NSF C-130 Mission Summary Report (EPIC)

RF15 - C-130 SST Front Stacks

Mission Summary - This flight represented the first of two SST front stack
missions.  The weather of the area included a suppressed ITCZ, although
some cells were observed, unlike on the previous day, 2 October, during
a 95 W transect mission by the C-130.  The operating region on this flight
was entirely south of 3.5 N, and except for descent and ascent soundings,
limited to the region of the ABL and immediately above.  The ABL over the 
SST front and cold tongue (as on the flight of 2 October) featured relatively
brisk southerlies over and on the north side of the SST front and relatively
high humidities above the ABL.  There were virtually no clouds above the
ABL.  The clouds over the cold tongue were quite shallow, with indistinct
bases near the surface and tops only to 300 m.  These clouds resembling
sea fog were observed on two of the early 95 W transects; more recent
95 W transects took place when the cold tongue clouds consisted of stratus
near the 700 m level.  Fifteen BT's were deployed as an add-on and thirteen
of these were successful.  The execution of the E-W stacks went well, with
each set consisting of legs at 100', just below cloud base, near and mostly
slightly below cloud top, and somewhat above cloud top.

Flight Notes -

1437	Take Off
1526	Lat 12.6, Over As at 2.5 km, flight-level winds 135 @ 8 m/s
1538	Lat 11.8, no more As, CLR below, SCT-BKN Ci above
1620	Lat 8.6, flight-level wind 105 @ 12 m/s, mostly SCT BL Cu with
	some blobs of more vigorous, but still low-topped Cu congestus
1720	Beginning descent for low-level work
1735	Lat 3.1, at 100', SST 27.4, TA 25.6, wind 170 @ 10 m/s, thetae 342,
	q 15, SABL shows BL Sc between 400-700 m, CLR above
1743	Lat 2.9, BT (maybe OK), cloud base/top at 300/900 m
1748	Lat 2.4, 5000', BT (good), uniform undercast, CLR above
1751	Lat 2.2, 5000', BT (good), wind 60 @ 9-10 m/s, thetae 343, q 13
1755	Lat 2.0, 100', SST 26.2, TA 24.2, wind 165 @ 10 m/s, whitecaps
	light (sometimes even close to moderate) chop, SABL shows clouds
	between 400 and 800 m, thetae 336, q 14
1757	Passed R/V Brown in middle of 100' leg
1800	Start ascent for 1000' leg
1803	Lat 2.0, near ship, 1000', wind 160 @ 11 m/s, thetae 335, q 14
1808	Ascent for 2500', cloud base 400 m, wind shear 1000-1100 m
1810	BT (dud)
1811	2500', staying virtually entirely within BL clouds, thetae 337, q 14
1817	Start of above cloud leg, BT (good), 1060 m, wind 80 @ 6 m/s,
	thetae 340, q 13, uniform undercast, CLR OVHD, flight-level near
	inversion top, BT indicates Tsfc of 25.8, MLD 45 m
1821	BT (good)
1823	Start descent, cloud top/base about 900/400-450 m, resp.
1825	Lat 1.9, start of 100', SST 26.2, TA 23.8, thetae 337, q 14
	lots of whitecaps, wind 160@ 11-12 m/s, some breaks in OVC
1829	A temporary ascent due to miscommunication, SABL shows clouds
	between 400-600 m, and some widely SCT at 1.7 km
1834	Lat 1.4, BT (good), cloud base/tops 450/800 m
1839	Lat 1.2, BT (good)
1840	Lat 1.1, 4500', undercast below, thin As near 1.8 km, lost
	WINDS system temporarily
1844	Lat 0.85, BT (good), still some As at 1.7 km
1849	Lat 0.6, 100', WINDS back
1851	Lat 0.5, SST 21.3, TA 20.7, wind 160 7-8 m/s, thetae 330, q 13
	SABL shows clouds between 100-400 m, starting to lose As deck
	light chop, thick OVC, starting to partially lose horizon
1855	Lat 0.3, Ascent, cloud tops 350 m, no clouds above BL, BT (good)
1859	Lat 0.05, BT (good) wind 50 @ 8 m/s, thetae 340, q 12
1903	Lat -0.2, start descent, BT (good), wind max near 400 m (160 @ 12)
1909	Lat -0.5, start of 100' E-W run, SST 18.2, TA 20.3, Ophir 17.9,
	very low bases/sky obscured in spots, widely isolated whitecaps
	light chop, wind 140 @ 7 m/s, thetae 329, q 13, SABL sometimes
	showing two layers and sometimes just a single low layer of BL
	clouds
1913	Sudden clearing near east end for two brief periods
1914	Starting ascent for 300'
1916	Start of 2nd (300') leg
1917	In cloud, dropped slightly to 80-90 m, light chop, within low-level
	wind shear zone, wind 150 @ 7 m/s, thetae 329, q 13
1921	Climbing for 3rd (cloud top) run
1924	BT (good), skimming cloud tops at 850'/270 m, in cloud roughly
	2/3 to 3/4 of the time, wind 140 @ 10-11 m/s, look to be just a
	bit below wind max, light chop, SABL indicates no clouds above
1931	BT (good)
1934	BT (good)
1936	Begin ascent for inbound ferry
2321	Landing