Comparison of cloud liquid water paths derived from in situ and microwave radiometer data taken during the SHEBA/FIREACE

Mean cloud liquid water path LWP derived from microwave measurements using the standard ARM retrieval technique is nearly twice as large as coincident in situ aircraft data taken over the SHEBA ice camp in the Arctic during FIRE ACE. Using an algorithm adopted from satellite remote sensing that more completely accounts for the temperature dependence of water absorption and atmospheric gas absorption results in a 25 to 45 % reduction in LWP values relative to the standard ARM estimates. If possible precipitation cases are excluded, the mean results from the new technique differ by only 3% from the in situ data. Greater differences for heavier clouds may result from in situ probe uncertainties. This algorithm should provide accurate LWP retrievals for a variety of cloud conditions from the tropics to the highly supercooled Arctic clouds.