FIGURE CAPTIONS

Figure 1.  Surface-level circulation in the various monsoon regions. (a) Northern-hemisphere summer.  (b) Northern-hemisphere winter.  Hatched areas denote heated continental regions while dotted ones are cooled.  Regions enclosed in solid contours are those with heavy monsoon  rains.  The abreviations denote the northeast trades (NET), southeast trades (SET), North American summer and winter monsoons (NAmSM, NAmWM),  West African monsoon (WAfM), African winter monsoon (AfWM), Indian summer  monsoon (ISWM), East Asian monsoon (EAM) and northeast winter monsoon and  Australian winter monsoon (ANWM).  The components over the Arabian Sea  are typically referred to as the northeast and southwest monsoons (NE, SW). Original figure is from Webster (1987a).

Figure 2. Rainfall along the western Indian coast during 1963 and 1971 from Webster (1987b). These are two fairly normal monsoon years as shown in Fig. 3. 

Figure 3. Rain and drought indices for India based on area effected.  Figure shows clusters of years dominated by either dry or wet conditions over a decade time scale (from Bhalme et al., 1983).

Figure 4. Monsoon winds for (A) December 1986, (B) January, (C) July, and (D) August 1987 from Bauer et al. (1991). The original data are from the COADS data set. Scale for the wind vectors is shown in panel (A).

Figure 5. Temperature sections through the central Arabian Sea (60-64_E) in December 1986 and August 1987. Only the upper 500 db are shown although the effect of the monsoon forcing was evident to the 1200 db depth of the CTD casts. Data was taken on the RRS Darwin. See Bauer et al. (1991) for further discussion.

Figure 6. Chlorophyll in the northern Arabian Sea from the (A) December and (B) August Darwin cruises (Bauer et al., 1991). Stippled regions denote concentrations in excess of 0.4 mg m-3.  Panel (C) shows productivity estimates (mg m-3 h-1) from deck incubations during the SW monsoon in 1987. The dashed line is the depth of the one percent light level while the dot-dashed line provides an estimate of the depth of the nitracline. 

Figure 7.  Sections showing the distribution of oxygen (ml l-1) and salinity (%_) along the Darwin cruise track in the Arabian Sea (December, 1986).  The high-salinity water at the northern end of the section is Persian Gulf Water.  Note that it is slightly oxygenated.  The hatched region in the oxygen section has concentrations <0.1 ml l-1.  (see also Olson et al., 1993).

Figure 8. Profiles of potential temperature (theta), salinity and oxygen for a Darwin station in the Gulf of Oman and at 21_N in the Arabian Sea.
Figure 9.  Density of zooplankton (displacement volume in ml per standard vertical haul (or per m2) for 0-200 m) based on 212 night samples collected during the entire IIOE period.  (From Prasad, 1969).

Figure 8.  Regional and seasonal variation in zooplankton biomass (ml m-2) for a 200 m water column in the Indian Ocean, (a) December-February (northeast monsoon), (b) July-September (southwest monsoon). (From Rao, 1973).

Figure 10.  Distribution of Copepoda in the Indian Ocean from IIOE sampling, (a) 16 April to 15 October (southwest monsoon), (b) 16 October to 15 April (northeast monsoon).  (From Kasturirangan et al., 1973; data originally from IOBC, 1970a).

Figure 11.  Candacia and Paracandacia spp. Distribution maps of selected species in the Indian Ocean.  (From Lawson, 1977).

Figure 12.  Euphausiid distributions and abundance in the Arabian Sea from IIOE sampling.  Pseudeuphausia latifrons during (A) May to September (southwest monsoon) and (D) November to March (northeast monsoon); Euphausia distinguenda during (B) May to September and (E) November to March; Euphausia diomediae (filled circles) during (C) May to September and (F) November to March. (From Brinton and Gopalakrishnan, 1973).

Figure 9.  (a) Average zooplankton biomass (ml m-3) at selected sections of the southwest coast of India for September 1971 to October 1975. (b) Plots of depths 1 ml l-1 oxygen isoline (related to upwelling processes) for the southwest coast of India for September 1971 to October 1975. (From Menon and George, 1976).

Figure 15.  Distribution and abundance (no. m-2 for 0-500 m) of the ostracod, Pyrocypris sp. in the Indian Ocean.  (From Vinogradov and Voronina, 1962b).

Figure 13.  Distribution of (a) the amount of plankton (cm3 per 1000 m3) and (b) oxygen (ml l-1) on sections from (I) the Seychelles to Bombay and (II) Bombay to Cape Guardafui. (From Vinogradov and Voronina, 1962a).

Figure 14.  Distribution of certain forms of zooplankton on a section from the Seychelles to Bombay, (1) region of spread of Neocalanus gracilis, (2) Haloptilus longicornis, (3) Pleuromamma indica, (4) Pleuromamma gracilis, (5) Pleuromamma xiphias, and (6) isolines of oxygen concentration (ml l-1).  (From Vinogradov and Voronina, 1962a).

Figure 15.  Composition of gut contents from Benthosema pterotum at various sites on various occasions in terms of numbers of prey items.  (From Delpadado and Gj¿s¾ter, 1988).

Figure 16.  Daytime division and nightime coalescence of scattering from Benthosema pterotum in the Gulf of Oman in March 1976.  Different levels of hatching indicate (1) schools and very dense aggregations, (2) dense recordings, and (3) scattered recordings.  (From Gj¿s¾ter, 1981).

Figure 17.  Fecundity versus length curve for Benthosema pterotum from the northern Arabian Sea.  Data are counts of fully ripe eggs.  (From Hussain and Ali Khan, 1987).

Figure 21.  Egg and larval development of Benthosema pterotum from the Arabian Sea.  Left from Gj¿s¾ter and Tilseth (1988).  Right from Tsokur (1982).

Figure 18.  Tentative locations of U.S. JGOFS and ONR moorings planned for the Arabian Sea in 1994-1996 (from Arabian Sea presentation made by S. Smith at December 1992 AGU meeting in San Francisco).  The main research transects for U.S. JGOFS cruises are line A, which crosses the coastal and mid-ocean upwelling regions; line B, which extends towards the region of minimum subsurface oxygen concentration; and line C, which extends south into the region of permanent oligotrophy.

Figure 19.  Locations of various studies being conducted in the Arabian Sea during 1992-1996 (modified from the International JGOFS Implementation Plan).  Large solid circles indicate locations of intensive or time-series stations.  The group of stations off Pakistan are the NASEER program; the stations off Somalia are the Netherlands Indian Ocean Program.  The dashed lines indicate proposed cruise tracks of the RV Baldridge (USA-NOAA).  The lines of stations extending off Oman indicate the U.S. JGOFS study.  This chart does not include the WOCE sampling lines in the region (Figure 20) or the locations of moorings (Figure 18).

Figure 20.  Proposed WOCE cruise tracks in the Indian Ocean.

Figure 21.  List of ships presently under discussion for participation in Arabian Sea research during 1994 to 1996.  SW indicates the southwest monsoon; I indicates Intermonsoons (in text called transitions); NE indicates northeast monsoon.  Meteor and Sonne are German vessels; Discovery is British; Tyro is from the Netherlands; Sagar Kanya is from India; Thompson and Baldridge are from the U.S.; NASEER is the Pakistani program conducted from various chartered vessels; and Vodyanitsky is a vessel from the Ukraine.