Kenichi Ueno

Turbulent exchange of heat, water vapor, and momentum over a Tibetan prairie by eddy covariance and flux variance measurements

[1] Land-atmosphere interactions on the Tibetan Plateau are important because of their influence on energy and water cycles on both regional and global scales. Flux variance and eddy covariance methods were used to measure turbulent fluxes of heat, water vapor, and momentum over a Tibetan shortgrass prairie during the Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) in 1998. Under unstable conditions during the monsoon period (July-September), the observed standard deviations of temperature and specific humidity (normalized by appropriate scaling parameters) followed the Monin-Obukhov theory. The similarity constants for heat C T and water vapor C q in their dimensionless functions of stability under a free convection limit were both 1.1, unlike the differences (i.e., C T ≤ C q ) reported in other studies. While the transfer efficiency of heat and water vapor exchange generally agreed with the prediction from the Monin-Obukhov theory, momentum exchange was less efficient than predicted. In comparison with the eddy covariance data, the flux variance method (with C T = Cq = 1.1) underestimated both heat and water vapor fluxes by <5%. When the eddy covariance data were absent, the flux variance method was used for gap filling the seasonal flux database. To estimate latent heat flux during the premonsoon period in June, C T /C q was approximated as r Tq (where r Tq is a correlation coefficient for the fluctuations of temperature and water vapor) because of the sensitivity of C q to changes in soil moisture conditions. The dramatic changes in the Bowen ratio from 9.0 to 0.4 indicate the shift of energy sources for atmospheric heating over the plateau, which, in turn, resulted in the shift of turbulent exchange mechanisms for heat and water vapor.

On measuring and remote sensing surface energy partitioning over the Tibetan plateau : from GAME Tibet to CAMP Tibet

Abstract The energy and water cycle over the Tibetan Plateau play an important role in the Asian monsoon system, which in turn is a major component of both the energy and water cycles of the global climate system. The intensive observation period and long-term observation of the GEWEX (global energy and water cycle experiment) Asian monsoon experiment on the Tibetan Plateau (GAME/Tibet) and CEOP (coordinated enhanced observing period) Asia–Australia monsoon project (CAMP) on the Tibetan Plateau (CAMP/Tibet) have been done successfully in the past five years. A large amount of data has been collected, which is the best data set so far for the study of energy and water cycle over the Tibetan Plateau. The field experiments of GAME/Tibet and CAMP/Tibet are introduced and some results on the local surface energy partitioning (imbalance, diurnal variation, inter-monthly variation and inter-yearly variation etc.) are presented by using the field observational data in this study. The study on the regional surface energy partitioning is of paramount importance over heterogeneous landscape of the Tibetan Plateau and it is also one of the main scientific objectives of GAME/Tibet and CAMP/Tibet. Therefore, the regional distributions of surface variables (surface reflectance and surface temperature), vegetation variables (NDVI, MSAVI, vegetation coverage and LAI) and surface heat fluxes (net radiation flux, soil heat flux, sensible and latent heat flux) are also derived by combining NOAA-14 AVHRR data with field observations in this study.

Genetics of neurofibromatosis 1 in Japan-mutation rate and paternal age effect

SummaryWe have performed formal genetic studies on 26 patients (14 males, 12 females) with neurofibromatosis 1 (von Recklinghausens disease, NF1) in Japan. Family studies of 74 members of 18 kindreds revealed that 50% of the cases were caused by a new mutation; the mutation rate was assumed to be 7.3–10.5 × 10-5. A tendency of paternal age effect, which was not accounted for by the maternal age effect, was observed, but live-birth order had no significant effect. Genetic linkage of neurofibromatosis 1 to the NF1 gene or the genetic marker in the pericentric region of chromosome 17 was established in 3 informative families.

Snow Cover Conditions in the Tibetan Plateau Observed during the Winter of 2003/2004

ABSTRACT Surface conditions in the non-mountainous areas of the central Tibetan Plateau were measured in a field survey in February 2004, and water balance parameters such as precipitation, sublimation, and water equivalent of snow cover were examined through the 2003/2004 winter by in situ automated measurements. Snow cover was shallow and coexisted with snow-free areas, producing large surface temperature heterogeneity under strong insolation. Clear diurnal variation was found in the meteorological observation. The precipitation and total sublimation from November 2003 to January 2004 were estimated as 15 mm and 17 mm, respectively, and the remaining equivalent snow water quantity in the beginning of February 2004 was 8 mm. Imbalance of the water budget was mainly due to the uncertainty of snow cover proportion within the mesoscale area. Importance of a redistribution process of the snow was proposed to explain the consistency of surface heating and remaining snow cover.

Heat island of a small city and its influences on the formation of a cold air lake and radiation fog in Xishuangbanna, Tropical China

Abstract In Xishuangbanna, Yunnan Province, China, cold air lakes and radiation fog are formed in basins at frequencies of 70–90% of winter days. In January, 1989, mobile observations were carried out in order to clarify the urban effects on these local climatic phenomena. The small city, Jinghong, is located in the northwestern part of the Jinghong basin. The basin bottom has an area of about 76 km2. The city had a population of about 40 000 in 1988. Heat islands with an intensity higher than 1 °C were clearly observed in the city. The formation of radiation fog was also observed simultaneously on the slope located in the northeastern part of the basin. It was found that radiation fog was formed first in an air layer at a height of several tens of meters above the city and then it spread over the whole basin within about one hour. It disappeared from the northwestern part of the basin, where the city is located. The mechanism of the urban effect on radiation fog is discussed. On the other hand, some previous studies have pointed out that the local climate in Xishuangbanna has been changing; it has become drier, sunshine duration has increased, and the number of fog-days and the duration of fog at night have decreased. By comparing the meteorological data in the 1960s, when the population of the city was less than 10 000, and in the 1980s, when it was about 40 000, the effects of urbanization and deforestation on the local climate phenomena, such as cold air lakes and radiation fog, are analyzed.

Ni-substitution Effect of Single Crystalline Bi2Sr2CaCu2O8+δ

The substitution effect of 3d metals (Ni and Zn) for Cu in Bi2Sr2Ca(Cu1-XMX) 2O8+δ(M=Ni, Zn) single crystal was investigated from the anisotropy measurement of the angular dependence of the ab-plane resistivity and estimating the γ-values. For both impurities, the γ-values were decreased with increase the impurity concentration. But the reduction rate for the Ni-substituted sample was weaker than the Zn-substituted one. We believe that the different rate is caused by the different spin moment state in Ni2+ and Zn2+.