Space geodesy is based on observation of dynamics of the earth such as rotation of the earth on its own axis, changes in the shape of the earth and external gravity field which enable monitoring of earth system. Observation is done by artificial satellites embedded on various space geodetic techniques each for specific application. These techniques includes Global Navigation Satellite System (GNSS), Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Interferometric Synthetic Aperture Radar (InSAR), Satellite Radar Altimetry and Doppler Orbitography and Radio positioning Integrated by Satellite (DORIS).
Inspite of other applications, Space geodesy is applied in ocean monitoring and forecasting where knowledge about current state of the ocean is accessed that enable prediction of future ocean state. Through space geodesy, satellite based observations provide information as alerts for high waves, tides, currents and tsunami. Wind speed over the oceans can be observed by GNSS-Reflectometry. Ocean subsurface condition can also be observed through space geodesy from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Such observations serve as early warning information for all sectors associated with oceanic activities.
Ocean monitoring and forecasting are very important aspects in the case of ensuring safety for marine resources and oceanic activities such as ship navigation together with all activities taking place along the coast. Ocean forecasting systems finds application in marine institutions, research institutions, port authorities, offshore industries and fisheries.
Mozambique, Madagascar and Comoros are among African countries which have benefited from ocean forecasting system that is based on marine satellites. The system was installed last year at the third meeting of Regional Integrated Multi-Hazard Early Warning System for Asia and Africa (RIMES) by Indian National Centre for Ocean Information Services (INCOIS).
For the case of Madagascar, the Integrated Ocean Information and Forecast System provides the ocean forecast of three days earlier in temporal resolution of 3-6 hours. The forecast for specific location are available at 10, 20 and 50km away from shoreline. The forecast products are provided in numeric and mapped form. They include wind speed and direction, sea waves, currents, depth and sea surface temperature.
The forecast information can be obtained through incois website, For example, the forecast of one day obtained on 28th of December 2018 for wind speed and direction for the part of Madagascar from longitude (10-20) South and latitude (42-52) East.
Another example is for sea monitoring whereby detailed sea condition for Mozambique for 28th December 2018 is provided on the same date.
The International Association of Geodesists (IAG) controls the Global Geodetic Observing System (GGOS) which is the result of integration of space geodetic techniques. The system is more reliable and consistent. Thus improvement in the contribution of space technology.