West Monsoon Research Articles

An investigation into the influence of climate extreme on groundwater regimes and human health in the Periyar Basin: a fast growing urban centre in India

ABSTRACT A total of 212 groundwater samples were collected during North East Monsoon (NEM), South West Monsoon (SWM), Pre-Monsoon (PREM), and Post-Monsoon (POM) seasons of 2020–2021 from the Periyar River Basin, draining the south western flanks of Western Ghats. The analytical results revealed the order of abundance of cations as Ca2+ > Na+ > Mg2+ > K+ and anions in the order of HCO3− > Cl− > SO42− > NO3− for all seasons. The major hydrochemical facies identified were CaHCO3 and mixed Ca–Mg–Cl in all the seasons with rock–water interaction as the key process regulating water chemistry. Ionic ratios of Ca2+ + Mg2+/Na+ + K+ and Ca2+/Mg2+ suggested significant effect of silicate minerals and other sources. The Water Quality Index (WQI) shows that the majority of the samples, namely, 98% in NEM, 86% in POM, 82% in PREM, and 95% in MON, fall in the categories ranging from excellent to good for drinking purposes. Furthermore, the health risk assessment based on carcinogenic and non-carcinogenic risk of the United States Environmental Protection Agency (US EPA) during monsoon and non-monsoon seasons for adults and children revealed the potential risk posed by Pb via oral exposure in the study area suggesting children are more susceptible to the damaging effects than adults.

Climate Extremes Related with Rainfall Trends in Agniyar River Basin

The rainfall extremes variability due to climate change can be detected by the trend analysis. The trend analysis is implemented for the precipitation data period starting from year 1980 to 2021 (42 years) for the Agniyar river basin. The Mann-Kendall (M-K) test is employed to identify trends in precipitation, while The trend's magnitude is calculated using the Sen's slope method. The rainfall trend in Yearly Maximum Daily Rainfall (YMDR), South West Monsoon (SWM), Summer season, North East Monsoon (NEM), winter season and annual rainfall are computed. The results of twelve rain gauge stations in the Agniyar river basin revealed increasing, decreasing, and non-significant trends, with a notable increase in precipitation observed at some locations with acceptable significance. Most of the stations showing declining trend in precipitation based on Sen’s magnitude and negative slope. The outcome of this study needs of hour to the hydrologists, water resources engineers, water resources managers, environmentalist, sustainable development policy makers, inter-disciplinary climate change researchers and consultants involved in solving problems related to change in climate impact. The results of precipitation extremes are necessary for creating adaptation strategies in response to climate change.

A Comparative Investigation of Monsoon Active and Break Events over the Western North Pacific

Abstract This study identifies 86 active events and 66 break events of the western North Pacific summer monsoon (WNPSM) from 1979 to 2020. These active and break events exhibit sharp contrast in large-scale convection and circulation fields. During the active period, deep convection almost covers the entire WNP domain (0°–25°N, 120°–170°E), accompanied by the strengthening of a local monsoon trough and monsoon westerlies extending from the Arabian Sea to the WNP. In contrast, during the break period, along with weakened monsoon westerlies, the subtropical high replaces the monsoon trough to dominate the WNP domain, leading to the disappearance of deep convection. Results about the convection evolution at multiple time scales indicate that active/break events are primarily contributed to by the wet/dry phases of intraseasonal oscillations (ISOs). The phase transitions of ISOs are nearly symmetric between active and break events. However, these two types of events present notable asymmetric features in convection anomalies relative to climatology, which can be attributable to the modulation of the seasonal mean component. Specifically, both active and break events correspond to anomalously strong seasonal mean convection, which amplifies (weakens) the convection enhancement (suppression) during the active (break) period and results in normal (enhanced) convection during adjacent periods. The preferred occurrence of active and break events in strong summer monsoons is because related mean backgrounds, including increased low-level positive vorticity, specific humidity, and easterly vertical shear, facilitate the intensification of ISOs. These mean backgrounds are likely induced by SST cooling in the north Indian Ocean and warming in the equatorial central Pacific during the simultaneous summer. Significance Statement The subseasonal variation in monsoon rainfall typically manifests as fluctuations between active events with abundant rainfall and break events with deficit rainfall, which can induce converse extremes such as floods and droughts, significantly affecting water management, agriculture planning, and economic activities. This study aims to reveal the characteristics, formation, and occurrence regularity of active and break events during the western North Pacific summer monsoon (WNPSM). We note that the occurrence of these active and break events is determined not only by intraseasonal oscillations but also by seasonal mean backgrounds, which result in certain asymmetrical features between the two types of events. These results will enhance our understanding of the monsoon’s intraseasonal variability and the physical association between multiple time scales over the WNP domain (0°–25°N, 120°–170°E).

Precession Controls on Climate and Water Isotope Signals in Northern Africa

AbstractPrecessional forcing is a key driver of quaternary climate change. Based on 24 experiments covering a full precession cycle, this study explores spatio‐temporal variations of both climate and isotope signals in Northern Africa. We find a synchronous phasing of precipitation variations with solar radiation levels and an asynchronous timing of surface air temperature changes across different sub‐regions of Northern Africa. Based on daily precipitation, our results reveal earlier onset and withdrawal, as well as a shorter duration of the West Africa summer monsoon (WASM) at minimum precession compared to maximum precession. The onset of the WASM is controlled by the intensity of the Sahara Heat Low, while the monsoon termination is linked to subtropical solar radiation and interhemispheric thermo contrast. Using a novel scale‐flux tracing technique, we find that, precipitation during minimum precession is more influenced by evaporation from warmer and more humid regions compared to maximum precession. Additionally, certain inland areas of Northern Africa exhibit positive temporal isotope‐precipitation gradients, violating the “amount effect.” This phenomenon mainly occurs during precession phases associated with Green Sahara periods. The isotope composition changes in such places primarily reflect changes in upstream rainfall quantity, rather than changes in local precipitation as is inferred from present day analogs. Conversely, the “amount effect” remains applicable during dry periods in Africa when the Sahara desert is present. This suggests that isotope‐based reconstruction of past precipitation variations during Green Sahara periods over Northern Africa needs to be taken with caution.

Analysis of Forecasted Rainfall Across Blocks in Guntur District, Andhra Pradesh, India

This paper represents a block and district level analysis of agro meteorological forecasted rainfall of Guntur district, Andhra Pradesh, during 2022-23. The forecasted rainfall data which was issued by IMD, Amaravathi, Guntur, Andhra Pradesh and the data was validated by employing both qualitative (success rate) and quantitative analysis (Ratio score, Hanssen and Kuipers Score and Probability of Detection). The quantitative analysis was performed by calculating ratio score analysis values ranged from 0.6 to 0.9 during the monsoons, indicating good forecast. Hansen and Kuipers score test results found to have good agreement during north east monsoon (0.5 to 0.8) with highest score values which indicates better forecast agreement, followed by monsoon period (0.3 to 0.5) and south west monsoon (0 to 0.3). Probability of Detection values found in the range of 0.7 to 1.0 indicated that better score values resulting in good forecast during the monsoon seasons. Whereas, the qualitative analysis was performed by deriving success rate for forecasted rainfall accuracy and the results reported that highest success rate was observed during north east monsoon followed by south west monsoon across different blocks and also in the entire Guntur district. The per cent deviation in the analysed data might be due to the spatio-temporal variations in the rainfall distribution pattern over the study area.

Morphodynamic Cartography Visualization of Wulan River Estuary Systems from Space to Numerical Approach Based on Multi-Season Analysis

This research aims to investigate the morphodynamics of the Wulan River estuary in Demak Regency using the integration of multispectral remote sensing images and numerical modeling. In this study, PlanetScope for a manualvisual analysis of estuary morphodynamics and Sentinel-2 MSI Level 2A to obtain periodic total suspended solids (TSS) information for the east and west monsoon seasons. MIKE by DHI software used to develop hydrodynamic numerical modeling in order to characterize the current circulation and sediment transport model. Based on a marine cartography aspect, the obtained results illustrated that the climatological phenomenon of seasonal forcing plays a role in the development of the current circulation and indirectly influences the sediment transport. During the west season, the morphodynamics in the Wulan River estuary are much more massive and significant as compared to the east season. A projection of the deposition that results from the sediment transport is described in the bed-thickness change; this occurs in the western part of the Wulan River estuary during the east season, while the bed-thickness change occurs predominantly in the northern part during the west season (where there was previously a beach sandbar phenomenon). This was verified through multi-temporal satellite imagery that the deposition that occurs in the northern part of the Wulan River estuary during the west season is increasingly progressive and massive.

Trajectory of microplastic particles with 2-dimensional hydrodynamic modelling approach at Pekalongan waters, Central Java, Indonesia.

This research aims to understand the extent of microplastic contamination in Pekalongan waters, Central Java, and its potential impact on fishing grounds, aligning with Indonesia's National Action Plan for Handling Marine Debris 2018-2025. The study employs a 2D hydrodynamics modelling approach with Mike 21 Software to map the spatial distribution of microplastic movement concerning fishing areas during the west and east monsoon seasons. The results showed that microplastic particles follow tidal currents in Pekalongan waters, with their movement influenced by factors such as current, wind, and tidal conditions. The trajectory of microplastics entering fishing ground areas poses potential contamination risk for fish caught by fishermen, threatening the health of marine ecosystems and the stability of their structure and function.

Characteristics and Distribution of Chemical-Biological Parameters in The Seawaters of Eastern Java Sea

The Java Sea is influenced by the west and east monsoons, which have an impact on hydrodynamic processes and chemical-biological water quality. Chemical-biological parameters play an important role in the food chain cycle that occurs in these waters. The quality of the eastern Java Sea waters is still limited by chemical-biological parameters, so the characteristics and distribution of these waters can be comprehensively known. chemical-biological. This study aimed to analyze the characteristics and distribution of nitrate, phosphate, oxygen, chlorophyll-A, and NPP parameters in the eastern Java Sea waters. This study used secondary data with daily temporal resolution from January to December 2020. Spatial analysis uses the climatological averaging method for 6 months as a statistical representative of the west monsoon and east monsoon. For each parameter, a vertical analysis was conducted to compare parameter values between the coastal waters of Tuban, Java Sea, and Banjarmasin Waters. Correlation analysis between parameters was conducted using the Pearson correlation method. Nitrate, phosphate, oxygen, chlorophyll-A, and NPP concentrations have temporal and spatial variability. Monsoon factors in Indonesia have a strong influence on the variability of nitrate, phosphate, oxygen, chlorophyll- A, and NPP concentrations. During the east monsoon, the concentration of chemical-biological parameters decreases, while in the west monsoon, the concentration increases and reaches its highest value. Generally, high concentrations occur in the northern and southern parts of the study site, around the coastal areas of Java and Kalimantan. Key Word: Chemical-Biological Parameters, Java Sea, Tuban Waters

Mean flow and eddy summer moisture transport over East Asia in reanalysis data and a regional climate simulation

Understanding the impact of atmospheric variability on climatological mean moisture transport is crucial because moisture transport determines continental water availability as well as convective organization and resulting precipitation. Here, we analyze the mean flow and eddy components of summer moisture transport in the downwind of the Tibetan Plateau (TP), a region that is characterized by interactions between monsoon systems, extratropical circulation, and mountainous weather systems. Using 40 years of ERA5 reanalysis data and a regional WRF simulation, we determine the absolute and relative contributions of mean flow and eddy moisture transport from multi-daily to sub-daily scales. We also link these components to large-scale circulation indices, precipitation, evaporation, and mesoscale convective systems (MCSs). The results show that the largest contributions of eddies to the climatological mean moisture transport are found in the immediate downwind region of the TP. Half of the total eddy transport downwind of the TP is due to multi-daily eddy transport and the other half is due to daily to sub-daily eddy transport. Regional precipitation anomalies are dominated by the mean flow component of southerly moisture influxes which in turn are positively correlated with different South Asian summer monsoon indices and negatively correlated with the West Northern Pacific monsoon index. The eddy transport from the south is positively correlated with a lower jet latitude but does not show any significant correlations with precipitation or MCS activity, likely due to the dominant role of the mean flow moisture transport. While the relative contributions of eddies to the climatological mean moisture transport are similar in ERA5 and WRF, the correlations between moisture transport components and large-scale circulation indices are generally weaker in WRF. This suggests that the dynamical downscaling does not significantly change the role of eddy moisture transport averaged for the region, but it resolves processes that decouple the moisture transport from its large-scale forcing.

Detection Of The Thermal Front Using The Cayula-Cornillon Alghorithm: A Case Study Of The State Fisheries Management Area 713, Indonesia

Thermal fronts are pivotal in shaping the marine ecosystem, influencing the presence and distribution of marine species. This study delves into the fluctuating patterns of thermal fronts in Indonesian waters, specifically focusing on the State Fisheries Management Area of the Republic of Indonesia, known as WPPNRI, 713. We identified the distribution and frequency of thermal fronts across different monsoon seasons. Utilizing the extended Cayula Cornillon Algorithm – Single Image Edge Detection (CCA-SIED), we deploy a precise methodology for detecting these fronts, relying on sea surface temperature (SST) gradients to identify specific periods and regions. Our analysis encompasses extensive satellite data collected from Moderate Resolution Imaging Spectroradiometer (MODIS) level 3. Our findings unveil distinct seasonal variations, with a decrease in thermal fronts during the west monsoon and a surge during the east monsoon. Moreover, we identify regional disparities, with denser thermal fronts observed in the southern and middle regions compared to the northern areas. Furthermore, our study underscores the critical need to integrate oceanographic data with fisheries management strategies to address the impacts of climate variability on marine resources. The observed relationships between thermal fronts, nutrient distribution, and fish migration emphasize the necessity for ongoing, localized monitoring to develop adaptive management solutions. This research marks a significant step in characterizing thermal fronts in WPPNRI 713, laying the groundwork for future investigations into other ecologically significant fronts, including those related to chlorophyll, salinity, and nutrients, thereby enhancing our understanding of marine ecosystem dynamics.Keywords: Cayula Cornillon; Fishing Zone; Marine Ecosystem; Sea Surface Temperature; Thermal Fronts

The impact of weather Condition Changes on Vertical Distribution of Sulfides in Lake Maninjau Based on Observation Data

Sulfide is a crucial parameter in volcanic lakes, as its levels and fluctuations in the lake determine the origin of sulfide and the extent of its impact on the lake ecosystem. In stratified lakes, the sulfide produced tends to be retained beneath the oxic layer. The sulfides rise towards the surface as the oxic layer thins triggered by decreased water column thermal stratification. Meanwhile, the strength or weakness of thermal stratification is greatly influenced by weather conditions. Lake Maninjau is a volcanic lake with a relatively high sulfide content. Its vertical distribution in the water column is highly dependent on the stratification of the water column. When stratification disappears, sulfide rises to the surface (locally known as tubo belerang) and has a negative impact on surface biota. The objective of this study is to examine the distribution of sulfides in the water column of Lake Maninjau under two different weather conditions. We perform two surveys to measure physicochemical parameters and sulfide concentration on 26‒29 November 2022 and 25‒26 August 2023 considering the seasonal pattern. We found that air temperatures and sunshine duration combined with precipitation and wind speed drive the thermal stratification of the water column. The lower air temperature, shorter sunshine duration, higher precipitation, and stronger wind speed in the first survey (west monsoon) compared with the second survey (east monsoon) resulted in lower stratification and triggered the elevated sulfide to the surface. In the middle of the lake, the surface sulfide measured during the first survey was 4.16 µg/L. Meanwhile, in the second survey, it was only observed at 1.16 µg/L. The distribution of sulfides within the water column of Lake Maninjau is regulated by the stratification of the water column, a process directly impacted by weather conditions.

Reproductive Biology Status Reproductive Biology Status of Moonfish (Mene maculata) in Palabuhanratu Bay during West Monsoon

The moonfish (Mene maculata) is a demersal fish with important ecological and economic value. The high use of pitcher fish as food fish has the potential to disrupt reproductive patterns, recruitment and stock availability of pitcher fish resources, for which information on reproductive biology is minimal during the west monsoon. This research aims to analyze the reproductive biology status of moonfish in Palabuhanratu Bay. The research period took place from September 2021 to February 2022 (representing the west monsoon), with a sample of 522 fish. Fish samples were taken using a simple random sampling method at Palabuhanratu Nusantara fishing port. The data was analysis to obtain the sex ratio, allometric growth pattern, spawning season, the reproductive potential, and the size at maturity. Results shown that the sex ratio was 1:0.76, which is dominated by male fish. Moonfish have a negative allometric growth pattern. The peak of spawning season during the study period was in September and October. Reproductive potential ranges from 11,988 to 21,164 eggs. The spawning pattern of moonfish is indicated as total spawner. The result of Spearman-Karber method analysis showed that the size of the first maturity of female and male moonfish (Lm50) was 143 mm and 150.5 mm TL, respectively. So, female moonfish mature gonads earlier than male fish.

Evaluation of High Yielding Groundnut Varieties for North Transitional Zone of Karnataka State, India

Groundnut (Arachishypogaea L.) is an important oil seed crop grown in the arid andsemi-aridtropics of India under rainfed condition. The productivity is around 800 kg ha-1 in Karnataka as against national productivity of 1500 kg ha-1. The reasons for low productivity are many among them lack of improved variety in groundnut cultivation. Hence, study conducted to evaluate the high yielding groundnut varieties on farmers filed under farmers participatory mode approach. On field 25 FLD’s were planned by AICRP on Groundnut, MARS, UAS, Dharwad, Karnataka on farmers’ participatory mode approach under National Mission on Oilseeds and Oil Palm(NMOOP) programme and were conducted during kharif2021 with 25 farmers from Dharwad district. Each farmers field was considered as replication (25 no.) with 5 varieties as treatments and data was analysed statistically using Randomized complete block design. Statistical significance was tested with F test at 5 per cent level of probability. The study revealed that Dh-256(2850 kg ha-1) and K-1812 (Kadri Lepaxi) (2745 kg ha-1) recorded statistically on far dry pod yield. However, Dh-256 numerically out yielded K-1812 to the extent of 105 kg ha-1. Haulm yield when compared to the other varieties. A significant reduction in stem rot incidence was observed with respect to Dh-256(3.5%), K-1812(3.8%), G2-52(4.5%) and GPBD-4(4.7%) when compared to JL-24(8.1%) which resulted significant reduction plant population of JL-24 at harvest though it was having higher harvest index. The additional cost of cultivation of Rs. 2000 was spent on JL-24 to manage foliar diseases. Significantly higher gross returns were of Rs.148405 ha-1 and Rs.143460 ha-1, respectively by cultivating Dh-256 and K-1812 as against Rs.115740 ha-1 and Rs. 98728 ha-1 of local improved popular variety GPBD-4 and farmers check variety JL-24, respectively. From the results, farmers were very satisfied with Dh-256 and K-1812 newly released varieties of UAS, Dharwad, Karnataka and ARS, Kadiri, Andhra Pradesh. During, kharif2021, groundnut crop growth season was normal (496 mm from South West Monsoon i.e., June to September) for the Dharwad district and it was 4% higher than normal rainfall of 479 mm for the same period in the region, Further, groundnut crop not suffered due to dry spell any point of its growing period.

IJCM_281A: Climatic Factors And Vector Indices In The Occurrence Of Dengue Fever Cases In Northern Kerala

Background: The number of dengue cases reported to WHO increased over 8-fold over the last two decades, from 505,430 cases in 2000, to over 2.4 million in 2010, and 5.2 million in 2019. The disease is now endemic in more than 128 countries with Asia representing ~70% of the global burden of disease. The transmission of dengue is dependent on various environmental factors and socio-demographic and economic factors. This study aimed to describe the climatic factors and vector Indices in the occurrence of dengue fever cases in Northern Kerala. Objectives: 1) To describe the epidemiological factors for occurrence of dengue cases in Northern Kerala. 2) Serological typing of Dengue confirmed cases admitted in a tertiary care Centre in Northern Kerala. Methodology: Data of dengue fever cases admitted to a tertiary care centre in Northern Kerala for a period of one year were collected from Regional Prevention of Epidemics and Infectious Diseases Cell (R-PEID CELL). Vector indices data obtained from District vector control unit. Serology details were collected from Microbiology lab of the tertiary centre and Regional Virus Research and Diagnostic Laboratory (RVRDL). Geographical mapping and analysis of occurrence of dengue cases with rainfall done. Results: Total 518 cases were admitted to the tertiary centre during January 23-October 23. 68% Male and 32% female.77.7% Cases were reported from Kozhikode district.25 % cases were belonging to age group 20-29. Admission of cases were more during October followed by August. Serological typing of sub sample showed DEN2 as the predominant serotype. DEN1 and DEN3 serotypes were also identified. Conclusion: There is increased case transmission occurred during rainy season i.e. in North East and South West Monsoon which is in accordance with district vector indices data. DEN2 was the predominant serotype followed by DEN1.

Estimation of Suspended Particulate Matter Using Landsat 9 Imagery: Generating Algorithms and Spatio-Temporal Distributions

The fluctuation of suspended particulate matter (SPM) is essential to the biogeochemical cycle and ecological health of coastal waters. Anthropogenic activities potentially trigger an increase in SPM, so it needs to be monitored continuously. Spatial and temporal monitoring of SPM can be carried out cost-effectively with broad coverage using a remote sensing application. This study aims to build the SPM algorithm and estimate its temporal variability. The algorithm model in this study is based on an empirical formula between field data and reflectance data with the same acquisition. Water samples were taken from 100 stations in July 2022. Half were used for model building and the other for model validation. Suspended Particulate Matter was determined gravimetrically and estimated their temporal variability was based on Landsat 9 image records from December 2021 - November 2022. The results of the analysis show that the best algorithm for SPM estimation can be built based on coastal aerosol canals (B1), blue canals (B2), and green canals (B3) with the accuracy test result of (R2 = 0.68; RMSE = 5.551 mg.L-1; MAPE= 7.07%; Bias= 0.28). The SPM temporal fluctuations were generally higher in the west monsoon and lowered in the east monsoon, ranging from 30 to 70 mg.L-1. On the other hand, the spatial distribution shows a higher magnitude in the estuary than in the offshore waters, with a deviation of about 30 mg.L-1. Regional authorities can use the results obtained to improve the management of coastal water quality and monitoring systems.

Dynamical Constraint on Precipitation Biases Over the Indo‐Pacific Region During Boreal Summer in AMIP6 Models

AbstractClimate models suffer from longstanding precipitation biases, much of which has been attributed to their atmospheric component owing to unrealistic parameterizations. Here we investigate precipitation biases in 37 Atmospheric Model Intercomparison Project Phase 6 (AMIP6) models, focusing on the Indo‐Pacific region during boreal summer. These models remain plagued by considerable precipitation biases, especially over regions of strong precipitation. In particular, 22 models overestimate the Asian‐Pacific monsoon precipitation, while 28 models underestimate the southern Indian Ocean Intertropical Convergence Zone precipitation. The inter‐model spread in summer precipitation is decomposed into Empirical Orthogonal Functions (EOFs). The leading EOF mode features an anomalous anticyclone circulation spanning the Indo‐northwest Pacific oceans, which we show is energized by barotropic conversion from the confluence of the background monsoonal westerlies and trade‐wind easterlies. Our results suggest precipitation biases in atmospheric models, though caused by unrealistic parameterizations, are organized by dynamical feedbacks of the mean flow.

Spatiotemporal assessment of rainfall and drought projection for integrated dam management in Benut River Basin, Malaysia under CMIP6 scenarios

This study assesses the influence of climate change on rainfall and drought in the Benut River Basin (BRB) to support the integrated management of Machap dam. The study seeks to reshape dam safety components in the near future through a technical focus group discussion (FGD) with key stakeholders. Utilizing the Coupled Model Intercomparison Project Phase 6 (CMIP6) dataset for the immediate future (2020–2040) under various scenarios (SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5), historical Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) rainfall datasets (1981 to 2021) are employed. A multi-filtration process ranks twenty-three Global Climate Models (GCMs) using seven relative importance metrics (RIMs). This work's novelty lies in a focused GCM evaluation through individual contributions quantified with RIMs, providing a refined ranking that address the limitations of traditional metrics. Then, the Compromise Programming Index (CPI) aggregates the ranked models, with the top subset selected through Jenks Optimised Classification (JOC), identifying ACCESS-ESM1–5 and CMCC-ESM2 as top models. The selected GCMs were bias-corrected using the linear scaling method and validated before ensembled, effectively replicating the probability distribution function (PDF) of CHIRPS data, as confirmed by a Taylor diagram indicating the closest agreement. The study reveals a generally wetter tendency in the northernmost area of Machap dam under all SSPs, with 5–9 % maximum increasing percentages. Conversely, downstream areas anticipate decreasing rainfall. June (6–22 %) and July (7–22 %) project higher rainfall, indicating increased water availability in a relatively dry period, while December (3–11 %) suggests increasing flood risk. The South West monsoon (SWM) anticipates lower rainfall in early March (3–7 %) and more severe dry periods in August (8–11 %). Future drought occurrences are projected homogeneously across scenarios, with drought months ranging from 15 % to 19 % of the 252 months under all severity classifications. In particular, the study enhances myDAMS by proposing continuous development of the guideline under diverse scenario for Machap dam's overall management and sustainability. Projected scenarios, coupled with outcomes from FGD, can inform basin-scale dam management, aiding risk mitigation for critical dam infrastructure.

Asian Anthropogenic Aerosol Forcing Played a Key Role in the Multidecadal Increase in Australian Summer Monsoon Rainfall

Abstract Observations show a significant increase in Australian summer monsoon (AUSM) rainfall since the mid-twentieth century. Yet the drivers of this trend, including the role of anthropogenic aerosols, remain uncertain. We addressed this knowledge gap using historical simulations from a suite of Coupled Model Intercomparison Project phase 6 (CMIP6) models, the CESM2 Large Ensemble, and idealized single-forcing simulations from the Precipitation Driver Response Model Intercomparison Project (PDRMIP). Our results suggest that Asian anthropogenic aerosol emissions played a key role in the observed increase in AUSM rainfall from 1930 to 2014, alongside the influence of internal variability. Sulfate aerosol emissions over Asia led to regional surface cooling and strengthening of the climatological Siberian high over eastern China, which altered the meridional temperature and sea level pressure gradients across the Indian Ocean. This caused an intensification and southward shift of the Australian monsoonal westerlies (and the local Hadley cell) and resulted in a precipitation increase over northern Australia. Conversely, the influence of increased greenhouse gas concentrations on AUSM rainfall was minimal due to the compensation between thermodynamically induced wettening and transient eddy-induced drying trends. At a larger scale, aerosol and greenhouse gas forcing played a key role in the climate response over the Indo-Pacific sector and eastern equatorial Pacific, respectively (coined the “tropical Pacific east–west divide”). These findings contribute to an improved understanding of the drivers of the multidecadal trend in AUSM rainfall and highlight the need to reduce uncertainties in future projections under different aerosol emission trajectories, which is particularly important for northern Australia’s agriculture. Significance Statement Australian summer monsoon (AUSM) rainfall plays a vital role in sustaining northern Australia’s unique biodiversity and extensive agricultural industry. While observations show a significant increase in AUSM rainfall since the mid-twentieth century, the causes remain uncertain. We find that anthropogenic aerosol emissions from Asia played a key role in driving this multidecadal AUSM rainfall trend by inducing dynamic adjustments over the Indo-Pacific sector. These findings highlight the need to consider different aerosol emission trajectories when assessing future projections of AUSM rainfall.

Flood countermeasure management in bulak banteng Surabaya

The rainy season in Indonesia occurs due to the west monsoon wind blowing from the Asian continent which carries a lot of water vapor to the Australian continent due to climate change, it causes high rainfall and can potentially cause floods. In addition, the phenomenon of garbage accumulation in the river and the failure of the drainage system are the reasons for flooding in metropolitan cities, especially in Surabaya. This study aims to determine the preparedness of the community, especially the people of Bulak Banteng Village, in facing floods during the rainy season. Data were collected using the Simple Random Sample (SRS) method with 30 correspondents randomly selected at the research location. The results showed that many people were aware of the causes of flooding and the signs and impacts caused by flooding. Therefore, some people have prepared themselves in case of flooding by raising the floor of their houses so that water does not enter the house. In the event of a flood, the community prefers to evacuate themselves to a relative's place that is not affected by flooding rather than going to the disaster evacuation site provided by the local government, this happens because of the lack of training or socialization of flood response in the community, resulting in the lack of flood disaster information obtained by the community.

Performance and process-based evaluation of the BARPA-R Australasian regional climate model version 1

Abstract. Anthropogenic climate change is changing the Earth system processes that control the characteristics of natural hazards both globally and across Australia. Model projections of hazards under future climate change are necessary for effective adaptation. This paper presents BARPA-R (the Bureau of Meteorology Atmospheric Regional Projections for Australia), a regional climate model designed to downscale climate projections over the Australasian region with the purpose of investigating future hazards. BARPA-R, a limited-area model, has a 17 km horizontal grid spacing and makes use of the Met Office Unified Model (MetUM) atmospheric model and the Joint UK Land Environment Simulator (JULES) land surface model. To establish credibility and in compliance with the Coordinated Regional Climate Downscaling Experiment (CORDEX) experiment design, the BARPA-R framework has been used to downscale ERA5 reanalysis. Here, an assessment of this evaluation experiment is provided. Performance-based evaluation results are benchmarked against ERA5, with comparable performance between the free-running BARPA-R simulations and observationally constrained reanalysis interpreted as a good result. First, an examination of BARPA-R's representation of Australia's surface air temperature, precipitation, and 10 m winds finds good performance overall, with biases including a 1 ∘C cold bias in daily maximum temperatures, reduced diurnal temperature range, and wet biases up to 25 mm per month in inland Australia. Recent trends in daily maximum temperatures are consistent with observational products, while trends in minimum temperatures show overestimated warming and trends in precipitation show underestimated wetting in northern Australia. Precipitation and temperature teleconnections are effectively represented in BARPA-R when present in the driving boundary conditions, while 10 m winds are improved over ERA5 in six out of eight of the Australian regions considered. Secondly, the paper considers the representation of large-scale atmospheric circulation features and weather systems. While generally well represented, convection-related features such as tropical cyclones, the South Pacific Convergence Zone (SPCZ), the Northwest Cloudband, and the monsoon westerlies show more divergence from observations and internal interannual variability than mid-latitude phenomena such as the westerly jets and extratropical cyclones. Having simulated a realistic Australasian climate, the BARPA-R framework will be used to downscale two climate change scenarios from seven CMIP6 global climate models (GCMs).