Every year, plants experience both regular prosperity and decline, both on land and in the ocean.
"These visual images show our planet, with unbelievable appeal," oceanographer Jean Karl Feldman of the NASA Goddard Space Flight Center (Gene Carl Feldman) said, "this is the earth, every day in the breath of the earth, it will change with the season of the sun, wind, ocean currents and temperature to make the response"
NASA has been using satellites for 20 years of continuous observations of plant life on land and sea. In 1997, NASA launched the Sea-viewing Wide Field-of-View Sensor (SeaWiFS), which is exactly the 20th anniversary of this fall. In these 20 years, satellite observations have witnessed the Arctic getting greener as temperatures rise and have found other worrying phenomena, such as the expansion of "biological deserts." "Biological desert" refers to a region where there are extremely few nutrients in the oceans and extremely low productivity.
This visualization shows 20 years of observations, dating back to 1997. Terrestrial vegetation coverage varies from brown (low) to green (high); and marine surface phytoplankton from purple (low) to yellow (high).
These maps also show clear seasonal changes in land and sea as plants thrive and decline during the year. The picture shows the "Wake Up" vegetation in North America during the spring.
Since 1997, SeaWiFS has been providing uninterrupted observations and mapping of the global ocean color. Chlorophyll green can be used as an indicator of plant abundance. Scientists found that the most green and shallow regional centers are located in the subtropical circulation areas of the Pacific, the Atlantic and the South Indian Ocean. The total area of all these "biological deserts" accounts for about 40% of the Earth's surface. Observations over the past decade have revealed that the area of the global marine life desert is expanding and far exceeding the results predicted by the global warming model.
Although scientists used satellites to observe the Earth as early as 1997, the launch of SeaWiFS triggered the first sustained global effort. When SeaWiFS data was first released, many were skeptical. NASA said people were not sure at the time whether they would see the Earth's surface clearly from space.
"We were all shocked when we saw the first pictures," said Compton Tucker, a scientist at NASA Goddard Space Flight Center, speaking of a 1985 study on grassland greening and degradation in Senegal, 1985.
Researchers have developed a method to compare satellite data from two wavelengths. They used the Normalized Difference Vegetation Index to assess the growth of green vegetation on the Earth's surface. "These images are incredible because they show how the vegetation changes every year, year after year," Tucker said. "When we were writing this paper, people blamed us for" painting with numbers, "or fabricated data However, this is the first time that plant - based photosynthesis has been used to study vegetation from space.
In 1978, a device called the Coastal Zone Color Scanner (CZCS) enabled scientists to observe water color for the first time. The image above shows the color change of the El Niño-La Niña during the Eastern Equatorial Pacific Ocean in 1998.
NASA has been using satellites for 20 years of continuous observations of plant life on land and sea. In 1997, NASA launched the Sea-viewing Wide Field-of-View Sensor (SeaWiFS), which is exactly the 20th anniversary of this fall.
In 1978, a device called the Coastal Zone Color Scanner (CZCS) enabled scientists to observe water color for the first time. The instrument reveals many notable changes, such as the shift from El Niño to La Niña in 1998.
"Across the eastern Pacific, from the coast of South America to the line of change of dates, the area equivalent to the biological desert turned into a thriving" rainforest, "Feldman said." And we see it all happening in real time. For me, this is the first time such observations have demonstrated the power to see how the oceans react to the worst environmental disturbance in just a few weeks, and it also shows the oceans and their lives All life has incredible resilience - if you get the chance. "
Satellite data also show the evolution of marine phytoplankton over many years. In the "Biological Desert" area, currents have low rates of flow and organisms grow extremely slowly. Satellite data can also reveal the impact of climate change on crops around the world. NASA hopes to go further and study photosynthesis in space and learn where plants are and when they begin to convert light energy into sugars.
For example, the corn belt (Corn Belt) is a region located in the midwestern United States, due to the large number of food crops, is very conspicuous in the satellite image. "This is a bit unexpected, yes, you can measure it," the NASA Goddard Space Flight Center Joanna Joyner (Joanna Joiner) said, "at the peak, these plants have the highest rate of fluorescence on the earth. An important problem is not solved, these plants can absorb carbon uptake, why every year is different, and those regions caused by this change"