Content area
Full text
ABSTRACT
Predictive skills of retrospective seasonal climate forecasts (hindcasts) tailored to Philippine rice production data at national, regional, and provincial levels are investigated using precipitation hindcasts from one uncoupled general circulation model (GCM) and two coupled GCMs, as well as using antecedent observations of tropical Pacific sea surface temperatures,warmwater volumes (WWV), and zonalwinds (ZW).Contrasting cross-validated predictive skills are found between the ''dry'' January-June and ''rainy'' July-December crop-production seasons. For the dry season, both irrigated and rain-fed rice production are shown to depend strongly on rainfall in the previous October-December. Furthermore, rice-crop hindcasts based on the two coupled GCMs, or on the observed WWV and ZW, are each able to account for more than half of the total variance of the dry-season national detrended rice production with about a 6-month lead time prior to the beginning of the harvest season.At regional and provincial levels, predictive skills are generally low. The relationships are found to be more complex for rainyseason rice production. Area harvested correlates positively with rainfall during the preceding dry season, whereas the yield has positive and negative correlations with rainfall in June-September and in October-December of the harvested year, respectively. Tropical cyclone activity is also shown to be a contributing factor in the latter 3-month season.Hindcasts based on theWWVand ZWare able to account for almost half of the variance of the detrended rice production data in Luzon with a few months' lead time prior to the beginning of the rainy season.
1. Introduction
Rice is the most important crop for the people of the Philippines. Because the fluctuation in domestic rice production has significant impacts on food security, especially for the poorest people, its stabilization is a critical concern for the Philippines in terms of food security and the alleviation of poverty (Dawe et al. 2006, 2009).
Paddy rice is known to be one of the most highly susceptible cereal crops to climate variability because of its high water requirements. Relationships between rice and climate are well documented by past research (e.g., Lansigan et al. 2000; Naylor et al. 2001; Selvaraju 2003; Lansigan 2005; Dawe et al. 2009; Roberts et al. 2009). In the case of the Philippines, much attention has been paid to El Nñ o-Southern Oscillation (ENSO) because of its large...