Summary of Abstract Submission

Abstract Submission No. IO50-08-0027PresentationPoster

AN INNOVATIVE TECHNIQUE TO REDUCE POINTING ERROR IN HAND-HELD SUN PHOTOMETER MEASUREMENTS ON BOARD A SHIP

Sureshkumar Munaka*1, S. Rajasekhar2

1 IETE SAMEER, India
2 SAMEER, India

ABSTRACT :

Hand-held Sun photometers (HSPs), using narrow band pass optical filters with ~ 1o- 2o field of view, have been in use for quite some time for measuring Aerosol Optical Depth (AOD). Affordable, portable and user-friendly HSPs are preferred to fixed-automated sun photometers on ships. However, for ship-borne observations especially during rough sea conditions, bias towards higher AOD is observed which can be largely attributed to the pointing error of HSP to the Sun. An approach to minimize this pointing error in the HSPs by automating the sun-pointing device is discussed. The technique combines selective averaging of sampled readings and image processing of the sun-pointing screen. On the basis of laboratory experiments and simulation studies, it is inferred that this technique is capable of reducing the pointing error in HSPs in a moving ship on rough seas. In addition to this, the proposed technique can also be used in Langley plot calibration method to reduce the pointing errors in HSP for better extraterrestrial calibration constants.