The Asia Pacific AERONET Calibration and Training Center (APAC) is a regional center dedicated to supporting NASA’s AERONET program through the calibration of Cimel Sunphotometers, ensuring the precision and accuracy of atmospheric aerosol measurements. In addition, APAC provides comprehensive training programs for scientists, researchers, and technicians to enhance their expertise in aerosol monitoring and data analysis. The center also fosters satellite ground-based validation efforts and promotes regional collaborations to strengthen climate change and air quality monitoring across the Asia-Pacific region.