SCOPE AND METHODS OF CHEMICAL INVESTIGATIONS 



station 151. South oif this it increases more or less 

 regularly, reaching 100 meters at station 160. 



Section VI (Stations 130 to 125) .--This section Is in 

 the northeastern Pacific and runs from San Francisco 

 northwestward to a point south of the Gulf of Alaska 

 (latitude 52° north, longitude 151° west). It lies in the 

 eastern end of the North Pacific West Wind Drift and its 

 south -flowing continxiation, the California Current; both 

 of which are noticeable to a depth of 400 meters. Sta- 

 tions 129 and 130 are in the region of the coast of Cali- 

 fornia where upwelling occurs above 400 meters. The 

 convection layer is thin, reaching a depth greater than 

 50 meters only at station 129. 



Section Vll (Stations 139 to 143) . --This is a more 

 or less north and south section in the central North Pa- 

 cific approximately along the meridian of 160° west and 

 extending from the Hawaiian Islands (latitude 22 ° north) 

 to about latitude 34° north. In this section the currents 

 are weak, being mostly easterly in the northern part, 

 whereas in the southern part they are westerly. The 

 convection layer is generally about 50 meters thick but 

 varies from 40 meters at station 143 to 70 meters at 

 station 140. 



Section VIII (Stations 94 to 104). --This section lies 

 in the tropical western Pacific, running from the Samo- 

 an Islands (latitude 13° south, longitude 172° west) north 

 and west to station 104 (latitude 20° 12' north, longitude 

 161° 19' east). This is a section obliquely across the 

 equatorial currents in the western Pacific similar to 

 Section V in the central Pacific. Station 99 is in the 

 center of the eastward-flowing Equatorial Countercur- 

 rent which reaches a depth of 300 meters. To the north 

 and south of this the water in the equatorial currents is 

 moving in the opposite direction. As in Section V, there 

 are vertical water movements descending in the counter- 

 current and ascending at its borders. The convection 

 layer is at least 250 meters thick at the most north- 

 western station, station 104, but narrows to 100 meters 

 at station 99. At station 98, near the equator, it is 

 greater, approximately 150 meters, whereas south of 

 the equator it Is about 50 meters. Thus it will be seen 

 that in the equatorial region this section differs consid- 

 erably from Section V where the convection layer was 

 extremely thin. 



Section IX (Stations 107 to 120) . --This section runs 

 from Guam (latitude 14° north, longitude 146° east) 

 north to station 113 near Yokohama (latitude 35° north). 

 From here it continues northeast to station 120 (latitude 

 47° 02' north, longitude 166° 20' east). Stations 107 and 

 108 in the southern part of the section are within the 

 westerly-moving North Equatorial Drift, but farther 

 north, at stations 109 to 111, there is a weak flow of 

 water eastward. Stations 112 and 113 are in the Kuro- 

 shio, a strong current of warm water flowing northward 

 along the east coast of Japan. Stations 114 and 115 are 

 located in the region where the Kuroshio and a south- 

 flowing current of cold water, the Oyashio, meet, thus 

 causing Irregular currents. Stations 116 to 120 are in 

 an easterly current of cold water formed partly by the 

 turning eastward of water from the Oyashio and partly 

 by water flowing out from the Bering Sea. Sverdrup 

 states (1931) that the source of the intermediate water 

 3f the North Pacific, which circulates clockwise like 

 the water in the troposphere, is near stations 115 and 

 116, where the two above-mentioned currents con- 

 verge. The convection layer to the south of station 



112 is 40 to 50 meters thick, but to the north of station 

 112, it is less than 10 meters thick. 



Section X (Stations 51 to 52 and 55 to 60). --This sec- 

 tion, in the southeastern Pacific, runs southeastward 

 from about latitude 29° south and longitude 115° west, to 

 latitude 40° south and longitude 98° west. In the tropo- 

 sphere the currents run mostly to the southeast. The 

 southern end of the section is in a part of the South Pa- 

 cific East Drift. The convection layer is thin, exceeding 

 30 meters only at stations 55, 56, and 57. 



Stations 53 and 54. --Stations 53 and 54 are not suf- 

 ficiently in line with other stations to be included in Sec- 

 tion X. They lie to the north of station 56 and east of 

 station 51, south of Easter Island. At stations 53 and 54 

 the convection layer is thin as at most of the stations in 

 Section X. 



Section XI (Stations 93 to 71) . --This section runs 

 practically east and west between latitudes 18° and 10° 

 south, from the Samoan Islands (longitude 168° west) to 

 Callao, Peru (longitude 78° west). The stations to the 

 extreme east are in the Peruvian Current and the region 

 of upwelling along the Peruvian coast. The general 

 movement of the water, however, throughout the upper 

 layers of this section is westward. From the coast to 

 longitude 120° west (stations 71 to 80) divergent cur- 

 rents are found to a depth of 100 meters, owing to as- 

 cending motion in the region to the southwest of the Ga- 

 lapagos Islands. Below a depth of 200 meters water 

 from the northwest appears to flow toward this region. 

 In the western part of the section between longitudes 

 120° and 170° west (stations 81 to 93) the currents have a 

 considerable component from the south to a depth of 

 200 meters. The northward flow of water toward the 

 equator is probably intermittent, thus causing vertical 

 movements that may bring subsurface water to the sur- 

 face. The convection layer is very thin off the South 

 American coast, mostly less than 20 meters thick. It 

 increases westward, reaching lower than 50 meters at 

 several stations. 



Section XII (Stations 45 to 40). --This section lies in 

 the equatorial southeastern Pacific, and extends approx- 

 imately along the parallel of 2° south from longitude 

 105° west to the South American coast. The currents 

 are weak and indefinite and the stations are in the area 

 of low temperature which stretches westward from the 

 coast of South America. The convection layer Is thin at 

 the coast but increases westward to almost 60 meters 

 deep at the westernmost stations. 



Section Xin (Stations 107 to 101). — This section is 

 in the tropical western Pacific. It runs eastward from 

 Guam (latitude 14° north, longitude 146° east) to station 

 101 at latitude 13° 23' north, longitude 177° 27' east, 

 forming a regular curve to the north with station 104 at 

 latitude 20° 12' north, longitude 161° 19' east. This cur- 

 vature toward the north decides the characteristic verti- 

 cal distribution which appears in the central part of the 

 section. The surface currents in this section are west- 

 erly except at station 104 where, in the upper 50 meters, 

 there is probably an easterly movement. The convection 

 layer is at least 50 meters thick at all stations and ap- 

 proaches 100 meters at some stations. 



Section XIV (Stations 140 to 130). — This section ex- 

 tends from the Hawaiian Islands to San Francisco. Sta- 

 tions 130 to 134 are included also in Section V, under 

 which they were discussed. Stations southwest of station 

 134 are in a region of weak and irregular currents flowing 



