Above Mean Sea Level Research Articles

Influence of the Inclusion of Off-Nadir Images on UAV-Photogrammetry Projects from Nadir Images and AGL (Above Ground Level) or AMSL (Above Mean Sea Level) Flights

UAV-SfM techniques are in constant development to address the challenges of accurate and precise mapping in terrains with complex morphologies. In contrast with the traditional photogrammetric processes, where only nadir images were considered, the combination of those with oblique imagery, also called off-nadir, has emerged as an optimal solution to achieve higher accuracy in these kinds of landscapes. UAV flights at a constant height above ground level (AGL) have also been considered a possible alternative to improve the resulting 3D point clouds compared to those obtained from constant height above mean sea level (AMSL) flights. The aim of this study is to evaluate the effect of incorporating oblique images as well as the type of flight on the accuracy and precision of the point clouds generated through UAV-SfM workflows for terrains with complex geometries. For that purpose, 58 scenarios with different camera angles and flight patterns for the oblique images were considered, 29 for each type of flight (AMSL and AGL). The 3D point cloud derived from each of the 58 scenarios was compared with a reference 3D point cloud acquired with a terrestrial laser scanner (TLS). The results obtained confirmed that both incorporating oblique images and using AGL flight mode have a positive effect on the mapping. Combination of nadir image blocks, obtained from an AGL crosshatch flight plan, with supplemental oblique images collected with a camera angle of between 20° and 35° yielded the best accuracy and precision records.

From source to lake: Multi‒taxon alpha and beta diversity patterns along a river above 4500 ​m AMSL on the Qinghai‒Tibetan Plateau

Understanding the distribution of species is highly important for optimizing future conservation priorities and strategies at the regional scale. Relatively little attention has been given to multi-taxon aquatic biota in extreme alpine environments. We examined the spatial and temporal patterns of alpha and beta diversity, site-specific contributions to beta diversity and assembly mechanisms of four taxonomic groups (fishes, macroinvertebrates, zooplankton and phytoplankton) from the source to the estuary of the Za'gya Zangbo River above 4500 ​m AMSL (above mean sea level) on the northern Qinghai-Tibetan (Q–T) Plateau. A total of 4 fish species, 45 macroinvertebrate taxa, 17 zooplankton taxa and 56 phytoplankton taxa were found in the study area. No consistent patterns in taxonomic richness were observed across taxa from upstream to estuary. The fish communities had the lowest dissimilarity between communities, the phytoplankton community had the highest dissimilarity in the dry season, and the macroinvertebrate community had the highest dissimilarity in the wet season. The relative importance of the turnover and nestedness components varied considerably across taxa and along spatial gradients. The diversity patterns of macroinvertebrate, zooplankton and phytoplankton communities were significantly correlated with several environmental factors, whereas only the beta diversity of fish was correlated with altitude. Stochastic processes dominated in shaping the macroinvertebrate communities whereas deterministic processes dominated the assembly of the phytoplankton communities. Weak congruence of diversity patterns across taxonomic groups suggested that biological groups cannot serve as reliable surrogates for one another and that multiple biological groups should be included in the biomonitoring of high-altitude rivers on the Q‒T Plateau. The relatively unique species in the upstream area and estuary of the Za'gya Zangbo River harbor should receive more attention in future conservation and management schemes.

Impact of Greenhouse Size on the Growth and Yield of Warm Season Vegetables During the Summer Ladakh, India

No guidelines exist on the size of naturally ventilated passive solar greenhouses in mountain regions, especially above 10,000 feet above mean sea level (AMSL). Two different-sized greenhouses in Ladakh were studied, and it was figured out that a large greenhouse (60 feet in length, 24 feet in width, 9 feet 6 inches in height) was better than a small greenhouse (32 feet in length, 18 feet width, 9 feet 6 inches height) for growing cucumber, capsicum, and brinjal in summer. The mean maximum and minimum temperature of the large greenhouse was 3.6±4.1°C and 1.3±1.6°C warmer in comparison to the small greenhouse. Cucumber was harvested seven days earlier, while capsicum and brinjal were harvested 17 days earlier in the large greenhouse. The marketable fruit numbers in cucumber, capsicum, and brinjal were 50.5 %, 46.9 %, and 67.7 % higher in the large greenhouse. The average marketable fruit yield of cucumber, capsicum and brinjal was 112 %, 55 % and 71.4 % higher in the large greenhouse than in the small greenhouse. Hence, large greenhouses are suggested for high-altitude Ladakh regions for growing warm-season crops in summer.

Heavy rainfall and thunderstorms in south interior Karnataka: a case study on august 31, 2023

Study aims to conduct a synoptic and thermodynamic analysis of significant rainfall events that happened during the break monsoon season. During the investigation of meteorological events, it was observed that the monsoon trough at mean sea level passed along the foothills of the Himalaya. On August 31, 2023, there was a cyclonic circulation observed in the northeast Bay of Bengal as well as adjacent areas, reaching an altitude of 5.8 km above mean sea level (AMSL). This circulation tilted southwestward with height. During the period of August 31-September 2, 2023, there was a cyclonic circulation persistent that occurred inside a particular geographical area. This phenomenon extended up to a height of 4.5 km AMSL and exhibited a south-westward tilt as the altitude increased. On August 31, 2023, the Convective Available Potential Energy (CAPE) was measured to be 2153 J/kg, whereas the Convective Inhibition Energy (CINE) was recorded as 0 J/kg. INSAT-3D satellite image showed a cloud top temperature of – 40 °C to – 60 °C. The Doppler Weather Radar (DWR) pictures also showed convective clouds to support this phenomenon. The synoptic and thermodynamic indices indicate a high likelihood of significant precipitation occurring over Bengaluru and its surrounding regions.

Hazards of sea level rise and dams built on the River Nile on water budget and salinity of the Nile Delta aquifer

Study regionThe Nile Delta region consists of flat, low-lying areas, where most areas are used for agriculture. It covers an area of 22,000 km2, which is 2.20% of the total area of Egypt. Study focusThis study evaluates the water budget and the salinity due to the Sea Level Rise (SLR) and the reduction in the river water flow caused by the Grand Ethiopian Renaissance Dam (GERD) using the numerical code SEAWAT. Three filling scenarios were considered for the GERD reservoir at elevations 600 m, 621 m, and 645 m above mean sea level (AMSL) for the storage volumes of 17 billion cubic meters (BCM) (scenarios #1), 37.30 BCM (scenarios #2), and 74 BCM (scenarios #3). The impact of these fillings scenarios was combined with SLR of 25 cm, and increasing the abstraction rates from the Nile Delta aquifer by 25%, 50%, and 100%, respectively. New hydrological insights for the regionThe study findings indicated that the SLR and the GERD reservoir filling with increasing pumping rates, especially during the filling periods, would influence the groundwater resources in the Nile Delta. The GERD reservoir filling could alter the freshwater, in which the aquifer salinity increased by 4.47%, 11.48%, and 29.99% for the three scenarios, respectively. The methodology and findings presented in this study might be useful for investing and comparing the impact of SLR and upstream dam projects on the downstream water budget and salinity at other coastal regions.

Offshore Wind Power Resource Assessment in the Gulf of North Suez

Growing population, industrialization, and power requirements are adversely affecting the environment through increased greenhouse gases resulting from fossil fuel burning. Global greenhouse gas mitigation targets have led nations to promote clean and self-renewable sources of energy to address this environmental issue. Offshore wind power resources are relatively more attractive due to high winds, less turbulence, minimal visualization effects, and no interaction of infrastructure. The present study aims at conducting an offshore wind power resource assessment (OWPRA) at some locations in the Gulf of North Suez. For this purpose, the long-term hourly mean wind speed (WS) and wind direction above mean sea level (AMSL), as well as temperature and pressure data near the surface, are used. The data is obtained from ERA5 (fifth generation global climate reanalysis) at six (L1–L6) chosen offshore locations. The data covers a period of 43 years, between 1979 and 2021. The WS and direction are provided at 100 m AMSL, while temperature and pressure are available near water-surface level. At the L1 to L6 locations, the log-term mean WS and wind power density (WPD) values are found to be 7.55 m/s and 370 W/m2, 6.37 m/s and 225 W/m2, 6.91 m/s and 281 W/m2, 5.48 m/s and 142 W/m2, 4.30 m/s and 77 W/m2, and 5.03 and 115 W/m2 and at 100 m AMSL, respectively. The higher magnitudes of monthly and annual windy site identifier indices (MWSI and AWSI) of 18.68 and 57.41 and 12.70 and 42.94 at the L1 and L3 sites, and generally lower values of wind variability indices, are indicative of a favorable winds source, which is also supported by higher magnitudes of mean WS, WPD, annual energy yields, plant capacity factors, and wind duration at these sites. The cost of energy for the worst and the best cases are estimated as 10.120 USD/kWh and 1.274 USD/kWh at the L5 and L1 sites, corresponding to wind turbines WT1 and WT4. Based on this analysis, sites L1, L3, and L2 are recommended for wind farm development in order of preference. The wind variability and windy site identifier indices introduced will help decision-makers in targeting potential windy sites with more confidence.

Causes and effects of coastal dunes erosion during storm surge Axel in January 2017 on the southern Baltic Polish coast

The study is dedicated to researching the storm surge Axel, the largest on the South Baltic coast in the 20th and 21st centuries. This unique event resulted in a very large erosion along the whole Polish Baltic Sea coast in January 2017 (max. HSL = 1.65 m, the average for the coast 1.36 m). Storm surge effects on the coast were followed based on field observations of dune retreat and analysis of hydrodynamic and meteorological parameters of the surge and its passage through the Baltic Sea. The material of dune erosion was collected based on cross-shore profiling of almost every 1 km, along the whole Polish sand barrier coast, before and after this storm. The work also studies the parameters of smaller storm surges from the end of 2016, which caused the lowering of beaches and dune erosion. A relationship was observed between erosion, and beach height and sea level (SL). The higher the beach, the lower the erosion that occurred. The average dune toe retreat was 5.1 m, and the largest exceeded 9–19 m (max. 42 m). The most important for dune erosion was the height of run-up, beach height and shore exposition for a surge. The largest dune erosion was observed during the heaviest SL with wave run-up higher than 3.8 m above mean sea level (AMSL). Each coast section was eroded, which also caused losses in infrastructure.

Mitigation of urban waterlogging from flash floods hazards in vulnerable watersheds

Study regionThe Aswan region is a vast plateau in the South of Egypt located 150 m above mean sea level (AMSL). Within this region, the tourist city of Aswan is Egypt’s southernmost city, located on the east bank of the Nile River. Study focusThe occurrence of flash floods can severely impact low-lying and densely populated areas. Therefore, highly vulnerable areas require effective mitigation measures to guarantee public safety and preserve archeological sites of great importance. This study investigates the interaction between the soil, surface water, and groundwater in the Aswan region of Egypt. Based on the rainfall analysis and the watershed hydrology, six different scenarios were run using the MODFLOW and Watershed Modeling System (WMS) software, which simulated rainfall recurrence intervals of 2, 5, 10, 25, 50 and 100 years. New hydrological insights for the regionThe model's results indicated that an increase in the recurrence interval produced a rise in the groundwater level (GWL) up to 8.82 m (AMSL). Therefore, constructing three dams was proposed as a solution at the three basins of Al- Haytah, Al-Kimab, and Umm-Buwayrat. The proposed solution allows the storage of large volumes of water upstream. It mitigates GWL's rise within and near Aswan City. The presented study can be applied to vulnerable watersheds in arid and semi-arid regions. It can help policymakers to integrate additional sustainable solutions into construction dams and their implementation in development plans.

Study of Physico-chemical and Nutrient Status of the Soil in Chiraigaon Block, Varanasi District, Uttar Pradesh, India

A study was conducted to evaluate the soil fertility and their quality parameters of Chiraigaon Block of Varanasi district Uttar Pradesh (U.P.) which is located at Latitude 25.3°N, and Longitude is 82.9°E and at elevation of 81m above mean sea level (AMSL) in the centre of Gangatic plain of Northern India. A total of 54 soil samples were collected from the farmland of six different villages of Chiraigaon Block. Physico-chemical property analyses showed average bulk density and particle density of 1.22 and 2.37 mg/m3 respectively whereas water holding capacity ranged from 29.80 to 51.70 %, pH ranged from 7.1 to 8.3, EC ranged from 0.18 to 1.68 dSm-1 and organic carbon content ranged from 0.21 to 0.76 % with low organic carbon content in 70.37% of the soil samples. Macronutrient analysis showed low to medium range for nitrogen, phosphorus and sulphur with average values of 244.15 Kg/ha, 14.78 kg/ha and 10.60 mg/kg respectively whereas medium to high range of potassium (481.7 kg/ha) and high range of exchangeable calcium (11.82 mEq/100g) and magnesium (9.89 mEq/100g) were found. Micro-nutrient analysis showed low to high range for manganese and zinc with values ranging from 3.08 to 56.1 mg/kg and 0.58 to 19.62 mg/kg respectively, with iron in the medium to high range (5.1 to 72 mg/kg) while available copper (2.2 to 4.08 mg/kg) was in the high range in the tested samples. The current study is expected to help the farmers of the study location in providing guidelines required for long-term soil fertility management and to improve soil quality and for developing suitable crop varieties that can grow without any yield reduction.

New field observations on the Quaternary geology and vertebrate palaeontological occurrences in the Narsinghpur region of Narmada valley (central India)

Abstract Since the beginning of the nineteenth century, the Narmada River Valley has been well known for discoveries of abundant vertebrate fossil localities, a wide range of prehistoric archaeological assemblages and the first-known hominin fossil site in India at Hathnora. The fossil and archaeological remains are found in various sedimentary contexts: boulder conglomerate, pebble-rich sand, cross-bedded, coarse-to-fine sand and reddish brown clay in the Early to Late Pleistocene deposits. Our preliminary field investigations in the Narsinghpur region of the basin mark the presence of 26 individual localities within a stretch of 70 km of the Narmada River and adjoining tributaries. Each location was documented by GPS and the geological details were recorded while collecting the fossils. Past and current palaeontological research has revealed that a variety of fauna adapted to the sub-humid climate of both aquatic and terrestrial landscapes that thrived in this area during the Pleistocene period. One of our long-term goals is to understand the reasons for the high number of palaeontological occurrences compared with other parts of India and use such information to predict the locations of new occurrences, including hominin fossils. Various taphonomic processes in this region are responsible for the preservation and destruction of fossil assemblages in different geological formations: soil type, climatic conditions, rich calcium carbonate presence, encrustation, patination and modern anthropogenic activities (among others). Most of the fossil localities are found at an elevation range of 310–350 m above mean sea level (AMSL). The Narmada Basin was inhabited by prehistoric human populations and a variety of fauna, as evidenced by the ample lithic and fossil assemblages across the region. There are definitive contextual patterns of occurrences of the Quaternary vertebrate fossils and archaeological assemblages in the landscape, which require detailed investigations and mapping to understand the spatial distribution pattern and nature of associated sedimentary environments. In addition, this uniquely fossil-rich area requires proper protection and long-term preservation as it is heavily impacted by modern anthropogenic factors such as agriculture, sand mining and other activities.

Offshore wind resource assessment off the coast of Daejeong, Jeju Island using 30-year wind estimates

Long-term offshore wind resource assessment was performed for the offshore site off the Daejeong coast on Jeju Island of South Korea. A jacket type offshore met mast was installed at the site to measure wind and meteorological conditions for 1 year from 1 July 2015 to 30 June 2016. The wind conditions were measured at 32.5 m, 72.5 m and 100.5 m above mean sea level (AMSL). Fundamental wind characteristics such as average wind speed, wind direction frequency, turbulence intensity and so on were analyzed utilizing 1-year wind measurements. In order to correct the limited period of 1-year measurements to long-term conditions, the Measure-Correlate-Predict (MCP) method was applied to estimate 30-year wind conditions using nearby Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data. Also, wind turbine classes suitable for the offshore site were determined based on extreme wind speed estimations and the measured ambient turbulence intensity. Five commercial wind turbines were chosen for estimation of the 30-year annual energy productions (AEPs) and capacity factors (CFs). As a result, it was estimated that the 30-year average wind speed was 7.86 m/s at 100.5 m AMSL. The wind turbine class II rating was estimated to be suitable for enduring extreme wind speed for a return period of 50 years. For the 30-year results, the minimum CF of 30.48% was estimated, while the maximum nearly reached 45%.

Investigation of Atmospheric Dynamic and Thermodynamic Structures of Typhoon Sinlaku (2020) from High-Resolution Dropsonde and Two-Way Rawinsonde Measurements

Profiling the vertical atmospheric structure for typhoons remains challenging. Here, the atmospheric dynamic and thermodynamic structures were investigated during the passage of Typhoon Sinlaku (2020) over Xisha Islands in the South China Sea for the period 28 July to 2 August 2020, mainly based on two-way rawinsonde and dropsonde measurements in combination with surface-based automatic weather station observations, disdrometer measurements, and Himawari-8 geostationary satellite images. The study period was divided to three stages: the formation stage of tropical depression (pre-TD), tropical depression (TD), and tropical storm (TS). The wind speed and local vertical wind shear reached the maximum value at 3 km above mean sea level (AMSL) before the typhoon approached the Xisha islands. Pseudo-equivalent potential temperature (θse) was found to decrease with the altitude below 2 km AMSL; temperature inversions occurred frequently within this altitude range, particularly during the TS stage. This seemed a typical capping inversion that indicated a downward motion above 2 km AMSL. The temperature increased slightly with the development of Typhoon Sinlaku (2020) at altitudes of 8–10 km AMSL. This indicated that our observations presumably captured the air mass warmed by the condensation, which was a good signature of an upper air in the tropical cyclone. In addition, wind speed (particularly in the lower stratosphere), specific humidity, and equivalent potential temperature escalated significantly when the tropical depression strengthened into Typhoon Sinlaku (2020), which indicated that the typhoon constantly obtained energy from the sea surface during its passage over the study region. The thermodynamic and dynamic structures of atmosphere advance our understanding of the inner structure of typhoons during the different evolutionary stages.

Influence of AGL flight and off-nadir images on UAV-SfM accuracy in complex morphology terrains

In the field of geosciences and engineering, situations arise where special attention have to be paid to the planning of the UAV-photogrammetric project, that is, terrain with complex geometry and steep slopes. The use of off-nadir imagery and flights at a fixed height above ground level (AGL) are postulated as possible factors to be considered to achieve high accuracies. The objective of this study is to evaluate the influence of image angle, frontal and side overlaps, and type of flight (above mean sea level (AMSL) or AGL), on the accuracy of the dense 3 D point cloud yielded by UAV-SfM. The results obtained showed that imagery with an angle between 20° and 35° in two perpendicular flight line directions, 90/90, 90/70 or 70/70 overlap and AGL flight is the optimal combination for best accuracy and high precision. With nadir imagery, the combination of factors that gives the most accuracy results are AGL flights with a 90/70 overlap.

Wind resource assessment uncertainty for a TLP-based met mast

The current work presents wind resource assessment results of a complete one-year offshore measurement campaign in the Aegean Sea, at 65 m deep waters, with a floating tension leg platform (TLP) equipped with a met mast reaching the height of 44 m above mean sea level (AMSL). Wind conditions uncertainty is evaluated according to the existing standards and guidelines and the additional uncertainty, due to the platform motion, is addressed with two different methods: First by performing wind tunnel experiments, in which the wind sensors are submitted to various controlled motions and second by comparing results of the onboard lidar to a nearby onshore one. Both methods converge that the motion effects are minimal and the additional uncertainty of the mean values due to the TLP motion is ≤1%.

Offshore Wind Resource Assessment of Thailand Using Remote Sensing Technique

This paper presents the evaluation of the offshore wind resource of Thailand (the Gulf of Thailand and the Andaman Sea) using remote sensing technique. The wind speed at height of 10 m above mean sea level (A.M.S.L.) was measured using SeaWinds Scatterometer on QuickSCAT by NASA. The QuickSCAT satellite images in 1999-2009 with resolution of 1ox1o was interpreted and validated using the measured wind speed provided by the ship observation, buoy data and numerical weather prediction models. The wind speed was interpolated for 1 km resolution enhancement and extrapolated to the height of 50 m A.M.S.L.. The monthly and annual mean wind speed maps were presented in order to show the spatial and temporal variation of offshore wind energy potential. Results showed that QuickSCAT satellite images interpretation gave lower bias in the rage of wind speed of 3-18 m/s, however, the bias was high for wind speed more than 20 m/s. It found that offshore mean wind speed at height of 50 m A.M.S.L. was in the range of 3.0-6.0 m/s where the middle part of Thai offshore had the highest potential with the wind speed in the rage of 7.0-10.0 m/s. The offshore wind speed had high potential during June until August due to the influence of southwest monsoon.

Long-term MAX-DOAS measurements of NO<sub>2</sub>, HCHO, and aerosols and evaluation of corresponding satellite data products over Mohali in the Indo-Gangetic Plain

Abstract. We present comprehensive long-term ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of aerosols, nitrogen dioxide (NO2), and formaldehyde (HCHO) from Mohali (30.667∘ N, 76.739∘ E; ∼310 m above mean sea level), located in the densely populated Indo-Gangetic Plain (IGP) of India. We investigate the temporal variation in tropospheric columns, surface volume mixing ratio (VMR), and vertical profiles of aerosols, NO2, and HCHO and identify factors driving their ambient levels and distributions for the period from January 2013 to June 2017. We observed mean aerosol optical depth (AOD) at 360 nm, tropospheric NO2 vertical column density (VCD), and tropospheric HCHO VCD for the measurement period to be 0.63 ± 0.51, (6.7 ± 4.1) × 1015, and (12.1 ± 7.5) × 1015 molecules cm−2, respectively. Concerning the tropospheric NO2 VCDs, Mohali was found to be less polluted than urban and suburban locations of China and western countries, but comparable HCHO VCDs were observed. For the more than 4 years of measurements during which the region around the measurement location underwent significant urban development, we did not observe obvious annual trends in AOD, NO2, and HCHO. High tropospheric NO2 VCDs were observed in periods with enhanced biomass and biofuel combustion (e.g. agricultural residue burning and domestic burning for heating). Highest tropospheric HCHO VCDs were observed in agricultural residue burning periods with favourable meteorological conditions for photochemical formation, which in previous studies have shown an implication for high ambient ozone also over the IGP. Highest AOD is observed in the monsoon season, indicating possible hygroscopic growth of the aerosol particles. Most of the NO2 is located close to the surface, whereas significant HCHO is present at higher altitudes up to 600 m during summer indicating active photochemistry at high altitudes. The vertical distribution of aerosol, NO2, and HCHO follows the change in boundary layer height (BLH), from the ERA5 dataset of European Centre for Medium-Range Weather Forecasts, between summer and winter. However, deep convection during the monsoon transports the pollutants at high altitudes similar to summer despite a shallow ERA5 BLH. Strong gradients in the vertical profiles of HCHO are observed during the months when primary anthropogenic sources dominate the formaldehyde production. High-resolution MODIS AOD measurements correlate well but were systematically higher than MAX-DOAS AODs. The ground-based MAX-DOAS measurements were used to evaluate three NO2 data products and two HCHO data products of the Ozone Monitoring Instrument (OMI) for the first time over India and the IGP. NO2 VCDs from OMI correlate reasonably with MAX-DOAS VCDs but are lower by ∼30 %–50 % due to the difference in vertical sensitivities and the rather large OMI footprint. OMI HCHO VCDs exceed the MAX-DOAS VCDs by up to 30 %. We show that there is significant scope for improvement in the a priori vertical profiles of trace gases, which are used in OMI retrievals. The difference in vertical representativeness was found to be crucial for the observed biases in NO2 and HCHO surface VMR intercomparisons. Using the ratio of NO2 and HCHO VCDs measured from MAX-DOAS, we have found that the peak daytime ozone production regime is sensitive to both NOx and VOCs in winter but strongly sensitive to NOx in other seasons.

Topographical influence on pedogenesis – Insights from Rock Magnetism

Topography being a pedogenic factor influences the physico-chemical and biological properties of soil profiles. Besides, the magnetic characteristics of soil profiles may also be varied, as iron minerals in soils are strongly redox sensitive. However, hardly any study has been reported from the topographic implication on the magnetic characteristics of soils to date. Hence, the present study aims to delineate the influence of topography on the in-situ soil profiles developed on hill topography by studying their rock magnetic properties.Two soil profiles each, formed at different altitudes of the two hills named Doddabathi Siddeshwara (14.58° N; 75.66° E) with peak ~650 m above mean sea level (AMSL) and Elimale (12.5° N; 75.5° E) with peak ~200 m AMSL were chosen for the investigation. Rock magnetic measurements were carried out on soil samples; Rock Magnetism is a geophysical technique applied on environmental samples such as rocks, soils, dust and sediments for determining their intrinsic magnetic properties namely, magnetic susceptibility, anhysteretic remanent magnetization and isothermal remanent magnetisation. These intrinsic magnetic properties are the result of concentration, mineralogy and grain-size of magnetic minerals present in the samples that are unique for every environmental condition. Hence, determination of rock magnetic properties of environmental samples leads to the corresponding environmental set-up in which the samples are formed. Particle size and organic matter content were also estimated to support the rock magnetic interpretation. Based on the investigation it was concluded that topography has indeed influenced the magnetic properties of soil profiles of the hills, irrespective of rainfall and organic matter content. Both depletion in magnetic mineral concentration and coarsening of magnetic grains towards the profile-top were observed in all the soil profiles; this indicates the effect of soil erosion. The decrease in the magnetic properties of hill-top soil profiles was determined to be dominantly due to the removal of finer pedogenic magnetic minerals. Whereas the lowered magnetic characteristics of the hill-bottom soil profiles were attributed to the mixing of bulk materials eroded from higher elevations. Meanwhile, the greater difference in magnetic properties of Doddabathi soil profiles than that of Elimale was attributed to the combined effect of slope-angle and lateral-distance between their respective hill-top and -bottom profiles. Thus, exploring the applicability of rock magnetism to address the spatial-spread of magnetic minerals on hill topography, the study confirms the suitability of the technique to be used as a proxy for the same.

PENINJAUAN STATUS LINGKUNGAN EKSISTING SUNGAI MARIKINA, FILIPINA

Abstract: The physico-chemical characteristics of the Marikina River in an urban area of Metro Manila, Philippines was determined to evaluate the current degree of pollution. The study focused on one source at the site with general coordinates of 14°38’07.95” N, 121°05’36.33” E based on the World Geodetic System (WGS), at an average surface water elevation of around 9 m above mean sea level (AMSL). The area was chosen because of its proximity to a main road and the presence of an outfall from a cemented pipe near a major shopping mall. Comparing the results from the sampling source with the DENR effluent standards for surface waters based on (DAO-2016-08, US-EPA), the effluent is considered as too polluted to be discharged to the surface water in terms of Total Dissolved Solids (TDS: 608.9 mg/L) and Phosphates (PO4: 12.46 mg/L). The pH (6.9) and Nitrate (0.17 mg/L) of the effluent conforms to standards. A Stream Visual Assessment Protocol was conducted with a resulting Protocol Score of 5.7, which is relatively low for a moving water body. The failure to conform to set standards using the physico-chemical components is supported by the land-use profile which shows that domestic (85%), industrial/commercial (10%) and agricultural wastes (5%) greatly affect the water quality of the river. It is our recommendation therefore that continuing information and education campaigns for the maintenance of water quality be regularly conducted for the residents along the riverbanks to create awareness of the importance of keeping the water clean through minimum direct waste contributions. Keywords: Physico-Chemical characteristics, Marikina river, water quality

P status of Andisol and Its correlation with P content of Arabica coffee leaves in Bener Meriah District

Bener Meriah district is one of the arabica coffee producing regions in Indonesia with an average production of 700-800 kg ha−1 year−1. Most of arabica coffee in this area are grown in Andisol. This study aims to determine the P status of Andisol, namely P-available, P-total, P-retention, P content of arabica coffee leaves and the correlation between soil P-available and P content of arabica coffee leaves in Bener Meriah district. This research was conducted using survey methods. The observed parameters were made on Andisol planted with arabica coffee which is located at an altitude of 1,200-1,400 m above mean sea level (AMSL) at slopes 0-3, 3-8, 8-15, 15-30, and >30% respectively. The results showed that Andisol Bener Meriah has a P-available ranging from 0.3 to 12.81 ppm (very low-high). Most of the Andisol observed (73.33%) had P-available at very low and low levels. Andisol Bener Meriah has a P-total ranging from 159.4 to 1,246.7 ppm (low-very-high). Most of the Andisol observed (73.33%) have P-total at moderate, high and very high levels. Andisol Bener Meriah has a P-retention ranging from 85.2 to 87.4%. Arabica coffee leaves have P content levels ranging from 0.10% to 0.23%. Most of the arabica coffee leaves (78.57%) were observed have P content at a minimum level.; there is a close relationship between soil P-available with P content of arabica coffee leaves with a value of r = 0.97.

Evidence of the complexity of aerosol transport in the lower troposphere on the Namibian coast during AEROCLO-sA

Abstract. The evolution of the vertical distribution and optical properties of aerosols in the free troposphere, above stratocumulus, is characterized for the first time over the Namibian coast, a region where uncertainties on aerosol–cloud coupling in climate simulations are significant. We show the high variability of atmospheric aerosol composition in the lower and middle troposphere during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) field campaign (22 August–12 September 2017) around the Henties Bay supersite using a combination of ground-based, airborne and space-borne lidar measurements. Three distinct periods of 4 to 7 d are observed, associated with increasing aerosol loads (aerosol optical thickness at 550 nm ranging from ∼0.2 to ∼0.7), as well as increasing lofted aerosol layer depth and top altitude. Aerosols are observed up to 6 km above mean sea level during the later period. Aerosols transported within the free troposphere are mainly polluted dust (predominantly dust mixed with smoke from fires) for the first two periods (22 August–1 September 2017) and smoke for the last part (3–9 September) of the field campaign. As shown by Lagrangian back-trajectory analyses, the main contribution to the aerosol optical thickness over Henties Bay is shown to be due to biomass burning over Angola. Nevertheless, in early September, the highest aerosol layers (between 5 and 6 km above mean sea level) seem to come from South America (southern Brazil, Argentina and Uruguay) and reach Henties Bay after 3 to 6 d. Aerosols appear to be transported eastward by the midlatitude westerlies and towards southern Africa by the equatorward moving cut-off low originating from within the westerlies. All the observations show a very complex mixture of aerosols over the coastal regions of Namibia that must be taken into account when investigating aerosol radiative effects above stratocumulus clouds in the southeast Atlantic Ocean.