Venus I. Carbon monoxide distribution and molecular-line searches

An observational program to study variations of the vertical distribution of CO in the Venus atmosphere is presented. Measurements of the J = 0 → 1 absorption line at 2.6 mm wavelength are reported for two phase angles in 1977, one near eastern elongation (Feb.) and the other near inferior conjunction (Apr.). The two spectra are significantly different, with the April absorption line being narrower and deeper. The results of numerical inversion calculations show that the CO mixing ratio increases a factor of ～ 100 between 78 and 100 km and that the CO abundance above ～ 100 km is greatest on the night-side hemisphere. These conclusions are in qualitative agreement with theoretical models. In addition to the CO observations, a search for other molecules was made to provide further information on the composition of the Venus middle atmosphere. The J = 0 → 1 transition of ¹³CO was detected and upper limits were derived for nine other molecules.     

Land Subsidence of Jakarta (Indonesia) and its Geodetic Monitoring System

Jakarta is the capital city of Indonesia with a population of about 10 million people, inhabiting an area of about 25 × 25 km. It has been reported for sometime that locations in Jakarta are subsiding at different rates. Up to the present, there has been no comprehensive information about the characteristics and pattern of land subsidence in the Jakarta area. Usually land subsidence in Jakarta is measured using extensometers and ground water level observations, or estimated using geological and hydrological parameters. To give a better picture about land subsidence, geodetic-based monitoring systems utilizing leveling and GPS surveys have also been implemented.The land subsidence characteristics of Jakarta and its surrounding area areinvestigated using data from three repeated leveling surveys performed in1982, 1991, and 1997, and two repeated GPS surveys conducted in 1997and 1999. Leveling surveys detected subsidence up to about 80 cm duringthe period of 1982–1991, and up to about 160 cm during the 1991–1997period; while GPS surveys observed subsidence up to about 20 cm duringthe period of 1997–1999. Comparison with the hydrological data shows thatland subsidence in Jakarta is strongly related to excessive groundwater extraction.     

Geodetic Datum of Indonesian Maritime Boundaries: Status and Problems

Indonesia has maritime boundaries with 10 countries namely: Australia, Timor Leste, Papua New Guinea (PNG), Palau, Philippines, Vietnam, Thailand, Malaysia, Singapore, and India. Many treaties have been ratified concerning these boundaries. Unfortunately, many coordinates of boundary points mentioned in the treaties are not clear in relation to their geodetic datum. The uncertainty in geodetic datum of boundary points introduces complications and problems in spatial management of Indonesia's maritime boundaries, since it can displace the boundary lines from their assumed true location. This study investigates the possible original geodetic datums for the maritime boundaries between Indonesia and neighboring countries, in the case they are not explicitly stated in the treaties. The displacements of boundaries in WGS84 datum are generally in the order of a few hundred meters, i.e., about 200 to 400 m, depending on the assumed original geodetic datum being considered. These boundary displacements are spatially advantageous for Indonesia in some cases and also disadvantageous in others. The study will sum up with some conclusions and recommendations.     

Geodetic Datum of Indonesian Maritime Boundaries: Status and Problems

Indonesia has maritime boundaries with 10 countries namely: Australia, Timor Leste, Papua New Guinea (PNG), Palau, Philippines, Vietnam, Thailand, Malaysia, Singapore, and India. Many treaties have been ratified concerning these boundaries. Unfortunately, many coordinates of boundary points mentioned in the treaties are not clear in relation to their geodetic datum. The uncertainty in geodetic datum of boundary points introduces complications and problems in spatial management of Indonesia's maritime boundaries, since it can displace the boundary lines from their assumed true location. This study investigates the possible original geodetic datums for the maritime boundaries between Indonesia and neighboring countries, in the case they are not explicitly stated in the treaties. The displacements of boundaries in WGS84 datum are generally in the order of a few hundred meters, i.e., about 200 to 400 m, depending on the assumed original geodetic datum being considered. These boundary displacements are spatially advantageous for Indonesia in some cases and also disadvantageous in others. The study will sum up with some conclusions and recommendations.