Outline

Further Reading: Chapter 11 of the text book

- boreal forest regimes

- tundra regimes

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(1 of 9)

- ice-sheet regimes

Introduction

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(2 of 9)

• Previously,– We looked at mid-latitude climates– Climate regimes are differentiated by their temperature characteristics as

well as their precipitation characteristics– Much more varied than low-latitude climates– Six climatic regimes in the mid-latitudes

• Today,– We want to look at high-latitude climates– Relatively simple – Tend to be uniformly cold– Also tend to have less precipitation than in low-latitude and mid-latitude

regions

Introduction

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(3 of 9)

– Found in the sub-arctic and Arctic circle (50N-70N)

– Dominated by mP, cP air masses

– Also influenced by general circulation

• Southerly winds in southern portion of the region, with strong easterly winds over the poles

– Usually associated with high seasonality in temperature and persistently dry precipitation

– Results in 3 types of climate regimes – Boreal Forest Climates– Tundra Climates– Ice Sheet Climates

Boreal Forest Climate-1

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(4 of 9)

Jet Stream

– Found in the interiors of continents (N. America and Eurasia)

– Slight seasonality in precipitation

• Winter is dry

• Summer, it can rain from

– Poleward shift of polar front

– Intrusion of mid-latitude cyclones

Boreal Forest Climate-2

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(5 of 9)

– Most notable aspect is the strong seasonality in temperature

• Seasonality in declination

• Continental effects

– Results in highest seasonality in temperatures of any of the climate regimes

• Typified by Boreal forests - needleleaf trees

Tundra Climate-1

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(6 of 9)

– Found at the coastal fringes of continents

– Wide range in precipitation characteristics• Moist on the Atlantic and Pacific

• Dry near the Arctic

Tundra Climate-2

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(7 of 9)

– Strong seasonality in temperature

• Long, cold winters

• Short summers

• However, because of the influence of the ocean, the temperatures are milder than in the Boreal forests

• Typified by tundra (grasses, sedges, and lichens) and permafrost

Ice-Sheet Climate-1

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(8 of 9)

– High latitude ice sheets over Greenland and Antarctica – Influenced by the Arctic high– Source of A and AA air mases

Ice-Sheet Climate-2

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L26: High Latitude Climates

Apr-02-07(9 of 9)

– Cold all year round

– Very dry

• No real vegetation