Name five controlling factors of oceanic salinity.

Five Controlling Factors of Oceanic Salinity (महासागरीय लवणता के नियंत्रक कारक):

Oceanic salinity (average global value: $35 ext{ ppt / } ext{‰}$) is dynamically regulated by five fundamental physical factors:

• 1. Rate of Evaporation: Higher atmospheric temperature and dry winds accelerate surface water evaporation, leaving dissolved salts concentrated (e.g., Red Sea salinity reaches $41 ext{‰}$, Subtropical High Pressure belts).
• 2. Influx of Fresh River Water: Massive discharge of fresh water from major river systems significantly dilutes oceanic salinity (e.g., Bay of Bengal has low salinity of $30 ext{–}32 ext{‰}$ due to Ganga, Brahmaputra, Godavari discharge).
• 3. Precipitation (Rainfall): Heavy equatorial precipitation ($>200 ext{ cm}$) dilutes surface seawater, lowering equatorial salinity compared to subtropical horse latitudes.
• 4. Freezing and Thawing of Polar Ice: Melting of polar icebergs in summer adds fresh water (reducing salinity), while seawater freezing in winter concentrates salts in surrounding water.
• 5. Ocean Currents and Atmospheric Winds: Warm and cold currents mix water masses, redistributing salinity globally (e.g., North Atlantic Drift increases salinity of NW European coast).