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The MLS Ice Water Path

Contact: Alyn Lambert

Basic Information
Cloud ice water content (IWC) is defined as cloud ice mass in unit volume of atmospheric air. It can vary largely from 0.0001 g/m3 in thin cirrus to 1 g/m3 inside convective core. The vertically integrated column of IWC is ice water path (IWP).
MLS Viewing Geometry and Spacial Averaging
Sample ice water path map

How it is part of MLS Science Objectives

Like IWC, MLS IWP can provide observational constraints on climate model parameterizations so as to improve the model skills in predicting future climate changes.

How EOS MLS derives IWP

MLS standard IWP is retrieved from cloud-induced radiances (Tcir) of the 240-GHz window channel at 650 hPa tangent pressure. It represents a partial column above ~6 km, and is stored in the v2.2 L2GP IWC file as a separate swath. For the IWP retrieval, Tcir is first converted to a hIWP along the slant path with a ~3 degree elevation angle using the modeled Tcir-hIWP relation, The hIWP is then converted to the nadir IWP at the tangent point location, and interpolated to MLS standard horizontal grid.

Time series of IWP maps

Quick Product Information for data version v4.2

  • Swath Name: IWP
  • Units: g/m2
  • Useful Ranges: Column above ~6km
  • DAAC Short Name: ML2IWP
  • Precision: typically 3 g/m2
  • Accuracy: ~50% (estimated from CloudSAT comparisons)
Download EOS Aura MLS IWC v4.2 data

Publications related to the MLS IWP data product


  1. Su, H., J.H. Jiang, J.D. Neelin, B.H. Kahn, J.W. Waters, N.J. Livesey, Y. Gu, "Reply to comment by Roberto Rondanelli and Richard S. Lindzen on “Variations in convective precipitation fraction and stratiform area with sea surface temperature”", Journal of Geophysical Research 115, D06203, doi:10.1029/2009JD012872, 2010. reprint

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