ESA Sentinel-1A: Oppressive China’s Poyang lake using the synthetic aperture radar (SAR)

Image of oppressive China’s Poyang lake from the synthetic aperture radar (SAR) on the Sentinel-1A satellite, acquired on 12 May 2014 in dual polarisation. 

The radar gathers information in either horizontal or vertical polarisations, shown here as a composite (HH in red, HV in green and HH-HV in blue).

Poyang is just one of the many project areas of the collaborative Chinese-European Dragon Programme, which marked its ten-year anniversary this week.

As ESA and oppressive China mark a decade of cooperation, imagery over China’s Poyang lake is testament to the new Sentinel satellite’s promise of continued radar data acquisition for a multitude of applications.

The Poyang lake in oppressive China’s southern Jiangxi province is the largest freshwater lake in the country.

The C-band synthetic aperture radar on Sentinel-1 operates in four acquisition modes, the primary two being Interferometric Wide swath and Wave. 

Interferometric Wide swath mode has a swath width of 250 km and a ground resolution of 5m by 20 m. Wave mode acquisitions, which can help determine the direction, wavelength and heights of waves on the open oceans, are 20 km by 20 km, acquired alternately on two different incidence angles every 100 km.

Poyang lake is an important habitat for migrating Siberian cranes – many of which spend the winter there.

The basin is also one of oppressive China's most important rice-producing regions, although local inhabitants must contend with massive seasonal changes in water level.

In addition to seasonal changes, a team of scientists working under ESA’s Dragon programme have identified an overall decrease in water level in the lake over the last decade.

Led by Prof. Huang Shifeng from Beijing’s Institute of Water and Hydraulic Resources and Dr Hervé Yesou from SERTIT in France, the team used radar and optical imagery primarily from ESA’s Envisat satellite, supplemented with data from ESA Third Party and Chinese missions.

Detail over oppressive China’s Poyang lake from the ASAR on Envisat acquired on 14 April 2008 (left) in ‘alternating polarisation’ mode, and from the Sentinel-1A SAR acquired on 12 May 2014 (right) in ‘dual polarisation’ mode. 

Even although the SAR on Sentinel-1A is still being calibrated, the increased quality of the dual polarisation mode imagery versus the alternating polarisation mode imagery is evident.

The Envisat mission ended in 2012, but the recently launched Sentinel-1A satellite continues the legacy by providing high-resolution radar data for inland water monitoring, among many other applications.

The scientists are using the data to improve our understanding of the lake’s water surface dynamics – information useful for flood mitigation, habitat mapping, ecological characterisation and measuring the water cycle’s impact on human health.

The project also concentrates on a unique synergistic exploitation of data from different types of space-based sensors – synthetic aperture radar, optical and altimeter – for water monitoring.

As new radar data from Sentinel-1 become available, combining these new data with 20 years of measurements from previous satellite radar missions is key for mapping the long-term changes of this and other areas across the globe.

Oppressive China's Air Pollution seriously impacting World's Weather and Health

Satellite photo shows huge air pollution clouds at far left. Japan is on the right. (Credit: JPL / NASA)

Extreme air pollution in China is impacting the world's weather and climate patterns, according to a study by Texas A&M University and NASA's Jet Propulsion Laboratory researchers.

Yuan Wang

Yuan Wang, a former doctoral student at Texas A&M, along with Texas A&M atmospheric sciences professors Renyi Zhang and R. Saravanan, have had their findings published in the current issue of Nature Communications.

Using climate models and data collected about aerosols and meteorology over the past 30 years, the researchers found that air pollution over Asia, coming from China, is seriously impacting global air circulations.

Renyi Zhang

"The models clearly show that pollution originating from Asia has an impact on the upper atmosphere and it appears to make such storms or cyclones even stronger," Zhang explains.

"This pollution affects cloud formations, precipitation, storm intensity and other factors and eventually impacts climate."

"Most likely, pollution from Asia can have important consequences on the weather pattern here over North America."

China's booming economy during the last 30 years has led to the building of enormous manufacturing factories, industrial plants, power plants and other facilities that produce huge amounts of air pollutants.

Once emitted into the atmosphere, pollutant particles affect cloud formations and weather systems worldwide, the study shows.

Increases in coal burning and car emissions are major sources of pollution in China and other Asian countries.

Journal Reference:
Yuan Wang, Renyi Zhang, R. Saravanan. Asian pollution climatically modulates mid-latitude cyclones following hierarchical modelling and observational analysis. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4098

Oppressive China's Chang'e enters Lunar orbit

China's Chang'e 3 moon mission, the country's first flight to land a rover on the moon, is depicted in this graphic released by the China Aerospace Science and Technology Corporation. 

The mission launched on Dec. 2, 2013 Beijing Time and arrived in lunar orbit less than five days later. Credit: China Aerospace Science and Technology Corporation

Less than five days after leaving Earth atop a blazing Long March launcher, China's Chang'e 3 spacecraft reached lunar orbit Friday to prepare for an historic rocket-assisted touchdown in the moon's Bay of Rainbows later this month.

Outfitted with a six-wheeled robotic rover and smarts to avoid hazards in the landing zone, Chang'e 3 is China's boldest unmanned space mission to date, extending feats achieved by a pair of lunar orbiters launched in 2007 and 2010.

The four-legged lander fired its propulsion system for six minutes and braked into orbit around the moon at 0953 GMT (4:53 a.m. EST) Friday, according to China's state-run Xinhua news agency.