On 7 July 2015, the Japan Meteorological Agency’s new satellite Himawari-8 began collecting weather data in the Asia-Pacific region. The geostationary satellite remains above the western Pacific and eastern Indian Oceans and monitors reflected sunlight and infrared radiation (IR) emitted by the Earth’s surface. Now Kurihara et al. have created a new algorithm that uses the satellite’s IR data to calculate sea surface temperatures for the region.
The new algorithm aims to surpass the accuracy of older satellite-based measurements by more precisely incorporating the physical processes behind sea surface IR emission. It also avoids directly incorporating numerical weather prediction—or weather forecasting—data, which often relies on sea surface temperatures. Thus, leaving forecasts out of the algorithm avoids circular dependence.
The researchers tested the new algorithm by comparing its sea surface temperature measurements to data collected by the National Oceanic and Atmospheric Administration’s international buoy network. From June to September 2015, each sea surface temperature measurement from the satellite was compared to the closest buoy data point within 3 kilometers and 3 hours. More than 630,000 pairs of satellite and buoy data points were compared.
For the most part, the satellite data were in good agreement with the buoy data. The satellite temperature measurements tended to be lower than those of the buoys, but this may be because buoy measurements were collected at slightly different depths from the satellite measurements.
Himawara-8 measured slightly higher temperatures than the buoys along the boundaries of the region monitored by the satellite, especially in the northern Pacific Ocean. But more research is necessary to reveal the reason for this positive border bias. The scientists also plan to see how the biases observed so far hold up for different seasons and regions, after they collect a full year’s worth of satellite data. (Geophysical Research Letters, doi:10.1002/2015GL067159, 2016)
—Sarah Stanley, Freelance Writer
Citation: Stanley, S. (2016), New weather satellite captures sea surface temperatures, Eos, 97, doi:10.1029/2016EO046207. Published on 19 February 2016.