The North Slope of Alaska/Adjacent Arctic Ocean Cloud and Radiation Testbed (CART) site is providing data about cloud and radiative processes at high latitudes. These data are being used to refine models and parameterizations as they relate to the Arctic. The NSA/AAO site is centered at Barrow and extends to the south (to the vicinity of Atqasuk), west (to the vicinity of Wainwright), and east (perhaps to Oliktok). The Adjacent Arctic Ocean was probed by the Surface Heat Budget of the Arctic (SHEBA) experiment, a multi-agency program led by the National Science Foundation and the Office of Naval Research. SHEBA involved the deployment of an instrumented ice camp within the perennial Arctic Ocean ice pack that began in October 1997 and lasted for 12 monthsB. For the planning period covered here, a major focus will be on completing the facilities at Atqasuk, 100 km inland from Barrow. Presently, the instrumentation shelters are located on a gravel pad turn-around at the end of a dead end road between the town of Atqasuk and its airport. To comply with the terms of our land lease, we will construct a platform on pilings adjacent to the gravel pad and move the shelters off the roadway and onto the platform. The platform will permit long-term deployment of the Atqasuk instrumentation in a manner very similar to that at Barrow. Sky radiation (SKYRAD) radiometric instrumentation will be mounted above the level of the roof of the shelters so as to avoid shadowing, and the ground radiation (GNDRAD) instrumentation will be mounted on a tip tower such as the one about to be installed at Barrow. At Atqasuk, during the CY 2000 melt season, the science team heat flux study begun during the CY 1999 melt season will resume in spring with the redeployment of a laser scintillometer. In addition, heat flux measurements will begin near Barrow on the shore of the Beaufort Sea in the same time frame. Also at Barrow, a mini-IOP is planned during spring 2000 that will bring together two extended-range atmospheric emitted radiance interferometers (ER-AERIs) (including the one permanently installed at Barrow), one normal range downward-looking AERI (for snow characterization), and one or two other extended-range upward-looking Fourier transform infrared spectrometers (FTIRs). Various other less major enhancements will be made to the instrumentation suites of both Barrow and Atqasuk. Both facilities, however, will continue to be strongly focused on Instantaneous Radiative Flux (IRF) experiments for this planning period. A Single-Column Model (SCM) experiment utilizing either subscale or full scale aircraft that had been proposed for the NSA/AAO for CY2000 will be put off for a year.