GEOGRAPHY OPTIONAL – PAPER I
PAGE 15 : OCEAN SALINITY, DENSITY & CURRENTS
UPSC / UPPSC Geography Optional
Shaktimatha 369 Learning
1. Ocean Salinity – Meaning
Salinity refers to the total amount of dissolved salts present in ocean water, expressed in parts per thousand (‰).
The average salinity of ocean water is about 35‰.
Exam Importance: Direct PYQs + strong diagram orientation
2. Factors Affecting Ocean Salinity
- Evaporation
- Precipitation
- Freshwater inflow (rivers, ice melt)
- Ocean currents
- Latitude & climate
Key Concept: High evaporation → high salinity
3. Distribution of Salinity
(a) Horizontal Distribution
- High salinity in subtropical regions
- Low salinity near equator & poles
(b) Vertical Distribution
- Surface salinity varies greatly
- Salinity decreases with depth
- Halocline zone present
Diagram Tip: Salinity profile with depth
4. Salinity in Indian Ocean
- High salinity in Arabian Sea
- Low salinity in Bay of Bengal
- Seasonal variation due to monsoon
GS Link: Monsoon circulation & marine ecosystems
5. Ocean Density
Ocean water density depends on salinity, temperature and pressure.
Factors Affecting Density
- Temperature (inverse relationship)
- Salinity (direct relationship)
- Depth / pressure
Concept: Cold, saline water sinks
6. Ocean Currents – Meaning
Ocean currents are large-scale movements of ocean water in definite directions, driven by wind, temperature, salinity and Earth’s rotation.
7. Types of Ocean Currents
(a) Warm Currents
- Flow from equator towards poles
- Example: Gulf Stream, Kuroshio
(b) Cold Currents
- Flow from poles towards equator
- Example: Labrador, Canary
8. Factors Affecting Ocean Currents
- Planetary winds
- Earth’s rotation (Coriolis force)
- Temperature & salinity differences
- Configuration of continents
Diagram Mandatory: World ocean currents map
9. Importance of Ocean Currents
- Regulate global climate
- Influence coastal temperatures
- Control rainfall patterns
- Affect fisheries
Example: Gulf Stream & Western Europe climate
10. Indian Ocean Currents
- Seasonal reversal due to monsoon
- Somali Current
- Agulhas Current
Relevance: Monsoon prediction & marine economy
11. Answer Writing Strategy
- Define salinity / currents clearly
- Use labelled diagrams
- Include Indian Ocean examples
- Link with climate & monsoon
Golden Rule: World current map = sure-shot marks
PYQ Orientation
- Factors affecting salinity
- Warm vs cold currents
- Indian Ocean circulation
NEXT PAGE
Geography Optional – Page 16:
El Niño, Ocean–Atmosphere Interaction & Upwelling
End of Geography Optional – Page 15
Shaktimatha 369 Learning
UPSC / UPPSC Geography Optional – Complete Master Library
Shaktimatha 369 Learning
Paper–I & Paper–II | Concepts • Diagrams • PYQs • Answer Writing
📍 PART–A : Physical Geography
- Geography Optional Overview & Strategy
- Earth Origin & Plate Tectonics
- Geomorphic Processes (Endogenic & Exogenic)
- Fluvial Landforms
- Glacial Landforms
- Aeolian Landforms
- Coastal & Marine Landforms
🌦️ PART–B : Climatology
- Atmospheric Structure
- Insolation & Heat Budget
- Atmospheric Circulation & Winds
- Moisture, Clouds & Precipitation
- Köppen Climate Classification
🌊 PART–C : Oceanography
- Ocean Relief & Temperature
- Salinity, Density & Ocean Currents
- Ocean–Atmosphere Interaction & Fisheries
🌱 PART–D : Biogeography & Soils
🏘️ PART–E : Human Geography
- Population Distribution & Migration
- Demographic Transition & Policies
- Settlement Geography (Rural & Urban)
🏭 PART–F : Economic Geography
🌍 PART–G : Regional, Environmental & Political Geography
- Regional Planning & Development
- Environmental Geography & Sustainability
- Political Geography & Geopolitics
- Social Geography
🛰️ PART–H : Applied Geography
📚 COMPLETE UPSC / UPPSC STUDY HUB
End of Geography Optional Master Library
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