Under-ice observations of water column temperature, salinity and spring phytoplankton dynamics: Eastern Bering Sea shelf

P. J. Stabeno,¹ J. D. Schumacher,¹ R. F. Davis² and J. M. Napp³

¹NOAA, Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, Washington  98115
²Department of Oceanography, Dalhousie University, Nova Scotia, Canada
³NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle  98115

Journal of Marine Research, 56, 239–255, 1998.
This paper is not subject to U.S. copyright. Published in 1998 by the Journal of Marine Research

Gallery of Figures and Tables

Figure 1. A map of the eastern Bering Sea continental shelf indicating the locations of the three moorings. Maximum ice extent during 1995 is shown by a dashed line. Depth contours are in meters.

Figure 2. Wind velocity derived from atmospheric pressure and interpolated to a point midway between moorings 1 and 2. North is along the y-axis.

Figure 3. At mooring site 2, (a) concentration of chlorophyll-a as measured from CTD casts taken on deployment (circle) and recovery (triangle) and (b) concentration of dissolved nitrate upon deployment (circle) and recovery (triangle). The density structure upon deployment (dashed) and recovery (solid) is also shown in each panel.

Figure 4. At mooring site 1, (a) concentration of chlorophyll-a as measured from CTD casts on March 14 (open circle), April 23 (closed circle), May 5 (open triangle), and May 17 (closed triangle); (b) concentration of dissolved nitrate for same days as in (a).

Figure 5. As in Figure 3, except for mooring site 3.

Figure 6. (a) Temperature measured at mooring 2. The vertical location of each instrument is indicated by an arrow along the depth axis. Plotted over the contours of temperature at the appropriate depths are 6 hourly low-pass filtered current vectors (upward indicates northward flow). (b) Chlorophyll-a as determined by an A-3 (7 m) and as inferred from a fluorometer (44 m). The estimated period when ice covered the mooring is indicated by the blue line. Salinity at 44 m (the shallowest SEACAT that gave data) is shown in red.

Figure 7. (a) Wind speed derived from atmospheric pressure. (b) Daily averaged shear (s) determined from hourly ADCP records at mooring 2. Velocity was measured in 4-m bins. The 2-hourly depth of the mixed layer (defined by differing by 0.1° from the temperature at 1 m) at 6-hr intervals is indicated by +.

Figure 8. (a) Temperature measured at mooring 3. The vertical locations of the measured temperatures are indicated by arrows. Plotted over the contours of temperature at the appropriate depths are 6 hourly low pass filtered current vectors. (b) chlorophyll-a as measured by an A-3 (7 m) is shown in green. The period when ice covered the mooring is indicated by the blue line. Salinity at 10 m is shown in red.

Figure 9. The 2-hourly depth of the mixed layer and hourly concentration of chlorophyll-a estimated from A-3 for (a) mooring 1, (b) mooring 2, and (c) mooring 3.

If your browser cannot view the following table correctly, click this link for a GIF image of Table 1

Table 1. Mooring location, water depth, deployment period, and depths (m) of subsurface instruments. ADCPs (with SEACAT) were deployed within 1 km of surface mooring. Instruments that failed and provided no data are indicated by asterisks (*).
	MTR				SEACAT				Fluorometer				A-3
Mooring 1		1
55°04 : 164°31		15				10								5	*
65 m		20				26								21
March 14-June 15		32				44
600 KHz ADCP		38				60
		50
Mooring 2		1
56°36 : 164°37		15				11	*			11	*			7
75 m		20				22	*			22	*			14	*
March 14-April 29		32				44				44
150 KHz ADCP		38				68
		50
		56
Mooring 3		1				10								7
56°02 : 166°23		15				26
123 m		20				44
March 13-May 8		32				80
150 KHz ADCP		38				118
		50
		56

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