The fruit size of melon (Cucumis melo var. reticulatus) is determined by the number of pericarp cells that are defined during early fruit development. It has been reported that the expression and ...activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is required for early fruit growth in tomato and avocado. In this study, we cloned a melon HMGR gene and investigated its involvement in the regulation of melon fruit size. The melon HMGR gene (Cm-HMGR; GenBank accession no. AB021862) showed high similarity to other plant HMGRs, and complemented a yeast HMGR-deficient mutant. The level of Cm-HMGR transcripts and HMGR activity in the developing melon increased during early fruit development. Flow cytometry and western blot analysis revealed a correlation between cell division in the pericarp and the expression of Cm-HMGR. In the pericarp, where frequent cell division occurs, the expression of Cm-HMGR protein increased at the beginning of the cell division stage. These results suggest that Cm-HMGR is involved in cell division in the pericarp, which determines melon fruit size.
We use a relatively high resolution (T106) atmospheric general circulation model to simulate precipitation along the tracks of tropical cyclones (TCs) within the western North Pacific basin under ...present-day and doubled CO sub(2) climates. The simulated mean precipitation associated with TCs is in agreement with observational data. The simulation predicts that a doubling of atmospheric CO sub(2) will result in an increase in TC precipitation. We attribute the predicted increase in precipitation to increased atmospheric moisture content, which is partly offset by the effects of decreased TC intensity. Mean TC precipitation and the frequency of extreme precipitation ( greater than or equal to 150 mm/day) over Japan are predicted to increase with CO sub(2) doubling, despite an accompanying decrease in the frequency and intensity of TCs.
A dense tipping-bucket rain gauge network was established in the Mae Chaem watershed in the mountains of northwestern Thailand as part of the Global Energy and Water Cycle Experiment (GEWEX) Asian ...Monsoon Experiment-Tropics (GAME-T). Investigations of rainfall amounts, intensities, durations, and frequencies in the rainy season revealed strong orographic rainfall enhancement in the region. The larger amount of high-altitude rainfall was attributed to duration and frequency rather than intensity. Despite large rainfall variations, similar patterns were found in the two study years, 1998 and 1999.
With gradually progressing climate change in the future, the frequency and scale of hot summers like those observed in various places around the world in recent years will undoubtedly increase, ...giving rise to strong concerns over increased risk of death due to heat stress. Based on this background, we have developed a method to assess future changes in mortality due to heat stress with the entire globe as the target, and performed trial calculations using this method. The purpose of this report is to draw people's attention to the possible severe consequences of climate change by presenting the severest estimates in the uncertainty range due to adaptation/acclimation expected in the future, so as to induce further analysis and discussion on policies and measures. For the trial calculations, future changes in temperature were derived from the results of simulation using an Atmosphere-Ocean General Circulation Model with the highest spatial resolution in the world at the time of the study. Population densities were assumed not to alter in the future. Assuming that no adaptation or acclimation takes place, when the rates of change of excess mortality due to heat stress are examined by country, the results of our calculations show increases of approximately 100% to 1000%. It is confirmed that the burden of climate change impact is quite unequal among countries, at least from the viewpoint of heat stress mortality. When considered together with present population densities, significant increases in excess mortality density can be seen in China, India, and Europe. These regions are characterized by large losses due to climate change in absolute quantitative terms. The need to consider the adoption of adaptation measures is therefore most urgent in these regions.
The hydrologic changes and the impact of these changes constitute a fundamental global-warmingrelated concern. Faced with threats to human life and natural ecosystems, such as droughts, floods, and ...soil erosion, water resource planners must increasingly make future risk assessments. Though hydrological predictions associated with the global climate change are already being performed, mainly through the use of GCMs, coarse spatial resolutions and uncertain physical processes limit the representation of terrestrial water/energy interactions and the variability in such systems as the Asian monsoon. Despite numerous studies, the regional responses of hydrologic changes resulting from climate change remains inconclusive. In this paper, an attempt at dynamical downsealing of future hydrologic projection under global climate change in Asia is addressed. The authors conducted present and future Asian regional climate simulations which were nested in the results of Atmospheric General Circulation Model （AGCM） experiments. The regional climate model could capture the general simulated features of the AGCM. Also, some regional phenomena such as orographic precipitation, which did not appear in the outcome of the AGCM simulation, were successfully produced. Under global warming, the increase of water vapor associated with the warmed air temperature was projected. It was projected to bring more abundant water vapor to the southern portions of India and the Bay of Bengal, and to enhance precipitation especially over the mountainous regions, the western part of India and the southern edge of the Tibetan Plateau. As a result of the changes in the synoptic flow patterns and precipitation under global warming, the increases of annual mean precipitation and surface runoff were projected in many regions of Asia. However, both the positive and negative changes of seasonal surface runoff were projected in some regions which will increase the flood risk and cause a mismatch between water demand and water availability in the agricultural season.
This paper describes a Multilayered Integrated Numerical Model of Surface Physics – Growing Plants Interaction (MINoSGI), which represents interactions between the dynamics of forest ecosystems and ...microclimate. Aiming at a large‐scale study in the future, we describe forest dynamics by using area‐averaged prognostic equations for thedistributions of plant density and plant weight with respect to plant height classes, instead of individual‐based treatments for small‐scale forest patches. Growth and mortality of plants are modelled based on the carbon balance of each plant height class. The area‐averaged microclimate (e.g., light, wind speed, temperature, humidity, CO2 concentration) within the forest canopy is simulated by a one‐dimensional multilayer canopy model, which includes most of the physical and physiological processes that control the forest microclimate. Owing to its multilayered framework, a direct specification is possible for the difference in the growing environment among plants of different size and species. Given hourly meteorological conditions, the model outputs energy, water, CO2 and momentum fluxes to and from a forest, of which the structure changes through competition among plants. The model's performance was tested by comparing its outputs with observed data on the development of plant size distribution taken over a 5‐year period in an evergreen coniferous (Cryptomeria japonica) forest. The model produced realistic estimates of the total biomass increments during the period. The ratio of net primary production to gross primary production (=0.45) was consistent with previous estimates for temperate forests. The bimodal seasonal pattern in net ecosystem production was similar to the seasonal trend in the CO2 flux measured over a forest of the same species. Although some limitations due to the one‐dimensional representation of microclimate were noticeable, the model adequately simulated distributions of annual growth rate, plant weight and diameter across plant height classes. Since the basic equations can be extended to include the effect of spatial variability with marginal increase of computational costs, the present model framework is feasible for large‐scale studies.
Using a high‐resolution climate model, we projected future sea level and its variability based on two scenarios for 21st century greenhouse gas emission. The globally averaged sea level rise ...attributable to the steric contribution was 23 and 30 cm for the two scenarios. The results of the high‐resolution model and a medium‐resolution version of the same model for global and local sea level change agreed well. However, the high‐resolution model represented more detailed ocean structure changes under global warming. The changes affected not only the spatial distribution of sea level rise, but also the changes in local sea level variability associated with ocean eddies. The enhanced eddy activity was responsible for extreme sea level events.
A regional climate model, NIES/CCSR RAMS, was used with the ECMWF objective analysis data as boundary conditions to reproduce the precipitation pattern over East Asia in June, including that ...accompanying the Baiu front. In the control experiment, the simulated precipitation pattern was unrealistic, mainly in two respects: precipitation over the Baiu front was too weak, and strong precipitation was found over the North Pacific subtropical high at around 20°N. According to the ECMWF data, strong potential instability is maintained over the subtropical high, under which condition, the cumulus parameterization used in the model predicts strong precipitation to stabilize the atmosphere. Because the lower free atmosphere is very dry over the subtropical high, it is conjectured that the development of deep cumulus convection is suppressed by this dry air in the real atmosphere. When the cumulus parameterization was modified to include this assumption, the intensity of precipitation over the Baiu front as well as the unrealistic precipitation pattern over the subtropical high was clearly ameliorated. The intensification of precipitation over the Baiu front is considered to be due to the increased water vapor transport to the Baiu front, and the decreased stability with respect to the moist convection around the Baiu front. In semi-prognostic experiments with CCSR/NIES AGCM, this modification was found to be also effective in many other parts of the globe. Because problems in precipitation distribution similar to that discussed in the present study are found in many other climate models, the modification of cumulus parameterization suggested here could also be effective in those models.
For the first time, using a high‐resolution atmosphere‐ocean coupled general circulation model (CGCM), we succeed in reproducing the far‐reaching effects of the Hawaiian Islands, recently showed by ...satellite observations. The model reproduces the distributions of sea surface temperature (SST), surface winds and cloud liquid water (CLW) in the wake of the Hawaiian Islands. It is revealed that these distributions are caused by the Hawaiian Lee Counter Current (HLCC) and that this current is driven by the wind‐curls induced by the orographic effect of the islands, as suggested from an observational study. It is also shown that wind changes around the Hawaiian Islands can further affect the speed of the North Equatorial Current (NEC) and SST over the current, and intra‐annual variability in CLW to the west of the islands is governed, not only by SST but also by wind speed.
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