First Images Press Conference April 19, 2000

introduction / modis / misr / aster / mopitt / ceres / conclusion MODIS, Vincent Salomonson     The members of the Science Team for the Moderate-resolution Imaging Spectroradiometer, which we call MODIS, were among those Dr. Kaufman mentioned as being delighted and relieved when Terra successfully reached its orbit. MODIS is a powerful instrument that will contribute, along with the other Terra instruments, to answering many important questions about the Earth, including: How is the Earth system changing? How does the Earth respond to natural and human-induced changes? What are the consequences of these changes for human civilization? How well can we predict future changes to the Earth system? MODIS views a large swath of the Earth on every orbit, as seen in the first MODIS images taken on February 24. This image of eastern North America is 2300 km, or more than 1300 miles, across. With this type of image we can now study snow and ice cover, cloud cover and cloud type, vegetation cover and other land covers, the temperature of the oceans, and much more. Combining the swaths MODIS produces each day gives us frequent global views, such as this recently assembled view of land features. Such maps will be produced for 40 or more different properties of the land, ocean, and atmosphere, some as frequently as every day. The next images show several of the more powerful, new observations that MODIS will give us. We now have the capability to observe changes in vegetation on land in extremely fine detail. These images of the Eastern United States and the Chesapeake Bay show areas of healthy and vigorous plant growth at the highest resolution possible. As MODIS observes these areas every day, we can now see how vegetation changes due to drought, excessive rainfall, and activities of humankind that extend over large areas. MODIS can also monitor plant life in the oceans-the microscopic phytoplankton that float in the surface layers of the ocean-and its degree of photosynthetic activity. Because of its improved detection capabilities, MODIS can better measure the concentration of chlorophyll associated with the phytoplankton. And by observing the fluorescence of the phytoplankton-a new capability unique to MODIS-we can now gauge the health of phytoplankton. When these plants are under stress, they no longer photosynthesize and begin to emit absorbed sunlight as both heat and fluorescent light. In this series of MODIS images taken over the Arabian Sea, we first see high concentrations of chlorophyll in red tones and lower concentrations in shades of blue. In the next image, we see levels of fluorescence. By comparing those two quantities, we can see the degree of photosynthetic activity that is occurring. In this image, the highest amounts of photosynthetic activity are in blue and the lower ones are in red. MODIS will essentially monitor the "metabolism" of the Earth globally and regionally. We can essentially watch the Earth "breathe" and see how it is coping with stresses associated with expanding humankind and natural variability in weather and climate. With these types of observations, we will gain new insights into some of the "biological pump" processes associated with the cycling of carbon in the form of carbon dioxide between the land, ocean, and the atmosphere.   One of the most important and variable features to watch as the Earth changes is cloudiness and tiny particles suspended in the atmosphere called aerosols. The role of clouds and aerosols in Earth's climate is very complex. Some types of clouds, such as low-lying, bright water clouds, cool the planet by reflecting solar radiation back into space. Other types of clouds, the thin, high- altitude ice clouds, increases the absorption of infrared radiation from the Earth and warms the atmosphere. MODIS possesses unique capabilities to measure, in fine detail, how much of the Earth is covered in clouds and what types and sizes of water droplets and ice crystals are in the clouds. In this image over the southern tip of Africa, the thickest clouds are in shades of red and the thinner clouds in blue. We can estimate the cloud droplet or particle size, which is a key factor in how the clouds absorb and reflect radiation. The clouds with large particles, usually ice crystals, are shown in shades of red and the clouds with smaller water droplets in shades of blue. MODIS can also separate high clouds, even rather thin ones perhaps not visible to the eye. The next image off the coast of South America shows this capability. This capability allows us to study in detail the effect different clouds have on the heat balance of the Earth-atmosphere system. It also lets us strip off the clouds from the image to better reveal features hidden below. The last image I wish to show is MODIS' observations of water vapor. By far the most dominant greenhouse gas, water vapor is an important factor in studying weather and climate change.   In the coming months, data from MODIS will be used by scientists around the world to assess the state of the Earth and its highly linked land, ocean, and atmospheric systems. We are excited knowing that we will provide global and regional data sets at daily, weekly, monthly, and annual intervals that will improve our scientific knowledge of the Earth and enable better management of natural resources. Perhaps most importantly, MODIS will assist in better educating present and future generations about the workings and evolution of this marvelous and precious planet we call Earth. introduction / modis / misr / aster / mopitt / ceres / conclusion