Abstract Details
| Name: TARUN KUMAR SHARMA Affiliation: CURRENTLY NOT AFFILIATED TO ANY INSTITUTE Conference ID: ASI2017_1424 Title : RESULTS FROM ONE YEAR OPERATION OF SCANNING CLOUD MONITOR AT IAO HANLE Authors and Co-Authors : P.S. PARIHAR P.M.M. KEMKAR RAVINDER KUMAR BANYAL INDIAN INSTITUTE OF ASTROPHYSICS, BANGALORE Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : A CCD camera based all-sky monitor is an inexpensive tool, however, the appearance of clouds in the optical wavelength images is very deceptive due to its strong dependency on apparent sky brightness, which in turn depends on phases of the Moon, local light pollution, and other atmospheric variables. Automated software tools developed to derive a quantitative information of cloudiness from all-sky images usually fail to extract cloud information reliably, and results are often found to be inconsistent with other methods. Therefore, we have developed an instrument free from the above-mentioned shortcomings, which can provide very reliable cloud cover statistics. Our cloud monitor uses thermopile sensors which measure sky brightness temperature. Since there is a significant contrast between the temperature of clear sky and sky covered with cloud, therefore, we found this method to be more precise and reliable in detecting the cloud. The device uses an array of thermopile sensors mounted on a curved plate which is rotated in azimuth in steps. The device has gone through tedious laboratory as well as on-sky calibration, and tests and was found to meet the expected performance. Scanning cloud monitor was installed at IAO Hanle in December 2015. So far we have operated the instrument for one year and collected the cloud coverage data for more than 200 nights. In this paper, we briefly describe the operating principle, hardware and software design of the instrument. The results generated by the instrument are also presented. |