New NASA data sheds (Sun) light on climate models

Scientists at the University of Michigan, NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and University of Colorado Boulder recently used TSIS-1 SSI satellite data in a global climate model for the first time – and got a few surprises. Another dent in the myth of ‘settled’ climate science.
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Have you ever worn a dark T-shirt on a sunny day and felt the fabric warm in the Sun’s rays? asks NASA-GISS.

Most of us know dark colors absorb sunlight and light colors reflect it – but did you know this doesn’t work the same way in the Sun’s non-visible wavelengths?

The Sun is Earth’s power source, and it emits energy as visible sunlight, ultraviolet radiation (shorter wavelengths), and near-infrared radiation, which we feel as heat (longer wavelengths).

Visible light reflects off light-colored surfaces like snow and ice, while darker surfaces like forests or oceans absorb it. This reflectivity, called albedo, is one key way Earth regulates its temperature – if Earth absorbs more energy than it reflects, it gets warmer, and if it reflects more than it absorbs, it gets cooler.

The picture becomes more complicated when scientists bring the other wavelengths into the mix. In the near-infrared part of the spectrum, surfaces like ice and snow are not reflective – in fact, they absorb near-infrared light in much the same way a dark T-shirt absorbs visible light.

“People think snow is reflective. It’s so shiny,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies in New York City and acting NASA senior climate adviser. “But it turns out in the near-infrared part of the spectrum, it’s almost black.”

Clearly, for climate scientists to get the whole picture of how solar energy enters and exits the Earth system, they need to include other wavelengths besides visible light.

That’s where NASA’s Total and Spectral Solar Irradiance Sensor (TSIS-1) comes in. From its vantage point aboard the International Space Station, TSIS-1 measures not only the total solar irradiance (energy) that reaches Earth’s atmosphere, but also how much energy comes in at each wavelength.

This measurement is called spectral solar irradiance, or SSI. TSIS-1’s Spectral Irradiance Monitor (SIM) instrument, developed by the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics, measures SSI with an accuracy better than 0.2%, or within 99.8% of the true SSI values.

“With TSIS-1, we have more confidence in the measurements of visible and near-infrared light,” said Dr. Xianglei Huang, professor in the department of Climate and Space Sciences and Engineering at the University of Michigan. “How you partition the amount of energy at each wavelength has implications for the mean climate.”

Full article here.