Climate Pattern & Modes of Variability

Climate Pattern

Introduction

Any recurrent aspect of the climate is referred to as a climatic pattern. It might endure thousands of years, as in glacial periods within ice ages, or it can happen every year, as in the case of the Monsoon. 

A climactic pattern can take the following forms:

Modes of Variability

A distinct climate pattern with regional ramifications & oscillating behavior. Listed below are a few examples:

The Arctic Oscillation (Arctic Oscillation):

The Arctic Oscillation (A0), also known as the Northern Hemisphere annular mode, is a large-scale pattern of climate variability. The Arctic Oscillation (AO) is a climate phenomenon typified by counterclockwise winds flowing around the Arctic at roughly 55 degrees north latitude. A ring of strong winds swirling around the North Pole acts to trap colder air throughout Polar Regions when the AO is in its positive phase. In the negative phase of the AO, this belt of winds grows thinner and more distorted, allowing for easier southerly entry of colder, arctic air masses and enhanced storminess into the mid-latitudes.

The Antarctic Oscillation

The Antarctic Oscillation is a low-frequency pattern of atmospheric variability that occurs in the southern hemisphere. The Southern Annular Mode is another name for it (SAM). It’s a belt of westerly winds or low pressure that surrounds Antarctica and moves north or south as its pattern of fluctuation. The westerly wind belt contracts towards Antarctica in its positive phase, while it moves towards the Equator in its negative phase.

The Indian Ocean Dipole (IOD)

The difference in sea surface temperature between two locations (or poles, therefore dipole)-a western pole in the Arabian Sea (western Indian Ocean) and an eastern pole in the eastern Indian Ocean south of Indonesia-defines the Indian Ocean Dipole (IOD). The Indian Ocean Dipole (IOD) has an impact on the climate of Australia and other countries in the Indian Ocean Basin and is a major contributor to rainfall variability in this region.

North Atlantic Oscillation:

The North Atlantic Oscillation (NAO) is a weather phenomenon that occurs in the North Atlantic Ocean and is defined by oscillations in the difference in atmospheric pressure at sea level (SLP) between the Icelandic low & the Azores high. It regulates the strength and direction of westerly winds as well as the location of storm tracks over the North Atlantic by varying the strength of the Icelandic low and the Azores high. It’s a part of the Arctic oscillation, and it changes over time with no discernible pattern.

Factors Underlying Climate Patterns

The most important factors contributing to climate patterns are:

• The temperature of the air
• The humidity of the air
• The amount and type of cloudiness
• The type and amount of precipitation
• Air pressure
• Astronomical, oceanographic, atmospheric, and geological factors
• Energy from sun-sunspots and solar storms
• Earth position, solstices, and geometry
• Geography, tilt angles, and equinoxes
• Geological, plate tectonics, polar ice caps, and monsoon
• Fossil fuels
• Green House Gases emissions.

All these factors are interrelated and affect one another.