Balloon-borne radiation measurements demonstrate radiative forcing by water vapor and clouds

Solar shortwave and terrestrial thermal longwave irradiance are measured at radiation sites at the Earth's surface and on satellite platforms high up in space, since many years. Radiation profiles through the Earth's atmosphere, however, have only sporadically been measured from enhanced upper-air radiosondes. Here we show profiles of solar and terrestrial radiation measured with balloon-borne radiometers through cloud-free and cloudy atmospheres, which reveal radiative effects of temperature, water vapor, ozone and clouds on downward and upward radiation. Shortwave radiation profiles show solar absorption in the free atmosphere and strong reflection in clouds and albedo effects on the ground and the atmosphere above. Longwave upward radiation profiles visualize terrestrial radiation emitted from the Earth's surface, which is partly absorbed and reemitted in the boundary layer and in the atmosphere by water vapor and other greenhouse gases. Longwave downward radiation profiles show the absorbed terrestrial radiation in the atmosphere and reveal the warming effect of increasing greenhouse gases, and by this visualize and demonstrate radiative forcing and a changing greenhouse effect by water vapor in the Earth's atmosphere. Longwave net radiation profiles show terrestrial emission into space to be reduced by water vapor and clouds. Measured radiation profiles are compared to numerically calculated radiation profiles.