Earth Observatory: Reference

Global Warming
Global warming is happening now, and scientists are very confident that greenhouse gases are responsible. This article explains what global warming is, how scientists know it's happening, and how they predict future climate.

Aura Fact Sheet
On July 15, 2004 at 3:02 a.m., NASA launched the Aura satellite, the third flagship in a series of Earth-observing satellites designed to view Earth as a whole system, observe the net results of complex interactions within the climate system, and understand how the planet is changing in response to natural and human influences.

CALIPSO Fact Sheet
From reports of increasing temperatures, thinning mountain glaciers and rising sea level, scientists know that Earth's climate is changing. But the processes behind these changes are not as clear. Two of the biggest uncertainties in understanding and predicting climate change are the effects of clouds and aerosols (airborne particles). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite mission, currently under development, will help scientists answer significant questions about climatic processes by providing new information on these important atmospheric components.

NOAA-M Continues Polar-Orbiting Satellite Series
Since the 1960s, NASA has developed polar-orbiting operational environmental satellites for the National Oceanic and Atmospheric Administration (NOAA). NOAA-M, the latest NOAA spacecraft, is scheduled for launch June 24, 2002.

Overview of the Earth Science Enterprise
Our Earth is unique among the planets with an abundance of water and highly diversified life. Its land, atmosphere, oceans, and all forms of life interact in many complex ways to form a complex Earth system. NASA provides a unique vantage point from space that is the only way to effectively study global scale phenomena and to understand local, regional and global-scale changes in their larger context. The mission of NASA's Earth Science Enterprise (ESE) is to develop a scientific understanding of the Earth system and its response to natural and human-induced changes to enable improved prediction of climate, weather, and natural hazards for present and future generations.

The Ozone We Breathe
Ozone in the lower atmosphere (troposphere) is toxic to human beings and many species of plants, causing harm without visible symptoms. The Ozone We Breathe focuses chiefly on the ozone's effects on human respiratory health and and the productivity of agricultural crops.

Global Warming Fact Sheet
With the possible exception of another world war, a giant asteroid, or an incurable plague, global warming may be the single largest threat to our planet. For decades human factories and cars have spewed billions of tons of greenhouse gases into the atmosphere, and the climate has begun to show some signs of warming. Many see this as a harbinger of what is to come. If we don't curb our greenhouse gas emissions, then low-lying nations could be awash in seawater, rain and drought patterns across the world could change, hurricanes could become more frequent, and El Niños could become more intense. On the other hand, there are those, some of whom are scientists, who believe that global warming will result in little more than warmer winters and increased plant growth. In truth, the future probably fits somewhere between these two scenarios.

Stratospheric Aerosol and Gas Experiment III
The Stratopsheric Aerosol and Gas Experiment (SAGE III) is a fourth generation satellite instrument designed to observe the long-term health of the upper atmosphere. SAGE III, managed by NASA Langley Research Center, is part of NASA's Earth Science Enterprise program of climate research. The goal of SAGE III is to measure high-resolution vertical profiles of key components of the upper atmosphere-the most important being ozone, aerosols, (suspended particles) and water vapor.

Weather Forecasting Through the Ages
Only fifty years ago, weather forecasting was an art, derived from the inspired interpretation of data from a loose array of land-based observing stations, balloons, and aircraft. Since then it has evolved substantially, based on an array of satellite and other observations and sophisticated computer models simulating the atmosphere and sometimes additional elements of the Earth's climate system. The AIRS/AMSU/HSB combination on board the [soon to be launched] EOS Aqua satellite should further these advances, enabling more accurate predictions over longer periods.

Solar Radiation and Climate Experiment (SORCE) Fact Sheet
Earth scientists will move a step closer to a full understanding of the Sun's energy output with the launch of the Solar Radiation and Climate Experiment (SORCE) satellite. SORCE will be equipped with four instruments now being built at the University of Colorado that will measure variations in solar radiation much more accurately than anything now in use and observe some of the spectral properties of solar radiation for the first time. With data from NASA's SORCE mission, researchers should be able to follow how the Sun affects our climate now and in the future.

Research Satellites for Atmospheric Science, 1978-Present
NASA and its affiliated agencies and research institutions developed a series of research satellites that have enabled scientists to test new remote sensing technologies that have advanced scientific understanding of both chemical and physical changes in the atmosphere.

The Carbon Cycle
Carbon (C), the fourth most abundant element in the Universe, after hydrogen (H), helium (He), and oxygen (O), is the building block of life. On Earth, carbon cycles through the land, ocean, atmosphere, and the Earth's interior in a major biogeochemical cycle.

Ultraviolet Radiation: How It Affects Life on Earth
Stratospheric ozone depletion due to human activities has resulted in an increase of ultraviolet radiation on the Earth's surface. The article describes some effects on human health, aquatic ecosystems, agricultural plants and other living things, and explains how much ultraviolet radiation we are currently getting and how we measure it.

Biomass Burning
Biomass burning is the burning of living and dead vegetation, including both human-initiated burning for land clearing, and burning induced by lightning and other natural sources. Researchers with the Biomass Burning Project at NASA Langley Research Center are seeking to understand the impact that biomass burning has on the Earth's atmosphere and climate.

Hurricanes: The Greatest Storms on Earth
Few things in nature can compare to the destructive force of a hurricane. Called the greatest storm on Earth, a hurricane is capable of annihilating coastal areas with sustained winds of 155 mph or higher and intense areas of rainfall and a storm surge.

The Water Cycle
One of the most unique features of our home planet is the water, in both liquid and frozen forms, that covers approximately 75% of the Earth's surface. This article introduces the hydrologic cycle — the notion that water is continually circulating from the ocean to the atmosphere to the land and back again.

Ozone in the Stratosphere
Ozone is a relatively unstable molecule found in Earth's atmosphere. Depending on where ozone resides, it can protect or harm life on Earth. High in the atmosphere ozone acts as a shield. Closer to Earth ozone is a harmful pollutant.

Changing Global Cloudiness
Clouds are visible collections of small particles of water or ice, or both, suspended in the atmosphere. They are one of the most obvious and influential features of Earth's climate system. They are also one of its most variable components.

What are Aerosols?
Aerosols are tiny particles suspended in the air. Taken as a whole these particles tend to cool Earth's atmosphere, and are an important factor in global change.

Clouds and Radiation
The study of clouds, where they occur, and their characteristics, play a key role in the understanding of climate change. Whether a given cloud will heat or cool the surface of the Earth depends on several factors.

Gravity Recovery and Climate Experiment (GRACE) Fact Sheet
The Gravity Recovery and Climate Experiment is the inaugural mission of the Earth System Science Pathfinder program. Launched in March 2002, it is a five-year mission intended to produce maps of the Earth's gravity field with unprecedented precision and resolution. Not only will GRACE benefit studies in the field of geodesy, but also, the Earth Science community eagerly anticipates the mission. More precise gravity measurements will improve the accuracy of inputs into models used by many disciplines that study Earth's climate - including hydrology, oceanography and studies of the solid earth.

Ocean and Climate
How will changes in climate trends and changes in climate variability affect life in the ocean? How do the ocean's temperature, chemistry and biology influence climate? Are human activities contributing to changes in the marine environment and, in turn, how might these changes feed back to affect us?

Polar Ice
Polar ice consists of sea ice formed from the freezing of sea water, and ice sheets and glaciers formed from the accumulation and compaction of falling snow.

What is El Niño?
Every three to seven years during the months of December and January, fish in the coastal waters off of South America virtually vanish, causing the fishing business to come to a standstill.

What is La Niña?
The cold counterpart to El Niño is known as La Niña.

What are phytoplankton?
Phytoplankton are microscopic plants that are the foundation of the marine food chain. Because they also exert a global-scale influence on climate, phytoplankton are of primary interest to oceanographers and Earth scientists around the world.

What is a coccolithophore?
Coccolithophores are one-celled plants that live in large numbers throughout the upper layers of the ocean.

Tropical Deforestation
Tropical forests are home to half the Earth's species, and their trees are an immense standing reservoir of carbon. Deforestation will have increasingly serious consequences for biodiversity, humans, and climate.

Measuring Vegetation (NDVI & EVI)
In an effort to monitor major fluctuations in vegetation and understanding how they affect the environment, scientists began using satellites to measure and map the density of green vegetation over the Earth. These "vegetation indices" identify where plants are thriving and where they are under stress (i.e., due to lack of water).

Global Fire Monitoring
Forest fires, brush fires, and slash and burn agriculture are a significant force for environmental change. Remote sensing of fires, smoke and burn scars allows for improved detection of fire characteristics as well as their short- and long-term effects on ecosystems.

Tropical Deforestation
The loss of tropical rain forest is more profound than merely destruction of beautiful areas. If the current rate of deforestation continues, the world's rain forests will vanish within 100 years-causing unknown effects on global climate and eliminating the majority of plant and animal species on the planet.

Changing Global Land Surface
Human presence across the face of the Earth is substantial and growing. Scientists estimate that between one-third and one-half of our planet's land surface has been transformed by human enterprises. Yet, scientists cannot say what, if any, long-term impacts this presence will have on global climate systems.

Drought: The Creeping Disaster
While much of the weather that we experience is brief and short-lived, drought is a more gradual phenomenon, slowly taking hold of an area and tightening its grip with time. In severe cases, drought can last for many years, and can have devastating effects on agriculture and water supplies.

Land Cover Classification
Nearly every aspect of our lives is tied into the vegetation and ground cover that surround us. For years scientists across the world have been mapping changes in the landscape to prevent disasters such as floods and drought. By using imaging satellites, scientists have the ability to observe large tracts of the Earth's surface in a fraction of the time needed to complete aerial or ground surveys.

What is a coccolithophore?
Coccolithophores are one-celled plants that live in large numbers throughout the upper layers of the ocean.

Sunspots and the Solar Max
A sunspot is a region on the surface of the sun that is temporarily cool and dark compared to surrounding regions. Sometimes the sun contains a large number of sunspots—a "solar maximum"—while at other times, few or none are seen—a "solar minimum." The year 2000 marks another solar maximum.

Why Isn't Earth Hot as an Oven
Sunlight is the source of energy for the Earth's oceans, atmosphere, land, and biosphere. It would take 1.7 billion large power plants to equal the energy coming to the Earth from the Sun! Where does all the Sun's heat go? Why doesn't the Earth just keep getting hotter?

Human Spaceflight Fact Sheet
Astronaut photography of Earth from the first space flights in the 1960s formed the foundation for the remote sensing technologies that followed

Aqua - First Light
On May 4, 2002, NASA launched Aqua, the sister to the EOS "flagship" — Terra — launched in December 1999. Aqua carries six state-of-the-art instruments to observe the Earth's oceans, atmosphere, land, ice and snow covers, and vegetation, providing high measurement accuracy, spatial detail, and temporal frequency.

Earth Observing-1 (EO-1)
On November 21, 2000, NASA will launch the first mission of the New Millenium Program (NMP), Earth Observing-1 (EO-1). While flying at an altitude of 705-kilometers, EO-1's primary focus is to test advanced instruments, spacecraft systems, and mission concepts in flight.

Space-based Observations of the Earth
Following the development of rockets during World War II, smaller, lighter launch vehicles called "sounding rockets" were eventually developed to permit man to view the Earth from space. This article provides an introduction to the history of viewing our planet from space and how we are better able to understand our environment as a result.

Terra
On December 18, 1999, NASA launched the EOS "flagship" — Terra — to begin collecting a new 18-year global data set on which to base future scientific investigations about our complex home planet.

ACRIMSAT
NASA's ACRIMSAT launched on December 20, 1999 on a five-year mission that will measure the total energy emitted by the sun.

Remote Sensing
The term "remote sensing" is commonly used to describe the science—and art— of identifying, observing, and measuring an object without coming into direct contact with it.

QuikSCAT
The Quick Scatterometer launched in June 1999 will provide climatologists, meteorologists, and oceanographers with daily, detailed snapshots of the winds swirling above the world's oceans.

Landsat 7
The latest mission in the Landsat series was launched in April 1999 to continue gathering remotely sensed images of the land surface and surrounding coastal regions.

Tropical Rainfall Measuring Mission
The TRMM is the first mission dedicated to measuring tropical and subtropical rainfall through microwave and visible infrared sensors, and includes the first spaceborne rain radar.

On the Shoulders of Giants
These geoscientists revolutionized our understanding of the atmosphere, oceans, climate, and environment. Their work formed the foundation on which current research depends.

William Smith discovered that he could identify rock layers by the unique fossils they held. His discovery helped later generations of scientists to understand the history of life on Earth.

Joanne Simpson pioneered studies of cloud models, hurricanes, weather modification, and guided the development of the Tropical Rainfall Measuring Mission.

Nicolaus Steno established some of the most important principles of modern geology.

Rachel Carson’s passionate plea for restraint, common sense, and stewardship resulted in fundamental changes not only in North America, but also throughout the world.

Verner Suomi used a unique combination of determination, hard work, inspiration and freshman physics to become known as the "father of satellite meterology."

Wernher von Braun is, without a doubt, the greatest rocket scientist in history. His crowning achievement, as head of NASA's Marshall Space Flight Center, was to direct the mission to land the first men on the Moon in July 1969.

John Martin devoted his career to understanding the basic chemical processes that govern life in the ocean. His famous "iron hypothesis" not only changed the way in which scientists view the ocean, but also introduced a controversial method for lowering carbon dioxide levels in the atmosphere.

Alfred Wegener proposed the theory of continental drift—the idea that the Earth's continents move over hundreds of millions of years of geologic time—long before the idea was commonly accepted.

Robert Goddard is considered by many to be the father of modern rocketry, and was a physicsit of great insight who had a genius for invention.

Vilhelm Bjerknes is considered by many to be one of the founders of modern meteorology and weather forecasting.

Roger Revelle was once described as "one of the world's most articulate spokesmen for science" and "an early predictor of global warming."

Samuel P. Langley made contributions both to research about the sun's effect on weather—and indeed life on Earth—and to the development of manned flight.

Milutin Milankovitch dedicated his career to developing a mathematical theory of climate based on the seasonal and latitudinal variations of solar radiation received by the Earth as a result of the Earth's orbital motions.

Svante Arrhenius was the first person to investigate the effect that doubling atmospheric carbon dioxide would have on global climate, the effect known as "global warming."

John Tyndall was a man of science whose research on the radiative properties of gases contributed greatly to the understanding of how these gases affect the heating and cooling of the Earth's atmosphere.

Benjamin Franklin established that lightning was an electric spark, made early weather and climate predictions based on meteorological observations, and first mapped the Gulf Stream.