Abstract. Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP) and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8), which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms) and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

Abstract. Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP) and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8), which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms) and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

It is found that slow interstellar electrons moving in the vicinity of the earth under the influence of a radial electric field caused by the earth's interception of cosmic rays as charged particles predominantly of one sign and the magnetic field of the earth's dipole will produce a continuous series of shell currents concentric with the earth. The current density in the shells varies with the inverse fifth power of the distance from the earth's center and the cosine of the latitude. These currents contribute to the earth's field a uniform component parallel to the magnetic axis in a direction from south to north. It is found that if either cosmic-ray intensity or the density of positive ions in the vicinity of the earth varies, there will result a variation in magnetic field intensity at the earth's surface. It is shown that the ratio (AI/I)/(AH/H), where I represents cosmic-ray intensity and H the horizontal component of the earth's magnetic field intensity, for a variation caused by a change in cosmic-ray intensity is of the same order of magnitude as observed experimentally.