Flow Simulation Using 2D Hydrodynamic Model at the Palu Estuary Based on National DEM (DEMNAS) Source Data

2D hydrodynamic simulation is very important to be performed to interpret the flow characteristics of a river segment. The success of this simulation is determined not only by the input boundary data, but also by the quality of the data used to create the geometry model, such as terrestrial survey data, digital elevation model (DEM) or data from other sources. This paper aims to assess the use of National DEM data (DEMNAS) as the basis for constructing a 2D geometry model for flow simulation in the downstream segment of the Palu River, Sulawesi, Indonesia. The simulation results using this DEM were compared with simulations based on geometry generated from terrestrial survey data. The hourly observation discharge data at Point P3 and tidal observation data at Point P1 in the period March 17th – 18th, 2021 were assigned as the inputs at the upstream and downstream boundaries, respectively. The performance of the two model scenarios was evaluated by comparing the water surface elevation observed and simulated during the time range at Point P2 using the efficiency of Nash–Sutcliffe (NSE). The simulation results show that the two geometry-forming data provide different performance against NSE. The terrestrial survey data shows a fairly good performance, while the DEMNAS data indicates a poor performance with a negative NSE. Based on the NSE of these two scenarios, it can be interpreted that the DEMNAS data is still not sufficient to construct the model geometry for the case in this area. This is not only related to the DEMNAS resolution, especially the vertical resolution, but is also related to the very low topographical slope in the estuary of the river. However, the use of these data in areas of higher slope can be re-evaluated.

A COMPARISON BETWEEN TIDAL CONSTITUENTS DERIVED FROM SATELLITE ALTIMETRY AND IN-SITU DATA AROUND PENINSULAR MALAYSIA

Satellite altimetry technology has been widely used in exploring Earth’s Ocean activities. Achieving a remarkable accuracy in measuring sea level for ocean tide analysis has led the local researchers to investigate more details on tidal behaviour in the regional area. This study is an attempt to assess the reliability of derived tidal constituents between satellite radar altimetry and in-situ data which is referred to as coastal tide gauges. Three satellite missions denoted as TOPEX class missions namely TOPEX, Jason-1, and Jason-2 were used to derive along-track sea surface height (SSH) time series over 23 years. Besides, four selected coastal tide gauges were used for tidal analysis and validation where the tidal data have at least 19 years of hourly observation. Derivation of tidal constituents from both satellite altimetry and tide gauges were executed by adopting the harmonic analysis method. The comparisons were made by calculating the Root Mean Square Misfit (RMSmisfit) of each tidal constituent between the nearest altimetry point to the tide gauges. After RMSmisfit, Root Sum Square (RSS) values of tidal constituents at each tide gauge were also calculated. The results displayed the RMSmisfit of tidal constituents agreed well with the selected tide gauges which are within 10 cm except for M2 constituents which recorded 10.2 cm. Pelabuhan Kelang tide gauge station showed the highest RSS value followed by Pulau Langkawi which recorded 21.2 cm and 9.8 cm, respectively. In conclusion, overall results can be inferred that the satellite-derived tidal constituents are likely to have good agreement with the selected tide gauge stations. Nevertheless, further analysis should be executed in determining high precision satellite-derived tidal constituents, especially in the complex regional area.

Modifikasi Kotak Polistiren untuk Penyimpanan Dingin Sayur Kubis dengan Menggunakan Es Kering sebagai Media Pendingin

ABSTRAK Penelitian telah dilakukan pada kotak modifypolystyrene sebagai kotak pengiriman kubis segar menggunakan es kering sebagai media pendingin. Penelitian ini bertujuan untuk menguji kotak yang dimodifikasi untuk mengetahui kotak yang paling cocok dimodifikasi untuk menjaga kesegaran sayuran. Kotak polystyrene yang dimodifikasi dibuat dengan memisahkan kotak menjadi dua kompartemen, satu kompartemen untuk menempatkan es kering sebagai media pendingin, dan kompartemen lain untuk menyimpan kubis segar. Itu dibuat lima jenis kotak dimodifikasi, dua jenis media pendinginan mondar-mandir di bawah sayuran segar, sedangkan jenis sisanya menempatkan media pendingin di atas sayuran. Tes yang dilakukan selama 7 jam terdiri dari suhu di sekitar kotak, suhu di dalam kotak, dan suhu pusat kubis segar. Pengukuran lain yang dilakukan adalah berat es kering yang digunakan selama penyimpanan dingin, penurunan berat kubis segar, pengamatan visual kerusakan kubis segar, dan perhitungan keseimbangan energi. Menempatkan es kering di bawah kubis segar menyebabkan suhu tengah kubis segar jauh di atas suhu penyimpanan yang disarankan, 0oC, sementara menempatkan media pendingin di atas sayuran memberi dampak negatif pada sayuran di mana suhu tengah kubis segar di bawah 0oC untuk dua jenis kotak yang dimodifikasi, kecuali es kering yang ditempatkan di baskom yang terbuat dari piring zink. Berdasarkan perhitungan energi, terungkap bahwa hampir lebih dari 75% energi pendingin digunakan untuk mengatasi beban pendinginan di sekitarnya. Ditemukan bahwa kotak modifikasi yang paling cocok untuk menyimpan kubis segar adalah jenis kelima. ABSTRACT Research had been carried out to modify polystyrene box as fresh cabbage delivery box using dry ice as a cooling medium. The research aims were to find out the most suitable model box to maintain the freshness of the vegetables. Modified polystyrene box was made by separating the box into two compartments, one compartment for placing dry ice, and another compartment for storing the fresh cabbage. The box was modified into five types which consisted of two types of the box where the cooling medium was placed below the fresh vegetable, while for the rest, the cooling medium was placed above the vegetable. The tests were performed for 7 hours with the hourly observation that consisted of the temperature surrounding the model box, temperature inside the box, and temperature of the center of the fresh cabbage. Other conducted measurements were the weight of dry ice used during cold storage, weight loss of fresh cabbage, visual observation on the deterioration of the fresh cabbage, and energy equilibrium calculation. Placing dry ice below the fresh cabbage caused the center temperature of the fresh cabbage to far above the recommended storing temperature, 0oC, while placing the cooling medium above the vegetable gave a negative impact on the vegetable where the center temperature of the fresh cabbage was below 0oC for the two types of model boxes, except for the fifth type box where dry ice was placed in a basin made of zink plate. Based on energy calculation it was revealed that almost more than 75% of cooling energy was used to overcome the surrounding cooling load. It was found that the most suitable model box for storing the fresh cabbage was the fifth type.

Flood inundation simulations based on GSMaP satellite rainfall data in Jakarta, Indonesia

Jakarta is the capital of Indonesia and is considered one of the most vulnerable cities to climate-related disasters, including flooding, sea-level rise, and storm surges. Therefore, the development of a flood-forecasting system for Jakarta is crucial. However, the accurate prediction of flooding in Jakarta is challenging because of the short flood concentration time in highly urbanized basins and the shortage of rainfall data in poorly gauged areas. The aim of this study is to simulate recent flood inundation using global satellite mapping of precipitation (GSMaP) products. The GSMaP products (NRT and Gauge V7) were evaluated and compared with hourly observation data from five ground stations in the Ciliwung River Basin. In addition, a rainfall-runoff and flood inundation model was applied to the target basin. The results of the analysis showed that the GSMaP Gauge data were more accurate than the GSMaP NRT data. However, the GSMaP Gauge cannot be used to provide real-time rainfall data and is, therefore, inadequate for real-time flood forecasting. We conclude that the GSMaP Gauge is suitable for replicating past flood events, but it is challenging to use the GSMaP NRT for real-time flood forecasting in Jakarta.

Doppler lidar at Observatoire de Haute-Provence for wind profiling up to 75 km altitude: performance evaluation and observations

A direct-detection Rayleigh–Mie Doppler lidar for measuring horizontal wind speed in the middle atmosphere (10 to 50 km altitude) has been deployed at Observatoire de Haute-Provence (OHP) in southern France starting from 1993. After a recent upgrade, the instrument gained the capacity of wind profiling between 5 and 75 km altitude with vertical resolution up to 115 m and temporal resolution up to 5 min. The lidar comprises a monomode Nd:Yag laser emitting at 532 nm, three telescope assemblies and a double-edge Fabry–Pérot interferometer for detection of the Doppler shift in the backscattered light. In this article, we describe the instrument design, recap retrieval methodology and provide an updated error estimate for horizontal wind. The evaluation of the wind lidar performance is done using a series of 12 time-coordinated radiosoundings conducted at OHP. A point-by-point intercomparison shows a remarkably small average bias of 0.1 m s−1 between the lidar and the radiosonde wind profiles with a standard deviation of 2.3 m s−1. We report examples of a weekly and an hourly observation series, reflecting various dynamical events in the middle atmosphere, such as a sudden stratospheric warming event in January 2019 and an occurrence of a stationary gravity wave, generated by the flow over the Alps. A qualitative comparison between the wind profiles from the lidar and the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System is also discussed. Finally, we present an example of early validation of the European Space Agency (ESA) Aeolus space-borne wind lidar using its ground-based predecessor.

Doppler lidar at Observatoire de Haute Provence for wind profiling up to 75 km altitude: performance evaluation and observations

A direct-detection Rayleigh-Mie Doppler lidar for measuring horizontal wind speed in the middle atmosphere has been deployed at Observatoire de Haute Provence (OHP) in southern France since 1993. After a recent upgrade, the instrument gained the capacity of wind profiling between 5 and 75 km altitude with high vertical and temporal resolution. The lidar comprises a monomode Nd:Yag laser emitting at 532 nm, three telescope assemblies, and a double-edge Fabry-Perot interferometer for detection of the Doppler shift in the backscattered light. In this article, we describe the instrument design, recap retrieval methodology and provide an updated error estimate for horizontal wind. The evaluation of the wind lidar performance is done using a series of twelve time-coordinated radiosoundings conducted at OHP. A point-by-point intercomparison shows a remarkably small average bias of 0.1 m/s between the lidar and the radiosonde wind profiles with a standard deviation of 2.2 m/s. We report examples of a weekly and an hourly observation series, reflecting various dynamical events in the middle atmosphere, such as a Sudden Stratospheric Warming event in January 2019 and an occurrence of a stationary gravity wave, generated by the flow over the Alps. A qualitative comparison between the wind profiles from the lidar and the ECMWF Integrated Forecast System is also discussed. Finally, we present an example of early validation of the ESA Aeolus space-borne wind lidar using its ground-based predecessor.

Studi Laboratorium Siklus Hidup Anopheles vagus Pradewasa sebagai Vektor Filariasis dan Malaria di Provinsi Nusa Tenggara Timur

Anopheles vagus is one of the vectors that plays an essential role in malaria infection in East Nusa Tenggara, Indonesia. This vector’s density is related to population dynamics and the environment. The high population density is fluctuated according to the birth and death rate of the mosquitos on their life cycle. This is an observational study that employed a cross-sectional design aimed to identify the life cycle of pre-adult An. vagus mosquitos. The sample was collected from Manggarai Barat and Kupang regions. Sample was taken from around cattle’s cages between 6.00pm-12.00am and were the ones that have sucked cattle’s blood. Identification and colonization were conducted in Loka Litbangkes Waikabubak Laboratory. Data was collected through an hourly observation form and then analyzed descriptively. The results indicated that an adult An.vagus could produce 42-184 eggs each time it laid eggs with 79% hatching rate succeed. The life cycle of an An.vagus under a controlled environment in the laboratory was as following phases: egg (1-4 days), larvae (9-19 days), pupa (1-8 days). Anopheles vagus needed an average of 57.2 minutes to mate and 13 hours to suck blood after the mating process. The highest death rate (28.05%) occurred in instar IVof larvae stage. Pre-adult of An. vagus needed 11-31 days in with the environment that conditioned at 21.1°C and 74.3% humidity for their development,while the highest death rate observed at instar IV.

Assessing Diurnal Variability of Biogeochemical Processes Using the Geostationary Ocean Color Imager (GOCI)

Short-term (hours) biological and biogeochemical processes cannot be fully captured by the current suite of polar-orbiting satellite ocean color sensors, as their temporal resolution is limited to potentially one clear image per day. Geostationary sensors, such as the Geostationary Ocean Color Imager (GOCI) from the Republic of Korea, allow the study of these short-term processes because their geostationary orbits permit the collection of multiple images throughout each day. To assess the capability to detect changes in water properties caused by these processes, however, requires an understaning of the uncertainties introduced by the instrument and/or geophysical retrieval algorithms. This work presents a study of the variability during the day over a water region of low-productivity with the assumption that only small changes in the water properties occur during the day over the area of study. The complete GOCI mission data were processed using the SeaDAS/l2gen package. Filtering criteria were applied to assure the quality of the data. Relative differences with respect to the midday value were calculated for each hourly observation of the day. Also, the influence of the solar zenith angle in the retrieval of remote sensing reflectances and derived products was analyzed. We determined that the uncertainties in water-leaving “remote-sensing” reflectance ($R_\text{rs}$) for the 412, 443, 490, 555, 660 and 680 nm bands on GOCI are 8.05$\times10^{-4}$, 5.49$\times10^{-4}$, 4.48$\times10^{-4}$, 2.51$\times10^{-4}$, 8.83$\times10^{-5}$, and 1.36$\times10^{-4}$ sr$^{-1}$, respectively, and 1.09$\times10^{-2}$ mg m$^{-3}$ for the chlorophyll-a concentration (Chl-{\it a}), 2.09$\times10^{-3}$ m$^{-1}$ for the absorption coefficient of chromophoric dissolved organic matter at 412 nm ($a_{\text{g}}(412)$), and 3.7 mg m$^{-3}$ for particulate organic carbon (POC). We consider these to be the floor values for detectable changes in the water properties due to biological, physical or chemical processes.

Development of a cloud cover reader from whole sky images

Since the cloud amount in the sky is one of major variables to decide amount of sunshine or solar irradiance. A traditional method is eye-observation and it is widely used up to now. It requires one of observers at observation site for 24 hours due to the hourly observation. Another disadvantage is that there is individual difference and error between observers. Some of leading countries about weather observation have been trying to develop a cloud automatic observation system to replace the eye-observation. As a result, several methods have developed to replace the cloud observers, which have some restriction such as measurement range, accuracy and reliability. The conventional approach distinguishes between clouds and sky regions by RGB color and the ratio of each color in the image, but our proposed method extracts the cloud region using the optical properties of clouds and sky. The suggested method is applied to a randomly selected one day for 24 hours. The result shows that the amount of cloud compatible with the results of the existing observations be abele to obtained, and further quantified data can be obtained.

Exploring the severe winter haze in Beijing

Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012–2013, causing major environmental and health problems. To better understand these extreme events, we analyzed the hourly observation data of PM2.5 and its major chemical composition, with support of model simulations. Severe winter haze was shown to result from stable synoptic meteorological conditions over a large part of northeastern China, rather than from an abrupt increase in emissions. Build-up of secondary species, including organics, sulfate, nitrate, and ammonium, was the major driving force behind these polluted periods. The contribution of organic matter decreased with increasing pollution level while sulfate and nitrate contributions increased. Correspondingly, the ratio of secondary organic carbon to elemental carbon decreased and had a stable diurnal pattern during heavily polluted periods, indicating weakened photochemical activity due to the dimming effect of high loading of aerosol particles. Under such conditions, the strong increase in sulfate and nitrate contributions to PM2.5 was attributed to an elevated conversion ratio, reflecting more active heterogeneous reactions with gradually increasing relative humidity. Moreover, we found that high aerosol concentration was a regional phenomenon. The accumulation process of aerosol particles occurred successively from southeast cities to Beijing. The "apparent" sharp increase in PM2.5 concentration of up to several hundred μg m−3 per hour recorded in Beijing represented rapid "recovery" from an "interruption" to the continuous pollution accumulation over the region, rather than purely local chemical production. This suggests that regional transport of pollutants played an important role during these severe pollution events.