Figure 6.7.1 Average July-June PED (mm) composited over El Niño and La Niña periods

Text description of figure

The figure consists of two maps of New Zealand showing the average anomaly in July-June potential evapotranspiration deficit (PED), composited for El Niño and La Niña periods separately. The anomalies range between about -100mm and +100mm. The maps show a lot of spatial detail, but there are clear regional patterns.

In the El Niño composite (years ending June 1973, 1977, 1978, 1983, 1987, 1988, 1992, 1995, 1998 and 2003), the PED anomaly is positive over almost the whole country. The largest positive anomalies (+80mm and above) are found in the Bay of Plenty, East Cape, Hawke’s Bay, Nelson and Marlborough. The next largest values (+60 to +80mm) are found directly inland from these regions plus parts of the Wairarapa, Canterbury and North Otago. All eastern regions, including east Northland, Coromandel, inland Bay of Plenty and inland Canterbury and Otago have a PED anomaly of over +40mm. Smaller positive PED anomalies, and occasional small negative PED, are found in western areas of both Islands and in Southland.

In the La Niña composite (years ending June 1974, 1976, 1984, 1985, 1989, 1996, 1999, 2000 and 2001), regions of both positive and negative PED anomaly can be found, but the magnitudes are typically much smaller than during El Niño. Negative PED anomalies (down to about -40mm) are found in Northland, Coromandel, Bay of Plenty to Gisborne, and Marlborough. Positive PED anomalies (up to about +40mm) are found in Manawatu, Wanganui and coastal Otago.