85th AMS Annual Meeting

Thursday, 13 January 2005
The use of SST and SOI anomalies as indicators of crops yield variability
Maria I. Travasso, Instituto Nacional de Tecnologia Agropecuaria, Castelar, Argentina; and G. O. Magrin, M. O. Grondona, and G. R. Rodriguez
Interannual climate variability accounts for most of the observed crops yield fluctuations in the main agricultural region of Argentina. Moreover in this region climatic variations are strongly related to Sea Surface Temperatures (SST) or the Southern Oscillation Index(SOI). In the present study we aimed to obtain indicators of crops yield variability based on these drivers. For this purpose monthly anomalies corresponding to SSTís from the Equatorial Pacific (SSTN3) and South-Atlantic (SSTSA) Oceans and the Southern Oscillation Index (SOI) were related to maize, sunflower and soybean grain yield anomalies. Historical data (1923-2000 for maize, 1934-2000 for sunflower and 1969-2000 for soybean) were used to obtain grain yield anomalies at the county level after removing technology trends by smoothing techniques. By means of correlation analysis we obtained the counties presenting significant association (p< 0.05) between monthly SST/ SOI anomalies and yield anomalies, for the period 1950-1997. Those indicators showing spatial consistency were classified in percentiles and we found that the values corresponding to the upper and lower terciles showed to be useful to discriminate between positive and negative yield anomalies (high and low yields). SOI and SSTSA resulted the best indicators of crops yield variability in most of the region.

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