□ Adiabatic --*— Sub-adiabatic

qdDq QD

n nn -

Figure 6. Latitudinal variation of d ln D/dT obtained for low-level, single-layer clouds over the Pacific Ocean between 55°S and 55°N. Results are obtained for the overcast pixels based on the adiabatic and subadiabatic values of the liquid water content.

subadiabatic or adiabatic rate. Similarly, the positive value in the tropics implies that cloud geometrical thickness would have increased by about 0.05 km per kilometer cloud thickness. However, there is no information available for the cloud geometrical thicknesses. Also, there is no information concerning the absolute values of the cloud LWC and their rate of change for the clouds under the investigation.

3.5. Cloud droplet effective radius and liquid water path

Current operational satellite retrieval algorithms employ the near-IR radiances from a single channel at either 3.7 ¡m (e.g. AVHRR algorithm) or 2.1 ¡m (e.g. MODIS algorithm) for the retrieval of the cloud droplet effective radius (re). The retrieved re is used together with the retrieved cloud optical depth, t, to compute the cloud LWP, given by (Hansen and Travis, 1974)

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