In Thailand, the world's largest rice exporter, rice constitutes a major export on which the economy of the whole country depends. Climate change could affect rice growth and development and thus jeopardize Thailand's wealth. Current climatic conditions in Thailand are compared to predictions from four general circulation models (GCMs). Temperature predictions correlate well with the observed values. Predictions of monthly rainfall correlate poorly. Virtually all models agree that significant increases in temperature (from 1 to 7 ~ will occur in the region including Thailand following a doubling in atmospheric carbon dioxide (CO2) concentration. The regional seasonality and extent of the rise in temperature varies with each model. Predictions of changes in rainfall vary widely between models. Global warming should in principle allow a northward expansion of rice-growing areas and a lengthening of the growing season now constrained by low temperatures. The expected increase in water-use efficiency due to enhanced CO 2 might decrease the water deficit vulnerability of dryland rice areas and could make it possible to slightly expand them.
Similarities in ozone regimes at sites in or near forests of the western United States were investigated using hierarchical cluster analysis on a (63 × 17) matrix of frequencies of occurrence of 17 characteristic diurnal patterns in hourly ozone concentrations. Eight groups of sites with similar ozone patterns were identified. Sites within these groups showed geographical consistency at a local scale, but more complex spatial relationships exist regionally. Unlike kriging analyses of ozone concentrations over the United States as a whole and California in particular, our analysis does not identify large areas of gradation in ozone levels. Instead, hotspots linked to populated valleys were identified with gradations in ozone exposure occurring from these hotspot areas. Considering the complex nature of terrain across the West and the restrictive role that such topography plays in atmospheric transport, hotspots in ozone concentrations are more likely than regional gradation from large urban centers. Comparisons of group memberships determined from common univariate statistics (SUM06, SUM08, 7-hour and 24-hour) with our results lead to the conclusion that regional analyses of ozone concentrations using univariate statistics are insensitive to important differences in ozone exposure regimes. Of particular concern is the inability of univariate statistics to consistently discriminate between sites with urban and non-urban characteristics.
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