Validation of TOVS Path-P data during SHEBA

[1] Products from the TIROS-N Operational Vertical Sounder (TOVS) Polar Pathfinder (Path-P) data set are compared with surface measurements and other satellite remote sensing retrievals during the Surface Heat Balance of the Arctic Ocean (SHEBA) field program (October 1997 to September 1998). The comparison provides estimates of Path-P retrieval uncertainties. Results are placed in the context of the natural variability and timescales of variability to allow potential users to judge the applicability of the data set for their purpose. Results show temperature profiles to be accurate within 3 K, total column precipitable water within 2 mm annually, and surface temperature within 3 K. Uncertainties in temperature retrieval are below within-season'' variability during all times of the year. Uncertainties in water vapor retrieval during winter and summer are slightly below observed variability in those seasons but are well below during spring. Uncertainty in retrieved cloud fraction is highly dependent on the timescale of observations. Cloud fractions from the surface and satellite are well correlated (correlation coefficient > 0.7) at timescales greater than 4 days but show weaker correlation at shorter timescales. Uncertainty in TOVS-retrieved cloud fraction is less than 20% for 5-day averages. In winter, TOVS-retrieved cloud fractions are higher than those reported in standard meteorological observations but match those derived from lidar data. This supports the notion that standard meteorological observations may underestimate cloudiness in winter. Cloud-top temperatures measured from the surface (lidar/radar) are significantly different from those estimated using TOVS and Advanced Very High Resolution Radiometer (AVHRR) radiances, which highlights the fundamental and inherent dissimilarity between these two measurement techniques.