Monsoon Months Research Articles

Seasonal Trend Analysis in Rainfall and Temperature for Udaipur District of Rajasthan

The present study is mainly focused on to detection of changing trend in rainfall and temperature for Udaipur district situated in the Rajasthan state of India. The district situated in the western part of India which obtained less rainfall as compared with the average rainfall of India. In the present article, the approach has been tried to analysis to detect rainfall trend, maximum temperature trend and minimum temperature trend for the area. For this daily rainfall data of 39 years (1975 to 2013) add seasonally and the temperature has been calculated by averaging of daily temperature for a period of 39 years. For determining the trend the year has been shared out into four seasons like the winter season, pre-monsoon season, monsoon season and post-monsoon season. To obtained magnitude of trend San’s slope estimator test has been used and for significance in trend Mann-Kendall statistics test has been applied. The results obtained for the study show significantly decreasing rainfall trend for the season winter and season post-monsoon whereas pre-monsoon and monsoon show increasing rainfall trend. The maximum temperature of pre-monsoon and monsoon months shows a significantly increasing trend whereas, in minimum temperature, winter season and pre-monsoon season shows an increasing trend which is significant at 10% level of significance and post-monsoon shows a decreasing trend which is also significant at 10% level of significance.

Nocturnal, seasonal and intra-annual variability of tropospheric aerosols observed using ground-based and space-borne lidars over a tropical location of India

The nocturnal, seasonal and intra-annual variation of vertical distribution of tropospheric aerosols over two nearby stations Gadanki (13.5oN, 79.2oE) and Tirupati (13.6oN, 79.4oE) is investigated using ground-based Micro Pulse Lidar (MPL) and space-borne Lidar (CALIPSO) systems during 2010–2017. The nocturnal variation of aerosol extinction (AE) coefficient reveal high AE below ∼2 km in midnight hours and aerosols are slowly descending towards the surface during early morning hours. From the seasonal variation, AE values are found to be higher at lower altitudes (<2 km) during winter and post-monsoon seasons, a sharp decrease with increasing altitude is found in tandem with boundary layer and low wind speeds. Interestingly, during monsoon season, significant aerosol loading is found in the altitude range of ∼2–5.5 km mainly due to the influence of strong Low Level Jet (LLJ). The clean environment observed below ∼2 km during this season is attributed to the wet scavenging, downward vertical winds and existance of no strong local source. The seasonal mean AE profile derived from CALIPSO matches well with the MPL in all the seasons except in monsoon season where a large bias is noticed below 2 km. The intra-annual variation revealed more than 80% of aerosols existing above (below) the boundary layer during monsoon (winter) months contribute to the total Aerosol Optical Depth (AOD). The depolarization ratio (>0.2) in the month of July shows the dominance of dust particles which includes long-range transport over this locations. Back trajectories reveals that potential sources are changing from season to season at different altitudes and confirms that the aerosols observed at higher altitudes are advected from other land and oceanic regions. Thus, aerosol vertical distribution is mainly controlled by meteorology and dynamics over this region. Further, the reasonably good correlation found between MPL and MODIS AODs suggests that MODIS could provide reliable AOD over land region also.

Submicron aerosol composition in the world's most polluted megacity: the Delhi Aerosol Supersite study

Abstract. Delhi, India, routinely experiences some of the world's highest urban particulate matter concentrations. We established the Delhi Aerosol Supersite study to provide long-term characterization of the ambient submicron aerosol composition in Delhi. Here we report on 1.25 years of highly time-resolved speciated submicron particulate matter (PM1) data, including black carbon (BC) and nonrefractory PM1 (NR-PM1), which we combine to develop a composition-based estimate of PM1 (“C-PM1” = BC + NR-PM1) concentrations. We observed marked seasonal and diurnal variability in the concentration and composition of PM1 owing to the interactions of sources and atmospheric processes. Winter was the most polluted period of the year, with average C-PM1 mass concentrations of ∼210 µg m−3. The monsoon was hot and rainy, consequently making it the least polluted (C-PM1 ∼50 µg m−3) period. Organics constituted more than half of the C-PM1 for all seasons and times of day. While ammonium, chloride, and nitrate each were ∼10 % of the C-PM1 for the cooler months, BC and sulfate contributed ∼5 % each. For the warmer periods, the fractional contribution of BC and sulfate to C-PM1 increased, and the chloride contribution decreased to less than 2 %. The seasonal and diurnal variation in absolute mass loadings were generally consistent with changes in ventilation coefficients, with higher concentrations for periods with unfavorable meteorology – low planetary boundary layer height and low wind speeds. However, the variation in C-PM1 composition was influenced by temporally varying sources, photochemistry, and gas–particle partitioning. During cool periods when wind was from the northwest, episodic hourly averaged chloride concentrations reached 50–100 µg m−3, ranking among the highest chloride concentrations reported anywhere in the world. We estimated the contribution of primary emissions and secondary processes to Delhi's submicron aerosol. Secondary species contributed almost 50 %–70 % of Delhi's C-PM1 mass for the winter and spring months and up to 60 %–80 % for the warmer summer and monsoon months. For the cooler months that had the highest C-PM1 concentrations, the nighttime sources were skewed towards primary sources, while the daytime C-PM1 was dominated by secondary species. Overall, these findings point to the important effects of both primary emissions and more regional atmospheric chemistry on influencing the extreme particle concentrations that impact the Delhi megacity region. Future air quality strategies considering Delhi's situation in both a regional and local context will be more effective than policies targeting only local, primary air pollutants.

Study on biological rhythm of bovine trypanosomosis in Braj Bhoomi region of Uttar Pradesh, India

ABSTRACT An epidemiological and biological rhythm study was conducted in bovines naturally infected with Trypanosoma evansi in Braj Bhoomi region of Uttar Pradesh, India. A total of 2312 blood samples of bovines (cattle-797 and buffaloes-1515) suspected for trypanosomosis were collected and screen for T. evansi infection using buffy coat method and blood smear examination. Overall prevalence of 18.94% (438) was recorded indicating endemicity of trypanosoma in bovine population of this region. Trypanosomosis was found prevalent throughout the year in this region and higher prevalence was observed in monsoon and post-monsoon months followed by winter months and least in summer months. Prevalence of trypanosomosis in bovines does not vary with the host related factors viz. sex, breed, and pregnancy in this region. However, there is significant increase in prevalence with increase in age and parity. Alteration in twenty-seven (27) different types of reported clinical markers in this study can be considered as snap short diagnostic markers of trypanosomosis in field conditions where diagnostic facilities are lacking.

Thermal comfort level in Chennai Metropolis under present and future climate scenarios

Climate change poses unprecedented challenges to urban inhabitants. Thermal comfort is one of the major issues in cities and it is expected to change in future due to climate change. The change of climate parameters particularly, temperature and relative humidity will affect the thermal comfort environments of people. Discomfort levels are largely preventable and requires prior assessment. In this study, the observed and projected thermal comfort level of Chennai Metropolis are calculated using Thermo-Hygrometric Index (THI) under present and future climate scenarios. The observed climate data of Chennai Metropolis for the period 1951-2010 procured from IMD are used to find the long term changes in observed thermal comfort. Monthly trends of THI are calculated for different periods to understand the thermal comfort behaviour in recent decades. On long term observation, high discomfort level is noticed during May and June months followed by July, August, April and September months. While there is a sharp increase in THI during winter months of recent decades. There is a considerable increase in discomfort level notice in post-monsoon season especially in December and November months. Future THI is calculated using high-resolution future climate scenarios developed using PRECIS. The deviations of THI from baseline to mid-century (2041-2070) and end-century period (2071-2099) are calculated and geospatially mapped using ArcGIS. There would be 2.0°C increase of THI is expected during winter and post monsoon months in mid-century scenario. Changes in future THI warrants the need for better cooling requirements and city planning to adapt with the future trends of external environment. Thus the study urges urban planners to evolve climate smart adaptation strategies to provide the congenial climate for a better living.

Role of lunar phases, rainfall, and wind in predicting Hilsa shad (Tenualosa ilisha) catch in the northern Bay of Bengal

AbstractHilsa (Tenualosa ilisha) is an important commercial fish in India. This study investigates relationships among Hilsa catch per unit effort (CPUE) and the corresponding lunar phase, rainfall variability, wind vector, and month in the northern Bay of Bengal. Hilsa catch during the monsoon season of three consecutive years (2013–2015) was analyzed by using a Generalized Least Square model with lunar phase and monsoon months (June–September) as categorical variables and wind direction as circular variable. Significantly higher Hilsa catch was observed during the waning crescent and waxing gibbous lunar phases and during easterly winds. There was no significant effect of wind velocity. Daily rainfall was significantly correlated with Hilsa migration toward the estuary. Among the four monsoon months, September exhibited the most positive significant correlation with the Hilsa CPUE. Model predicted CPUE underestimated the actual CPUE in 2016 by 20%.

Role of premonsoon meridional SST gradient of north Indian Ocean and frequency of typhoon activities on monsoon depression over Bay of Bengal

The paper presents the impact of premonsoon meridional sea surface temperature (SST) gradient of a part of north Indian Ocean (84°E–92°E, 0°N–18°N) and frequency of north-west Pacific weather systems (mainly typhoons and super-typhoons) on the formation of monsoon depressions over Bay of Bengal. Analysis shows that decreasing frequency of monsoon depression over BOB may occur as a result of decreasing trend of premonsoon meridional SST gradients over the region 84°E–92°E and 0°N–18°N. Higher frequency of north-west Pacific weather systems (i.e. higher the total number of typhoons and super-typhoons) during the monsoon month (June, July, August, September-JJAS) may be considered as one of the important aspect for the reduction in monsoon depression frequency over BOB (mostly, during last decade). Tropical easterly jet (TEJ) strength (60°E–100°E, 5°N–20°N) is also analysed to check the relationship between convection over BOB and monsoon circulation pattern which is dependent on SST gradient as well as north-west Pacific weather system frequency. Possible explanation is also presented.

Dynamic of channel potholes on Precambrian geological sites of Chhota Nagpur plateau, Indian peninsula: applying fluvio-hydrological and geospatial techniques

Dynamic channel bed potholes or sculpted forms (circular, elliptical, oval, elongated, etc.) on riverbeds are generally formed due to the variation of lithology with structures and dominant fluvio-hydrological processes. Most of the channel bed potholes are confined at Bhakuyadi, Guridih and Ghatsila on Precambrian Chhota Nagpur granitic gneiss and tonalite gneiss of the river Subarnarekha and its tributaries. A total of 215 channel bed potholes are studied at three sites [Site 1 Bhakuyadi (n = 115), Site 2 Guridih (n = 65) and Site 3 Ghatsila (n = 35)]. The main objective is to find out the multi-dimensional growth on Precambrian bed rock channel and analyze the role of fluvio-hydrological factors toward their growth. Geospatial, fluvio-hydrological and statistical techniques have been applied to find out the potholes dynamic on lithological diversity of extended part of the Chhota Nagpur plateau of gneissic complex. Lineament features have been extracted using different SWIR and VNIR bands of two specific images like ETM and ASTER. Arc Hydrology tool (Hydro tool of ArcGIS) has been used to delineate stream networks and watershed of river Subarnarekha. Morphology of potholes like shape–form analysis has been done through morphometric index such as Surface Index, Bottom Index and Vertical Index. Downward and sideward potholes growth rate are calculated using mathematical indices, and depth–radius ratio has been assessed applying descriptive statistics. The results show that the multi-dimensional growth or pothole dynamics are immensely regulated by local condition such as rock types with structural imprints (fractures, joints, etc.). The absence of micro-geological structures on others lithological unit have failed to give birth to multi-dimensional growth of channel potholes along the flow path of river Subarnarekha and its tributaries within the Subarnarekha watershed. Chhota Nagpur granitic gneiss and tonalite gneiss with structural signatures help to form channel bed potholes within the flow path of river Subarnarekha and its tributaries. Statistical analysis reveals that there is a strong positive correlation between depth and radius of potholes. Subsequently, fluvio-hydrological factors (like corrasion, cavitation, hydraulic action, change of channel gradients, monsoonal bankfull discharge, etc.) clearly reflect the dynamic growth of channel bed potholes specifically during monsoonal months.

Spatial and Temporal Trends in High Resolution Gridded Temperature Data over India

The changing temperature, directly and indirectly, has significant effect on the agricultural production and economy of the country which necessitates detailed study of the spatial and temporal variability of temperature. This paper focuses on the spatio-temporal trend analysis of minimum and maximum temperature over India. Daily gridded temperature data with spatial resolution of 1° × 1° for the period of 1969–2005 were analysed using Mann-Kendall (MK) non-parametric test at 3 levels of significances, namely, 1%, 5%, and 10%. The diurnal temperature range was also analysed. Results showed that maximum temperature experienced significant decreasing trends in the entire Indo-Gangetic plains extending up to the NE region while the Southern region experienced warming. For minimum temperature, all regions except the Central region reported increasing trends indicating warming. As a result, diurnal temperature range showed decreasing trends in many places in the upper half of the country while the lower half is dominated by increasing trends. On a regional scale, the Southern region, in particular, showed increasing trends in all three parameters. On seasonal scale, pre-monsoon and monsoon months remained mostly trendless for all three parameters. Maximum significant decreasing trends were observed during January–May while maximum increasing trends were reported during June–December. Also, a higher Sen slope value of the yearly maximum increase in the minimum temperature indicated steeper increase in minimum temperature over maximum temperature.

Genetic Diversity of Human Respiratory Syncytial Virus in Children with Acute Respiratory Infections in Chennai, South India

AbstractIntroduction: Human respiratory syncytial virus (HRSV) an RNA virus belonging to Pneumoviridae family, is an important cause of acute respiratory infections (ARIs) in young children. HRSV circulates as two subgroups A and B, which are further categorised into several genotypes. New genotypes may replace existing ones over successive epidemic seasons and multiple genotypes may cocirculate in the same community rendering it important to monitor them at the molecular level. The present study assessed the circulating genotypes of HRSV in Chennai. Materials and Methods: Two hundred and sixty-seven children with ARI were recruited during the study from April 2016 to March 2018 for detecting HRSV A and B by real-time reverse transcription-polymerase chain reaction. Phylogeny and selection pressure analysis were done. Results: Fifty-seven of the 267 samples (21.3%) were positive for HRSV, of which 7.1% and 14.2% were HRSV A and B, respectively, indicating that HRSV B was the major subgroup circulating in Chennai. Peak activity of HRSV was observed during the monsoon and winter months. Phylogenetic analysis of 2nd hypervariable region (HVR) of attachment glycoprotein gene (G gene) revealed that the HRSV A strains belonged to ON1 and HRSV B strains belonged to BA9 genotypes. Several unique amino acid substitutions were observed among the study strains. The Shannon entropy plot revealed that the HRSV A strains from our study have a high potential for amino acid substitutions in the 2nd HVR of G gene. Conclusion: This study underlines the genetic diversity of HRSV and emphasises the need for continued molecular surveillance for infection management and prevention strategies.

Seasonal and annual variation of AIRS retrieved $$\hbox {CO}_{{2}}$$ CO 2 over India during 2003–2011

The present study shows spatio-temporal variability in carbon dioxide $$(\hbox {CO}_{2})$$ in the mid-tropospheric region over India (0–32 $$^{\mathrm{o}}\hbox {N}$$ , 60–100 $$^{\mathrm{o}}\hbox {E}$$ ) during 2003–2011. The $$\hbox {CO}_{2}$$ data used in the study is retrieved from Atmospheric Infra-Red Sounder (AIRS). Analysis of 9 yrs of data shows that the $$\hbox {CO}_{{2}}$$ exhibits a linear increasing trend of 2.01 ppm/year. Besides displaying the linear increasing trend, data show strong seasonal and annual variability. Concentration of $$\hbox {CO}_{{2}}$$ is observed to be highest around April–May (summer months), which decreases by 4–5 ppm during the monsoon months. Seasonal decrease in $$\hbox {CO}_{2}$$ concentration appeared to be influenced by the monsoonal activity. Low OLR (proxy of convection) associated with high rainfall during summer monsoon via increasing vegetation index (NDVI) appears to be the primary cause for the seasonal decrease in $$\hbox {CO}_{{2}}$$ through photosynthesis. Correlation coefficient between $$\hbox {CO}_{{2}}$$ and NDVI is of the order of –0.90 suggesting vegetation as a seasonal sink of $$\hbox {CO}_{{2}}$$ . Decrease in $$\hbox {CO}_{{2}}$$ concentration takes place at a delay of 2–3 months of rainfall. However, convection seems to be another component, which causes uplifting of $$\hbox {CO}_{{2}}$$ during dry summer (April and May) making high concentration in the mid-troposphere as shown by increase in the planetary boundary layer (PBL) height in this period. Eastward propagating intra-seasonal oscillations with period 30–40 days in OLR anomalies are found to modulate (with a fluctuation of 1–2 ppm) mid-tropospheric $$\hbox {CO}_{{2}}$$ . Analysis of seasonal anomalies in $$\hbox {CO}_{{2}}$$ over four different regions (northern, southern, western and eastern) of India is also being investigated. The regional variability of $$\hbox {CO}_{2}$$ in northern region show marginal larger values suggesting more anthropogenic activities especially during late winter.

Geological and geotechnical characterisation of the Khotila landslide in the Dharchula region, NE Kumaun Himalaya

On 04 October 2016, a severe landslide had occurred in the vicinity of Khotila village in Dharchula, region of NE Kumaun Himalaya. This landslide may be classified as typical rockslide, involving thin veneer of debris on the slope as well as the highly shattered rockmass. The slide has been divided into three morpho-dynamic zones, viz., (i) Zone of detachment between elevation 1000 and 960 m, (ii) Zone of transportation between elevation 960 and 910 m, and (iii) Zone of accumulation between elevation 910 and 870 m. The landslide had occurred at the end of the monsoon season when the slope was completely saturated. It has been noted that the area received $${\sim }88\%$$ rainfall during the monsoon months which is about two times more rainfall during 2016 monsoon than during 2015 monsoon. Geotechnical testing of the soil overlying the rockmass, corroborate the soil as ‘soft soil’ with compressive strength of 42 kPa and friction angle of $$27.4{^{\circ }}$$ . Granulometry confirms the soil as having $${>}97\%$$ sand and silt size particles and $${<}3\%$$ clay size particles, indicating higher permeability. Mineralogically, the soil dominantly constitutes quartz, muscovite and clinochore. Though no swelling clay minerals has been observed, the higher permeability and low strength of the soil, and concentrated higher rainfall during 2016 are the main causes for the landslide to occur. This landslide has partially blocked the flow of Kali river that serve as a boundary between India and Nepal and is endangering the habitants of the Khotila and Bangabagar villages, situated downstream in the Indian and Nepalese side of the Himalaya. In order to understand the stability of the slope, finite element modelling of the landslide has been carried out that points towards higher concentration of stresses in the landslide zone, indicating that there is further probability for the failure of landslide mass. It is therefore suggested that the landslide must be monitored continuously, particularly during the rainy season and also the risk posed by this landslide must be evaluated so as to avoid any further loss to life and infrastructure in the region.

Comparing Multiple Precipitation Products against In-Situ Observations over Different Climate Regions of Pakistan

Various state-of-the-art gridded satellite precipitation products (GPPs) have been derived from remote sensing and reanalysis data and are widely used in hydrological studies. An assessment of these GPPs against in-situ observations is necessary to determine their respective strengths and uncertainties. GPPs developed from satellite observations as a primary source were compared to in-situ observations, namely the Climate Hazard group Infrared Precipitation with Stations (CHIRPS), Multi-Source Weighted-Ensemble Precipitation (MSWEP), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) and Tropical Rainfall Measuring Mission (TRMM) multi-satellite precipitation analysis (TMPA). These products were compared to in-situ data from 51 stations, spanning 1998–2016, across Pakistan on daily, monthly, annual and interannual time scales. Spatiotemporal climatology was well captured by all products, with more precipitation in the north eastern parts during the monsoon months and vice-versa. Daily precipitation with amount larger than 10 mm showed significant (95%, Kolmogorov-Smirnov test) agreement with the in-situ data, especially TMPA, followed by CHIRPS and MSWEP. At monthly scales, there were significant correlations (R) between the GPPs and in-situ records, suggesting similar dynamics; however, statistical metrics suggested that the performance of these products varies from north towards south. Temporal agreement on an interannual scale was higher in the central and southern parts which followed precipitation seasonality. TMPA performed the best, followed in order by CHIRPS, MSWEP and PERSIANN-CDR.

Bacterial Community Composition Markedly Altered by Coastal Hypoxia

Monsoonal upwelling along south and central west coast of India leads to intense biological productivity. As a consequence of excess organic matter production following upwelling during June-October and low dissolved oxygen in the upwelled waters, denitrification occurs in the near shore waters. Implicitly, these processes ought to bring alterations in microbial communities. Therefore, diversity and community structure of bacteria from subsurface layers of a tropical region experiencing intense seasonal lows of oxygen were analyzed through sequencing of 16S rRNA gene clones. The overall diversity was more during hypoxic period of Fall intermonsoon (FIM, October) compared either to Spring intermonsoon (SIM, March) or summer monsoon (SuM, June) months. As many as 14 lineages of bacterial domains: Gammaproteobacteria (37%), Alphaproteobacteria (21%), Cyanobacteria (20%), Deltaproteobacteria (3%), Firmicutes (3%), Betaproteobacteria (2%), Acidobacteria (2%), Actinobacteria (7%), Marinimicrobia (2%), Bacteroidetes (1%), Verrucomicrobia (1%), Planctomycetes (0.4%), Chloroflexi (0.2%) and Omnitrophica bacterium (0.2%), were recognized from our coastal location. Notably, sequences of Planctomycetes, Chloroflexi and Omnitrophica bacterium were found exclusively during FIM. A generally higher representation of sequences of Betaproteobacteria during SuM and of Actinobacteria and Firmicutes during SIM was discernible. This study is thus useful to recognize that microbial community might undergo strong temporal shifts in the monsoon affected tropical coastal ecosystems.

Morphometric analysis of watershed using remote sensing and GIS—a case study of Nanganji River Basin in Tamil Nadu, India

Morphometric analysis of a river basin is essential to identify and assess seasonal changes in drainage basin characteristics, understand the groundwater potential, and address issues related to management of soil erosion due to flash floods during the high flows. Nanganji River Basin is one of the least studied seasonal river basins in India which carry substantial flows during the monsoon period. In this study, morphometry of Nanganji River Basin, located in the central Tamil Nadu prairies, has been studied using remote sensing and GIS. The interrelationship between the various morphometric factors of the basin has been studied using a correlation matrix. Factor analysis has been applied to group the individual morphometric parameters into a smaller number of factors. Further, these factors have been studied in relation to the sub-basins to understand the existing relation between the factors and the sub-basins. Finally, the study identifies environmental issues of the Nanganji River Basin mostly related to the river flow regime which widens significantly during the monsoon months.

Monthly variations in crustacean zooplankton abundances in Sundarapandian Pattinam and Manamelkudi in the Palk Strait, India (9-10°N, Arabian Sea)

Abstract The present investigation has been made to study the distribution of crustacean zooplankton, and its qualitative and quantitative composition, as well as for making an assessment of species abundances and of the evenness of zooplankton in two habitats along the Palk Strait, between the east coast of Tamil Nadu (India) and Sri Lanka. The sampling programme was executed from July 2005 to June 2006. The two sampling sites, Sundarapandian Pattinam (Station I) and Manamelkudi (Station II), respectively, are located in one of the most productive marine zones of the world. The various groups of crustacean zooplankton were Ostracoda, Copepoda, Amphipoda, Isopoda, Cumacea, Euphausiacea, and Decapoda. Maximum occurrences were observed during the summer and the pre-monsoon seasons, and minimum occurrences were observed during the monsoon months. The present study showed that the distribution pattern of total zooplankton fluctuated at both stations. Station II is richer in absolute abundance in comparison with Station I.

Studies on epidemiology, clinical markers and pathological alterations in equines trypanosomosis in semi-arid zone of northern plains of India

ABSTRACT An epidemiological study was conducted along with clinicodiagnostic markers and pathological alteration in equines naturally infected with Trypanosoma evansi in seven district on semi-arid zones of northern plains of India. A total of 515 blood samples of equines (horse-227, mule-249 and donkey-39) suspected for trypanosomosis were collected and screened for T. evansi infection using Ab-ELISA and blood smear examination. Overall seroprevalence of 22.33% (115) was recorded, indicating endemicity of trypanosoma in equines of this region. Maximum prevalence was recorded in district Mathura (24.81%) followed by Bharatpur (23.26%) and the lowest was recorded in Hathrash (16.23%) district. Trypanosomosis was found prevalent throughout the year in this region, and a higher prevalence was observed in monsoon and post-monsoon months followed by winter months and the least prevelance was observed in summer months. Out of 115 seropositive equines, 36 animals possessing clinical infections were again evaluated for alteration in pathological parameters, and the values were compared with six healthy equines. The infected equines showed marked anaemia, significant increased activities of serum blood urea nitrogen, creatinine, lanine aminotransferase and lipid peroxidases as well as significant decreased activities of serum glucose and antioxidant enzymes like superoxide dismutase and catalase compared to healthy animals, indicating impairment of hepatorenal system and oxidative stress-related cellular injuries in trypanosomosis.

Role of container type, behavioural, and ecological factors in Aedes pupal production in Dhaka, Bangladesh: An application of zero-inflated negative binomial model

The container-inhabiting Aedes mosquitoes are the major vectors transmitting dengue and several other arboviral diseases such as chikungunya and zika across the tropical world. Surveillance for immature Aedes, particularly pupae, is an effective tool for measuring dengue outbreak risk. While in Bangladesh, the greatest burden of dengue fever and dengue hemorrhagic fever cases has periodically been occurring since the first major outbreak in 2000, very limited research has yet been pursued to understand the dynamics of Aedes pupal production in this country. In this backdrop, this study was carried out to i) identify containers at household premises contributing to dengue vector productivity; ii) measure the extent of pupae productivity of household containers; and, iii) determine the effects of household ecological factors upon productivity of pupae in the city of Dhaka, Bangladesh. During the monsoon months of 2013, a total of 1,033 containers (674 wet and 363 dry) in 727 household premises in 12 wards of the city of Dhaka were inspected to measure container productivity and collect household ecological, and human behavioural data. The results reveal that the majority of immature mosquitoes (73.52% larvae and 84.91% pupae) developed in containers located outdoor that are used mostly for household chores. Plastic containers (57.55% of all immature mosquito-positive containers) used for household chores produce most of the immature mosquitos. The results of the zero-inflated negative binomial (ZINB) model reveal that pupae production significantly varies by container type (p-value = 0.0136) for the count regression group. However, when considering container size along with container type, container size is found significant for pupae production (p-value = 0.0041), showing that container size is confounded with the container type and the pupae production. Containers greater than 50 litres (L) are likely to produce 4.9 times more pupae than containers with <1L. Two household ecological factors are found to be significant (shade: p-value = 0.005 in the count regression group and type of water: p-value = 0.001 in the excess zero group) for pupae production. We found that containers with partial shade produce 4.6 times more pupae than without any shade, whereas in the excess zero group the expected number of observed zero pupae count is 86.5% lower in containers filled with rain water than those with tap water, tube-well water, ring well water and water from other sources. The most commonly used plastic-made containers (i.e., refrigerator trays, drums, buckets) and flower tubs/trays are the most abundant immature mosquito-positive containers. These findings would help the concerned authorities to formulate programs for changing human behaviour targeting the most productive containers for Aedes habitat management and vector control in the city of Dhaka, Bangladesh.

Disentangling the influencing factors driving the cooling trend in boreal summer over Indo-Gangetic river basin, India: role of Atlantic multidecadal oscillation (AMO)

Using the Community Earth System Model (CESM)-Large Ensemble (LE) surface air temperature (SAT) data, we investigate the multidecadal changes in SAT variability over Central Indian landmass, particularly the Indo-Gangetic (IG) river basin. This region comes under the active influence of the Indian summer monsoon, and during the summer monsoon months (JJA), we observe an amplified cooling (< − 3 °C) trend (1961–2000) in SAT. This SAT trend is considered as a superposition of external forcings and natural climatic variability. The forced response is computed by averaging the trend in 35 ensemble members, which displays a moderate cooling trend due to aerosol-, ozone-, and volcano-only forcings. But the internal variability introduces a wide range of uncertainties in SAT, with majority of the members display a strong cooling trend in the Central Indian region. During the entire period, natural climatic variability dominates over the forced response, which strongly overrides the greenhouse gas (GHG) warming. Here, we separate out the influence of global climate variability on regional climate variability and identify the specific internal variability which is responsible for the multidecadal cooling trend in the analyzed region. Furthermore, we investigate the specific physical mechanism driving the cooling trend and analyze the role of Atlantic multidecadal oscillation (AMO) in its negative phase. The covariability is − 0.74, i.e., AMO accounts for ~ 55% of total variance in the multidecadal variability. In the negative phase of AMO, strong signals of Rossby waves emanating from North Atlantic Ocean propagate across the Eurasian continent, and in the latter half of the twentieth century, the effect of this cold sea surface temperature (SST) anomaly is felt in the Central Indian landmass (particularly over IG river basin) through teleconnection. This study will increase the predictability of multidecadal variability in SAT during summer monsoon season over the Central Indian region with AMO as a strong driving component.

Waterlogging and coastal salinity management through land shaping and cropping intensification in climatically vulnerable Indian Sundarbans

Sundarbans in West Bengal, India located in the eastern coast of the Bay of Bengal is one of the vulnerable zones subjected to abrupt climate change. The region receives 2.7 times surplus rainfall as compared to crop evapotranspiration during monsoon months causing widespread waterlogging of the low lying agricultural fields and impedes the productivity. The present study assessed the effects of different land shaping models namely, farm pond (FP), deep furrow and high ridge (RF) and paddy cum fish (PCF) systems for rainwater harvesting in restoring the productivity of degraded coastal soils in Sundarbans. A water balance was run to estimate the soil moisture, crop evapotranspiration, runoff and water depth in the reservoir during normal, excess and deficit rainfall years. The average annual harvested runoff was 2709, 1650 and 1169 m3 per hectare in FP, RF and PCF systems, respectively. The runoff going out of the system was 19.5, 29.1 and 27.75% of the annual rainfall in FP, RF and PCF systems, respectively, whereas in monocrop rice-fallow system it was 34.6% of the annual rainfall. We estimated all the three components of water footprints (WF) i.e., blue WF (WFblue), green WF (WFgreen) and gray WF (WFgray) as an aggregative indicator to evaluate environmental impact. The results indicated that total as well as the components of WF was higher in rice-fallow and rice-rice systems than in each of the land shaping system. Large scale adoption of different land shaping systems increased the cropping intensity and net farm income and there was reduction in salinity during summer and waterlogging during rainy season and overall improvement in soil quality. The dominant soluble salts identified in the study region were NaCl and MgSO4.