EFFECT OF VOLCANIC AEROSOLS ON SATELLITE-DERIVED SEA-SURFACE TEMPERATURES AROUND NEW-ZEALAND

Sea surface temperatures (SSTs) from five coastal sites around New Zea land were compared with SST products from satellite AVHRR (Advanced Ve ry High Resolution Radiometer) measurements between mid 1989 and late 1994. The objectives of this analysis were to test the accuracy and st ability of the AVHRR product, and to distinguish how the coastal SST m easurements represent the larger coastal areas which the satellite pro duct measures. The AVHRR product is comparable with the coastal data u p until mid 1991, after which the AVHRR product is colder by approxima tely 1 degrees C. The difference peaked in late 1992 and probably died away by late 1993. This may be a result of the eruptions of Mt Pinatu bo (June 1991) and/or Cerro Hudson (August 1991). The coastal measurem ents from relatively exposed sites are representative of the larger co astal regions measured by the satellites. In the case of more enclosed waters, particularly within harbours, the long-term means of the coas tal and AVHRR measurements agree before mid 1991, but the coastal meas urements have larger seasonal cycles.