A study conducted by the Japan Aerospace Exploration Agency has now revealed how scientists can observe cloud dynamics globally. This study peers beyond the internal motion of clouds in a bid to understand things like precipitation and the interaction between clouds and solar radiation.
Breaking The Ice In Observing Cloud Dynamics
To better observe cloud dynamics, a team of researchers from the Japan Space Agency (JAXA), the University of Tokyo, and Kyushu University used data from a satellite and a supercomputer simulation. By blending the output from these two instruments, the team was able to better understand cloud dynamics and how they cause the varying weather conditions.
The satellite in question is the EarthCARE (Earth Cloud Aerosol and Radiation Explorer), and the supercomputer is the Non-hydrostatic Icosahedral Atmosphere Model (Nicam). Both of these instruments have features that make them ideal for this study.
The EarthCARE satellite comes with a Cloud Profiling Radar (CPR), which doesn’t provide a static snapshot of cloud density like other satellites. Instead, it measures “Dopper velocity”, which is the frequency shift of microwaves as they bounce off moving cloud particles.
This velocity comprises the terminal fall velocity and vertical velocity of the atmosphere. By separating Dopper velocity, researchers will be able to determine where moisture in clouds is and how it is transported through the atmosphere.
After gathering data from the EarthCARE satellite, the next stop for the researchers was the Non-Hydrostatic Icosahedral Atmosphere Model (Nicam). This supercomputer is a global cloud-resolving model which divides the Earth into a mesh of sub-kilometre scales.
To compare the simulations from the Nicam supercomputer with real clouds, the researchers had to use the Joint Simulator for Satellite Sensors. This generates a synthetic radar signal based on the Nicam simulation, and it is similar to that of the EarthCARE satellite.
What Was Revealed By This Research?
What exactly did this research conducted by the Japan Space Agency reveal? First, this research showed that the two components of Doppler velocity mentioned earlier can not only be separated but also estimated accurately from the satellite data.
Next, the Nicam simulation in this research was able to accurately reproduce the boundary structures between the rainy and snowy regions in comparison with satellite observations. The study was also able to identify what is referred to as “random satellite-specific estimation errors” often seen in satellite data.
Pin-pointing these errors will help researchers more accurately calibrate future observations, separating the satellite errors from atmospheric events. This research is now laying the foundation for further study into cloud dynamics.
