The relationship between the PDO and New Mexico precipitation was studied in several ways. An annual PDO average was calculated for each year from 1931 through 1997. Figure 2 Years were determined for which the PDO varied substantially from zero. Approximately 175 stations were used in these calculations. Precipitation was considered to be normal for years in which the average for the division was within 10 percent of the long-term average.
Percentages are in parentheses.
There is a strong relationship between the Pacific Decadal Oscillation and precipitation in New Mexico. During the positive phase of the PDO, approximately 30 percent of the years have normal precipitation, while normal precipitation occurs during approximately 40 percent of the negative phase. When looking at precipitation on the cold side of the cycle for each climate division, all divisions had far more dry years than wet. Western New Mexico, especially the southwest, seemed to benefit most from the positive PDO years. Tables 8 and 9 show how the quantity of precipitation varies with the PDO cycle.