Water surface altitude (in meters) over the Amazon river (near the confluence of Amazon and Madeira rivers) along the Saral #063  and #478 ground tracks, between cycle 1 and cycle 3 (no data from pass #063 on cycle 1). Each curve represents the altitude in meters (Y-axis) along the ground track (X-axis represents the latitude) at a given cycle so each curve for a given pass is spacen from 35 days. Use the <link internal-link>pass locator to visualize the ground tracks with Google Earth. CréditsCnes/Legos/IRD, S.Calmant.

Water levels time series derived from ERS-2 (triangles) between 1995-2002, Envisat (squares) between 2002-2010 and Saral (circles) from 2013. The blue and cyan colors used for the water level derived from altimetry correspond to passes #063 and #478. Both tracks are separated of 14 days for a given cycle. The red line superimposed are derived from in situ measurements at the Iracèma gauge, located 3 km upstream. Missing blue squares between 2010 and 2012 correspond to an orbit change for Envisat beyond November 2010. The missing red line between  2011 and 2013 correspondonds to a lack of in situ measurements. Credits Cnes/Legos/IRD, S.Calmant.