Figure 1. Cruise track for the NOAA Ship Ronald H. Brown for EPIC2001. The large square box indicates the primary ITCZ operation region. TAO buoys are the small circles; the WHOI IMET buoy at 20 S 85 W is indicated by the circled X.

Figure 2. ITCZ time series of daily-averaged rainfall (upper) and flux components (lower panel). The flux components are net solar warming of the ocean (blue circles); net IR cooling (cyan); sensible heat (green line) and latent heat (red x's). The periodicity evident in the precipitation and fluxes is caused by the passage of atmospheric easterly wave disturbances.

Figure 3. Time-height cross section from the 35 Hhz cloud radar for September 23, 2001 (Day 266) showing a period of deep convection. Upper panel shows the backscatter intensity (calibrated). The melting layer is apparent as the bright band at about 4.5 km near the end of the period; clouds above this altitude are predominantly ice. Middle panel is the mean Doppler shift of the return showing the fall velocity of the particles combined with the air motion. Heavy rain appears in blue and red colors. Attenuation of the return by heavy rain is apparent in the black vertical regions around 1700 and 1900.

Figure 4. Near-surface properties measured on the transect from the S edge of the ITCZ, through the ITCZ entry region, and into the suppressed boundary layer at the equatorial cold tongue: wind speed (upper panel); SST- blue circle and air T - green x's (middle panel); sensible heat flux - blue circles and latent heat flux - green x's (lower panel). Fluxes are suppressed in the stable boundary layer caused by warm air crossing the cold tongue from the south. The warm SST front triggers convective turbulence which increases fluxes and mixes down higher momentum (thus, the increase in wind speed).

Figure 5. Stratocumulus cloud characteristics on Oct. 18, 2001. Upper panel: total liquid water path (LWP) from two microwave radiometer systems (green line and red dots) and cloud fraction from a ceilometer (blue circles). Lower panel: cloud radar backscatter intensity (color contours) and ceilometer cloud base heights (white dots).

Figure 6. Optical thickness computed from =cosine(solar zenith angle), Tr, and LWP using the model of Stephens (1978, upper panel) and model of Dong et al. (1998, lower panel) as a function of LWP. The green line is a mean curve from measurements made at San Nicolas Island off the coast of California in 1987. The red line is from ship measurements made near the equator at 145 W longitude in 1992. These characteristic lines are typical of the kinds of relationships used in climate models.