A team of researchers from GERS including Zhu and NRE Ph.D. student Tian Li, along with researchers from NASA and the University of Maryland Earth System Science Interdisciplinary Center has developed a method that is capable of providing daily global moderate resolution nighttime light change maps. The results are published in the journal Remote Sensing of Environment. Though Black Marble already reduces quite a bit of exterior noise, Zhu and Li sought a way to further reduce the fluctuations and make the data even better. Many factors cause temporal variation in the signal that reaches the sensors. Zhu gives the example of moonlight, which impacts how much illumination the sensors receive throughout the moon’s phases and movement across the night sky. Some objects can distort the reflection of moonlight, like buildings, trees, or other structures. Atmospheric conditions can cause further signal deviations, with things like aerosols or haze.