Rainy Monsoon Research Articles

Second-Life Electric Vehicle Batteries for Home Photovoltaic Systems: Transforming Energy Storage and Sustainability

Solar-based home PV systems are the most amazing eco-friendly energy innovations in the world, which are not only climate-friendly but also cost-effective solutions. The tropical environment of Malaysia makes it difficult to adopt photovoltaic (PV) systems because of the protracted rainy monsoon season, which makes PV systems useless without backup batteries. Large quantities of lithium-ion battery (LIB) trash are being produced by the electric vehicle (EV) sector. A total of 75% of the highest capacity levels have been discarded. By 2035, it is predicted that the wasted LIBs held as a result of expensive recycling and difficult material separation would carry up to 1200 GWh. An economical and sustainable option is offered by our study, which prototypes a replicated LIB pack that is incorporated into a PV home system. This study investigates the transformational power of second-life electric vehicle batteries (SLEVBs) when incorporated into home photovoltaic (PV) systems. The concept entails reusing existing electric vehicle batteries for stationary applications, offering a unique approach to extending the life of these batteries while meeting the growing need for sustainable domestic energy storage. The study looks at the technological feasibility, economic viability, and environmental effect of introducing SLEVBs into household PV systems, giving vital insight into their role in revolutionizing energy storage techniques and promoting sustainability. In comparison to the Lead–Acid Battery (LAB) system, the SLEVB system has a cheaper total cost of ownership, with savings of 12.62% compared with new LABs. A CO2 emission reduction of at least 20% is achieved by using the SLEVB system compared with LABs. Electricity can be provided in houses in rural areas where there is no electricity. As a result, the security and superiority of the life of rural residents will improve. It is anticipated that the suggested strategy will lower EV pricing, enabling EV adoption for M40 and B40 groups. Consequently, the Malaysian and worldwide EV business will remain viable.

Red-necked Falcons Falco chicquera track changing environments by shifting their trophic niche during the rainy monsoon season

ABSTRACT Capsule Red-necked Falcons Falco chicquera shift their trophic niche, from eating birds to bats, during the rainy monsoon season. Aims To explore seasonal changes in prey weight, diet composition, and mobbing interactions of the globally Near Threatened Red-necked Falcon in Bangladesh. Methods We analysed long-term direct observations of 19 adult pairs feeding on prey between 2002 and 2019, exploring changes in mean prey weight, prey group, and mobbing interactions throughout the cool dry winter, hot pre-monsoon, and rainy monsoon seasons. Results The probability of bats being present within the diet increased over time, from 16% in the cool dry winter and 11% in the pre-monsoon hot season, to 48% in the rainy monsoon season. This coincided with a significant decline in mean prey weight and biomass consumed during the rainy monsoon season. Probabilities of falcons being mobbed during feeding varied throughout the seasons, depending on mobbing species. Conclusion Red-necked Falcons appeared to track changing environments by shifting their trophic niche during the rainy monsoon season. This may be due to: (a) an optimal foraging response to bat population fluxes, itself a response to weather-induced increases in flying insect abundances, (b) opportunistic hunting of bats during periods of crepuscular activity peaks, and/or (c) the energetic demands of fledglings during the rainy monsoon season.

Variability and predictability of the Northeast India summer monsoon rainfall

AbstractThe mesoscale orography over one of the wettest regions of the world makes the Northeast India (NEI) vulnerable to hydrological disasters while sustaining a biodiversity “hotspot.” The monsoon rainy season over the NEI is known to be longer than June–September (JJAS), but an objective definition has been lacking. Understanding the drivers and predictability of rainfall variability over the region is key for sustainable development planning and adaptation to increasing disasters in the backdrop of a warming climate but remained poor due to lack of a working definition of “summer monsoon season” over NEI. Here, using the relationship between rainfall over the region and winds at 850 hPa over North Bay of Bengal (BoB), we provide an objective definition of the monsoon season over NEI and argue that the “summer monsoon rainy season” over the NEI (NEIR) is from May to September (MJJAS). In contrast to a significant negative relationship between JJAS Central India (CI) rainfall and a JJAS El Niño–Southern Oscillation (ENSO) index, the MJJAS rainfall over the NEI has no relationship with MJJAS or JJAS ENSO. Instead, we unravel that (a) the tropical Northwest‐Pacific (TNWP) sea surface temperature (SST), (b) the South Equatorial Indian Ocean Dipole (SEIOD) and (c) the Atlantic Zonal mode (AZM) are potential drivers of the NEIR variability. Using a causal inference algorithm, namely the Peter and Clark Momentary Conditional Independence (PCMCI) method, we show that SEIOD directly influences NEIR while TNWP SST has a two‐way connection with the NEIR. While “internal variability” may be higher over the NEI, significant modulation of the variances of the subseasonal fluctuations by predictable drivers like the Atlantic Niño and North Atlantic water temperature provides optimism for seasonal prediction of the NEIR.

Uncertainty analysis of future summer monsoon duration and area over East Asia using a multi-GCM/multi-RCM ensemble

This study examines the spatiotemporal characteristics of the summer monsoon rainy season over East Asia using six regional climate models (RCMs) participating in the Coordinated Regional Domain Experiment (CORDEX) East Asia Phase II project. The framework combining multiple global climate models (GCMs) with multiple RCMs produces a larger spread in summer monsoon characteristics than driving GCMs only, enabling a better quantification of uncertainty factors. On average, the RCM simulations reproduce the observed summer monsoon duration and area better than the corresponding boundary GCMs, implying the added values of downscaling. Both the area and duration of the East Asian summer monsoon are projected to increase by the late 21st century, more strongly in high emission scenarios than in low emission scenarios, particularly in China. Different responses between scenarios, which indicate warming mitigation benefits, only become significant in the late 21st century due to large intersimulation uncertainties. Analysis of variance results show that uncertainty in future monsoon area and duration is larger between boundary GCMs than between RCMs over East Asia and its coastal subregions. A strong intersimulation relationship between RCMs and GCMs supports that boundary GCMs substantially diversify downscaled RCM projections through different climate sensitivities. Furthermore, the distinct subregional responses in future monsoon area and duration emphasize the importance of fine-resolution projections with appropriate uncertainty measures for better preparing region-specific adaptation plans.

Investigating Nitrate with Other Constituents in Groundwater in Two Contrasting Tropical Highland Watersheds

Nitrate is globally the most widespread and widely studied groundwater contaminant. However, few studies have been conducted in sub-Saharan Africa, where the leaching potential is enhanced during the rainy monsoon phase. The few monitoring studies found concentrations over drinking water standards of 10 mg N-NO3− L−1 in the groundwater, the primary water supply in rural communities. Studies on nitrate movement are limited to the volcanic Ethiopian highlands. Therefore, this study aimed to evaluate the transport and fate of nitrate in groundwater and identify processes that control the concentrations. Water table height, nitrate, chloride, ammonium, reduced iron, and three other groundwater constituents were determined monthly in the groundwater in over 30 wells in two contrasting volcanic watersheds over two years in the Ethiopian highlands. The first watershed was Dangishta, with lava intrusion dikes that blocked the subsurface flow in the valley bottom. The water table remained within 3 m of the surface. The second watershed without volcanic barriers was Robit Bata. The water table dropped rapidly within three months of the end of the rain phase and disappeared except near faults. The average nitrate concentration in both watersheds was between 4 and 5 mg N-NO3− L−1. Hydrogeology influenced the transport and fate of nitrogen. In Dangishta, water was blocked by volcanic lava intrusion dikes, and residence time in the aquifer was larger than in Robit Bata. Consequently, nitrate remained high (in several wells, 10 mg N-NO3− L−1) and decreased slowly due to denitrification. In Robit Bata, the water residence time was lower, and peak concentrations were only observed in the month after fertilizer application; otherwise, it was near an average of 4 mg N-NO3− L−1. Nitrate concentrations were predicted using a multiple linear regression model. Hydrology explained the nitrate concentrations in Robit Bata. In Dangishta, biogeochemistry was also significant.

Piriformis Syndrome in Pre-monsoon, Monsoon, and Winter: An Observational Pilot Study.

Piriformis syndrome (PS) is a rare focal soft tissue rheumatic disease. Due to heavy rural work, we questioned whether PS was more prevalent in the rainy monsoon than in other seasons. In this pilot research, we studied the pattern of PS, the frequency of PS over the seasons, and whether there were typical preceding events. Methods: In this time-series descriptive study, PS cases diagnosed in a community-based clinic between January 2018 and December 2019 were enrolled. PS was diagnosed by clinical features and a 50% immediate pain relief from ultrasonogram-guided lidocaine (2%) injection in the piriformis muscle (PM). PS mimics were excluded. A total of 38 PS cases (11 males) were enrolled consecutively.In 2018, during dry winter (November-February), pre-monsoon (March-May), and rainy monsoon (June-October), nine, seven, and one PS cases were diagnosed, respectively; in 2019, the numbers were three, eight, and seven, respectively. Thus, over two years, 12 PS patients were diagnosed in dry winter, 15 in pre-monsoon, and eight in rainy monsoon. There was no correlation with the type of preceding events. There were no differences in the pattern of PS between the seasons. In this pilot study, over two years more new PS cases were observed in the pre-monsoon and dry winter than in the rainy season; this was not supporting our research question. There was no association with specific preceding events.

Changing Epidemiology of Acute Respiratory Infections in Under-Two Children in Dhaka, Bangladesh.

Objectives: Risk factors for acute respiratory infections (ARIs) in community settings are not fully understood, especially in low-income countries. We examined the incidence and risk factors associated with ARIs in under-two children from the Microbiota and Health study.Methods: Children from a peri-urban area of Dhaka (Bangladesh) were followed from birth to 2 years of age by both active surveillance of ARIs and regular scheduled visits. Nasopharyngeal samples were collected during scheduled visits for detection of bacterial facultative respiratory pathogens. Information on socioeconomic, environmental, and household conditions, and mother and child characteristics were collected. A hierarchical modeling approach was used to identify proximate determinants of ARIs.Results: Of 267 infants, 87.3% experienced at least one ARI episode during the first 2 years of life. The peak incidence of ARIs was 330 infections per 100 infant-years and occurred between 2 and 4 months of age. Season was the main risk factor (rainy monsoon season, incidence rate ratio [IRR] 2.43 [1.92–3.07]; cool dry winter, IRR 2.10 [1.65–2.67] compared with hot dry summer) in the first 2 years of life. In addition, during the first 6 months of life, young maternal age (<22 years; IRR 1.34 [1.01–1.77]) and low birth weight (<2,500 g; IRR 1.39 [1.03–1.89]) were associated with higher ARI incidence.Conclusions: Reminiscent of industrialized settings, cool rainy season rather than socioeconomic and hygiene conditions was a major risk factor for ARIs in peri-urban Bangladesh. Understanding the causal links between seasonally variable factors such as temperature, humidity, crowding, diet, and ARIs will inform prevention measures.

Climatology of the Global Summer Monsoon Rainy Seasons: Revisited from a High-Resolution Satellite Climate Data Record

Climatology of the Global Summer Monsoon Rainy Seasons: Revisited from a High-Resolution Satellite Climate Data Record

A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)

ABSTRACTWe comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi‐proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp) in the early Late Paleolithic. The palynoflora consisted of pollen and non‐pollen palynomorphs. Under the air‐circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad‐leaved forest with an understory of pteridophytes flourished around the north‐east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ18O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food.

Assessing vulnerability of freshwater minnows in the Gangetic floodplains of India for conservation and management: Anthropogenic or climatic change risk?

Minnows are the most ignored yet indispensable group of freshwater fishes in Asian inland waters. The reproductive resilience of minnows facing climatic variability, using a wetland inhabiting species Amblypharyngodon mola (Mola carplets) in lower Indo-Gangetic floodplains, was validated. Results revealed that spawning decision in females (threshold gonadosomatic index ≥ 5 units) is neither cued by water temperature nor rainfall. They can maintain pre-spawning fitness (condition factor 1.12–1.25 units) within a broad temperature (22–33 °C) and rainfall (0–800 mm) window by active feeding, thus no risk of skipped spawning decisions while facing future climatic variabilities. Present breeding phenology (May-December) might have prolonged in the recent decade, especially the tail-end, concomitant with increasingly hot and rainy monsoon (May-August) and warmer post-monsoon months (September-December). Minnows are expected to prosper in a future climatic scenario, contributing to ecosystem balance (algal grazers) and regional food security. Female first maturity (♀ puberty) was encountered at 4.7–5.1 cm total length, hinting at a probable increase in the recent decade. Climate-favored prolonged recruitment window, in absence of extreme fishing pressure (currently), might have led to such pattern. However, this state might be temporary and labile. Minnows may soon get altered to earlier puberty (=warning sign of stock collapse) if fishing pressure intensifies under a reproductively favoring climate progression. Threshold body girth for spawning females was estimated at 3.2–3.4 cm (+17% than non-breeding ones). Fishing nets having mesh sizes (=total circumference) at least > 32–34 mm will most likely be the key to minnows’ endurance or survival in the coming decades.

Water resources and flooding risk in Kumamoto based on observed hydrologic data analysis

Abstract Variability and change of precipitation were investigated in Kumamoto on Kyushu Island in southwestern Japan, to assess water resources and flooding risk. Annual precipitation, annual maximum daily precipitation, and annual maximum hourly precipitation have increased over the period from 1891 to 2018 (128 years). Trends are 26.2 mm per decade, 6.07 mm/day per decade, and 2.17 mm/h/decade, respectively. Precipitation in the rainy season (June and July) is on average 37% (ranging from 12 to 59%) of annual precipitation for the 128-year period. Maximum daily precipitation in a year occurred at Kumamoto in the rainy season in 92/128 (72%) of the years of observation from 1891 to 2018, in the typhoon (August to November) season in 23/128 (18%), and in the March to May season in 12/128 (10%). This indicates that the rainy monsoon season poses the largest daily flooding risk. A wavelet analysis revealed that from 1891 to 2018 annual precipitation and daily maximum precipitation fluctuate with 2 and 4 years periods, which may be related to the El Nino-Southern Oscillation (ENSO). It is likely that air temperature rises, ENSO and topographical characteristics contributed to an increase in precipitation in the period. The analysis also showed that typhoons hitting or approaching Kumamoto have significantly affected annual precipitation and annual maximum daily precipitation, while the interval between typhoons affecting Kumamoto has been getting longer since the 1970s.

Isotopic variability (δ18O, δ2H and d-excess) during rainfall events of the north American monsoon across the Sonora River Basin, Mexico

The economic activities of the Sonora strongly depend on groundwater extraction, which is generally of recent meteoric origin. Understanding the hydrological functioning in this semi-arid region, located in northwestern Mexico, is crucial for integrated water management in a changing climate. This study presents a spatio-temporal analysis of the isotopic composition (δ18O, δ2H, d-excess) during the 2018 rainy season in the Sonora River Basin (SRB), a region influenced by the characteristic weather conditions of the North American Monsoon (NAM). The basin is located in the central region of Sonora and covers an area of approximately 27,000 km2. Precipitation was collected using six passive totalizers, distributed spatially from the coast of the Gulf of California up to 1,425 m asl inland. The rainfall isotopic composition is comparable with the Global Meteoric Water Line (GMWL) and with the records of the Global Isotope Network in Precipitation (GNIP) in Chihuahua, Mexico, between 1962 and 1988, and Tucson, Arizona (2018). The temporal variability of rainfall isotope ratios was Δ18O = 7.4‰ and Δ2H = 49.8‰, with a clear depletion pattern (low δ18O) as the monsoon rainy season progressed. The isotopic lapse rate was found to be −1.0‰ in δ18O per km of elevation as a result of the topography relief and rainout effects within the basin. The influence of tropical cyclones such as Hurricane Sergio (October 2018) provided the opportunity to isolate the effects of a tropical storm with respect to the deep convective precipitation, typical of the NAM systems over northwest Mexico.

Assessment of the Catastrophic Asia Floods and Potentially Affected Population in Summer 2020 Using VIIRS Flood Products

Since 2 June 2020, unusual heavy and continuous rainfall from the Asian summer monsoon rainy season caused widespread catastrophic floods in many Asian countries, including primarily the two most populated countries, China and India. To detect and monitor the floods and estimate the potentially affected population, data from sensors aboard the operational polar-orbiting satellites Suomi National Polar-Orbiting Partnership (S-NPP) and National Oceanic and Atmospheric Administration (NOAA)-20 were used. The Visible Infrared Imaging Radiometer Suite (VIIRS) with a spatial resolution of 375 m available twice per day aboard these two satellites can observe floodwaters over large spatial regions. The flood maps derived from the VIIRS imagery provide a big picture over the entire flooding regions, and demonstrate that, in July, in China, floods mainly occurred across the Yangtze River, Hui River and their tributaries. The VIIRS 5-day composite flood maps, along with a population density dataset, were combined to estimate the population potentially exposed (PPE) to flooding. We report here on the procedure to combine such data using the Zonal Statistic Function from the ArcGIS Spatial Analyst toolbox. Based on the flood extend for July 2020 along with the population density dataset, the Jiangxi and Anhui provinces were the most affected regions with more than 10 million people in Jingdezhen and Shangrao in Jiangxi province, and Fuyang and Luan in Anhui province, and it is estimated that about 55 million people in China might have been affected by the floodwaters. In addition to China, several other countries, including India, Bangladesh, and Myanmar, were also severely impacted. In India, the worst inundated states include Utter Pradesh, Bihar, Assam, and West Bengal, and it is estimated that about 40 million people might have been affected by severe floods, mainly in the northern states of Bihar, Assam, and West Bengal. The most affected country was Bangladesh, where one third of the country was underwater, and the estimated population potentially exposed to floods is about 30 million in Bangladesh.

Understanding Future Change of Global Monsoons Projected by CMIP6 Models

AbstractProjecting future change of monsoon rainfall is essential for water resource management, food security, disaster mitigation, and infrastructure planning. Here we assess the future change and explore the causes of the changes using 15 models that participated in phase 6 of the Coupled Model Intercomparison Project (CMIP6). The multimodel ensemble projects that, under the shared socioeconomic pathway (SSP) 2–4.5, the total land monsoon rainfall will likely increase in the Northern Hemisphere (NH) by about 2.8% per one degree Celsius of global warming (2.8% °C−1) in contrast to little change in the Southern Hemisphere (SH; −0.3% °C−1). In addition, in the future the Asian–northern African monsoon likely becomes wetter while the North American monsoon becomes drier. Since the humidity increase is nearly uniform in all summer monsoon regions, the dynamic processes must play a fundamental role in shaping the spatial patterns of the global monsoon changes. Greenhouse gas (GHG) radiative forcing induces a “NH-warmer-than-SH” pattern, which favors increasing the NH monsoon rainfall and prolonging the NH monsoon rainy season while reducing the SH monsoon rainfall and shortening the SH monsoon rainy season. The GHG forcing induces a “land-warmer-than-ocean” pattern, which enhances Asian monsoon low pressure and increases Asian and northern African monsoon rainfall, and an El Niño–like warming, which reduces North American monsoon rainfall. The uncertainties in the projected monsoon precipitation changes are significantly related to the models’ projected hemispheric and land–ocean thermal contrasts as well as to the eastern Pacific Ocean warming. The CMIP6 models’ common biases and the processes by which convective heating drives monsoon circulation are also discussed.

Alstonia scholaris in the ethnomedicinal and religious tradition of Coastal Karnataka, India

Abstract. MJ Bhandary. 2020. Alstonia scholaris in the ethnomedicinal and religious tradition of Coastal Karnataka, India. Biodiversitas 21: 1569-1577. The tribal and non-tribal indigenous communities of coastal districts of Karnataka use Alstonia scholaris (L.) R. Br. for the treatment of various ailments such as fever, asthma, leucorrhea, eczema, indigestion and also to heal spider bites. An annual health-related ritual of mass drinking of a bitter juice or decoction of the stem bark of this tree on the new moon (amavasya) day of ‘aati’ month of the traditional ‘tulu’ calendar coinciding with the rainy monsoon season is popularly followed in the study area, especially by the rural families. The underlying belief is that this drink keeps away all ailments and ensures wellbeing. The recorded ethnomedicinal uses and the traditional practice of mass drinking of the bitter juice appear to be scientifically meaningful when interpreted on the background of the ayurvedic uses and the wide range of curative properties ascribed to this plant, many of which have been confirmed by reported pharmaco-chemical studies. Studies have also indicated that the toxicity of the bark extract was minimum during monsoon season and the concentration of active principle was maximum in the bark juice collected on the particular new moon day. This further justifies the timing of the described annual medicine drinking event. In addition, some Tulu language-speaking indigenous communities consider this tree as the reincarnation of a mythological demon called Bali and worship its branch during the festival days of Deepavali, in honor of him. Thus, A. scholaris emerges as a plant of great ethnobotanical significance in the study area.

Interdecadal variation of Changma (Korean summer monsoon rainy season) retreat date in Korea

AbstractThis study applied statistical change‐point analysis to the time series of the Changma retreat date (CRD) on the Korean Peninsula over a recent 30‐year period (1985–2014) and detected that the CRD has been delayed by about 10 days since 2000. The average CRD is July 14 for 1985–1999 and July 24 for 2000–2014. Corresponding to the CRD delay, the July rainfall is concentrated in the northern South Korea during 2000–2014, whereas tends to be intense along the southern coast during 1985–1999. The delayed CRD is associated with, in the lower and mid‐troposphere, a strengthened cyclonic circulation around Lake Baikal–eastern Sea of Japan and an enhanced anticyclonic circulation in East China Sea. Thus, northerlies from strengthened cyclones and anomalous southerlies from the enhanced anticyclones converge at the northern‐central Korean Peninsula. The anomalous anticyclone is associated with the strengthening of the western North Pacific subtropical high that has strengthened in meridional direction in the later epoch, supplying warm and moist air to Korean Peninsula. The result is verified by the enhanced warm and moist anomalous upward flows in the latitude where Korean Peninsula is placed. The delayed CRD in the latter epoch is related to the decreased spring snowfall over East Asia except for the vicinity of the Lake Baikal, which results in severely hot weather in the East Asia continent from spring to July. The continent heating from spring to July weakened (increases), the thermal gradient between continent and ocean, thereby forming a low‐pressure system on East Asia and a high‐pressure system in western North Pacific, resulting in the strengthening of Changma rain belt in July and delayed the Changma withdrawal.

Oyster breakwater reefs promote adjacent mudflat stability and salt marsh growth in a monsoon dominated subtropical coast

Oyster reefs have the potential as eco-engineers to improve coastal protection. A field experiment was undertaken to assess the benefit of oyster breakwater reefs to mitigate shoreline erosion in a monsoon-dominated subtropical system. Three breakwater reefs with recruited oysters were deployed on an eroding intertidal mudflat at Kutubdia Island, the southeast Bangladesh coast. Data were collected on wave dissipation by the reef structures, changes in shoreline profile, erosion-accretion patterns, and lateral saltmarsh movement and related growth. This was done over four seasons, including the rainy monsoon period. The observed wave heights in the study area ranged 0.1–0.5 m. The reefs were able to dissipate wave energy and act as breakwaters for tidal water levels between 0.5–1.0 m. Waves were totally blocked by the vertical relief of the reefs at water levels <0.5 m. On the lee side of the reefs, there was accretion of 29 cm clayey sediments with erosion reduction of 54% as compared to control sites. The changes caused by the deployed reefs also facilitated seaward expansion of the salt marsh. This study showed that breakwater oyster reefs can reduce erosion, trap suspended sediment, and support seaward saltmarsh expansion demonstrating the potential as a nature-based solution for protecting the subtropical coastlines.

Coupling the Common Land Model to ECHAM5 Atmospheric General Circulation Model

The ECHAM5 model is coupled with the widely used Common Land Model (CoLM). ECHAM5 is a state-of-the-art atmospheric general circulation model incorporated into the integrated weather and climate model of the Chinese Academy of Meteorological Sciences (CAMS-CSM). Land surface schemes in ECHAM5 are simple and do not provide an adequate representation of the vegetation canopy and snow/frozen soil processes. Two AMIP (Atmosph-eric Model Intercomparison Project)-type experiments using ECHAM5 and ECHAM5-CoLM are run over 30 yr and the results are compared with reanalysis and observational data. It is found that the pattern of land surface temperature simulated by ECHAM5-CoLM is significantly improved relative to ECHAM5. Specifically, the cold bias over Eurasia is removed and the root-mean-square error is reduced in most regions. The seasonal variation in the zonal mean land surface temperature and the in situ soil temperature at 20- and 80-cm depths are both better simulated by ECHAM5-CoLM. ECHAM5-CoLM produces a more reasonable spatial pattern in the soil moisture content, whereas ECHAM5 predicts much drier soils. The seasonal cycle of soil moisture content from ECHAM5-CoLM is a better match to the observational data in six specific regions. ECHAM5-CoLM reproduces the observed spatial patterns of both sensible and latent heat fluxes. The strong positive bias in precipitation over land is reduced in ECHAM5-CoLM, especially over the southern Tibetan Plateau and middle–lower reaches of the Yangtze River during the summer monsoon rainy season.

Phytoplankton nutrient deficiencies vary with season in sub-tropical lakes of Nepal

This is one of few studies to comprehensively examine seasonality and phytoplankton nutrient deficiency in sub-tropical lakes over multiple years, to our knowledge. We tested whether phytoplankton communities in two sub-tropical impoundments in the mid-hills of Nepal were nitrogen (N)-, phosphorus (P)-, or co-deficient in N and P across pre-monsoon, monsoon, and post-monsoon seasons spanning a decade. Nutrient limitation to phytoplankton growth was assessed via in situ stoichiometry of N and P (N:P ratios) and nutrient stimulation experiments (NSEs). The experiments indicated co-deficiency of N and P in 97–100% of NSEs in all seasons. N-deficiency was common (> 60% of N:P ratios and ~ 90% of NSEs) during the rainy monsoon, but P-deficiency occurred twice as often as N-deficiency during drier seasons (pre- and post-monsoon). These findings provide perspective for the ongoing debate over N and P as limiting nutrients in freshwater ecosystems by incorporating seasonality and corresponding hydrology. We also re-visit long-standing assumptions regarding the nutrient status of sub-tropical lakes. The warm, stratified season does not fully illustrate lake processes, and more research during dry periods will inform how seasonality affects phytoplankton nutrient deficiencies across aquatic systems.

Seasonal variation in stable isotope compositions of waters from a Himalayan river: Estimation of glacier melt contribution

AbstractStable isotopic compositions (δ18O and δD) in water samples collected from Parbati River in Himachal Pradesh, India, during 2002–2005 were measured to delineate the contributions from different sources in different seasons. A seasonal cycle with high δ18O and δD values (in ‰) during the spring (March to May; −9.2, −58.6), intermediate values during the winter (December to February; −10.1, −65.6), and low values during the south‐west monsoon (July to September; −10.9, −71.8) is observed. The d‐excess values (15.2 ± 2.1‰) are higher compared with the global meteoric waters indicating significant contribution (~26%) of moisture carried by western disturbances. Higher δ‐values during the spring are ascribed to enhanced contribution from snow melt. The lower δ‐values during the monsoon are due to various Rayleigh effects (altitude, continental, and amount effects) and large‐scale convection effect on rains. A three component‐mixing model using the isotopic data and some plausible end member isotopic values was applied to identify contributions to the river discharge from different sources such as groundwater or subsurface base flow, glacier/surface snow melt, and the monsoon rain. Meltwater from glacier and snow combines with the base flow in spring season. South‐west monsoon rain and glacier melt along with the base flow constitute the monsoon discharge. The post‐monsoon season and winter are dominated by groundwater contribution. About 80% of the discharge is contributed by glacier melts in spring season. In the rainy monsoon season, glacier/snow melt contributes ~41% of the discharge. The mean annual glacier melt contribution to the river water is estimated to be 44 ± 15%. The present estimate along with some previous studies suggest that glacier contribution to the river discharge increased from ~35% to 50% during the period 1990 to 2011. This is consistent with recent data on glacier retreats in the Himalayan region.