[1] In this study, it is demonstrated that a combination of VHF and millimeter-wave Doppler radars is a key tool for observing particle fall velocity in cirriform clouds. VHF (47-MHz) and millimeter-wave (95-GHz) Doppler radars observed cirriform clouds at West Sumatra, Indonesia (0.2°S, 100.32°E) from 2000 LT 14 to 0800 LT 15 November 2005. Radar reflectivity factor (Z e ) observed by the 95-GHz radar showed that echoes from cloud particles had tops around 12-14 km and bottoms around 8-10 km. Doppler velocity observed by the vertically pointed beam of the 95-GHz radar (V air+Z ) was compared with vertical air velocity (V air ) observed by the 47-MHz radar to confirm that V air+Z , a sum of V air and reflectivity-weighted particle fall velocity (V Z ), showed consistent changes with V air and hence V Z is able to be retrieved by subtracting V air from V air+Z . The correlation coefficient between V Z and Z e in the middle part of clouds (10.5-12.2 km) was À0.81, which was higher than that (À0.47) in the bottom part (7.2-10.5 km). The change of V Z for Z e in the middle part was larger (Z e = À31.9 V Z À 32.2) than that in the bottom part (Z e = À90.2 V Z À 71.8). These results suggest that particle size was a dominant factor that determined Z e in the middle part. Using V Z , median volume diameter (D 0 ) was estimated to suggest that D 0 was larger than $70 mm in the bottom part and ranged from $40 mm to larger than $106 mm in the middle part.

[1] Seasonal and interannual variations of temperature in the tropical tropopause layer (TTL) during 1992-1999 are investigated on the basis of operational rawinsonde data over Indonesia and surrounding stations at 90-140°E, 15°N-15°S. An annual variation characterized by a warm (cold) anomaly in the northern summer (winter) is observed at all analysis stations. Reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP Reanalysis) and European Centre for Medium-Range Weather Forecasts (ERA-40) failed to fully reproduce the observed seasonal variation over Indonesia, especially during northern winter. NCEP Reanalysis data are biased, and ERA-40 data agreed well only at surrounding stations. These results are reflections of the operational rawinsonde data over Indonesia which are incorrectly reported to the Global Telecommunication Systems (GTS). The cold point tropopause (CPT) temperature varies annually, having a warm (cold) phase in northern summer (winter) and a latitudinal structure having the warmest temperatures over the equator. The latitudinal structure over Indonesia is the inverse of that observed in the zonal and annual mean fields; therefore effective cold trap regions for water vapor dehydration events appear away from the equator. Longitudinally, the CPT temperature is lowest over Indonesia compared to other longitudinal sections and decreases eastward along the equator inside the analysis region (Indonesia). This east-west gradient in CPT temperature within the analysis region was affected during the 1997/1998 El Niño and 1998/1999 La Niña, but the longitudinal range of effect and time variation of the CPT temperature anomaly was independent of the El Niño and La Niña events.

An overview of the Interuniversity Upper atmosphere Global Observation NETwork (IUGONET) project is presented. This Japanese program is building a meta-database for ground-based observations of the Earth's upper atmosphere, in which metadata connected with various atmospheric radars and photometers, including those located in both polar regions, are archived. By querying the metadata database, researchers are able to access data file/information held by data facilities. Moreover, by utilizing our analysis software, users can download, visualize, and analyze upper-atmospheric data archived in or linked with the system. As a future development, we are looking to make our database interoperable with others.