Amplitude Of Seasonal Variation Research Articles

Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: I. Diurnal Tides

AbstractIn the mesosphere and lower thermosphere, diurnal tides are responsible for the dynamics and structures at low latitudes since they have largest amplitudes there. Based on the 20‐year (2002−2021) observations from Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics Doppler interferometer (TIDI), we investigate the seasonal variations of three diurnal tidal components (DW1, DE3, DW2), and their responses to stratospheric quasi‐biennial oscillation (SQBO) and solar cycle globally. The results show that: (a) DW1, DE3 and DW2 show prominent semiannual (SAO) and annual oscillations (AO) in their peak regions where the ratio of their annual mean amplitude to their maximum annual mean amplitude is larger than 0.8. DW1 also exhibit strong terannual oscillations (TAO) especially in meridional wind. (b) The responses of the amplitudes of seasonal variations of DW1, DE3 and DW2 to SQBO and solar cycle are comparable in magnitude to those of their annual mean amplitudes (for response to solar cycle, even stronger in some cases), and thus cannot be neglected. (c) In their respective peak regions, the responses of annual mean amplitudes of these diurnal tidal components to SQBO are uniformly positive except DW2, and their responses to solar cycle are uniformly negative. For these diurnal tides, the amplitudes of the dominant seasonal variations exhibit consistent response patterns with those of annual means to the SQBO/solar cycle. (d) Empirical formulas are given, which well describe the seasonal and interannual variations of dominant diurnal tidal components in their peak regions.

Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: II. Semidiurnal and Terdiurnal Tides

AbstractIn the mesosphere and lower thermosphere (MLT) region, semidiurnal and terdiurnal tides are dominant at middle and high latitudes and are important for the dynamics and structures. Using the global neutral horizontal wind data in the MLT region observed by TIMED Doppler interferometer from 2002 to 2021, the seasonal and interannual variations of six semidiurnal and terdiurnal tidal components (SW2, SW3, SW4, TW3, TW2 and TW4) are investigated. Particularly, the responses of these tidal components to the stratospheric quasi‐biennial oscillation (SQBO) and the solar cycle are presented. The results indicate that: (a) seasonal and interannual variations of these tidal components are pronounced in their peak regions. The peak region is defined as the region where the ratio of the annual mean amplitude to the maximum annual mean amplitude is larger than 0.8. (b) In their peak regions, migrating tidal components exhibit strong seasonal variations at annual (annual oscillations (AO)), semiannual (semiannual oscillations (SAO)) and terannual (terannual oscillations (TAO)) periods, whereas nonmigrating tidal components only exhibit prominent AO and SAO. (c) In their peak regions, the responses of the annual mean amplitudes of these tidal components to SQBO are negative; the responses of migrating tidal components to solar cycle are negative whereas those of nonmigrating tidal components are positive. (d) For these tidal components, the responses of the amplitudes of seasonal variations to SQBO and solar cycle are weaker than their annual mean amplitudes, and the latitude × altitude response patterns are not always consistent with those of the annual mean amplitudes.

Seasonal Variation of Rainfall in Indonesia under Normal Conditions without ENSO and IOD Events from 1981-2021

This study explores the seasonal rainfall variation in Indonesia under normal conditions, excluding the influence of El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events. Monthly rainfall data is sourced from the CHIRPS dataset, and wind and atmospheric movement data are obtained from the ECMWF ERA-5 dataset. Identification of normal conditions relies on the ONI and DMI indices. Results reveal that the seasonal rainfall patterns during these normal conditions align with previous studies encompassing all atmospheric conditions. Indonesia typically witnesses one or two peaks in rainfall annually, notably in December-January-February (DJF), May-June (MJ), and March-April-May (MAM), consistent with established rainfall zone classifications in earlier research. A nuanced discrepancy emerges in the timing of the May-June peak, previously noted in June-July. The congruence in peak rainfall patterns during normal conditions, as observed in prior comprehensive research, implies a negligible influence of ENSO and IOD on the timing of seasonal rainfall peaks. Although ENSO and IOD may impact the amplitude of seasonal variation, particularly in Indonesia's eastern and western regions, they do not alter the temporal occurrence of rainfall peaks. Consequently, the timing of rainfall peaks in Indonesia predominantly reflects the combined influence of the Asian and Australian monsoons.

Vegetation-cover control of between-site soil temperature evolution in a sandy desertland

Vegetation has an important influence on soil temperature (ST). However, the possible effects of surface vegetation on ST and their feedback on microclimate remain uncertain due to the lack of in-situ and long-term environmental records, especially for arid and semiarid regions of the world. A continuous, two-year study was implemented over a bare sand dune (BF) and two scrub-vegetation sites of variable cover in the Mu Us Desert of northwest China. Surface vegetation at the two non-bare sites varied from about 40% (moderate cover, MF) and 80 % (high cover, HF) of their respective surface area. Depiction of the vertical ST-profile was based on an array of field-based measurements taken within the uppermost 180 cm of the soil complex at each site. Compared with the BF site, mean ST at MF and HF decreased by 1.2 and 1.6 °C during the uniform thaw period and increased by 0.1 and 1 °C during uniform freezing. Amplitude of seasonal variation in ST for both vegetated sites, i.e., MF and HF, was reduced by 2.4 and 4.9 °C, respectively. As soil cooling during the uniform thaw period was greater than soil warming during uniform freezing, annual mean ST decreased at both vegetated sites by 1.6 and 1.2 °C (for MF and HF, respectively) compared to ST at BF. Differences in ST among the three sites during the uniform freeze and thaw periods were exponentially correlated with the extent of site vegetation cover, leaf area index, aboveground biomass, and on-the-ground litter thickness. Vegetation cover was shown to reduce the depth of the frost layer by 30 cm and prolonged the uniform thaw period by 1–35 days at the HF site. Mean daily STs at the center of each soil layer at the three sites were simulated with a two-equation model developed for this study, yielding a coefficient of determination (R2) of 0.91 when modeled STs were compared against their corresponding field observations. Increases in winter ST has potential to safeguard ground-dwelling grubs and other agriculturally harmful insects from freezing and dying. Likewise, decreases in annual ST could help promote decreases in litter decomposition, potentially lessening the effects of wind erosion.

Abstract #1412847: Seasonal Variation in Growth Velocity in Asian Indian Children

Earlier studies on seasonality have shown greater height gain in children in spring and has been attributed to the effect of melatonin, glucocorticoid receptor pathway, ghrelin and a number of other factors on growth hormone. This study aimed to find seasonal variations in growth velocity in Asian Indian children between 3 and 18 years of age. This was a longitudinal prospective study conducted in 16 schools and preschools of NTR district of Andhrapradesh, India. Date of birth was documented and height was recorded using standard anthropometric technique, described by WHO, at three monthly intervals for one year. At the baseline visit, 4,186 children were recruited. Data pertaining to 859 students was eliminated because of the presence of chronic illnesses or height SDS +/-5 or being lost for follow-up. Of the 3,327 children analyzed, 1,627 were boys and 1,700 were girls. There was no significant seasonal variation in height velocity between any of the four seasons in either boys or girls. The amplitude of seasonal variation is described in proportion to the distance from the Equator. However, improving agricultural conditions and changing lifestyle habits might have contributed to the absence of seasonal variation in growth.

Spatial and temporal variations of gross primary production simulated by land surface model BCC_AVIM2.0

Gross primary production (GPP) is the largest flux and a crucial player in the terrestrial carbon cycle and has been studied extensively, yet large uncertainties remain in the spatiotemporal patterns of GPP in both observations and simulations. This study evaluates the performance of the second version of the Beijing Climate Center Atmosphere−Vegetation Interaction Model (BCC_AVIM2.0) in simulating GPP on multiple spatial and temporal scales in the Coupled Model Intercomparison Project Phase 6 (CMIP6) experiments. Model simulations driven by two meteorological datasets were compared with two observation-based GPP products covering 1982–2008. Spatial patterns of annual GPP show a significant latitudinal gradient in each dataset, increasing from cold (tundra) and dry (desert) biomes to warm (temperate) and humid (tropical rainforest) biomes. BCC_AVIM2.0 overestimates GPP in most parts of the globe, especially in boreal forest regions and Southeast China, while underestimating GPP in subhumid regions in eastern South America and tropical Africa. The four datasets broadly agree on the GPP seasonal cycle, but BCC_AVIM2.0 predicts an earlier beginning of spring growth and a larger amplitude of seasonal variations than those in the observations. The observation-based datasets exhibit slight interannual variability (IAV) and weak GPP linear trends, while the BCC_AVIM2.0 simulations demonstrate relatively large year-to-year variability and significant trends in the low-latitudes and temperate monsoon regions in North America and East Asia. Regarding the possible relationships between annual means of GPP and climate factors, BCC_AVIM2.0 predicts more extensive regions of the globe where the IAV of annual GPP is dominated by precipitation, especially in mid-to-high latitudes of the Northern Hemisphere and tropical Africa, while the observed GPP in the above regions is temperature- or radiation-dominant. The positive GPP biases due to earlier spring growth in boreal forest regions and negative GPP biases in off-equator tropical areas in the BCC_AVIM2.0 simulations imply that cold stress on biomes in boreal mid-to-high latitudes should be strengthened to restrain plant growth, while drought stress in low-latitude regions might be eased to enhance plant production in the future version of BCC_AVIM.

A Retrospective Study of Seasonal Variation in the Number of Cases Diagnosed at a Tertiary Care Tuberculosis Hospital

To study the seasonality of tuberculosis (TB) in a tertiary care tuberculosis and respiratory hospital in Delhi. Data from a tertiary care respiratory hospital in south Delhi over a six years period from April 2002 to March 2008 were analysed. Symptomatics: A total of 192,863 patients were registered newly in the hospital during this period. Maximum number of symptomatic patients reported to the out-patient department during April-June and the minimum during October-December. An increase of about 25% in symptomatics was observed (p < 0.05) in the period from April to June in comparison to October to December. The amplitude of seasonal variation was estimated as 11% of the annual mean symptomatics. Tuberculosis cases: The maximum sputum-positive TB cases were diagnosed during the period from April to June and the number was least during October to December. There was an increase of about 34% in sputum-positive cases (p < 0.001) during the period from April to June against October to December. The amplitude of seasonal variation was estimated as 14.4% of the annual mean smear-positives per quarter. The extra-pulmonary TB (EPTB) cases were the maximum during April-June. Chest symptomatics of all types of TB cases were the lowest in January. A seasonal pattern of TB was observed for pulmonary TB and EPTB cases. This information would be useful for administration and managers to take extra care to arrange and provide extra facilities during the peak seasons.

Effects of warming, eutrophication and climate variability on acidification of the seasonally stratified North Yellow Sea over the past 40 years

The North Yellow Sea (NYS) is a productive marginal sea of the western North Pacific. In summer and autumn, CaCO3 saturation states beneath the seasonal thermocline in the NYS have frequently fallen below critical levels, indicating that marine calcifying organisms are under threat. To explore the long-term evolution of the acidification of the NYS, we reconstructed seasonal variations in subsurface aragonite saturation state (Ωarag) and pH during 1976–2017, using wintertime and summertime temperature, salinity, dissolved oxygen and pH data mainly from a quality-controlled oceanographic database. Over the past 40 years, the wintertime warming rate in the NYS was twice the rate of global ocean surface warming. Warming-induced decrease in CO2 solubility canceled out a part of the wintertime Ωarag decrease caused by atmospheric CO2 increase, and also had minor effect on pH changes in winter. Although the NYS is a semi-enclosed marginal sea, its interannual variations of wintertime temperature, salinity, pH and Ωarag were correlated to Pacific Decadal Oscillation with a lag of 2–3 years. Due to the eutrophication-induced enhancement of net community respiration beneath the seasonal thermocline, long-term declines of bottom-water Ωarag and pH in summer were substantially faster than the declines of assumed air-equilibrated Ωarag and pH in spring. Over the past 40 years, the amplitudes of seasonal variations of bottom-water Ωarag and pH from spring to summer/autumn have increased by 4–7 times. This amplification has pushed the NYS towards the critical threshold of net community CaCO3 dissolution at a pace faster than that forecast under scenarios of atmospheric CO2 increase. In summary, our results provide insights into the combined effects of ocean warming, eutrophication, atmospheric CO2 rise and climate variability on coastal hydrochemistry, explaining how the environmental stresses on local marine calcifying organisms and the benthic ecosystem increased over the past 40 years.

Pronghorn (Antilocapra americana) enamel phosphate δ18O values reflect climate seasonality: Implications for paleoclimate reconstruction.

Stable oxygen isotope (δ18O) compositions from vertebrate tooth enamel are widely used as biogeochemical proxies for paleoclimate. However, the utility of enamel oxygen isotope values for environmental reconstruction varies among species. Herein, we evaluate the use of stable oxygen isotope compositions from pronghorn (Antilocapra americana Gray, 1866) enamel for reconstructing paleoclimate seasonality, an elusive but important parameter for understanding past ecosystems. We serially sampled the lower third molars of recent adult pronghorn from Wyoming for δ18O in phosphate (δ18OPO4) and compared patterns to interpolated and measured yearly variation in environmental waters as well as from sagebrush leaves, lakes, and rivers (δ18Ow). As expected, the oxygen isotope compositions of phosphate from pronghorn enamel are enriched in 18O relative to environmental waters. For a more direct comparison, we converted δ18Ow values into expected δ18OPO4* values (δ18OW‐PO4*). Pronghorn δ18OPO4 values from tooth enamel record nearly the full amplitude of seasonal variation from Wyoming δ18OW‐PO4* values. Furthermore, pronghorn enamel δ18OPO4 values are more similar to modeled δ18OW‐PO4* values from plant leaf waters than meteoric waters, suggesting that they obtain much of their water from evaporated plant waters. Collectively, our findings establish that seasonality in source water is reliably reflected in pronghorn enamel, providing the basis for exploring changes in the amplitude of seasonality of ancient climates. As a preliminary test, we sampled historical pronghorn specimens (1720 ± 100 AD), which show a mean decrease (a shift to lower values) of 1–2‰ in δ18OPO4 compared to the modern specimens. They also exhibit an increase in the δ18O amplitude, representing an increase in seasonality. We suggest that the cooler mean annual and summer temperatures typical of the 18th century, as well as enhanced periods of drought, drove differences among the modern and historical pronghorn, further establishing pronghorn enamel as excellent sources of paleoclimate proxy data.

Seasonal variation in mortality and the role of temperature: a multi-country multi-city study.

Although seasonal variations in mortality have been recognized for millennia, the role of temperature remains unclear. We aimed to assess seasonal variation in mortality and to examine the contribution of temperature. We compiled daily data on all-cause, cardiovascular and respiratory mortality, temperature and indicators on location-specific characteristics from 719 locations in tropical, dry, temperate and continental climate zones. We fitted time-series regression models to estimate the amplitude of seasonal variation in mortality on a daily basis, defined as the peak-to-trough ratio (PTR) of maximum mortality estimates to minimum mortality estimates at day of year. Meta-analysis was used to summarize location-specific estimates for each climate zone. We estimated the PTR with and without temperature adjustment, with the differences representing the seasonal effect attributable to temperature. We also evaluated the effect of location-specific characteristics on the PTR across locations by using meta-regression models. Seasonality estimates and responses to temperature adjustment varied across locations. The unadjusted PTR for all-cause mortality was 1.05 [95% confidence interval (CI): 1.00-1.11] in the tropical zone and 1.23 (95% CI: 1.20-1.25) in the temperate zone; adjusting for temperature reduced the estimates to 1.02 (95% CI: 0.95-1.09) and 1.10 (95% CI: 1.07-1.12), respectively. Furthermore, the unadjusted PTR was positively associated with average mean temperature. This study suggests that seasonality of mortality is importantly driven by temperature, most evidently in temperate/continental climate zones, and that warmer locations show stronger seasonal variations in mortality, which is related to a stronger effect of temperature.

Seasonal variation in mortality and the role of temperature: a multi-country multi-city study

BACKGROUND AND AIM: Although seasonal variations in mortality have been recognised for a long time, the role of temperature remains unclear. We aimed to assess seasonal variation in mortality and to examine the contribution of temperature. METHODS: We compiled daily data on all-cause, cardiovascular, and respiratory mortality, temperature, and indicators on location-specific characteristics from 719 locations in tropical, dry, temperate and continental climate zones. We fitted time-series regression models to estimate the amplitude of seasonal variation in mortality on a daily basis, defined as the peak-to-trough ratio (PTR) of maximum mortality estimates to minimum mortality estimates at day-of-year. Random-effects multivariate meta-analysis was used to summarise location-specific estimates for each climate zone. We estimated PTR with and without temperature adjustment, with the differences representing the seasonal effect attributable to temperature. We also evaluated the effect of location-specific characteristics on PTR across locations by using random-effects meta-regression models. RESULTS:Seasonality estimates and responses to temperature adjustment varied across locations. Unadjusted-PTR for all-cause mortality was 1.05 (95% confidence interval (CI): 1.00–1.11) in the tropical zone and 1.23 (95% CI: 1.20–1.25) in the temperate zone; adjusting for temperature reduced the PTR estimates to 1.02 (95% CI: 0.95–1.09) and 1.10 (95% CI: 1.07–1.12), respectively. Furthermore, unadjusted-PTR was positively associated with average annual mean temperature, and adjusting for temperature in PTR moved the estimate towards the null. CONCLUSIONS:This study suggests that seasonality of mortality is importantly driven by temperature, most evidently in temperate/continental climate zones, and that warmer locations show stronger seasonal variations in mortality, which is related to a stronger effect of temperature. On behalf of the MCC collaborative research network. KEYWORDS: Seasonality of mortality, temperature, a multi-country multi-city study

Isotopic compositions of atmospheric total gaseous mercury in 10 Chinese cities and implications for land surface emissions

Abstract. Land surface emissions are an important source of atmospheric total gaseous mercury (TGM); however, its role on the variations of TGM isotopic compositions and concentrations has not been properly evaluated. In this study, TGM isotope compositions, a powerful tracer for sources and transformation of Hg, were measured at 10 urban sites and one rural site in China. TGM concentrations were higher in summer than in winter in most cities except in Guiyang and Guangzhou in the low latitudes. The summertime high TGM concentrations coincided with prevailing low TGM δ202Hg and high TGM Δ199Hg signatures. These seasonal patterns were in contrast with those typically observed in rural areas in the Northern Hemisphere, suggesting that atmospheric oxidation chemistry, vegetation activity and residential coal combustion were likely not the dominant mechanisms contributing to the TGM concentration and isotopic composition seasonality in Chinese cities. The amplitudes of seasonal variations in TGM concentrations and Δ199Hg (or TGM δ202Hg) were significantly positively (or negatively) correlated with that of the simulated soil GEM emission flux. These results suggest that the seasonal variations in TGM isotopic compositions and concentrations in the 10 Chinese cities were likely controlled by land surface emissions that were observed or reported with highly negative δ202Hg signatures.

Cross‐Equatorial Anti‐Symmetry in the Seasonal Transport of the Western Boundary Current in the Atlantic Ocean

AbstractThe western boundary current in the equatorial Atlantic Ocean is a main conduit for water‐mass exchanges across the equator and thus a major pathway for the interhemispheric transports in the Atlantic Meridional Overturning Circulation (AMOC) system. In this study we quantify and examine the mean and seasonal variability of the equatorial western boundary current (EWBC) in the upper ocean layer using two data‐assimilated products, the Estimating the Circulation and Climate of the Ocean (ECCO4r3) and the Simple Ocean Data Assimilation (SODA3). It is found that the EWBC between 10°S and 10°N exhibits two pronounced features in its seasonal variability: (1) the transport varies anti‐symmetrically across the equator, that is, the northward EWBC strengthens to the north of the equator when it weakens to the south of the equator, and vice versa; and (2) the amplitude of seasonal variations is much greater in the northern hemisphere than in the south. We hypothesize that the cross‐equatorial anti‐symmetry in EWBC transport variability is attributable to the impingement of equatorial Rossby waves at the western boundary and the shape of the western boundary is the main cause for the amplified seasonal variability in the northern hemisphere. A simple 1 and 1/2‐layer model is used to test and validate this hypothesis and to elucidate the role of wind forcing and topography plays in the seasonal variability in the EWBC transport.

Retrieval of Carbon Dioxide Using Cross-Track Infrared Sounder (CrIS) on S-NPP

The Cross-track Infrared Sounder (CrIS) aboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite is a spaceborne Fourier transform infrared spectrometer. The study aims to retrieve carbon dioxide (CO2) information (the CO2 profile and column-averaged dry-air mole fraction of XCO2) from June 2018 to December 2019 based on the The National Oceanic and Atmospheric Administration (NOAA)-Unique Combined Atmospheric Processing System (NUCAPS) Cloud-Cleared Radiances (CCRs) via the CrIS. The CCRs products for the CrIS with 2223 channels have been available since 22 May 2018. Characteristics of the CO2 weighting functions inform the choice of multiple channels that are around 15 μm in size that differ by latitude and season to maximize retrieval sensitivity to CO2 and minimize sensitivity to other interfering atmospheric parameters. CO2 was retrieved from these channels using an adopted nonlinear optimization algorithm. The temperature, water vapor, and ozone profiles used in the inversion process were gathered from the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5). Validations of CO2 concentrations as retrieved from CrIS showed the following conclusions: (1) The relative error of the retrieved CO2 concentrations, as compared to Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) in situ aircraft measurements, was less than 0.5%, and the root mean square errors (RMSE) were less than 0.7 ppmv (with correlation coefficients of 0.56–0.86); (2) the retrieved XCO2 from June 2018 to December 2019 correlated well with the ground-based Total Carbon Column Observing Network (TCCON) observations, and the differences were within ±0.2 ppmv. Further analysis of the temporal and spatial distribution of the retrieved CO2 at 300 hPa demonstrated a strong seasonal variation of CO2 in 0–60° N in the Northern Hemisphere with the maximum values in June–August and larger amplitudes of seasonal variation in the northeast of Asia and northeastern part of North America. The variations likely occurred due to larger sinks of atmospheric CO2 that are dominated by CO2 uptake in the summer. In the Southern Hemisphere, the CO2 displayed high concentration anomalies in the latitudinal range of 30–60° S in September–November and December–February, which probably occurred due to the lofted smoke plumes from the strong fire seasons in South America and Southern Africa.

The relationship between seasonality, latitude and tuberculosis notifications in Pakistan

BackgroundPakistan ranks amongst the top 20 highest burden tuberculosis (TB) countries in the world. Approximately 369,548 cases of TB (all forms) were notified in 2018, with an estimated incidence of 265 per 100,000 people per year. In other settings, TB has been shown to demonstrate seasonal variation, with higher incidence in the spring/summer months and lower incidence in the autumn/winter; the amplitude of seasonal variation has also been reported to be higher with increasing distance from the equator.MethodsNotifications of newly-diagnosed pulmonary and extrapulmonary TB cases were obtained for 139 districts in Pakistan from 2011 to 2017. Data were provided by the Pakistan National TB Control Programme, Islamabad, Pakistan. Statistical analyses were performed to determine whether there was seasonal variation in TB notifications in Pakistan; whether the amplitude of seasonal variation in TB notifications varied according to latitude; whether the amplitude of seasonal variation of TB in Pakistan differed between extrapulmonary TB vs. pulmonary TB. To assess the quarterly seasonality of TB, we used the X-13-ARIMA-SEATS seasonal adjustment programme from the United States Census Bureau. The mean difference and corresponding 95% confidence intervals of seasonal amplitudes between different latitudes and clinical phenotype of TB were estimated using linear regression.ResultsTB notifications were highest in quarter 2, and lowest in quarter 4. The mean amplitude of seasonal variation was 25.5% (95% CI 25.0 to 25.9%). The mean seasonal amplitude of TB notifications from latitude 24.5°N- < 26.5°N was 29.5% (95% CI 29.3 to 29.7%) whilst the mean seasonal amplitude of TB notifications from latitude 34.5°N - < 36.5°N was 21.7% (95% CI 19.6 to 23.9%). The mean seasonal amplitude of TB notifications across Pakistan between latitudes 24.5°N to 36.5°N reached statistically significant difference (p < 0.001). The amplitude of seasonal variation was greater for extrapulmonary TB (mean seasonal amplitude: 32.6, 95% CI 21.4 to 21.8%) vs. smear positive pulmonary TB mean seasonal amplitude: 21.6, 95% CI 32.1 to 33.1%), p < 0.001.ConclusionTB notifications in Pakistan exhibit seasonal variation with a peak in quarter 2 (April–June) and trough in quarter 4 (October–December). The amplitude of seasonality decreases with increasing latitude, and is more pronounced for extrapulmonary than for pulmonary TB.

Assessing water storage changes of Lake Poyang from multi-mission satellite data and hydrological models

Understanding water storage changes in Lake Poyang, the largest freshwater lake in China, is essential for local hydro-ecological assessments and water resource management. The integration of multi-mission satellite data, hydrological models, and in situ measurements allows for a comprehensive estimate of Lake Poyang’s storage variations. We here estimated Lake Poyang water storage changes during the recent decade by using inundation areas mapped from optical satellite imagery and water levels measured by satellite radar altimetry and gauging stations. The amplitudes of seasonal variation from altimetry data are smaller than those from station measurements. This is likely attributed to their low temporal resolutions and limited footprint coverage, together with a complex surface gradient over Lake Poyang. The residual fields between land water storage changes assessed by the GRACE satellites and simulated by two hydrological models (GLDAS Noah and WGHM) were applied to estimate Poyang water storage changes. Leakage errors in the GRACE-model residuals are further corrected by a constrained forward modeling method, resulting in recovered water storage trends ~66 times of the uncorrected signals. Water level changes estimated by different methods are then compared. Results show that level changes inverted from recovered storage variations by GRACE-GLDAS and GRACE-WGHM are significantly larger than those from satellite altimetry and in situ measurements. This indicates that the combination of GRACE observation and global hydrological modeling is likely insufficient to estimate accurate water storage changes in Lake Poyang. Our methods and results provide a valuable example of using integrated methods for monitoring water storage changes in highly dynamic fluvial lake systems.

Growth pattern and oxygen isotopic systematics of modern freshwater mollusks along an elevation transect: Implications for paleoclimate reconstruction

Fossil mollusk shells are widely distributed in the geologic records and their oxygen isotopic compositions have been used to reconstruct seasonality, local climatic and elevation conditions. However, interpretation of isotope data from fossil shells to estimate paleoclimate and elevation is often ambiguous. This study examines the oxygen isotopic systematics of modern freshwater gastropods (Bellamya and Radix) shells along an elevation/climate transect in the Asian monsoon region of China to improve the accuracy of paleoclimate and paleoelevation reconstruction using stable isotopes in fossil shells. The results from sclerochronological analyses of the shells show that the intra-shell oxygen isotopic pattern is determined by seasonal variations in lake water temperature and water isotopic composition as well as the life cycle of the organism. Both Bellamya and Radix appear to grow throughout the year in lakes where water temperature does not fall below 13 °C. Radix in the high elevation cold habitat, although prefers to grow in the warmer months, can survive through the freezing temperature. The δ18O patterns in the shells are similar across the elevation/climate transect, showing high δ18O values in the winter months and low δ18O values in the summer months, consistent with the expected pattern in Asian monsoon region. The average growth rates of the shells were highest at the lowest elevation site (warm and humid climate) but were similar at the mid to high elevation sites. For large shells (>2.2 cm for Bellamya and >1.4 cm for Radix), average growth temperatures, calculated using the aragonite oxygen isotope thermometer, closely approximate the annual mean water temperature while their intra-shell variability is a good proxy for the amplitude of seasonal variations in monthly air temperature. This suggests that large shells of both Bellamya and Radix are excellent archives of lake environmental conditions and most suitable for paleoenvironmental studies.

Seasonal Variations in Specific Resistivity in the Upper Layers of the Earth Crust

To predict the effects of strong earthquakes, it is important to know the soil characteristics. The accepted methods for such assessment ignore the fact that soils properties can vary greatly throughout the year. This is apparently due to the lack of data required for such consideration. In this paper, based on an analysis of long-term monitoring data by vertical electric sounding (VES) in a stationary array with a large number of spacing, we analyze seasonal variations in specific resistivity at different near-surface depths of a section in the area of the Peter the Great Range in Tajikistan. Based on long-term precision daily measurement data, a horizontally four-layered model of the geoelectric section was constructed. The amplitude of seasonal variations in the specific resistivity in each layer was estimated as the ratio of the standard deviation of the seasonal variation to the mean interannual specific resistivity. In the upper part of the section (depth 0–1.5 m), the amplitude of the seasonal variation reaches 20%, and its shape agrees well with the seasonal variation of the apparent resistivity at small spacings. In the second (depth 1.5–10 m) and third (depth 10–66 m) layers, the amplitude of the seasonal wave decreases rapidly, being less than 1% in the third layer. In the fourth layer (depth from 66 m or more), this amplitude again increases, reaching 2%. The difference between the maximum and minimum values of the seasonal wave (i.e., its range) reaches 7%. One possible explanation for such a high amplitude of seasonal variations in specific resistivity at depths of hundreds of meters is the presence of a deep aeration zone with annual regulation of the level and salinity of groundwater. The results should be taken into account in exploration geophysics, in engineering surveys, and in accounting for soil properties when predicting the possible consequences of strong seismic impacts.

Recalibration of over 35 Years of Infrared and Water Vapor Channel Radiances of the JMA Geostationary Satellites

Infrared sounding measurements of the Infrared Atmospheric Sounding Interferometer (IASI), Atmospheric Infrared Sounder (AIRS), and High-resolution Infrared Radiation Sounder/2 (HIRS/2) instruments are used to recalibrate infrared (IR; ~11 µm) channels and water vapor (WV; ~6 µm) channels of the Visible and Infrared Spin Scan Radiometer (VISSR), Japanese Advanced Meteorological Imager (JAMI), and IMAGER instruments onboard the historical geostationary satellites of the Japan Meteorological Agency (JMA). The recalibration was performed using a common recalibration method developed by European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), which can be applied to the historical geostationary satellites to produce Fundamental Climate Data Records (FCDR). Pseudo geostationary imager radiances were computed from the infrared sounding measurements and regressed against the radiances from the geostationary satellites. Recalibration factors were computed from these pseudo imager radiance pairs. This paper presents and evaluates the result of recalibration of longtime-series of IR (1978–2016) and WV (1995–2016) measurements from JMA’s historical geostationary satellites. For the IR data of the earlier satellites (Geostationary Metrological Satellite (GMS) to GMS-4) significant seasonal variations in radiometric biases were observed. This suggests that the sensors on GMS to GMS-4 were strongly affected by seasonal variations in solar illumination. The amplitudes of these seasonal variations range from 3 K for the earlier satellites to &lt;0.4 K for the recent satellites (GMS-5, Geostationary Operational Environmental Satellite-9 (GOES-9), Multi-functional Transport Satellite-1R (MTSAT-1R) and MTSAT-2). For the WV data of GOES-9, MTSAT-1R and MTSAT-2, no seasonal variations in radiometric biases were observed. However, for GMS-5, the amplitude of seasonal variation in bias was about 0.5 K. Overall, the magnitude of the biases for GMS-5, MTSAT-1R and MTSAT-2 were smaller than 0.3 K. Finally, our analysis confirms the existence of errors due to atmospheric absorption contamination in the operational Spectral Response Function (SRF) of the WV channel of GMS-5. The method used in this study is based on the principles developed within Global Space-based Inter-calibration System (GSICS). Moreover, presented results contribute to the Inter-calibration of imager observations from time-series of geostationary satellites (IOGEO) project under the umbrella of the World Meteorological Organization (WMO) initiative Sustained and Coordinated Processing of Environmental Satellite data for Climate Monitoring (SCOPE-CM).

Long-Term Variability of the Dissolved Oxygen Content and Water Temperatures in the Upper Layer of the Black Sea

Based on the archival oceanographic databank of the Institute of Natural and Technical Systems, the annual and interannual variability was analyzed for the dissolved oxygen content and temperatures in the upper deep-water layer and northwestern parts of the Black Sea from 1923 to 2013. The seasonal variations in the dissolved oxygen content and temperatures are in antiphase. On average, over the considered time frame, the dissolved oxygen content was maximum in winter in the northwestern area of the sea and minimum in the open parts in summer. The amplitude of seasonal variations was over 50 µM/L. In general, this is in agreement with earlier publications. However, the seasonal trend changes considerably within certain 20- to 30-year time intervals, which is related to quasiperiodic variability of the oxygen content on a typical time scale of several decades, exhibited differently in different seasons and sea areas.