scholarly journals Modelling sea surface currents in the eastern coast of Bawean Island, East Java

2021 ◽  
Vol 925 (1) ◽  
pp. 012006
Author(s):  
Zainul Hidayah ◽  
Harish Wirayuhanto ◽  
Zafa Roga Norma Sari ◽  
Maulinna Kusumo Wardhani
Keyword(s):  
Model Simulation ◽  
Monsoon Season ◽  
Surface Current ◽  
Eastern Coast ◽  
Small Island ◽  
Significant Difference ◽  
On This Island ◽  
Adcp Measurements ◽  
Java Sea ◽  
Oceanographic Model

Abstract Bawean Island is located in the middle of the Java Sea, approximately 80 km north of Gresik Regency, East Java Province. The coastal area of Bawean Island is famous for its potential as a marine tourism area because it has a well-preserved coral reef ecosystem. The potential for tourism development on this island requires the support of environmental suitability. The dynamics of ocean currents as an important parameter for small island development is important to be analyzed. This study aims to determine the characteristics of currents in the eastern coast of Bawean Island through the hydro-oceanographic model. The data used in this modelling was hourly wind and tide data from the period of 2020-2021. The results showed that the velocity of surface current speed in the study area was weak (<0,5 m/s). There was a significant difference of current direction during the west monsoon season and the first transitional season. Validation of model simulation and ADCP measurements produce MAE values 0,014 and 0,035 as well as MAPE values 12,75% and 27,48%.

scholarly journals Assessment of Seasonal Variability in Soil Nutrients and Its Impact on Soil Quality under Different Land Use Systems of Lower Shiwalik Foothills of Himalaya, India

2021 ◽  
Vol 13 (3) ◽  
pp. 1398
Author(s):  
Tavjot Kaur ◽  
Simerpreet Kaur Sehgal ◽  
Satnam Singh ◽  
Sandeep Sharma ◽  
Salwinder Singh Dhaliwal ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Quality ◽  
Surface Soil ◽  
Sandy Loam ◽  
Monsoon Season ◽  
Soil Layer ◽  
Seasonal Effects ◽  
Land Use Systems ◽  
Post Monsoon ◽  
Significant Difference

The present study was conducted to investigate the seasonal effects of five land use systems (LUSs), i.e., wheat–rice (Triticum aestivum—Oryza sativa) system, sugarcane (Saccharum officinarum), orange (Citrus sinensis) orchard, safeda (Eucalyptus globules) forest, and grassland, on soil quality and nutrient status in the lower Satluj basin of the Shiwalik foothills Himalaya, India. Samples were analyzed for assessment of physico-chemical properties at four soil depths, viz., 0–15, 15–30, 30–45, and 45–60 cm. A total of 120 soil samples were collected in both the seasons. Soil texture was found to be sandy loam and slightly alkaline in nature. The relative trend of soil organic carbon (SOC), macro- and micro-nutrient content for the five LUSs was forest > orchard > grassland > wheat–rice > sugarcane, in the pre- and post-monsoon seasons. SOC was highly correlated with macronutrients and micronutrients, whereas SOC was negatively correlated with soil pH (r = −0.818). The surface soil layer (0–15 cm) had a significantly higher content of SOC, and macro- and micro-nutrients compared to the sub-surface soil layers, due to the presence of more organic content in the soil surface layer. Tukey’s multiple comparison test was applied to assess significant difference (p < 0.05) among the five LUSs at four soil depths in both the seasons. Principle component analysis (PCA) identified that SOC and electrical conductivity (EC) were the most contributing soil indicators among the different land use systems, and that the post-monsoon season had better soil quality compared to the pre-monsoon season. These indicators helped in the assessment of soil health and fertility, and to monitor degraded agroecosystems for future soil conservation.

Growth and movement of the South African abalone Haliotis midae: A reassessment

1995 ◽  
Vol 46 (3) ◽  
pp. 583 ◽  
Author(s):  
RJQ Tarr
Keyword(s):  
South African ◽  
Growth Rates ◽  
Growth Parameters ◽  
Eastern Coast ◽  
Island Population ◽  
Western Coast ◽  
Eastern Cape ◽  
The South ◽  
Significant Difference ◽  
Haliotis Midae

Growth rates of a number of Haliotis midae populations around the South African coast were studied by means of tagging. These populations ranged from the cool waters of the western coast to the more temperate environment of the eastern Cape. Standard von Bertalanffy growth curves were fitted and growth parameters derived. These ranged from 0.19 to 0.25 for K, the average rate at which L∞ is approached, and from 156 to 173 for L∞, the average theoretical maximum length. These indicate far higher growth rates than were previously published for this commercially fished species, and the reasons for this difference are discussed. The expectation that growth rates would be fastest in the warmer eastern Cape waters was not realized, there being no significant difference in growth between the Bird Island population on the eastern coast and the Robben Island population on the western coast. These new growth parameters indicate that H. midae in the commercial fishery grounds is attaining sexual maturity some four years earlier, and the minimum legal size some five years earlier, than previously considered. This has considerable significance for modelling studies presently underway. Movement of a small population of adult H. midae was studied over a three-year period, after which 47% of the original abalone were still present on the study site. Of these, 81.5% still occupied exactly the same position on the rocks. This indicates that H. midae that have located an optimum habitat, and that are not disturbed, tend not to move.

scholarly journals Fishing Ground Mapping Based on Chlorophyll-A Distribution Using Aqua Modis Satellite Imagery in The Fisheries Management Area (FMA) 712

2021 ◽  
Vol 324 ◽  
pp. 01007
Author(s):  
Yulius Yulius ◽  
Vaninda Aidina ◽  
Muhammad Ramdhan ◽  
August Daulat
Keyword(s):  
Chlorophyll A ◽  
Fisheries Management ◽  
Satellite Imagery ◽  
Time Series Data ◽  
Monsoon Season ◽  
Fishing Ground ◽  
Series Data ◽  
Chlorophyll A Concentration ◽  
Management Area ◽  
Java Sea

The fishing ground is identical and closely related to chlorophyll-a abundance in the waters, associated with its fisheries potential. This research has been conducted to determine the concentration and distribution of chlorophyll-a in the seas, especially in the Fisheries Management Area (FMA) 712 encompassing the Java Sea. The analysis used monthly time-series data collected from the satellite imagery over the last 11 years, taken through the ERDDAP website. The mean concentration of chlorophyll-a in the study area was 1.13 mg/l in June 2013. Based on 11 years of data processing, it can be concluded that the highest concentration of chlorophyll-a occurred in the west monsoon season from November to April, where increased rainfall caused the nutrient wash from terrestrial to the open waters. The lowest chlorophyll-a concentration happened in the east monsoon season from April to November, where the dry season arrived. The existence of pelagic fishes in FMA 712, such as Sardinella Lemurs and Sardinella Fimbriata, in waters highly influenced by the chlorophyll-a concentration, while Thunnus Sp. and Exocoetidae Sp. not affected significantly to the existence of chlorophyll-a concentration and its distribution.

A close look at the middle Adriatic upwelling: schematized ROMS model simulations

2021 ◽  
Author(s):  
Gordana Beg Paklar ◽  
Zoran Pasaric ◽  
Mirko Orlic ◽  
Antonio Stanesic
Keyword(s):  
Wind Stress ◽  
Coastal Upwelling ◽  
Cold Water ◽  
Model Simulation ◽  
Initial Density ◽  
Wind Component ◽  
Ekman Pumping ◽  
Flat Bottom ◽  
Roms Model ◽  
Adcp Measurements

&lt;p&gt;Strong upwelling driven by the NNW winds was detected off the eastern middle Adriatic coast in May 2017. High resolution CTD data revealed thermocline doming by about 20 m at approximately 20 km from the coast. Main characteristics of the upwelling event are reproduced in the realistic ROMS model simulation. Adriatic scale ROMS model having 2.5 km horizontal resolution, forced by the air-sea fluxes calculated using surface fields from operational weather forecast model ALADIN-HR (Tudor et al., 2013; Termonia et al., 2018), river discharges, tides and water mass exchange through the Strait of Otranto, reproduces cold water dome and two-layer offshore flow in accordance with CTD and shipborne ADCP measurements. Significant improvement in the upwelling simulations is obtained using increased drag coefficient. The location of upwelling is correctly modelled, although with somewhat lower upper layer temperatures if compared with measurements. Moreover, the surface cyclonic circulation indicated by ADCP measurements along the cross-Adriatic transect is also evident in the model results. In order to improve understanding of the upwelling mechanism, several schematized numerical experiments are conducted. Wind fields from dynamical adaptation (Zagar and Rakovec, 1999; Ivatek-Sahdan and Tudor, 2004) of ALADIN-HR8 (8 km horizontal grid spacing) wind forecast to 2 km grid, are decomposed by the Natural Helmholtz-Hodge Decomposition (HHD) into divergence-free (incompressible), rotation-free (irrotational), and harmonic (translational) component (Bhatia et al., 2014). The components thus obtained and their combinations are used for calculation of the wind stress instead of the total wind field. Simulations with decomposed wind stress are conducted in the Adriatic domains with both flat bottom and realistic topography. Schematized simulations reveal that the positive rotational wind component is responsible for the rising of thermocline through Ekman pumping and it is more pronounced in the flat bottom basin. In the simulations with divergent wind component, the thermocline doming disappears and only coastal upwelling is reproduced. Additional idealised simulations with homogeneous NW wind stress are performed assuming both two-layer and uniform initial density field.&lt;/p&gt;

Pola Arus Permukaan dan Kondisi Fisika Perairan di Sekitar Pulau Selayar pada Musim Peralihan 1 dan Musim Timur

2017 ◽  
Vol 2 (1) ◽  
pp. 83 ◽  
Author(s):  
Ahmad Bayhaqi ◽  
Mochamad Riza Iskandar ◽  
Dewi Surinati
Keyword(s):  
Surface Water ◽  
Average Velocity ◽  
River Flow ◽  
Climatic Factors ◽  
Monsoon Season ◽  
Surface Current ◽  
Current Pattern ◽  
Flow Discharge ◽  
Oceanographic Data ◽  
Mean Current

<strong>Surface Current Pattern and Physics Condition of Waters Around Selayar Island in the First Transitional and Southeast Monsoons. </strong> Seasonal observations of the flow of surface water and physics conditions around Selayar Island adjacent to Arlindo throughflow pathways of Makassar Strait have been conducted with a focus on the first transitional season and the southeast monsoon season. The purpose of this research is to obtain the pattern of seasonal surface current and physics characteristics of water column, i.e. temperature and salinity in Selayar Island waters during those seasons. The observations conducted on 22–27 May 2015 and 7–10 August 2015 illustrated the successive periods of the first transitional season and the southeast monsoon season. The methods used for taking oceanographic data such as temperature, salinity, and current were the stationary oceanographic measurement using CTD and currentmeter at 29 stations located in surrounding waters of Selayar Island. The surface current pattern generated from the interpolation process of the overall observation stations indicated that during the first transitional season the current moved eastward with an average velocity of 0.25 m/s. During the southeast monsoon season, the same pattern was still observed with a slightly higher average velocity of 0.26 m/s. The temperatures and salinity of Selayar Island waters during the southeast monsoon season were 2°C lower and 0.5 psu higher than during the first transitional season. Differences in mean current velocity values tended to be more affected by local tidal conditions. Different salinity was thought to be influenced by upwelling phenomena and local climatic factors such as rainfall, wind, and river flow discharge.

scholarly journals Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller

Fermentation ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 251
Author(s):  
Buta Singh ◽  
Kornél L. Kovács ◽  
Zoltán Bagi ◽  
József Nyári ◽  
Gábor L. Szepesi ◽  
...  
Keyword(s):  
Model Simulation ◽  
Biogas Production ◽  
Scale Up ◽  
Anaerobic Digester ◽  
Operating Conditions ◽  
Mixing Efficiency ◽  
Dead Zones ◽  
Helical Ribbon ◽  
Significant Difference ◽  
Mixing Intensity

The appropriate mixing system and approach to effective management can provide favorable conditions for the highly sensitive microbial community, which can ensure process stability and efficiency in an anaerobic digester. In this study, the effect of mixing intensity on biogas production in a lab-scale anaerobic digester has been investigated experimentally and via modeling. Considering high mixing efficiency and unique feature of producing axial flow, helical ribbon (HR) impeller is used for mixing the slurry in this experiment under various conditions. Three parallel digesters were analyzed under identical operating conditions for comparative study and high accuracy. Effects of different mixing speeds (10, 30, and 67 rpm for 5 min h−1) on biogas production rate were determined in 5-L lab-scale digesters. The results demonstrated 15–18% higher biogas production at higher mixing speed (67 rpm) as compared to 10 rpm and 30 rpm and the results proved statistically significant (p < 0.05). Biogas production at 10, 30, and 67 rpm were 45.6, 48.6, and 52.5 L, respectively. Higher VFA concentrations (7.67 g L−1) were recorded at lower mixing intensity but there was no significant difference in pH and ammonia at different speeds whereas the better mixing efficiency at higher speeds was also the main reason for increase in biogas production. Furthermore, model simulation calculations revealed the reduction of dead zones and better homogeneous mixing at higher mixing speeds. Reduction of dead zones from 18% at 10 rpm to 2% at 67 rpm was observed, which can be the major factor in significant difference in biogas production rates at various mixing intensities. Optimization of digester and impeller geometry should be a prime focus to scale-up digesters and to optimize mixing in full-scale digesters.

scholarly journals Methane plume over South Asia during the monsoon season: satellite observation and model simulation

2008 ◽  
Vol 8 (4) ◽  
pp. 13453-13478 ◽  
Author(s):  
X. Xiong ◽  
S. Houweling ◽  
J. Wei ◽  
E. Maddy ◽  
F. Sun ◽  
...  
Keyword(s):  
South Asia ◽  
Transport Process ◽  
Model Simulation ◽  
Monsoon Season ◽  
Satellite Observation ◽  
Satellite Observations ◽  
Atmospheric Pollutants ◽  
Local Surface ◽  
Atmospheric Infrared Sounder ◽  
Upper Troposphere

Abstract. Satellite observations of methane (CH4) using the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua platform from 2003–2007 demonstrate a strong, plume-like enhancement of CH4 in the middle to upper troposphere over the South Asia during July, August and September, and its maximum occurs in early September. Simulations using the global tracer model version 3 (TM3) also show similar seasonal enhancement of CH4 in the same region. The model results also suggest that this enhancement is associated with transport process and local surface emissions, thus the observations to tropospheric CH4during the monsoon season may be used to constrain the models for a better estimation of Asian CH4 sources. Further comparisons between AIRS observations and the model simulations indicate a possible overestimate of CH4 emissions from rice paddies in Southeast Asia. Moreover, the observed tropospheric CH4 enhancement from AIRS provides evidence for the strong transport of atmospheric pollutants from the lower to the upper troposphere in Asia during the monsoon season, and the observed rapid disappearance of local CH4 maximum in September may provide valuable information for studying the dissipation of the Tibetan anticyclone and the withdrawal of monsoon.

scholarly journals Morphometric study of banded gourami (Colisa fasciata) in Jessore, Bangladesh

2016 ◽  
Vol 2 (1) ◽  
pp. 113-120
Author(s):  
Sharmin Akter ◽  
Md Farid Uz Zaman ◽  
Md Hasan Uj Jaman ◽  
Iren Nahar Sithi ◽  
Dilruba Yesmin ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Fishery Management ◽  
Monsoon Season ◽  
B Value ◽  
Morphometric Study ◽  
Random Samples ◽  
Significant Difference ◽  
Mean Size ◽  
The Relationship ◽  
Group Distribution

Population morphometry including population demography, size group distribution, length weight relationship and sex ratio of an important freshwater fish, Colisafasciata was studied which collected fromJessore and Jhenaidah districts in Bangladesh during May, 2014 to April, 2015. Random samples of 201 individuals (108males and 93 females) were collected from different fish markets in Jessore (Monirampur, Borobazar, Chowgasa) and Jhenaidah (Mohespur, Barobazar, Kotchandpur) districst. The mean size of the specimen was recorded 65.08 ±14.32 mm in length and 7.43 ±3.09 g in body weight. Females were found little smaller than males. The specimens were larger in winter than summer and monsoon season. But in monsoon season the females were larger than males. The maximum length of the specimen collected from Jhenaidah district was smaller compare to the specimen of Jessore district. Most of the population (29%) was observed under 55-64 mm size class. Linear relationship was obtained between the log length (mm) and log weight (g) of the species in respects of sexes, seasons, and districts. The allometric coefficient ‘b’ of the relationship indicated negative allometric growth of the species as ‘b’ value was less than 3. The overall sex ratio (male: female=1:0.86)showed significant difference from the expected value 1:1. Overall males showed non-significant over females (?2 =1.119) in all season of both districts but in November males showed the significant (P<0.01) dominance over females. However, the findings of the present study have helped us to understand more about the species is the prerequisites in fishery management strategy and culture system.Asian J. Med. Biol. Res. March 2016, 2(1): 113-120

scholarly journals Trend analysis of weather parameters over Indian Sundarbans

2021 ◽  
Vol 21 (3) ◽  
pp. 307-615
Author(s):  
UTTAM KUMAR MANDAL ◽  
DIBYENDU BIKAS NAYAK ◽  
SOURAV MULLICK ◽  
ARPAN SAMUI ◽  
AMIT KUMAR JANA ◽  
...  
Keyword(s):  
Monsoon Season ◽  
Temporal Trends ◽  
Kendall Test ◽  
Eastern Coast ◽  
Annual Rainfall ◽  
Crop Evapotranspiration ◽  
Indian Sundarbans ◽  
Sunshine Hours ◽  
Weather Parameters ◽  
Rainy Days

Sundarbans in West Bengal of India by virtue of its strategic location in the Eastern coast on the Bay of Bengal falls in one of the most vulnerable zones of abrupt climate change. Temporal trends of weather parameters of Canning Town (22o18'10.8'' N Latitude, 88o39'58.4'' E Longitude, elevation 3.52 m msl) representing Indian Sundarbans were analysed by non-parametric Mann-Kendall test and Sen's slope approaches. Analysis of long term rainfall data (1966-2015) indicated that Canning receives a mean annual rainfall of 1821 mm (±341.8 mm) with a considerable variation (CV = 18.8%). The results revealed that total annual rainfall trend decreased non-signicantly at the rate of 0.94 mm yr-1. On an average 84.4 rainy days in a year was recorded in the region, whereas during last ten years (2006-2015), the number of rainy days was reduced to 79.7 days yr-1. There was no signicant change in maximum, minimum and mean temperature of the region. Bright sunshine hours declined signicantly at an annual rate of 0.055 hr yr-1. Reference crop evapotranspiration (ET ) calculated using FAO Penman-Monteith method revealed that annual ET signicantly decreased at the rate of 5.98 mm yr-1. There was 2.7 times surplus rainfall than  crop evapotranspiration during monsoon months indicating very high scope of water harvesting to tackle water logging during the monsoon season and unavailability of fresh water for irrigation during lean season.

scholarly journals Kinematic Analysis of a Clamp-Type Picking Device for an Automatic Pepper Transplanter

Agriculture ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 627 ◽  
Author(s):  
Md Nafiul Islam ◽  
Md Zafar Iqbal ◽  
Mohammod Ali ◽  
Milon Chowdhury ◽  
Md Shaha Nur Kabir ◽  
...  
Keyword(s):  
Kinematic Analysis ◽  
High Speed ◽  
Model Simulation ◽  
Mechanical Damage ◽  
Maximum Velocity ◽  
Operating Conditions ◽  
High Speed Photography ◽  
Virtual Model ◽  
Significant Difference ◽  
Simulation And Validation

Pepper is one of the most vital agricultural products with high economic value, and pepper production needs to satisfy the growing worldwide population by introducing automatic seedling transplantation techniques. Optimal design and dimensioning of picking device components for an automatic pepper transplanter are crucial for efficient and effective seedling transplantation. Therefore, kinematic analysis, virtual model simulation, and validation testing of a prototype were conducted to propose a best-suited dimension for a clamp-type picking device. The proposed picking device mainly consisted of a manipulator with five grippers and a picking stand. To analyze the influence of design variables through kinematic analysis, 250- to 500-mm length combinations were considered to meet the trajectory requirements and suit the picking workspace. Virtual model simulation and high-speed photography tests were conducted to obtain the kinematic characteristics of the picking device. According to the kinematic analysis, a 350-mm picking stand and a 380-mm manipulator were selected within the range of the considered combinations. The maximum velocity and acceleration of the grippers were recorded as 1.1, 2.2 m/s and 1.3, 23.7 m/s2, along the x- and y-axes, respectively, for 30 to 90 rpm operating conditions. A suitable picking device dimension was identified and validated based on the suitability of the picking device working trajectory, velocity, and acceleration of the grippers, and no significant difference (p ≤ 0.05) occurred between the simulation and validation tests. This study indicated that the picking device under development would increase the pepper seedling picking accuracy and motion safety by reducing the operational time, gripper velocity, acceleration, and mechanical damage.

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