Watching hurricanes slowly creeping toward land can be alarming. However, it is also important to track these storms' path over the ocean, which greatly influences their strength.

Satellite data such as sea surface temperature and height help scientists understand the ocean heat content available for storm intensification. Current forecasting tools do not include the effects of salinity, but new research shows that low sea surface salinity caused by the outflow of major rivers can have a considerable impact on how storms intensify. Why?

Outflow from rivers can form and maintain thin layers at the sea surface. Underneath, there can be a "barrier layer" where salinity changes dramatically, isolating the upper ocean from water below. This type of stratified water column can intensify passing hurricanes. How?

The answer is heat. Thinner surface layers warm up more quickly than surrounding waters. Not only that, the underlying barrier layer makes "stirring up" the water column by hurricanes - which brings up cold water in most places – more difficult. So, monitoring how certain river plumes change over time is key to understanding interactions between the ocean and hurricanes.

Use the tool below – based on a 5-year study by Fournier et al. (2017) – to investigate the characteristics of the Amazon/Orinoco plume during 2010 and 2014. Located in the eastern Caribbean Sea, the study area has been shown to lie directly in the path of many Atlantic hurricanes. Use the buttons to toggle between years or among data types.

• Study Area
• 2010
• 2014

• Defined by low salinity, the Amazon/Orinoco plume covers most of the study area.
• Defined by low salinity, the plume's water is warmer than average. Together, these properties help the plume "stay afloat".
• The depth of surface mixing – shown approximately in this diagram – differs between the plume and the surrounding ocean.
• Dissolved organic matter from the Orinoco River is a major contributor in 2010. More dissolved particles, especially with darker color, help trap more heat.
• The large extent of the 2010 plume was helped by low winds in the region. These winds allowed the plume to move well offshore.

1 2 3 4 5

• Defined by low salinity, the Amazon/Orinoco plume covers only 60% of the study area.
• Defined by low salinity, the plume’s water is warmer than average. Together, these properties help the plume "stay afloat".
• The depth of surface mixing – shown approximately in this diagram – differs between the plume and the surrounding ocean.
• During 2014, organic matter is low and concentrated in the southern portion of the study area.
• The 2014 extent is relatively small because of winds blowing toward South America. In addition, ocean eddies transported plume waters along the coast (rather than offshore).

1 2 3 4 5