On the possible use of satellite fixed positions for Argo profiles in case of GPS failures

INCOIS had deployed iridium based PROVOR Bio-Argo floats obtained from NKE, France. These floats are fitted with GPS for obtaining accurate position of the Argo profiles. However there are cases where in the GPS fitted with the Argo floats tend to give wrong positions owing to unknown reasons. In this present work we discuss the possibilities of using the Iridium satellite fixed position in case of GPS failures. For this, analysis was done by comparing the GPS and satellite fixed profiles positions of good floats. These statistics can be used for using the satellite fixed position in case of GPS failures. For each comparison the satellite fixed position with least circular error probability (CEP) radius was chosen. The study suggested that on a average the satellite fixed positions tend to differ from the GPS fixed positions by 0.03 degrees. CEP radii are found to be consistent with the difference between satellite fixed position and GPS position. Based on this we suggest a quality flag of 2 for positions with CEP radius <=4 and flag 4 for any other positions

Android App for Argo Floats

INCOIS has deployed more than 400 Argo floats till now and soon reaching a special milestone of 500 Indian Argo floats. In this context there is a necessity to have a unique application by which scientists can effectively and efficiently track all the information of these floats and also monitor the active floats among them regularly. The present work describes about an Android application or app which eases the work of researchers to track the information of these Argo floats as well as monitor them regularly. This app is designed and developed to give all the information related to Argo floats like its various types, its deployed positions, its current positions, its functionality, search option, etc., in the form of maps and charts in turn uses real time data to give latest status of Argo floats. In addition to it, this app is also useful in advising the scientists involved in Argo program about the floats in danger of getting grounded or beached that need immediate attention. This app is a very useful tool for the scientists to check the current status of Argo floats from anywhere or anytime using a smart phone

On the possible use of satellite fixed positions for Argo float profiles in case of wrong fixes by GPS

Indian National Centre for Ocean Information Services (INCOIS) had deployed Iridium based Provor Bio-Argo floats obtained from NKE Instrumentation, France. These floats are fitted with GPS for obtaining accurate position of the Argo profiles. However there are cases where in the GPS fitted with the Argo floats tend to give wrong coordinates of profile position owing to unknown reasons. In the present work we discussed the possibilities of using the Iridium satellite fixed position as a substitute of GPSfixed locations in place of wrong GPS positions. For this, statistical analysis was done by comparing the GPS and Iridium satellite fixed profiles positions of 258 profiles from 5 floats which had no problem with the GPS. For each comparison, the GPS fixed position with least Circular Error Probability (CEP) radius was chosen. It was observed that CEP radii are relatively consistent with distances between GPS and Iridiumsatellite fixes with a correlation of 0.85. The study suggests that on an average the Iridium satellite based positions tend to differ from the GPS fixed positions by 0.09°. On the whole CEP radii are found to be consistent with the difference between Iridium satellites and GPS fixed positions. Based on this we suggest a quality flag of 2 (implying probably well) for positions with CEP radius less than or equal to 4 Km and flag 4 (implying bad) for all other positions