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First Global Measurement of Cloud Ice in Upper Troposphere


The amounts of water vapor, rainfall and cloud amounts in the tropics all play a role in the Earth's climate. Scientists their models by comparing their results with observations, and until now, upper tropospheric cloud ice has been an "unconstrained parameters" in most climate models. This means that different models calculate different values, but there were no observations so no one could tell if their model made sense or not.

Cloud ice measurement will improve global circulation models used for weather and climate forecasts. The measurements will also help quantify the upper tropospheric (UT) hydrological cycle, including water vapor feedbacks on climate change.

(bottom right) This measurement shows that cloud ice is more frequently seen over warm oceans. Not unexpected, warm oceans lead to stronger convection and the lofting of water and ice into the upper troposphere. The break point is near 300K SST where there is significantly more water in the upper troposphere. This additional water and ice acts as a greenhouse gas blocking radiation from escaping to space. This slide suggests that warmer oceans will lead to more trapping of radiation leading to warmer oceans... a positive feedback.

MLS measurements

(above) This measurement of global cloud ice helps us answer that question. Note the differences between the models (especially over South America).

MLS measurements

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