Mixed tides are tidal patterns characterized by two high tides and two low tides each day, but with significant differences in the heights of successive high tides and successive low tides. In essence, the two high tides are of different heights, and the two low tides are also of different heights.
Key Characteristics of Mixed Tides:
- Twice Daily Occurrence: Similar to semidiurnal tides, mixed tides exhibit two high tides and two low tides within a lunar day (approximately 24 hours and 50 minutes).
- Unequal Heights: The defining characteristic is the inequality in height between the two high tides and the two low tides. One high tide will be significantly higher than the other, and similarly, one low tide will be much lower.
Geographic Distribution:
Mixed tides are commonly observed in the following regions:
- West Coast of the Continental United States: From California to Washington, the Pacific coastline experiences mixed tides.
- Alaska: Coastal areas of Alaska exhibit this tidal pattern.
- Hawai'i: The Hawaiian Islands are also characterized by mixed tides.
Comparison with Other Tidal Patterns:
| Tidal Pattern | Description | Example Locations |
|---|---|---|
| Semidiurnal | Two high tides and two low tides of roughly equal height each day. | East Coast of the United States, Europe |
| Diurnal | One high tide and one low tide each day. | Gulf of Mexico, parts of Southeast Asia |
| Mixed | Two high tides and two low tides each day, but the heights of successive high tides and successive low tides are significantly different. | West Coast of the United States, Alaska, Hawai'i |
Implications:
Understanding mixed tides is crucial for:
- Navigation: Mariners must account for the varying tidal heights to ensure safe passage.
- Coastal Planning: Predicting and managing coastal flooding requires accurate knowledge of mixed tide characteristics.
- Ecosystem Management: Tidal patterns influence coastal habitats and species distribution.
In summary, mixed tides are a specific type of tidal pattern where two high tides and two low tides occur daily, but with notable differences in the heights of the high tides and low tides. They are prevalent along the west coast of the United States, Alaska, and Hawai'i, and require careful consideration for navigation, coastal management, and ecological studies.
