268 MALKUS [chap. 4 



studying these developments, by actually entering the developing cyclone and 

 measuring its component processes as they interact within it. 



b. Exchange measurements in a young cyclone over the ocean 



On January 22, 1955, the Woods Hole Oceanographic Institution's research 

 aircraft flew from the Island of Bermuda (32° 20'N, 64° 44'W) to a location in 

 Rhode Island (41° 38'N, 71° 30'W) on the American continent. The path of the 

 airplane (Fig. 83, inset) cut through a young wave cyclone that had generated 

 on a cold front in the Gulf Stream area off Cape Hatteras and was accelerating 

 over the ocean in a northeasterly direction. An opportunity was thus provided 

 to measure the turbulent fluxes of momentum and heat (applying equations (22) 

 and (23) respectively) and to tie them in with the structure of the cyclone and 

 its air-masses. The work has been described in detail by Bunker (1957). 



Upon take-off from Bermuda the aircraft sounded the relatively cool air that 

 had arrived earlier from the continent and was drifting eastward under the 

 influence of the Atlantic high pressure cell. About 400 km along the flight path, 

 increased turbulence was encountered in a zone that marked a rapid transition 

 from the sluggish anticyclonic circulation to the "jet" of warm air that con- 

 stituted the warm sector of the cyclone. The warm sector was so narrow that 

 the airplane (flying at about 50 m/sec) passed from this transition zone to air 

 with prefrontal characteristics in just a few minutes. Here a large wafer of cold 

 air underlay the warm air ahead of the main cold front, creating an irregular 

 temperature pattern which increased the stability of the air. As the airplane 

 approached the cold front, the air became rougher, reaching a maximum in the 

 frontal zone itself. The dome of cold air behind the front was exceedingly stable 

 as it left the land and, in contrast to the Japan Sea case studied previously, 

 remained so even after flowing over 300 km of warmer water. As a result of this, 

 turbulence was slight and the heat flow was directed downward even at 100 m 

 above the sea surface. 



All the observations and computations therefrom are summarized in Fig. 83. 

 Fig. 84 shows more clearly the heat flux pattern through the cyclone. The 

 ordinate is height in meters, while the abscissae have the double scale of 

 Greenwich civil time of a given airplane observation and the approximate 

 (within 50 km) distance from Bermuda in kilometers. The heavy lines depict 

 the lines of constant potential temperature, 6, in degrees absolute computed 

 from the readings of the airplane psychograph. In Fig. 83 small dots on the 

 diagram show the location of a given temperature observation. Along the top 

 of the section a few notes have been entered concerning clouds and weather 

 encountered. The results of seventeen series of turbulence measurements have 

 been entered at the appropriate time and height on the diagram according to 

 the legend given in the center of this section. The units of the root-mean-square 

 values are cm/sec and °C. Heat flows are expressed in meal cm~2 sec~^ where 

 meal is 10"^ calories, and stresses are in dynes/cm^. Lastly, sea temperatures 

 are given in the ovals at the bottom of the diagram. The values are actually the 



