Five-years of Terra MODIS on-orbit spatial characterization

Abstract

The Moderate Resolution Imaging Spectroradiometer (MODIS) has 36 spectral bands that are distributed, according to their wavelengths, on four focal plane assemblies (FPAs): visible (VIS), near infrared (NIR), short- and mid-wave infrared (SMIR), and long-wave infrared (LWIR). One of the MODIS on-board calibrators, the spectro-radiometric calibration assembly (SRCA), is used to track the sensor's on-orbit spatial characterization. It is also capable of performing instrument radiometric stability monitoring and spectral characterization (measurements of the center wavelengths and bandwidths). This paper focuses on the SRCA's spatial characterization function and presents the results (on-orbit performance) derived from the observations made by the Terra MODIS since its launch in December 1999. The SRCA spectral characterization results of Terra MODIS over the same five-year period are covered in another paper in these proceedings (Xiong et. al.). The MODIS on-orbit spatial characterization discussed in this paper includes measurements of the detector-to-detector registration (DDR) in the along-scan direction, the band-to-band registration (BBR) in both along-scan and along track directions, and the focal plane-to-focal plane registration (FFR) in both directions. These measurements are typically performed bi-monthly. The results will show that the overall along-scan BBR performance of the Terra MODIS has been satisfactory (less than 0.16km), meeting the specification of 0.20km. Except for a few bands of slightly over 0.20km, the along-track BBR values are also within the specification.