ABSOLUTE RADIOMETRIC CALIBRATION OF THE GÖKTÜRK-2 SATELLITE SENSOR USING TUZ GÖLÜ (LANDNET SITE) FROM NDVI PERSPECTIVE

TÜBİTAK UZAY has conducted a research study on the use of space-based satellite resources for several aspects of agriculture. Especially, there are two precision agriculture related projects: HASSAS (Widespread application of sustainable precision agriculture practices in Southeastern Anatolia Project Region (GAP) Project) and AKTAR (Smart Agriculture Feasibility Project). The HASSAS project aims to study development of precision agriculture practice in GAP region. Multi-spectral satellite imagery and aerial hyperspectral data along with ground measurements was collected to analyze data in an information system. AKTAR aims to develop models for irrigation, fertilization and spectral signatures of crops in Inner Anatolia. By the end of the project precision agriculture practices to control irrigation, fertilization, pesticide and estimation of crop yield will be developed. Analyzing the phenology of crops using NDVI is critical for the projects. For this reason, absolute radiometric calibration of the Red and NIR bands in space-based satellite sensors is an important issue. The Göktürk-2 satellite is an earth observation satellite which was designed and built in Turkey and was launched in 2012. The Göktürk-2 satellite sensor has a resolution 2.5 meters in panchromatic and 5 meters in R/G/B/NIR bands. The absolute radiometric calibration of the Göktürk-2 satellite sensor was performed via the ground-based measurements - spectra-radiometer, sun photometer, and meteorological station- in Tuz Gölü cal/val site in 2015. In this paper, the first ground-based absolute radiometric calibration results of the Göktürk-2 satellite sensor using Tuz Gölü is demonstrated. The absolute radiometric calibration results of this paper are compared with the published cross-calibration results of the Göktürk-2 satellite sensor utilizing Landsat 8 imagery. According to the experimental comparison results, the Göktürk-2 satellite sensor coefficients for red and NIR bands estimated in this work sustained to agree within 2% of calibration coefficients estimated in the cross-calibration results

THE BENEFITS AND CHALLENGES OF HAVING AN OPEN AND FREE BASIS SATELLITE DATA SHARING PLATFORM IN TURKEY: GEZGİN

Turkey is a county that experiences rapid socioeconomic development, which, in turn, leads to high urbanization rates due to migration of people from rural to urban areas, many large-scale development projects (e.g. highways, dams, housing and infrastructure), and environmental problems that adversely affect agriculture, such as soil erosion and deforestation. Furthermore, Turkey lies in a region prone to natural disasters, especially earthquakes, landslides, flooding and forest fires. Successfully overcoming these challenges requires continuous monitoring to enable rapid response as well as the development of effective socioeconomic policies. In this regard, space-based earth observation (EO) systems play a critical role in the rapid acquisiton and extraction of crucial information. The first launch of the first Turkish-designed satellite, RASAT, in 2011 led to the wide-spread exploitation of space-based resources by Turkish institutions through the dissemination of EO data on an open and free basis via the GEZGIN internet portal (http://www.gezgin.gov.tr). The push for data sharing was further instigated by the nationally funded project GEOPORTAL (“Satellite Image Processing and Geoportal Development Project”) and European Union FP7 project EOPOWER (“Earth Observation for Economic Empowerment”), which strove to create conditions for sustainable economic development through the increased use of Earth observation products and services for environmental applications. In this work, the technical challenges involving processing and preparing raw satellite data for dissemination as well as software design of the GEZGIN Portal will be presented