TAO buoy temp. + ASCAT

• Moment of truth: composite ASCAT winds against buoy temperature; start with western equatorial Pacific.

• We define CPs by a temperature drop of 1.5°C over 1h, or 2°C over 2 h.

• After ASCAT winds, repeat compositing procedure for OLR, and for Seawinds (winds + rr).

• Now at 6°N.

• Seasonal cycle of CPs looks different at two buoys only 550 km apart.

• 0N appears to peak in DJF, while 5N hits a minimum in DJF (?).

• Who knows, maybe this metric is sensitive to the CP definition, or maybe need a few more years for reliable estimate.

• Buoys used to form composite.

• CP count in each bin, i.e. number of CPs for which ASCAT data is available. n≈100 at nadir (near t=0).

• Red line should be close to double blue line.• ±12 h bins larger (blue line) since they actually extend to

±13 h.

• Composite buoy air temperature (left) shows that air temperature doesn’t fully recover, even by 12 h.

• Min(div) and max(div), at right, show nothing.• Simplest explanation is that satellite can’t resolve downdrafts.• Other explanations include a mismatch in the buoy clock

(check against OLR), sensitivity to low winds (filter for stronger winds), or rain contamination (filter for clear-sky CPs).

• Composite winds and divergence show very little in common with NICAM.

• Easterly background winds still evident.

• Contour levels are 0.5×10-5 s-1.• Discouraging that no signal

exists at 0, 1 hr.

• Comparison of buoy wind speed vs. “point” ASCAT wind speed.

• Buoys show nice bump at t=-1,0, consistent with Addis et al., Young et al. 1995.

• Maybe search for highest wind speed in box? ASCAT might be able to resolve small-scale wake at buoy, but perhaps somewhere in box shows higher wind speed.

• Now compare (vector-averaged) u,v.

• Buoy and ASCAT show hint of W-IGW propagation, but phase is different.

• ASCAT, especially, appears to show a prominent wave with period 12–13 h.

• ASCAT u signal is actually consistent with divergence as W-IGW passes location.

• I should extend bins to ±24 h to hopefully better resolve wave. Also add 2 h spacing.

• Also I should record actual (u,v) values so I can compute std(u), std(v) in each bin.

• Top: min(IR temp.) within 115km of buoy, for Nov 2012-Jan 2013. Standard error shown by dashed lines.

• Right: Composite maps of IR temperature centered at buoy, for Nov 2012-Jan 2013. Lowest contour at t=1h is for 239K, ΔT≈25K. This is significant (cf. top plot), but also suggests that some shallow convection contributes, since “deep” usually 210K.

• Note that the spatial scale of the temperature depression is ~200 km.

• Composite buoy wind speed for just 3 months, now plotted with standard error (dashed).

• CP “spike” in wind speed easily exceeds standard error, even for this short record.

• Now at 6°N.

• Now at 6°N.