. Radial growth measurements showed that all three species contracted in the afternoon from 2.30--6.00 p.m., and the maximum enlargement occurred before 9 a.m. In this rainforest with high rainfall trees grow year-round, and radial growth rate depended on the water cycle rather than the weather conditions in the area. [ABSTRACT FROM AUTHOR]

Baseline emission values of greenhouse gases were not well established for commercial poultry barns in cold regions, including Canada, due to a lack of well-designed field studies. Emission factors of carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2 O), were acquired for a commercial broiler barn and cage-layer barn in the Canadian Prairies climate. Between March 2015 and February 2016, monthly measurements throughout the year for the layer barn and over 6 flocks for the broiler barn, and diurnal measurements in the mild, warm, and cold seasons for both barns were conducted, respectively. The ventilation rate was estimated based on a CO 2 mass balance method; thus CO 2 emissions were quantified by the CIGR (2002) models. The CH 4 and N 2 O emissions present at low levels from global perspective for both barns; the cold climate proved to be a major reason for the lower CH 4 emission from the layer barn. Considerable seasonal effect was observed only for N 2 O emissions from the broiler barn, and for CH 4 and N 2 O emissions from the layer barn, both with higher emissions in the mild and warm seasons than in the cold season. The big diurnal variations of CO 2 emissions for the layer barn demonstrated the uncertainty of the seasonal results by snapshot measurements and correction factors (from −20.9% to −22.5%) were obtained. Besides, the difference of CH 4 and N 2 O concentrations and emissions as well as CO 2 concentrations between best-case (the first day after manure removal) and worst-case conditions (the last day before manure removal) was not obvious for the layer barn. Additionally, changes of temperature and ventilation rate were likely to have more impact on N 2 O emission for the broiler barn and more impact on CH 4 emission for the layer barn than on the other two gas emissions, both with positive correlations. Image 1 • Emission rates of CO 2 , CH 4 and N 2 O were obtained for poultry barns in a cold region. • Seasonal and diurnal variations of concentrations and emissions were identified. • CH 4 and N 2 O emissions were lower than poultry barns in other climates. • T and VR positively impacted on N 2 O for the broiler barn and CH 4 for the layer barn. • Manure removal had no obvious effect on GHG emission for the layer barn. Diurnal and seasonal variations of three GHG (CO 2 , CH 4 , and N 2 O) emissions were characterized for poultry barns in a cold region climate. [ABSTRACT FROM AUTHOR]

Sixteen months of continuous measurements and the analysis of atmospheric mercury (gaseous elemental mercury GEM, gaseous oxidized mercury GOM, and particulate bound mercury PBM) under urban and coastal settings were conducted in Southeastern Texas. At the urban site, the GEM mean mixing ratio was 185 ppqv, 5%−10% higher than the Northern Hemisphere GEM background level. GOM and PBM mixing ratios were as much as six times higher than their background level. The coastal site GEM mean mixing ratio was 165 ppqv, higher than other coastal sites located in the Northern Hemisphere. GOM and PBM mean mixing ratios at the coastal site were 0.75 ppqv and 0.58 ppqv. The urban site had a higher frequency of high mercury events (>300 ppqv) compared to the coastal site. The diurnal patterns were found for both sites: In the urban environment, GEM accumulated to the maximum mixing ratio just after sunrise and decreased to the minimum mixing ratio in late afternoon. In the coastal environment, GEM decreased at night reaching its minimum mixing ratio before sunrise. The relationship between atmospheric mercury species and meteorological parameters was investigated. An examination of the relationship between atmospheric mercury species and key trace gases was conducted as well, showing that the concurrence of GEM, CO2, CO, CH4, and SO2 maximum mixing ratios was notable and provided evidence they may originate from the same emission source. The coastal site was at times influenced by polluted air from urban Houston and the cleaner Gulf of Mexico marine air at other times.

Background A scarcely studied consequence of urbanization is the effect of temporal stabilization of the environment on bird communities. This alteration is thought to dampen environmental variations between day and night, seasons and years, promoting a temporal persistence of bird composition in urban areas. The aim of this study was to review current evidence of temporal stabilization of biotic and abiotic factors in urban environments and the potential effects of such stabilization on temporal variation of bird species presence at different temporal scales. Methods I selected the literature by searching published articles and book chapters using Scopus and Google scholar. I only included articles that compared the temporal variation of bird composition or resources between different levels of urbanization. Results In general, there is evidence of temporal stabilization of abiotic and biotic factors at the three time scales considered. At the diurnal scale, the main factor considered was artificial light in the context of light pollution. At the seasonal and interannual scales, several case studies found a smaller temporal variation of primary productivity in urban than in natural and rural areas. Bird species composition showed more stabilization in urban environments at the three temporal scales: (1) several case studies reported bird activity at night, associated with artificial light; (2) studies in urban parks and along urbanization gradients showed smaller seasonal variation of bird composition in the more urbanized areas; and (3) in general, case studies along urbanization gradients showed smaller interannual variation of bird composition in the more urbanized areas, although some studies showed no relationships or opposite trends than expected. Discussion The published evidence suggests that urban areas dampen the natural cycles at several temporal scales. The stabilization of biotic and abiotic factors, such as light, temperature, food and habitat structure, is desynchronized from natural diurnal, seasonal and interannual cycles. However, there is a dearth of long-term comparisons of bird composition and studies that simultaneously analyze the relationship between resources and bird composition stabilization at the seasonal and interannual scales. More research is needed in the Southern hemisphere, where there is a lack of studies dealing with the seasonal and interannual variations of primary productivity along urbanization gradients and nocturnal activity of bird species. A future research agenda should include differentiation of spatial and temporal homogenization of avifaunas.

Background. A scarcely studied consequence of urbanization is the effect of temporal stabilization of the environment on bird communities. This alteration is thought to dampen environmental variations between day and night, seasons and years, promoting a temporal persistence of bird composition in urban areas. The aim of this study was to review current evidence of temporal stabilization of biotic and abiotic factors in urban environments and the potential effects of such stabilization on temporal variation of bird species presence at different temporal scales. Methods. I selected the literature by searching published articles and book chapters using Scopus and Google scholar. I only included articles that compared the temporal variation of bird composition or resources between different levels of urbanization. Results. In general, there is evidence of temporal stabilization of abiotic and biotic factors at the three time scales considered. At the diurnal scale, the main factor considered was artificial light in the context of light pollution. At the seasonal and interannual scales, several case studies found a smaller temporal variation of primary productivity in urban than in natural and rural areas. Bird species composition showed more stabilization in urban environments at the three temporal scales: (1) several case studies reported bird activity at night, associated with artificial light; (2) studies in urban parks and along urbanization gradients showed smaller seasonal variation of bird composition in the more urbanized areas; and (3) in general, case studies along urbanization gradients showed smaller interannual variation of bird composition in the more urbanized areas, although some studies showed no relationships or opposite trends than expected. Discussion. The published evidence suggests that urban areas dampen the natural cycles at several temporal scales. The stabilization of biotic and abiotic factors, such as light, temperature, food and habitat structure, is desynchronized from natural diurnal, seasonal and interannual cycles. However, there is a dearth of long-term comparisons of bird composition and studies that simultaneously analyze the relationship between resources and bird composition stabilization at the seasonal and interannual scales. More research is needed in the Southern hemisphere, where there is a lack of studies dealing with the seasonal and interannual variations of primary productivity along urbanization gradients and nocturnal activity of bird species. A future research agenda should include differentiation of spatial and temporal homogenization of avifaunas. [ABSTRACT FROM AUTHOR]

Temporal variations of vehicle emissions are affected by various compounding factors in the real world. The focus of this study is to determine the effects of ambient conditions and post-tailpipe changes on traffic emissions measured in the near-road region. Emission factors allowed for the isolation of the traffic signal and accounted for effects of local meteorology and dilution. Five month-long measurement campaigns were conducted at an urban near-road site that exhibited a broad range of ambient conditions with temperatures ranging between −18 and +30 °C. Particle number emission factors were 2.0× higher in the winter relative to the summer, which was attributed to changes in particles post-tailpipe. Conversely, toluene emissions were 2.5× higher in the summer relative to the winter, attributed to changes in fuel composition. Diurnal trends of emission factors showed substantial increases in emissions during the morning rush hour for black carbon (1.9×), particle number (2.4×), and particle-bound polycyclic aromatic hydrocarbons (3.0×), affected by fleet make-up. In contrast, particle number emission factors were highest midday with mean values 3.7× higher than at night. This midday increase was attributed to particle formation or growth from local traffic emissions and showed different wind direction dependence than regional events. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) emissions were quantified for a naturally ventilated free-stall dairy barn in the Canadian Prairies climate through continuous measurements for a year from February 2015 to January 2016, with ventilation rate estimated by a CO 2 mass balance method. The results were categorized into seasonal emission profiles with monthly data measured on a typical day, and diurnal profiles in cold (January), warm (July), and mild seasons (October) of all three gases. Seasonal CO 2 , CH 4 , and N 2 O concentrations greatly fluctuated within ranges of 593–2433 ppm, 15–152 ppm, and 0.32–0.40 ppm, respectively, with obviously higher concentrations in the cold season. Emission factors of the three gases were summarized: seasonal N 2 O emission varied between 0.5 and 10 μg s −1 AU −1 with lower emission in the cold season, while seasonal CO 2 and CH 4 emissions were within narrow ranges of 112–119 mg s −1 AU −1 and 2.5–3.5 mg s −1 AU −1 . The result suggested a lower enteric CH 4 emission for dairy cows than that estimated by Environment Canada (2014). Significant diurnal effects (P < 0.05) were observed for CH 4 emissions in all seasons with higher emissions in the afternoons and evenings. The total greenhouse gas (GHG) emission, which was calculated by summing the three GHG in CO 2 equivalent, was mainly contributed by CO 2 and CH 4 emissions and showed no significant seasonal variations (P > 0.05), but obvious diurnal variations in all seasons. In comparison with previous studies, it was found that the dairy barn in a cold region climate with smaller vent openings had relatively higher indoor CO 2 and CH 4 concentrations, but comparable CO 2 and CH 4 emissions to most previous studies. Besides, ventilation rate, temperature, and relative humidity all significantly affected the three gas concentrations with the outdoor temperature being the most relevant factor (P < 0.01); however, they showed less or no statistical relations to emissions. [ABSTRACT FROM AUTHOR]

Abstract: We investigate atomic hydrogen (H) variability from the mesopause to the upper thermosphere, on time scales of solar cycle, seasonal, and diurnal, using measurements made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite, and simulations by the National Center for Atmospheric Research Whole Atmosphere Community Climate Model‐eXtended (WACCM‐X). In the mesopause region (85 to 95 km), the seasonal and solar cycle variations of H simulated by WACCM‐X are consistent with those from SABER observations: H density is higher in summer than in winter, and slightly higher at solar minimum than at solar maximum. However, mesopause region H density from the Mass‐Spectrometer‐Incoherent‐Scatter (National Research Laboratory Mass‐Spectrometer‐Incoherent‐Scatter 00 (NRLMSISE‐00)) empirical model has reversed seasonal variation compared to WACCM‐X and SABER. From the mesopause to the upper thermosphere, H density simulated by WACCM‐X switches its solar cycle variation twice, and seasonal dependence once, and these changes of solar cycle and seasonal variability occur in the lower thermosphere (~95 to 130 km), whereas H from NRLMSISE‐00 does not change solar cycle and seasonal dependence from the mesopause through the thermosphere. In the upper thermosphere (above 150 km), H density simulated by WACCM‐X is higher at solar minimum than at solar maximum, higher in winter than in summer, and also higher during nighttime than daytime. The amplitudes of these variations are on the order of factors of ~10, ~2, and ~2, respectively. This is consistent with NRLMSISE‐00. [ABSTRACT FROM AUTHOR]

The Ionospheric Total Electron Content (TEC) data measured simultaneously by analyzing dual-frequency signals of the Global Position System (GPS) in two northern Nigeria equatorial stations: Ahmadu Bello University Zaria (ABUZ) with geographic latitude (11.16° N) and Longitude(7.65° E) and Birnin Kebbi Polytechnic (BKFP) with geographic latitude(12.46° N) and Longitude(4.20°E) during the year 2012 (Rz =57.58) was used to study the diurnal, monthly and seasonal variation of equatorial ionosphere. The result shows that the mean TEC varies from a minimum at 0600 hrs LT to a peak value at about 1500 to 1700 hrs LT and then decreases. The seasonal variation in TEC maximizes during the equinox months followed by winter and is minimum during the summer months. [ABSTRACT FROM AUTHOR]

The ionic composition of PM2.5 samples was investigated by their datasets of cationic (Na+, NH4+, K+, Mg2+, and Ca2+) and anionic components (Cl-, NO3-, and SO42-) along with relevant environmental parameters collected from an urban monitoring site in Korea at hourly intervals in 2010. The mean (and SD) annual concentration of PM2.5 was computed as 25.3 μg m-3 with the wintertime maximum. In addition, sum concentrations (neq m-3) of five cationic species (291) were slightly lower than 3 anionic species (308). Most cations exhibited the highest seasonal values in spring, while anions showed more diversified seasonal patterns. According to PCA, five major source categories were apparent with the relative dominance of secondary inorganic aerosols (SIA). The results of our study suggest consistently that the distribution of ionic constituents in an urban area is affected by the combined effects of both natural and anthropogenic processes.

Mood regulation is known to be affected by the change of seasons. Recent research findings have suggested that mood regulation may be influenced by the function of circadian clocks. In addition, the activity of brown adipocytes has been hypothesized to contribute to mood regulation. Here, the overarching link to mood disorders might be the circadian clock protein NR1D1 (nuclear receptor subfamily 1, group D, member 1).

This paper reports on the effects of diurnal, seasonal, geomagnetic and solar activity on GPS Vertical Total Electron Content (VTEC) measurements at a high-latitude station in Husafell, Iceland (64.7°N, 21.0°W) from March 2009 to February 2010. According to the diurnal VTEC pattern, there was generally a build-up region at sunrise (0500-1000 LT), a daytime plateau in the afternoon (1200-1400 LT), and a decay region from evening to pre-dawn (1800-0400 LT). The month-to-month analysis showed high VTEC variability, particularly in February 2010, due to an increase in solar activity. The VTEC showed a high variability during both winter and the equinoxes, with the highest value being 90%, but showed a low variability in summer. Two abnormal peaks appeared at sunrise and sunset in winter and the equinoxes. These peaks were the result of steep density gradients caused by the onset and turnoff of solar radiation. The correlation analysis yielded almost no correlation between the VTEC and geomagnetic activity but showed a high correlation with solar activity for all the seasons, particularly at night-time. [ABSTRACT FROM AUTHOR]

This article describes results from a new four-year (2009-2012) radar-based precipitation climatology for the southeastern United States (SE USA). The climatology shows that a size-based classification between mesoscale precipitation features (MPF) and isolated precipitation reveals distinct seasonal and diurnal variability of precipitation. On average, from 70 to 90% of precipitation is associated with MPF, generally less in the summertime and in southern coastal regions. MPF precipitation has a relatively small seasonal cycle except in Florida and the warm offshore waters of the Gulf Stream. In contrast, isolated precipitation has a dramatic seasonal cycle that outlines the SE USA coastline whereas the MPF precipitation does not, consistent with a thermodynamic mechanism for onshore isolated storms in coastal regions. In summer, the isolated precipitation preferentially forms offshore at night, and dramatically 'flips' inland by early afternoon. In contrast, MPF precipitation has no clear diurnal variations except in the southern coastal region in the summer, likely associated with sea breeze convection organized on the mesoscale. These results suggest that the MPF versus isolated precipitation system framework provides a useful basis for future studies of large-scale and local controls on precipitation and resulting implications for long-range predictability of precipitation. [ABSTRACT FROM AUTHOR]

Mood regulation is known to be affected by the change of seasons. Recent research findings have suggested that mood regulation may be influenced by the function of circadian clocks. In addition, the activity of brown adipocytes has been hypothesized to contribute to mood regulation. Here, the overarching link to mood disorders might be the circadian clock protein nuclear receptor subfamily 1, group D, member 1. [ABSTRACT FROM AUTHOR]

Continuous in-situ measurements of surface ozone (O), carbon monoxide (CO) and oxides of nitrogen (NOx) were conducted at Udaipur city in India during April 2010 to March 2011. We have analyzed the data to investigate both diurnal and seasonal variations in the mixing ratios of trace gases. The diurnal distribution of O showed highest values in the afternoon hours and lower values from evening till early morning. The mixing ratios of CO and NOx showed a sharp peak in the morning hours but lowest in the afternoon hours. The daily mean data of O, CO and NOx varied in the ranges of 5-51 ppbv, 145-795 ppbv and 3-25 ppbv, respectively. The mixing ratios of O were highest of 28 ppbv and lowest 19 ppbv during the pre-monsoon and monsoon seasons, respectively. While the mixing ratios of both CO and NOx showed highest and lowest values during the winter and monsoon seasons, respectively. The diurnal pattern of O is mainly controlled by the variations in photochemistry and planetary boundary layer (PBL) depth. On the other hand, the seasonality of O, CO and NOx were governed by the long-range transport associated mainly with the summer and winter monsoon circulations over the Indian subcontinent. The back trajectory data indicate that the seasonal variations in trace gases were caused mainly by the shift in long-range transport pattern. In monsoon season, flow of marine air and negligible presence of biomass burning in India resulted in lowest O, CO and NOx values. The mixing ratios of CO and NOx show tight correlations during winter and pre-monsoon seasons, while poor correlation in the monsoon season. The emission ratio of ∆CO/∆NOx showed large seasonal variability but values were lower than those measured over the Indo Gangetic Plains (IGP). The mixing ratios of CO and NOx decreased with the increase in wind speed, while O tended to increase with the wind speed. Effects of other meteorological parameters in the distributions of trace gases were also noticed. [ABSTRACT FROM AUTHOR]

Abstract: Black carbon (BC) aerosols were measured using an aethalometer (AE-31) at Pulchowk Campus, an urban location of Kathmandu valley, Nepal from May 2009 to April 2010. The amount of BC in the total mass of the suspended particulate matter (TSP) were estimated by comparing the average BC with mass of particulate matter simultaneously measured with frm Omni Ambient Air Sampler for the last two months (March–April, 2010). BC concentration shows significant temporal variation with monthly mean concentration varying between 14.9 μg m− 3 and 3.0 μg m− 3. The highest daily mean concentration was recorded as high as 39.9 μg m− 3. The highest concentration of BC occurred during winter and pre-monsoon seasons. The lowest concentration of BC was found during monsoon and post-monsoon seasons. A distinct diurnal variation of BC with two high peaks occurred; one in around 09:00 morning and another late evening around 20:00 local time. Minimum BC concentration was also observed in the afternoon. The annual average of BC for observation period was 8.6 ± 4.4 μg m− 3. The seasonal, monthly and diurnal variation of BC were found to be significantly influenced by the local traffic movements, the domestic and industrial fuel consuming activities, wind speed, wind direction and rain. The amount of BC in the total mass of particulate matters during the observed period varied between 11.6 and 56.2 percent. This variation is attributed to the high amount of re-suspension of dust particles in the atmosphere of the valley. [Copyright &y& Elsevier]

The ionic composition of PM2.5 samples was investigated by their datasets of cationic (Na+, NH4+, K+, Mg2+, and Ca2+) and anionic components (Cl-, NO3-, and SO42-) along with relevant environmental parameters collected from an urban monitoring site in Korea at hourly intervals in 2010. The mean (and SD) annual concentration of PM2.5 was computed as 25.3 μg m-3 with the wintertime maximum. In addition, sum concentrations (neq m-3) of five cationic species (291) were slightly lower than 3 anionic species (308). Most cations exhibited the highest seasonal values in spring, while anions showed more diversified seasonal patterns. According to PCA, five major source categories were apparent with the relative dominance of secondary inorganic aerosols (SIA). The results of our study suggest consistently that the distribution of ionic constituents in an urban area is affected by the combined effects of both natural and anthropogenic processes. [ABSTRACT FROM AUTHOR]

Abstract: The diurnal and seasonal changes of the variability (VR) of Maximum Useable Frequency (MUF) are compared with those of peak electron density (NmF2) at Ibadan (7.4°N, 3.9°E, 6°S dip) in the African sector. Also compared is the latitudinal effect on both characteristics by combining data from Singapore (1.3°N, 103.8°E, 17.6°S dip) in the East Asian sector and Slough (51.5°N, 359.4°E, 66.5°S dip) in the European sector. MUF VR is found to be about half of NmF2 VR at all the hours and seasons and during the solar cycle epochs considered for the three stations. While nighttime MUF VR is greater in June Solstice and September Equinox during both low and moderate solar activities and in September Equinox and December Solstice during high solar activity, nighttime NmF2 VR is greater in June Solstice and September Equinox during high solar activity and greater at the equinoxes during low and moderate solar activities. This signifies a shift in nighttime MUF peak VR from the middle six months during low and moderate solar activities to the last half of the year during high solar activity. Daytime VR of both characteristics are not observed to show any seasonal variation. MUF VR and that of NmF2 are found to increase and decrease alternately with the Zurich sunspot number (Rz) for Ibadan and Singapore. For Slough, the VR of both characteristics increases with Rz during the first half of the day. It then increases and decreases alternately with Rz during the remaining hours of the day. While nighttime MUF VR decreases with latitude, just like nighttime NmF2 VR, no latitudinal effect is found for daytime VR of both characteristics. [Copyright &y& Elsevier]

In order to investigate the thermal environment of the tidal flats of the Ariake Sea, Japan, two study areas, Iida and Higashiyoka tidal flats were selected. By installing five nos. of thermocouple at different specified depths (0.10, 0.20, 0.50,1.0 and 2.0 m) connected with data logger were used to observe diurnal variation of temperature during the 1st April to 8th April, 2006 at Higashiyoka tidal flat. The measured temperature was stored automatically at 1 h interval in the data logger. To observe seasonal variation of temperature in different depths , temperature was measured by inserting the thermocouple at 0.10 m depths interval in the last week of every month at both study areas in the Ariake sea tidal flat. The diurnal temperature variation was more visible near the surface (0.10 m and 0.20 m) indicating the influence of solar radiation in that portion, however in the deeper region (1.0 and 2.0 m depth) the temperature was dominated by thermal properties of the mud. From seasonal variation of temperature it was seen that during spring and summer heat was transferred from subsurface to the deeper area but during winter and autumn opposite phenomenon was observed. Finally, equations are proposed to predict the temperature in the tidal flat mud in different seasons. [ABSTRACT FROM AUTHOR]

The quantification of diurnal and seasonal gas (NH3, H2S, and CO2) and PM10 concentrations and emission rates (GPCER) from livestock production facilities is indispensable for the development of science-based setback determination methods and evaluation of improved downwind community air quality resulting from the implementation of gas pollution control. The purpose of this study was to employ backpropagation neural network (BPNN) and generalized regression neural network (GRNN) techniques to model GPCER generated and emitted from swine deep-pit finishing buildings as affected by time of day, season, ventilation rates, animal growth cycles, in-house manure storage levels, and weather conditions. The statistical results revealed that the BPNN and GRNN models were successfully developed to forecast hourly GPCER with very high coefficients of determination (R²) from 81.15% to 99.46% and very low values of systemic performance indexes. These good results indicated that the artificial neural network (ANN) technologies were capable of accurately modeling source air quality within and from the animal operations. It was also found that the process of constructing, training, and simulating the BPNN models was very complex. Some trial-and-error methods combined with a thorough understanding of theoretical backpropagation were required in order to obtain satisfying predictive results. The GRNN, based on nonlinear regression theory, can approximate any arbitrary function between input and output vectors and has a fast training time, great stability, and relatively easy network parameter settings during the training stage in comparison to the BPNN method. Thus, the GRNN was characterized as a preferred solution for its use in air quality modeling. [ABSTRACT FROM AUTHOR]

Abstract: Changes in vocal behaviour observed in temperate songbirds have been linked to changes in photoperiod. Research has focused on the fluctuation of hormones that lead to photosensitivity, photostimulation and photorefractoriness, as well as the ‘dawn chorus’ observed in numerous species. However, photoperiod in the natural environment is a complex event that occurs as seasons change. To determine the natural relationships between photoperiod and vocal behaviour we sampled vocal production of black-capped chickadees for three major vocal classes over one year at dawn, meridian and sunset. Fee-bee song production increased twice, once in the winter and once in the spring, and occurred almost exclusively at dawn. Chick-a-dee call production was highest in autumn and winter generally at the meridian. Gargle production did not differ significantly by season; however, the most gargle production occurred during the winter at the meridian. [Copyright &y& Elsevier]

Ambient measurements of hazardous air pollutants (HAPs, air toxics) collected in the United States from 1990 to 2005 were analyzed for diurnal, seasonal, and/or annual variability and trends. Visual and statistical analyses were used to identify and quantify temporal variations in air toxics at national and regional levels. Sufficient data were available to analyze diurnal variability for 14 air toxics, seasonal variability for 24 air toxics, and annual trends for 26 air toxics. Four diurnal variation patterns were identified and labeled invariant, nighttime peak, morning peak, and daytime peak. Three distinct seasonal patterns were identified and labeled invariant, cool, and warm. Multiple air toxics showed consistent decreasing trends over three trend periods, 1990–2005, 1995–2005, and 2000–2005. Trends appeared to be relatively consistent within chemically similar pollutant groups. Hydrocarbons such as benzene, 1,3-butadiene, styrene, xylene, and toluene decreased by approximately 5% or more per year at more than half of all monitoring sites. Concentrations of carbonyl compounds such as formaldehyde, acetaldehyde, and propionaldehyde were equally likely to have increased or decreased at monitoring sites. Chlorinated volatile organic compounds (VOCs) such as tetrachloroethylene, dichloromethane, and methyl chloroform decreased at more than half of all monitoring sites, but decreases among these species were much more variable than among the hydrocarbons. Lead particles decreased in concentration at most monitoring sites, but trends in other metals were not consistent over time. [Copyright &y& Elsevier]

To estimate the gross CO2 flux (F CO2 ) of deciduous coniferous forest from canopy spectral reflectance, we introduced spectral vegetation indices (VIs) into a light use efficiency (LUE) model of mature Japanese larch (Larix kaempferi) forest. We measured the eddy covariance CO2 flux and spectral reflectance of larch canopy at half-hourly intervals during one growing season, and investigated the relationships between the parameters of the LUE model (FAPAR, ɛ) and 3 types of VIs (NDVI, PRI, EVI) in both clear sky and cloudy conditions. FAPAR (fraction of absorbed photosynthetically active radiation) had a positive linear relationship with both NDVI (normalized difference vegetation index) and EVI (enhanced vegetation index), and the sky condition had little effect on the relationships. The relative RMSE (root mean square error) of the APAR (absorbed photosynthetically active radiation) based on the incoming PAR and estimated FAPAR from a linear function of NDVI was less than 10.5%, irrespective of sky condition. Half-hourly values of ɛ (conversion efficiency of absorbed energy) showed both seasonal variation related to leaf phenology and short-term variation related to light intensity due to varied sun position and sky condition. Both EVI and PRI (photochemical reflectance index) were significantly correlated with ɛ. EVI showed a positive linear relationship with ɛ as a result of their similar seasonal variation. However, since EVI did not detect short-term variation of ɛ, their relationship differed among sky conditions. On the other hand, although PRI could trace the short-term variation of ɛ in green needles, the relationship became non-linear due to drastic reduction of PRI in the senescent needles. EVI/(PRI/PRImin), a combined index based on a 6-day moving minimum value of PRI (PRImin), showed a linear relationship with half-hourly values of ɛ throughout the seasons irrespective of sky condition. This index allow us to estimate ɛ in all sky conditions with a smaller error (rRMSE = 35.2%) than using EVI or PRI alone (38.7%–48.7%). Consequently, this combined index-derived ɛ and NDVI-based FAPAR gave a low estimation error of F CO2 (rRMSE = 36.4%, RMSE = 8.3 μmol m−2 s−1). Although there are still various issues to resolve, including adaptive limit and combination of vegetation index type, we conclude that the combination of PRI and EVI increased the accuracy of estimation of CO2 uptake in deciduous forest even though sky conditions varied. [Copyright &y& Elsevier]

Abstract: Total gaseous mercury flux measurements were carried out over three urban ground surfaces for 1 year in Tuscaloosa, AL, USA. The objective was to provide insight into the characteristics of gaseous mercury flux from urban surface covers. Bare soil, grass, and pavement surfaces were sampled as the most representative terrestrial surfaces throughout Tuscaloosa. Measurements were quantified over diurnal and seasonal periods and relationships were developed between flux from each surface and major meteorological parameters. Averaging data over the entire year, fluxes from each surface were as follows: bare soil (6.48ng/m−2 h), pavement (0.02ng/m−2 h), and grass (0.28ng/m−2 h). Pavement and many grass fluxes were small and arguably indistinguishable from chamber blanks. The soil surface displayed the largest difference between evening and daytime flux, particularly during the spring and summer seasons (i.e., evening low (12ng/m−2 h) to daytime high (30ng/m−2 h) during summer). The grass surface showed the largest amount of atmospheric deposition, mainly during the spring and fall periods (up to −2.31ng/m−2 h), with pavement showing somewhat less (up to −1.05ng/m−2 h). Bare soil showed very little to negligible deposition. Diurnal flux variance was greater than seasonal flux variance for all surfaces. The regression results demonstrate that despite the highly dissimilar physical and geochemical make-up of pavement, bare soil, and grass, each surface displayed similar responses to time series change in meteorological parameters. However, each surface may be seasonally controlled or limited by different sets of meteorological parameters. [Copyright &y& Elsevier]

Abstract: To clarify how seasonal changes of environmental luminosity affect melatonin secretion in human beings, nocturnal urine samples were collected every 2 months throughout the year from 20 outdoor workers living in an area, for which exact data on solar irradiance and temperature were available (67–68°N). Melatonin secretion rates, determined by melatonin-specific radioimmunoassays, were found to be twice as high in December as in April, i.e. 0.88 ± 0.16 nmol/12 hr (mean ± S.E.) versus 0.43 ± 0.09 nmol/12 hr, P < 0.05. Regression analyses showed that melatonin values correlated best inversely with solar irradiance reflected off the ground (albedo). A 10-fold increase in albedo for 1–4 weeks prior to the date of urine sampling was associated with a ca. 50% reduction in melatonin secretion. Association with global irradiance was weaker and did not correlate with temperature. Thus, light reaching the eyes via snow or other reflecting surfaces appears to be most effective. These results assist us in understanding some of the mechanisms involved in certain biological phenomena that exhibit seasonal variations as, for instance, reproduction and self-destructive behavior. [ABSTRACT FROM AUTHOR]

Seasonal dynamics of net photosynthesis (Anet) in 2-year-old seedlings of Pinus brutia Ten., Pinus pinea L. and Pinus pinaster Ait. were investigated. Seedlings were grown in the field in two light regimes: sun (ambient light) and shade (25% of photosynthetically active radiation (PAR)). Repeated measures analyses over a 12-month period showed that Anet varied significantly among species and from season to season. Maximum Anet in sun-acclimated seedlings was low in winter (yet remained positive) and peaked during summer. Maximum Anet was observed in June in P. pinea (12 μmol m−2 s−1), July in P. pinaster (23 μmol m−2 s−1) and August in P. brutia (20 μmol m−2 s−1). Photosynthetic light response curves saturated at a PAR of 200–300 μmol m−2 s−1 in winter and in shade-acclimated seedlings in summer. Net photosynthesis in sun-acclimated seedlings did not saturate at PAR up to 1900 μmol m−2 s−1 in P. brutia and P. pinaster. Minimum air temperature of the preceding night was apparently one of the main factors controlling Anet during the day. In shade-acclimated seedlings, photosynthetic rates were reduced by 50% in P. brutia and P. pinaster and by 20% in P. pinea compared with those in sun-acclimated seedlings. Stomatal conductance was generally lower in shaded seedlings than in seedlings grown in the sun, except on days with a high vapor pressure deficit. Total chlorophyll concentration per unit leaf area, specific leaf area (SLA) and height significantly increased in P. pinea in response to shade, but not in P. pinaster or P. brutia. In response to shade, P. brutia showed a significant increase in total chlorophyll concentration but not SLA. Photosynthetic and growth data indicate that P. pinaster and P. brutia are more light-demanding than P. pinea. [ABSTRACT FROM PUBLISHER]

Aldehydes are an airborne byproduct of many industrial processes, vehicle transportation, and emissions from numerous natural sources. To characterize aldehyde concentrations in ambient air of the Savannah, Georgia area, air samples for 3 aldehydes (formaldehyde, acetaldehyde, and propionaldehyde) were collected at five sites on a monthly basis over a 12-month period from December of 1995 through November 1996. Four of the sites were in central Savannah and the fifth site was located in a rural area about 56 km south of Savannah. During each 24-hr sampling episode, samples were collected in two 12-hr periods approximating daylight and nighttime hours, following U.S. EPA Method TO-11. Formaldehyde concentrations ranged from 0.17 to 6.80 μg m-3, acetaldehyde concentrations ranged from 0.07 to 7.60 μg m-3, and propionaldehyde levels ranged from 0.02 to 9.10 μg m-3. On average, the four sites in Savannah had higher aldehyde concentrations than the rural site (2.0 versus 1.2 μg m-3 for formaldehyde, 2.3 versus 1.7 μg m-3 for acetaldehyde, and 1.2 versus 1.0 μg m-3 for propionaldehyde). The daytime concentrations for formaldehyde and acetaldehyde were higher than the nighttime levels. The data from all the sites were within published worldwide background values for aldehydes. [ABSTRACT FROM AUTHOR]

Circadian clocks have evolved a slowing-down mechanism. Temperature may be the original and universal time-giver to the organism. Brown adipose tissue generates heat and guides the circadian rhythm of core body temperature. The cryptochrome proteins regulate the temperature entrainability, and their dysfunction may let the activation of brown adipose tissue affect the brain more easily. Therefore, the activity of brown adipose tissue may compromise the slowing-down mechanism and thereby contribute to the emergence of mood disorders and the increase in suicide mortality around the time of puberty. [ABSTRACT FROM PUBLISHER]

1. A bird’s mass in winter should reflect the trade-off between the benefits of an increased energy store to reduce starvation risk, and its costs in terms of increasing mass-dependent predation risk. State-dependent models of this trade-off predict that as starvation risk increases then energy reserves should (i), increase, and (ii) be acquired earlier in the day. 2. Blackbirds increased their minimum weight by 25. ±. 1·5% in midwinter; adults weighed significantly more than juveniles in midwinter, but weighed less in late winter. Weight for both sexes, and particularly adults, decreased with increasing daylength, but weight increases with respect to temperature decreases were most pronounced in males. Female blackbirds showed relatively small seasonal weight changes so that their midwinter mass-dependent predation risk relative to males was independent of diurnal weight changes. 3. Blackbirds lost at least 1–9% of their body weight overnight depending on temperature. Over 60% of the weight lost was then regained in the first 3 hours after dawn, with only 5% being regained after 12.00 h. The pattern of early morning weight gain was maintained throughout the winter, with the ratio of weight gain rates in the first 4. h of dawn compared to the rest of the day being c.. 3:1 in midwinter (when individuals maintained high weights) and in early spring (when individuals were losing weight seasonally). 4. The results agree with the theoretical prediction that energy reserves should increase as risk of starvation increased (as measured by seasonal factors such as cold, short midwinter days). There was, however, little change in the seasonal pattern of diurnal weight gain, with weight always being gained early in the day. In the likely absence of foraging constraints within the study system, this result fits the predictions of state-dependent foraging models... [ABSTRACT FROM AUTHOR]

Limited studies, particularly in the low-latitudes, exist that monitor cave ventilation, an important process dictating cave geochemical properties. To investigate cave ventilation, we present multi-year monitoring results, including observations of cave-air CO 2 , cave-air temperature, and cave-air relative humidity, from three Brazilian caves: Paraíso (4.07°S, 55.45°W), Tamboril (16.19°S, 46.59°W), and Jaraguá (21.08°S, 56.58°W). Cave ventilation regimes on numerous temporal scales are established. Highest concentrations of cave-air CO 2 are recorded during austral summers from a multi-year monitoring effort at Jaraguá Cave. Conversely, lowest cave-air CO 2 concentration are recorded during austral winters. The variability in cave-air CO 2 is attributed to seasonally varying temperature contrasts between surface- and cave-air, which results in buoyancy-driven cave-air CO 2 exchange with surface-air CO 2. Speleothem growth as calcite precipitation is expected to be biased towards the austral winter season when cave-air CO 2 is lowest. This understanding of cave ventilation affects the geochemical interpretation of speleothems as recorders of past climate change from caves in the low-latitudes. Next, continuous CO 2 measurements near the entrance of Tamboril Cave suggest diurnal ventilation attributed to diurnal cave- and surface-air temperature differences. CO 2 monitored from the deeper part of Paraíso and Jaraguá Cave do not exhibit this diurnal cycle. Further, virtual temperature calculations suggest that buoyancy contrasts between cave- and surface-air drive daily to weekly cave ventilation in all three caves. The established cave ventilation regimes provide an additional framework to interpret speleothem based terrestrial environmental change spanning the low- and mid-latitudes. By investigating spatially disparate caves across Brazil, we find buoyancy driven cave ventilation to be a unifying mechanism. Our results suggest that exchange between cave- and surface-air occurs seasonally in caves across the low- and mid-latitudes. These results suggest buoyancy driven ventilation is important not only at mid-latitudes but also in the tropics where speleothems are typically suited to investigate paleomonsoon variability. Therefore, prior knowledge of cave ventilation in caves that contain speleothems suitable for paleoclimate reconstructions is critical to robustly infer subsequent geochemical trends across different timescales (seasonal - centennial). • We present multi-year monitoring of cave-air CO 2 , temperature, relative humidity from three caves across Brazil. • Seasonal ventilation associated with buoyancy depends on surface- and cave – air temperature gradient. •. • Diurnal ventilation at site near cave entrance is likely likely linked to diurnal surface-air temperature. • Cave ventilation regimes on multiple time-scales can be present in the same cave. [ABSTRACT FROM AUTHOR]

Sixteen months of continuous measurements and the analysis of atmospheric mercury (gaseous elemental mercury GEM, gaseous oxidized mercury GOM, and particulate bound mercury PBM) under urban and coastal settings were conducted in Southeastern Texas. At the urban site, the GEM mean mixing ratio was 185 ppqv, 5%–10% higher than the Northern Hemisphere GEM background level. GOM and PBM mixing ratios were as much as six times higher than their background level. The coastal site GEM mean mixing ratio was 165 ppqv, higher than other coastal sites located in the Northern Hemisphere. GOM and PBM mean mixing ratios at the coastal site were 0.75 ppqv and 0.58 ppqv. The urban site had a higher frequency of high mercury events (>300 ppqv) compared to the coastal site. The diurnal patterns were found for both sites: In the urban environment, GEM accumulated to the maximum mixing ratio just after sunrise and decreased to the minimum mixing ratio in late afternoon. In the coastal environment, GEM decreased at night reaching its minimum mixing ratio before sunrise. The relationship between atmospheric mercury species and meteorological parameters was investigated. An examination of the relationship between atmospheric mercury species and key trace gases was conducted as well, showing that the concurrence of GEM, CO2, CO, CH4, and SO2 maximum mixing ratios was notable and provided evidence they may originate from the same emission source. The coastal site was at times influenced by polluted air from urban Houston and the cleaner Gulf of Mexico marine air at other times. [ABSTRACT FROM AUTHOR]