Atmospheric Aerosol Loading (module 7)

Question 1

Identify the control variable for atmospheric aerosol loading, and explain why we can not yet quantify the planetary boundary.

Answer 1

• Control Variable: Aerosol Optical Depth
• Due to the complexity of aerosols (natural and human-made sources)
• Aerosols can warm and cool the climate
• Spatial and Temporal dynamics (concentrations vary across different regions and timescales)
• Lack of data make it difficult to define a planetary boundary

Question 2

Describe what atmospheric aerosols are and why they are important to monitor.

Answer 2

• tiny particles suspended in the atmosphere
• Sea Salt
• Volcanic Dust
• Desert Dust
• Smoke from forest fires
• Human-made aerosols (from burning of coal and oil)
• The influence of aerosols on the climate system
• Their adverse effects on human health at a regional and global scale

Question 3

Identify both natural and anthropogenic sources of atmospheric aerosols.

Answer 3

Natural - Sea Salt
- Volcanic Dust
- Desert Dust
- Smoke from forest fires
Anthropogenic - Deforestation
- agricultural burning
- air pollution
- burning of coal and oil

Question 4

Explain how aerosols are detected and measured.

Answer 4

• measured using sensors on NASA satellites and reveal patterns of aerosol emissions and transport in the atmosphere

Question 5

Describe, using a map, the patterns of aerosols in the atmosphere..

Answer 5

blue - seasalt
red - smoke or pollution
yellow - dust
green - organic and black carbon
white - sulfate
orange - high aerosol concentration

Question 6

Identify both effects of aerosols on human health.

Answer 6

• fine particulate air pollution from combustion of fossil fuels causes cardiopulmonary disease - tracheal, bronchial, lung cancer, and acute respiratory infection in urban areas worldwide
• bigger than 10 um gets caught in mucus anything smaller gets inhaled into your lungs and can enter the bloodstream
• exposure to indoor smoke from solid fuels

Question 7

Identify both direct and indirect effects of aerosols on climate and the hydrologic cycle.

Answer 7

Direct - aerosols (and the clouds they create) reflect 1/4 of the suns radiation back to space
- Black carbon aerosols absorb sunlight, this warms the layer of the atmosphere carrying the black carbon but also shades and cools the surface below
Indirect - clouds form when water vapor condenses in the troposphere but they need a condensation nucleus to condense onto
- aerosols provide condensation nuclei for cloud formation
- can impact the reflection of radiation, and regional precipitation patterns

Question 8

Give an example of how atmospheric aerosols and biogeochemical cycles are connected.

Answer 8

• Dried lake beds are abundant sources of atmospheric dust because they are filled with light, fine-grained sediment that winds can easily lift
• most harmful sources of dust worldwide
• built-up fertilizers, pesticides, heavy metals, and other chemical pollutants in Aral Sea lakebed dust can travel thousands of kilometers
• impacts soil and vegetation
• impacts physiological and mental health

Question 9

Describe the relationship between atmospheric carbon monoxide (CO) and aerosol concentrations

Answer 9

• higher CO levels are associated with higher aerosol optical thickness

Question 10

Investigate the possible sources of CO and aerosols

Answer 10

• Volcanic eruptions
• Wildfires
• Dust
• Vehicle emissions
• Industrial processes

Question 11

Effects of Volcanic Aerosols

Answer 11

• Mt. Tambora erupted in Indonesia and caused global cooling
• Mt. Pinatubo injected 14-26 million tons of sulfur into the stratosphere, resulted in global cooling
• dependent on size of volcano, its overall emissions, and height of the volcano

Question 12

Relationship between Dust and Amazon forest

Answer 12

• Large winds carry dust (Sahara desert), rich in phosphorous, provides crucial nutrients to the rain forest
• when higher rain = less dust, due to more vegetation in desert, leaving less sand available for powerful winds

Question 13

Aerosols vs. Greenhouse Gases

Answer 13

Greenhouse gases - most of the sunlight goes through to earths surface
- water vapor, methane, carbon dioxide
- creates warming effect
Aerosols - most of the tiny particles reflect earths sunlight back before it can make it through to the atmosphere
- creates cooling effect
- change weather patterns and reduce rainfall
- harmful to human health

Question 14

Aerosol Optical Thickness (Depth)

Answer 14

• <0.05 = clear sky
• 1 = hazy conditions
• > 2 or 3 very high concentrations of aerosols