World Ocean Atlas 2001 (WOA01)

This is adapted from
World Ocean Atlas 2001 CD-ROM Documentation

Ocean Climate Laboratory

National Oceanographic Data Center

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This documentation is for the data served here. Note: this is a summary of the full documentation offered by NOAA/OCL.

1. INTRODUCTION

The World Ocean Atlas 2001 (WOA01) Series consists of two set of products. The first set of products consists of three DATA CD-ROMs containing global data statistics at standard depth levels by one-degree and five-degree squares of several commonly measured ocean variables, as well as objectively analyzed fields (on a one-degree grid) of these variables. The ocean variables included in this series are: in-situ temperature, salinity, dissolved oxygen, apparent oxygen utilization (aou), percent oxygen saturation, dissolved inorganic nutrients (phosphate, nitrate, and silicate), and chlorophyll at standard depth levels, and plankton biomass sampled between 0m and 200m depth. The second set of products consists of three FIGURE DVDs containing PDF figures illustrating the fields found on the DATA CD-ROMs. For more information on ordering these CD-ROMs, see the WOA01 website.

This CD-ROM set is associated with the following products:

• NOAA Atlas NESDIS World Ocean Atlas 2001 Series (6 volumes): describes the methods used to generate the various statistics and objectively analyzed fields for each variable and each climatological compositing period: annual, seasonal, and monthly. It also includes figures at selected standard depth levels for all variables, except plankton biomass for which the figures represent values between the 0-200 meter depth layer;


• World Ocean Database 2001 (WOD01) CD-ROM set: contains observed and standard level data used to generate the WOA01 fields. WOD01 consists of 8 CD-ROMs;


• World Ocean Database 2001 Atlas Series (7 volumes): details the sources of the WOD01 data and shows distribution plots for each variable and instrument type as a function of year.

2. CONTENTS OF WOA01

As with previous works, we have vertically interpolated ocean profile data from "observed" depth levels to standard depth levels. We define 33 standard depth levels extending from the sea surface to 5500m depth as given in Table 1. Several statistics are then computed, by one-degree and five-degree squares, for the world ocean at the each standard depth level and for various climatological, all-data, compositing periods as documented in Table 2.

The DATA CD-ROMs contain objectively analyzed fields (one-degree grid) and statistics (unanalyzed) for one-degree squares and five-degree squares at standard depth levels (Table 1) for all ocean variables, and for the 0-200 meter layer for the plankton biomass values. The maximum depth for which objective analyses and statistics were computed for each variable and for each climatological compositing period is shown in Table 2.

The seasons are defined as Winter (January-March), Spring (April-June), Summer (July-September), Fall (October-December) (based on the Northern Hemisphere).

The following fields are available at annual, seasonal, and monthly time scales:

• Analyzed mean fields (objectively analyzed mean) - One-degree all-data objectively analyzed mean. For all variables, the annual analyzed field is the average of the twelve monthly fields for each standard level for which monthly fields exist - see Table 2. Below the deepest standard level for which a monthly field exists for a variable (from the surface layer for chlorophyll and plankton biomass), the annual field is the average of the four seasonal analyzed fields for each standard level for which seasonal fields exist. Below the deepest standard level for which seasonal fields exist for a variable, the annual field is the objectively analyzed mean field of all data. Similarly, the seasonal analyzed field is the average of the corresponding three monthly fields for each standard level for which monthly fields exist. Below the deepest standard level for which monthly fields exist, the seasonal field is the objectively analyzed mean field of all available data taken in the corresponding season. Monthly fields are the objectively analyzed mean fields of all data taken in the corresponding month.
• Difference fields (difference from annual) - One-degree seasonal and monthly analyzed mean minus annual analyzed fields.
• Grid point fields (grid point of influence) - One-degree number of grid points which contain data within the radius of influence for each grid box.
• Number of observations - One-degree and five-degree geographic distribution of data used in analysis
• Standard deviation - One-degree and five-degree standard deviation from the mean
• Standard error - One-degree and five-degree standard error from the mean
• Mean (unanalyzed mean) - One-degree and five-degree unanalyzed mean for all data used in analysis
• Interpolation error - One-degree analyzed field subtracted from one-degree unanalyzed (raw) mean

The available fields for plankton biomass include:

• annual and seasonal number of observations by one-degree square in the 0-200 meter layer;
• annual and seasonal fields of the unanalyzed mean by one-degree in the 0-200 meter layer.

Two masks used in the analyses are also available:

• basin - definition of basins used in the objective analysis. Table 3 lists the numeric value which identifies each basin (columns 1 and 4), the basin name, and the shallowest standard depth level for which each basin is defined (columns 3 and 6). The basin mask has 33 levels.
• landsea - bottom depth (standard depth levels given in Table 1) assigned to each one-degree latitude by one-degree longitude square. There are additional standard levels in the land-sea mask corresponding to areas where the bottom depth is greater than 5500m (additional seven levels starting at 6000m and incrementing by 500m to a depth of 9000m).

Table 1. Standard levels and depths (meters)

Depth	Level	Depth	Level	Depth	Level
0	1	300	12	1400	23
10	2	400	13	1500	24
20	3	500	14	1750	25
30	4	600	15	2000	26
50	5	700	16	2500	27
75	6	800	17	3000	28
100	7	900	18	3500	29
125	8	1000	19	4000	30
150	9	1100	20	4500	31
200	10	1200	21	5000	32
250	11	1300	22	5500	33

 

Table 2. Availability of objective analyses and statistics by climatological compositing periods for each ocean variable, and the maximum depth (meters) for which objective analyses and statistics were computed. A dash character "-" indicates these products were not computed for the specified variable and climatological period.

Variable	Annual	Seasonal	Monthly
Temperature	5500	5500	1500
Salinity	5500	5500	1500
Dissolved Oxygen	5500	5500	1500
Apparent Oxygen Utilization	5500	5500	1500
Percent Oxygen Saturation	5500	5500	1500
Phosphate	5500	500	500
Nitrate	5500	500	500
Silicate	5500	500	500
Chlorophyll	100	surface	-
Total Plankton Biomass: All biomass types+	0-200*	-	-
Total Plankton Biomass: Calculated carbon mass	0-200*	0-200*	-

+ - Includes Displacement Volume, Settled Volume, Wet Mass, Dry Mass, and Ash-free Dry Mass.
* - Plankton Biomass is a mean of net tows covering 0-200 meters.

Table 3. Basins defined for objective analysis and the shallowest standard depth level for which each basin is defined.
 

#	BASIN	STANDARD  DEPTH LEVEL	#	BASIN	STANDARD  DEPTH LEVEL
1	Atlantic Ocean	1	30	North American Basin	29
2	Pacific Ocean	1	31	West European Basin	29
3	Indian Ocean	1	32	Southeast Indian Basin	29
4	Mediterranean Sea	1	33	Coral Sea	29
5	Baltic Sea	1	34	East Indian Ocean	29
6	Black Sea	1	35	Central Indian Ocean	29
7	Red Sea	1	36	Southwest Atlantic	29
8	Persian Gulf	1	37	Southeast Atlantic	29
9	Hudson Bay	1	38	Southeast Pacific	29
10	Southern Ocean	1	39	Guatemala Basin	29
11	Arctic Ocean	1	40	East Caroline Basin	30
12	Sea of Japan	1	41	Marianas Basin	30
13	Kara Sea	8	42	Philippine Sea	30
14	Sulu Sea	10	43	Arabian Sea	30
15	Baffin Bay	14	44	Chile Basin	30
16	East Mediterranean	16	45	Somali Basin	30
17	West Mediterranean	19	46	Mascarene Basin	30
18	Sea of Okhotsk	19	47	Crosat Basin	30
19	Banda Sea	23	48	Guinea Basin	30
20	Caribbean Sea	23	49	Brazil Basin	31
21	Andaman Basin	25	50	Argentine Basin	31
22	North Caribbean	26	51	Tasman Sea	30
23	Gulf of Mexico	26	52	Atlantic Indian Basin	31
24	Beaufort Sea	28	53	Caspian Sea	1
25	South China Sea	28	54	Sulu Sea II	14
26	Barents Sea	28	55	Venezuela Basin	14
27	Celebes Sea	25	56	Bay of Bengal	1
28	Aleutian Basin	28	57	Java Sea	6
29	Fiji Basin	29	58	East Indian Atlantic Basin	32