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Overview - Joint Archive for Sea Level

The Joint Archive for Sea Level (JASL) is a collaborative arrangement between the National Oceanographic Data Center (NODC), the National Coastal Data Development Center (NCDDC), the World Data Center-A (WDC-A) for Oceanography, and the University of Hawaii Sea Level Center (UHSLC). The JASL was formed during the Tropical Ocean Global Atmosphere (TOGA) Project as sea level became recognized, mostly through the efforts of Dr. Klaus Wyrtki of the University of Hawaii, as an important proxy for monitoring the large-scale motions of the tropical currents. For example, Figure 1 shows the equatorial response of sea level to wind forcing and Figure 2 points out the use of sea level for determining indices for strengths of zonal eqatorial geostrophic currents .

The NODC appointed Mr. Patrick Caldwell as a field liaison at the UH in August 1987 to work closely with the sea level experts and to initiate the JASL. Prior to TOGA, international sea level was only maintained for monthly means through the efforts of the Permanent Service for Mean Sea Level (PSMSL) at the Bidston Observatory in the United Kingdom. The JASL is the first international effort to acquire, review, assess, manage, and distribute sea level for hourly and daily values, which allow a higher level of quality control and a wider range of applications. An important element of the JASL is the active scientific use of the data and the guidance provided by the UHSLC specialists, who help ensure a data set of high scientific integrity. Dr. Mark Merrifield is the Director of the UHSLC.

The JASL was initiated as an archive of research quality data from TOGA sites in the tropics and subtropics. During the 1990s, sites of oceanographic significance from higher latitudes were steadily added to the archive in support of the TOPEX/POSEIDON altimetry community, the World Ocean Circulation Experiment (WOCE), and the Global Sea Level Observing System (GLOSS). The JASL presently maintains contact with over 60 agencies in 70 countries . Data archeology has also been emphasized as over 60 series have been extended backwards by 30 years or more, allowing opportunities for trend analyses. The JASL welcomes contributions of hourly sea level data to its expanding archive.

The JASL encourages agencies to enhance the quality of their data by providing technical guidance, such as the public domain software package for quality control and tidal analysis. Training for use of this software has been provided in over ten countries, mostly in Central and South America, including GLOSS workshops in Brazil and India.

The research quality data sets are summarized in an annual data report and periodically submitted to the US NODC, WDC-A, and the PSMSL. The JASL dataset is readily available via various media, such as FTP and the World Wide Web, where it is referred to as the "research quality data" within the online archive system of the UHSLC.

Beginning in the Fall of 2000, the JASL is supported by the new NOAA National Coastal Data Development Center (NCDDC), which is a division of NODC yet separately located at the Stennis Space Center in Mississippi. The essential mission of the NCDDC is to provide the archive of, and access to, long-term coastal data records. The expanding coastal data bank is derived through contributions from federal, state, and local governmental agencies as well as academic institutions and the private sector. Although the primary mission of NCDDC is national, it also supports select international coastal programs, such as the JASL, in collaboration with the WDCA.


Questions or comments: Mr. Patrick Caldwell, caldwell@hawaii.edu


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