MOSL. Earth Watch. As part of the Space Lab s ongoing program you will monitor Earth s weather using satellite images.

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1 MOSL Earth Watch As part of the Space Lab s ongoing program you will monitor Earth s weather using satellite images. You will work closely with the ADAO (Atmospheric Data Analysis Officer) in Mission Control. You are responsible for tracking a hurricane that formed in the Atlantic Basin over the last week, and is now heading towards the United States mainland. If necessary, you will be responsible for issuing hurricane warnings. You will study satellite images of environmental changes. Record all information in your Mission Log. VSSEC Mission to the Space Lab Earth Watch 1

2 This material has been developed by: Victorian Space Science Education Centre 400 Pascoe Vale Road Strathmore, VIC VSSEC Mission to the Space Lab Earth Watch 2

3 Background Briefing There are two primary types of weather satellites. Weather Satellites Geostationary Satellites Geostationary satellites orbit the equator at a distance of 36,000 km at the same rate that the earth rotates. (The International Space Station orbits at 350 km). This high altitude allows a continuous fulldisc view of the Earth, but also means the resolution, or picture quality is lower. Fig 1 Geostationary Orbit In effect geostationary satellites orbit above a fixed spot on the Earth s surface and can transmit images in real time. Movies, or animations, can be compiled from these images to show such sequences as cloud movement, and the progress of large weather systems such as hurricanes. Polar Orbiting Satellites Polar Orbiting Satellites make approximately 14 orbits a day, passing over the north and south pole each revolution. As the Earth rotates beneath the satellite the instruments monitor an area to the west of the previous pass. Fig 2 Polar Orbit Their low orbital altitude of 850 km provides high-resolution images and detailed information about violent storms and cloud systems. However, images from Polar Orbiting Satellites are delayed, and each spot is only passed a couple of times a day. But their near-polar orbit allows global coverage over north and south latitudes, which are distorted by the angle of geostationary satellites. Polar Orbiting Satellites are often used for mapping and high resolution photography. Satellites can also capture images of dramatic events. VSSEC Mission to the Space Lab Earth Watch 3

4 Fig 3 Before and after images tsunami on December 26, 2004 Question 1: Which type of satellite provides the best high-resolution images? Question 2: Which type of satellite is best for continuous coverage of a major weather event? Question 3: What are the disadvantages of using a Polar satellite to track a hurricane? Weather Satellites Images Fig 4 Visible satellite image Fig 5 Infrared satellite image Visible satellite images are much like a black and white photo taken on earth. Bright areas reveal where the sunlight is reflected by clouds or snow cover. Land surfaces show as grey, and ocean surfaces as near black. They are useful during daylight, but cannot be used at night. Infrared satellite images are based on heat radiation. The warmer the surface the more infrared radiation it emits. Cooler surfaces are bright, whereas warmer surfaces are dark. IR images can be captured 24 hours a day. VSSEC Mission to the Space Lab Earth Watch 4

5 Fig 6 Enhanced Infrared satellite image Fig 7 Water vapour satellite image Enhanced Infrared Satellite images are shaded in different colours to reflect different temperatures. The warmest areas appear as black, and the coldest as red. Water vapour satellite images are modified from infrared data. Dry areas show up as black, and moisture as white. Jet streams may show up as grey streaks. Satellite visible and infrared images may help to locate storms but do not reveal the surface intensity. Only an active microwave sensor, for example the Scatterometer, can measure both wind speed and direction under a wide range of conditions with high spatial resolution. Fig 8 Scatterometer image Hurricane Floyd Weather satellites can also receive data from remote collection platforms on the surface. These can include instrumented buoys, river gauges, automatic weather stations, seismic and tsunami stations, and ships. Question 4: What are the advantages of using infrared images? Question 5: What information does a scatterometer provide? VSSEC Mission to the Space Lab Earth Watch 5

6 Tropical Storms All tropical storms begin when the sun heats up the ocean near the equator and enormous quantities of moisture evaporate high into the atmosphere. If the conditions are right, the storm might grow and develop into a cyclone or hurricane. Hurricanes (and cyclones) are classified as large tropical storms with winds of more than 119 km per hour. Cyclones can only form between 5 and 15 degrees latitude of the equator (north and south), and when the ocean temperature is above 26.5 o C. The warmer the ocean the more energy will be fed into the cyclone, and the faster the winds. First, convection currents inside a low pressure system begin to gather clouds. The system starts to spin and pulls in more clouds. Cyclones spin because the Earth spins, and south of the equator winds circle clockwise (creating cyclones), and to the north anti-clockwise (creating hurricanes). Fig 9 Anticyclone Fig 10 Blue ocean is visible through the eye of a hurricane. Fig 11 A typhoon. Cyclones are called typhoons near the South China sea. The relatively peaceful centre of a hurricane is called the eye. Low pressure in the centre of a hurricane causes the surface of the ocean to rise by several metres. This increased height creates a storm surge. A hurricane loses power if it crosses land or cooler water. VSSEC Mission to the Space Lab Earth Watch 6

7 * View an IR movie of Hurricane Katrina. Note the intensity of the hurricane lessens as it crosses Florida, intensifies as it crosses warm water in the Gulf of Mexico, and finally begins to dissipate when it makes landfall. (movie 1) Hurricanes are classified by the typical damage they cause and are based on the Saffir-Simpson Hurricane Scale. Saffir-Simpson Hurricane Scale Category Wind gust speed Storm surge Damage 1 Less than 125 km/h m Mild damage km/h m Significant damage to trees km/h Structural damage, power failure likely km/h m Most roofing lost 5 More than 280 km/h More than 5.4 m Almost total destruction * View an animation of Saffir-Simpson Hurricane Scale. Hurricane Tracking The path of a hurricane can be influenced by many factors. Atlantic hurricanes begin off the coast of Africa and are pushed towards North America by the prevailing easterly winds. As they approach land they are also influenced by Low and High pressure systems moving across the United States. High pressure systems blow in a clockwise direction. Low pressure winds blow in a counter-clockwise direction. A hurricane s progress can by slowed by westward-moving cold fronts. 1. Use the Tracking Data to plot the path of the hurricane for days 1-5 on the Atlantic Basin Hurricane Tracking Chart. Number each day and indicate AM or PM as you plot each position. 2. Connect the dots with a dashed line ( ) when the maximum wind speed is less than 125 km/h. Use a solid line if the maximum speed is more than 125 km/h (hurricane). Tracking Data Day LATITUDE LONGITUDE TIME WIND STATUS TROPICAL STORM HURRICANE HURRICANE HURRICANE HURRICANE HURRICANE HURRICANE HURRICANE HURRICANE HURRICANE 4 VSSEC Mission to the Space Lab Earth Watch 7

8 The ADAO will provide tracking information for days 6-7. Plot the path of the hurricane. The ADAO will provide tracking information for days Plot the path of the hurricane. The ADAO will provide tracking information for days Plot the path of the hurricane. Questions 6-9: As you receive new information from the ADAO consider the following points and make appropriate recommendations: Suggest reasons for any increase or decrease in hurricane intensity Predict when and where the hurricane will hit the United States mainland and identify any cities that might be under threat. Based on the Saffir-Simpson scale, issue warnings for the type of storm damage, and size of the storm surge that can be expected. Make a recommendation to residents whether they should evacuate, or attempt to ride out the storm in their homes. Were your predictions accurate? Can you explain what happened? VSSEC Mission to the Space Lab Earth Watch 8

9 Global Warming Global warming is the observed increase in the average temperature of the Earth s atmosphere and oceans over the last few decades. Human activity, particularly the burning of fossil fuels, is largely responsible for the increase in atmospheric gases such as carbon dioxide. Since the Industrial Revolution atmospheric concentrations of carbon dioxide have increased by 30% - enhancing the heattrapping capability of the atmosphere. Carbon dioxide acts like a blanket, creating a greenhouse effect. The Earth is warming up. Fig 12 Global Temperatures Ice Melt One of the most dramatic effects of global warming can be seen near the poles. About 90% of the world s ice (and 70 percent of its fresh water) covers the Antarctica landmass to an average of 2,133 metres thick. The Larsen Ice Shelf stretches along the eastern edge of the Antarctica Peninsula. Because the ice shelf sits on water, rather than the landmass, it is more vulnerable to rises in ocean temperatures. Scientists have been observing the ice shelf retreat for the last two decades. Then in just over a month in 2002, an entire section of the Ice Shelf collapsed, launching a flotilla of icebergs into the sea. Fig 12 and Fig 13, recorded by NASA's Moderate Resolution Imaging Spectrometer satellite sensor, show the Larsen B ice shelf and parts of the Antarctic Peninsula (on left). Fig 13 The first photo on January 31, 2002 shows the shelf in late summer. Fig 14 The next photo shows the main collapse on March 7, 2002, with thousands of sliver icebergs where the shelf formerly lay. VSSEC Mission to the Space Lab Earth Watch 9

10 Like the Antarctica shelf ice, sea ice at the North Pole floats on the ocean. Satellite images show that since 1979 the summer polar ice cap has shrunk by more than 20%. If this trend continues by 2100 there will be no ice at the North Pole in summer. Fig 15 Arctic sea-ice melt as measured by satellite data September Fig 16 Arctic sea-ice melt September Greenland holds the world s second largest ice cap, containing more than 2.85 million cubic kilometres of ice. Being closer to the equator than Antarctica, it is more vulnerable to ice melt. NASA has been surveying the Greenland ice sheet since Fig 17 Greenland ice-melt, 1992, Rising Sea Levels As the polar ice melts what s likely to happen to sea levels? It is estimated that sea levels have been rising by about 0.3 metres per century, but the biggest contributor to date is not melting ice, but warmer oceans. As oceans warm up the water expands and sea levels actually rise. Water is at its most dense at 4 0 C, above and below this temperature the density of water decreases (the same weight of water occupies a bigger space). This is called thermal expansion. If all the Antarctica ice melted sea levels would rise by about 61 metres. But because temperatures in most parts of the continent never get above freezing, this is most unlikely to happen. If the North Pole melts its affect on sea levels would be very small. But if the ice covering Greenland melted, sea levels would rise by about 7 meters. Scientists have estimated that an annual average temperature rise of 3 0 C would be enough to melt Greenland s ice-sheet. A sea level rise of just 1 meter would submerge a substantial part of Bangladesh and the Nile Delta. Less ice also means that less sunlight is reflected, thus increasing global warming. Water and earth, being darker than ice, absorb more sunlight and warm the whole planet. VSSEC Mission to the Space Lab Earth Watch 10

11 Fig 18 Potential impact of sea-level rise on Bangladesh Question 10: Why is Greenland s ice-sheet more vulnerable to global warming than the Antarctica? Question 11: Why would the melting of the North Pole be unlikely to affect sea levels? Observing the Earth from Space The most abundant life forms in the ocean are phytoplankton, microscopic marine plants that drift on or near the surface of the sea. Phytoplankton take in about half of all the world s carbon dioxide, using the carbon for growth and releasing oxygen during photosynthesis. When phytoplankton die their microscopic bodies settle to the bottom; storing vast amounts of carbon over geological time. In this way the oceans act as a sink, disposing of global carbon that would otherwise accumulate in the atmosphere as carbon dioxide. During the last 20 years there has been a marked decline in phytoplankton populations, and the greatest loss has occurred where ocean temperatures have risen most significantly. VSSEC Mission to the Space Lab Earth Watch 11

12 Fig 19 The Carbon Cycle The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project provides satellite data on global bio-optic properties ocean colour. Phytoplankton numbers are estimated by using satellite images, which monitor the green pigments in plants, or chlorophyll, which are responsible for the greenish-tint in ocean waters photographed from space. Satellite sensors can distinguish even slight variations in colour. Different shades of ocean colour reveals the presence of differing concentrations of sediments, organic materials, or even phytoplankton. * View animation of the SeaWiFS daily coverage of the world s oceans. (movie 2) Question 12: What sort of orbit does SeaWiFS cover? Suggest why. VSSEC Mission to the Space Lab Earth Watch 12

13 Fig This sequence of SeaWiFS ocean colour imagery shows the impact of the El Niño on the productivity of phytoplankton around the Galapagos Islands in the Pacific Ocean. The first image was taken during the height of the El Niño, while the last image was taken during the La Niña. Note the gradually flourishing bloom of phytoplankton as the surface waters cool, allowing the deeper, more nutrient-rich waters to upwell. Fig 20 Fig 21 Fig 22 Fig 23 Question 13: How do phytoplankton contribute to the carbon cycle? Draw a diagram if necessary. VSSEC Mission to the Space Lab Earth Watch 13

14 Marine Food Web Phytoplankton forms the base of the marine food web. Phytoplankton depend on sunlight, water and nutrients to survive, and are responsible for the major share of primary productivity in the marine environment. In the Arctic, loss of sea ice associated with global warming could diminish phytoplankton populations, leading to a knock-on-effect throughout the Arctic food chain, diminishing plankton-feeding fish, and other species such as marine mammals and seabirds. Fig 24 Marine Food Web Phytoplankton Phytoplankton are mainly unicellular plants known as algae, the two major groups are Diatoms and Dinoflagellates. Diatoms Diatoms are recognizable by their protective glass skeletons made from silica. Diatoms can be classified by their variety of shapes and can occur as single cells or in chains. Circular, triangular, and modified square shapes are known as centric diatoms. Elongated shapes are classified as pennate diatoms. Fig 25 Pennate diatom Fig 26 Colony of pennate diatoms Fig 27 Centric diatom Fig 28 Diatom top and side view VSSEC Mission to the Space Lab Earth Watch 14

15 Dinoflagellates Dinoflagellates usually occur as single cells, and are generally smaller than diatoms. They can swim using tiny whip-like flagella. They may possess spines, horns or other projections. Most dinoflagellates are photosynthetic, but some eat other organisms. Fig 29 Unarmoured Fig 30 Armoured Fig 31 Projections Fig 32 Exotic Fig 33 Bioluminescent Some dinoflagellates are bioluminescent and create light when disturbed by waves, boat wakes or predators. Other dinoflagellates produce toxins. Fig 34 Bioluminescent dinoflagellates Fig 35 Bioluminescent dinoflagellates in a Peruvian lake Fig 36 Dinoflaggellates ceratium Fig 37 Dinoflaggellates Ceratium create a Red Tide VSSEC Mission to the Space Lab Earth Watch 15

16 Harmful Algae Blooms Several species of phytoplankton produce toxins that cause illness or death in both marine life and humans. If environmental conditions allow toxic phytoplankton to increase rapidly they can create a harmful algae bloom or HAB. Algae blooms are influenced by such factors as warm weather and the availability of nutrients rich in phosphorous such as water run-off over land used for agriculture. Sometimes they are described as toxic Red Tides. HABs are of major concern globally. Their occurrence, spread and frequency of duration has been increasing over the past decades. Fig 38 Algae bloom in the Baltic Sea, July Identifying Phytoplankton Phytoplankton are currently being studied aboard the Space Lab. Carefully pipette a sample onto a clean slide and view under the microscope. Question 14: Describe your specimen with regard to the following: Colour of the phytoplankton colony: Size: Individual or colony formation: Mobility: Colour of individual phytoplankton: Visible features (eg. projections, armour, flagella.): Are any intracellular features visible? (eg. nucleus): VSSEC Mission to the Space Lab Earth Watch 16