重大新闻：Landsat 9 卫星影像已开放下载

USGS今天正式开放了Landsat 9数据的下载。自从2021年10月份以来，Landsat 9已经获取了57,000张影像，平均每天750张影像左右。数据可以通过https://earthexplorer.usgs.gov下载。

新闻稿：http://ow.ly/jl8r50HRZQ3

Each of the more than 57,000 Earth surface images gathered by Landsat 9 since October 2021 were made available on the morning of February 10, 2022 through USGS EarthExplorer, Machine to Machine (M2M) and LandsatLook platforms. Landsat 9 will gather an additional 750 images each day, which will be accessible to the public within hours of acquisition.

The release of Landsat 9 imagery stands as a major milestone for the Landsat Program, which began 50 years ago with the launch of Landsat 1, then known as the Earth Resources and Technology Satellite (ERTS).

“Landsat 9 is distinctive among Earth observation missions because it carries the honor to extend the 50-year Landsat observational record into the next 50 years,” said Chris Crawford, USGS Landsat 9 Project Scientist, who works at the USGS Earth Resources Observation and Science (EROS) Center near Sioux Falls, SD. “Partnered in orbit with Landsat 8, Landsat 9 will ensure continued eight-day global land and near-shore revisit.”

Crawford is co-chair of the Landsat Science Team (LST), which met virtually to discuss the impending release of Landsat 9 data on February 9, 2022. The LST includes members from the Federal government, academia, the private sector, and international organizations. It provides a voice for the global scientific community, which relies on the Landsat mission to provide a landscape-level view of the land surface, surface waters (inland lakes and rivers) and coastal zones, as well as to document the changes that occur from both natural processes and human-induced activity.

“We should all be proud of having worked on this program, and I’m proud of the contributions you’ve all made in the science community by making use of this tremendous data stream” USGS National Land Imaging Program Coordinator Tim Newman told the LST during its winter meeting.

Landsat 9, the first mission under the multi-decadal USGS-NASA Sustainable Land Imaging (SLI) partnership, was launched from Vandenberg Space Force Base on September 27, 2021. It became operational after its successful post-launch assessment review, marking the beginning of the satellite’s mission to extend Landsat's unparalleled, 50-year record of imaging the Earth. The satellite’s Operational Land Imager 2 (OLI-2) captures observations of the Earth’s surface in visible, near-infrared, and shortwave-infrared bands, while its Thermal Infrared Sensor 2 (TIRS-2) measures the thermal infrared radiation, or heat, emitted from the Earth’s surface.

Sources/Usage: Public Domain.

False color image of the Anchorage, Alaska area, as observed by Landsat 9 on November 20, 2021. The image was built using infrared, red, and blue bands of the electromagnetic spectrum. Landsat satellites’ ability to peer beyond visible light make the data acquired with each pass more valuable to the study of Earth's surface changes.

Landsat 9 detects more subtle differences than its predecessor, especially over darker areas such as water or dense forests. With this improved radiometric resolution, Landsat 9’s OLI-2 can differentiate 16,384 shades of a given wavelength. In comparison, Landsat 8 provides 4,096 shades. Landsat 9 takes the place of Landsat 7, which only has 256 shades. TIRS-2, meanwhile, has significantly reduced stray light, enabling improved atmospheric correction for more accurate surface temperature measurements.

All commissioning and calibration activities show Landsat 9 performing just as well, if not better, than Landsat 8. In addition to routine calibration methods, an underfly of Landsat 9 with Landsat 8 in mid-November 2021 provided cross-calibration between the two satellites’ onboard instruments, ensuring data consistency across the Landsat Collection 2 archive.

As with all Landsat imagery, satellite acquisitions from Landsat 9 will be processed, archived, and distributed from the USGS EROS Center. Since 2008, the USGS Landsat Archive has provided more than 100 million images to data users around the world, free of charge. The program’s unique long-term data record provides the basis for a critical understanding of environmental and climate changes occurring in the United States and around the world.

USGS and NASA are already planning the development of the follow-on SLI missions, Newman said, to include Landsat Next, the successor mission to Landsat 8.

Follow this link to learn more about Landsat 9 data access. Follow this link for the full technical announcement on the Landsat 9 data release.

Sources/Usage: Public Domain.

These images of Hawaii’s Kilauea Volcano, captured on January 25, 2022, show two of the USGS science products built from imagery collected by the Landsat 9 satellite. The left image shows Landsat surface reflectance, a product that removes atmospheric interference to best mirror on-the-ground conditions, as recorded here in the short-wave infrared, near infrared and red bands of the electromagnetic spectrum. On the right is the same image seen through the lens of the Landsat surface temperature product, which records temperature in Kelvin.