During February 2001, a unique data set was collected between Kwajalein, Republic of the Marshall Islands (8°44'N 167°44'E) and Wake Island, US Territory (19°17'N 166°39'E). NOAA polar-orbiting High-Resolution Infrared Radiation Sounder (HIRS) multispectral data were archived from both islands providing a look at oceanic data from 15°S to 40°N. This dataset is used to investigate any limb biases that may be present in the CO₂ cloud detection and height routine and the radiometer viewing pattern.

Previous climatological studies have used only data collected within view angles between 10° and 25° of nadir (Jin et al., 1996). This study will gain insight into the data differences between nadir and high scan angle measurements. Using a Lagrangian framework, data is divided into three groups: left, center and right. Each line of HIRS data has 56 bins of data. The left two bins, two center bins and right two bins are archived and used to make comparisons. Altitudes of high clouds can then be compared from the left, right, and center elevation angles versus latitude. Preliminary results indicate that cloud heights on the limbs are detected as higher than those at nadir. The amount of clouds detected, however does not appear to have a bias.

Jin, Y., W. B. Rossow and D. P. Wylie, 1996: Comparison of the climatologies of high-level clouds from HIRS and ISCCP. J. Climate, 9, 2850-2879.