JMSJ, 2016, Vol. 94, No. 5 (October)
Invited Review Articles
- We reviewed the long-term trends and inter-annual variations in surface shortwave irradiance in China and Japan. Pyranometer observations indicated a decrease followed by an increase in shortwave irradiance in China and Japan during the period from the 1960s to 2000s, while obvious long-term trends were not found from satellite observations after 1983.
- In China, surface shortwave irradiance decreased from 1961 to around 1990, but then began to increase. In Japan, on the other hand, the decreasing trend stopped in the 1960s, with little inter-annual variation during the 1970s and 1980s, and an increase that began around 1990.
- The causes of the difference in shortwave irradiance trends between China and Japan were ascribed to an increase in light-absorbing aerosols in China since the 1960s and a decrease in absorbing aerosols in Japan since the late 1970s. Although these aerosol influences are generally found under clear-sky conditions, absorbing aerosol could have a direct effect even under cloudy-sky conditions.
Mabuchi et al (2016)
Mabuchi, K., H. Takagi, and S. Maksyutov, 2016: Relationships between CO2 flux estimated by inverse analysis and land surface elements in South America and Africa. J. Meteor. Soc. Japan, 94, 415-430.
http://doi.org/10.2151/jmsj.2016-021. Graphical Abstract
- In this study, the features and validity of changes in the carbon dioxide (CO2) flux estimated by inverse analysis were verified by interrelation analysis with changes in precipitation, short-wave radiation, surface temperature, and Normalized Difference Vegetation Index (NDVI) in regions of South America and Africa where CO2 flux observation data are limited.
- Sufficient accuracy of the land surface elements is required for the analysis results to confirm the CO2 flux estimated by inverse analysis. An examination of the correlation of anomalies showed consistent relationships among the precipitation, short-wave radiation, surface temperature, and NDVI data used in this study, which were created independently.
- The relationships between change in the estimated CO2 flux and characteristic changes of the land surface elements in South America and Africa were consistent in each region. This study confirmed the physical and biological validity of the changes in the CO2 flux estimated by inverse analysis.
- During the period of this study, the NDVI anomaly was influential in South America, and the precipitation (soil wetness) anomaly was an essential factor in Africa for the CO2 flux anomaly. The short-wave radiation anomaly was also influential at the inverse analysis region scale in both South America and Africa. The distinctive relationships are detected more clearly in the results of inverse analysis using both ground-based CO2 concentration data and the Greenhouse gases Observing SATellite (GOSAT) data than in the results using only ground-based CO2 concentration data. This demonstrates the usefulness of GOSAT data in regions with limited atmospheric CO2 concentration data.
Iwasaki, H., 2016: Relating lightning features and topography over the Tibetan Plateau using the World Wide Lightning Location Network data. J. Meteor. Soc. Japan, 94, 431-442.
http://doi.org/10.2151/jmsj.2016-025. Graphical Abstract
- The lightning features over the Tibetan Plateau was studied using the World Wide Lightning Location Network dataset. Lightning strokes with energies above the 90th percentile (7666 J) globally are defined as strong lightning (S-lightning) strokes, and the ratio of the number of S-lightning strokes to the number of overall lightning (O-lightning) strokes is defined as the strong ratio (S-ratio). Figure 1 illustrates the distribution of the annual rainfall amount and these lightning features. Rainfall is concentrated along the southern foothills of the Himalayas (Fig. 1a), with lightning density also exhibiting high values in this region (Figs. 1b and 1c). The Tibetan Plateau east of 80°E shows high densities of O-lightning (>10-1 stroke km-2 yr-1) and S-lightning (>10-1.5 stroke km-2 yr-1). Most S-ratios in the analysis units exceeded 30% (Fig. 1d), which corresponds to three times the global mean. In particular, the S-ratios over the southern part of the Tibetan Plateau, including the Himalayas, were found to be high (50%) and to correspond with the zone that had the minimum O-lightning density.
Notes and Correspondence
Shibuya et al (2016)
Shibuya, R., H. Miura, and K. Sato, 2016: A grid transformation method for a quasi-uniform, circular fine region using the spring dynamics. J. Meteor. Soc. Japan, 94, 443-452.
http://doi.org/10.2151/jmsj.2016-022. Graphical Abstract
- Regionally enhanced meshes that have quasi-uniformly fine circular region is proposed by a new transformation method with icosahedral grids to obtain a cost-effective simulation for waves, transports and mixing processes, the behaviors of which depend strongly on the horizontal resolution.
- To realize this grid structure, the spring dynamics method can be used and the characteristic length of the spring connecting grid nodes should be determined through three parameters; (i) the number of grid points placed in the target region, (ii) the area of the target region and (iii) a parameter of the Schmidt transformation.
- Because the new grid system has a more homogenous resolution in the target region compared with that of the previous study, the estimation of the momentum fluxes of gravity waves are less affected by their dependence of the grid resolution.
Guo et al (2016)
Guo, Y., Y. Zhang, N. Ma, H. Song, H. Gao, 2016: Quantifying surface energy fluxes and evaporation over a significant expanding endorheic lake in the central Tibetan Plateau. J. Meteor. Soc. Japan, 94, 453-465.
http://doi.org/10.2151/jmsj.2016-023 Graphical Abstract
- On a seasonal scale, sensible heat flux (H) and latent heat flux (LE) were different from net radiation (Rn). The maximum Rn occurred in June, while the maximum of H and LE were observed in September. Besides, H showed best accordance with u*(Tw-Ta) and LE showed best accordance with u*(ew-ea) (Figure 1).
- Evaporation from Lake Serling Co was compared with two kinds of pan evaporation (D20 pan and E601B pan) and potential evaporation on land surface. The variability of conversion coefficients between lake evaporation and D20 pan, E601B pan and potential evaporation indicate that coefficients varied depending on the month and could not be defined as a single experimental value.