The University of Hawaii Sea Level Center

Mark Merrifield
Director, University of Hawaii Sea Level Center


With the leadership and vision of Professor Klaus Wyrtki, the University of Hawaii Sea Level Center (UHSLC) has been a vital component of the global sea level network since the early 1970's. The center has evolved from its beginnings as the Pacific Sea Level Network to include the TOGA Sea Level Center, the IGOSS Sea Level Project in the Pacific, the network expansion into the Indian Ocean, and the WOCE fast-delivery data center. This year, Dr. Mark Merrifield has assumed the duties of director of the UHSLC as Dr. Gary Mitchum moves on to join the faculty at the University of South Florida. Dr. Merrifield is an assistant professor in the Department of Ocean Engineering at the University of Hawaii and is also affiliated with the Department of Oceanography. He intends to maintain and improve the primary functions of the center and to continue its active research into climate and global change issues.

Under support from NOAA, the UHSLC currently includes three distinct activities: the Indo-Pacific Sea Level Network (IPSLN), the IGOSS Sea Level Project in the Pacific (ISLP-Pac), and the maintenance of the UHSLC research databases. The IPSLN is a network of sea level gauges, most with satellite data telemetry, designed to provide an effective long-term sea level observing system for the tropical portions of the Indian and Pacific Oceans. With an emphasis on island stations, the IPSLN is the largest open ocean sea level network in the world that is operated by a single group. IPSLN stations have served the needs of ephemeral programs, such as TOGA and WOCE, as well as GLOSS. At present just over 300 sites have been designated as GLOSS sites; nearly all of the IPSLN stations fall into this category.

The ISLP-Pac involves the compilation and distribution of sea surface topography maps for the Pacific Ocean within five weeks of the end of each month. This activity was an early and very successful example of operational oceanography. Products include monthly maps of the Pacific sea level deviations from the long-term mean as well as maps of the sea level anomalies from the annual cycle that are corrected for atmospheric pressure anomalies. The ISLP-Pac also produces indices of the tropical Pacific upper layer volume on a quarterly basis, and the ridge-trough system and equatorial currents for the Pacific Ocean at annual intervals.

The UHSLC databases are the progression of work started by the TOGA Sea Level and WOCE centers. The research quality database currently includes 330 sites with 3923 station-years of quality assured data. The "fast delivery" database involves the processing of sea level data from a globally distributed set of stations, currently numbering 94, and ensuring availability to users within three months of data collection. All of the above data are available on the Internet (

The UHSLC also conducts research with the data collected by its subordinate activities. Areas of interest include: tropical ocean dynamics, interannual and decadal climate fluctuations, impacts of climatic events on fisheries, comparison with satellite altimeter data, development of new cost-effective methods for collecting and maintaining sea level stations, and the physical oceanography of island regions.