No abstract

Regional‐ and national‐scale emission rates of halocarbons have been a great concern in the field of global environmental studies and policy making. Emissions have been inventoried mainly by bottom‐up approaches, which involve adding up emissions from various industrial sources. To verify and supplement those bottom‐up inventories, top‐down approaches based on measurements of air concentrations are required. In this study, aircraft monitoring over Sagami Bay, Japan, was used to estimate the emission ratios of halocarbons (perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), CFCs, hydrochlorofluorocarbons (HCFCs), and others) from Japan. The enhanced concentrations in the boundary layer of air masses having traveled over Japanese mainland were used for the calculation under the assumption that the air masses over Sagami Bay represented average emission ratios for anthropogenic halocarbons on a countrywide basis. Given their emission ratios, a single compound with a credible emission rate can yield the emission estimates for all the other compounds. When we employed an inventory‐based emission estimate of HCFC‐22 from the Pollutant Release and Transfer Register (PRTR) system 2002 of Japan (9.1 Gg/yr) as the reference, the estimated emission rates of HCFC‐141b, HCFC‐142b, CFC‐12, chloroform, and trichloroethylene for 2002 were consistent with their PRTR values within 10%. Emissions of carbon tetrachloride (CCl4) and 1,1,1‐trichloroethane (CH3CCl3) were much higher than their PRTR values, suggesting that their sources are not adequately accounted for in the current inventories. The present study also presents probable annual emission rates for individual HFCs and PFCs that previously had no reported estimates; for example, 4.4 Gg/yr for HFC‐134a as of 2002.

The benefits of combined use of the GLONASS and GPS navigation satellite constellations have become obvious for applications such as open-cast mining operations and highly dynamic vehicles such as spaceplanes. Moreover, using GLONASS satellites in addition to GPS is useful for long baseline applications since it increases the numbers of satellites in common view. Japan's National Aerospace Laboratory (NAL) has been conducting feasibility studies using combined GPS/GLONASS positioning for spaceplane landing systems and the precise navigation of stratospheric airships. This paper presents the results of the first Japanese kinematic GPS/GLONASS flight test. In the test, the difference in estimated position between dual frequency GPS and single frequency GPS/GLONASS systems was found to be within a few centimeters, indicating that GLONASS carrier phase ambiguities were correctly resolved. To demonstrate the benefits of combining GLONASS with GPS navigation, an on-the-fly (OTF) test of instantaneous ambiguity resolution with a 30 degree cutoff angle was performed. The OTF performance of the combined GPS/GLONASS system was found to be similar to that of a GPS system with a cutoff angle of 10 degrees, showing that augmentation of GPS with GLONASS will be useful for highly dynamic vehicle applications.

No abstract

We are pursuing the research and development of a practical airborne Doppler LIDAR that will detect air turbulence which is a major cause of significant injuries and aircraft damages. Although a longer detection range of air turbulence could be achieved by using higher powered laser to give advanced warning to crew and passengers, it implies larger and heavier devices which are not suitable for airborne applications. We introduce a colored noise reduction method which reduces the measurement errors and extends the measurement range for the air turbulence detection. We show that the detection range of air turbulence is improved by about 40% using the colored noise reduction method.