World Ocean Atlas 1998 (WOA98)

This is adapted from
WOA CD-ROM Documentation version 1.0

Ocean Climate Laboratory

National Oceanographic Data Center

April 1999

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1. INTRODUCTION

2. CONTENTS OF WOA98

3. DATA STRUCTURE

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1. INTRODUCTION

The World Ocean Atlas 1998 (WOA98) consists of 3 CD-ROMs (see original web site for more info and CD-ROM ordering WOA98) containing objectively analyzed fields of temperature, salinity, dissolved oxygen, derived oxygen variables (Apparent Oxygen Utilization and oxygen saturation), nutrients (phosphate, nitrate, silicate) and chlorophyll along with fields of various statistics. This CD-ROM set is associated with the following products:

• NOAA Atlas NESDIS World Ocean Atlas 1998 series (12 volumes): contains figures showing objectively analyzed fields of each variable for various climatological compositing periods (annual, seasonal, monthly) at selected standard depth levels and a description of the methods used to generate the objectively analyzed fields;

 
• World Ocean Database 1998 (WOD98) CD-ROM set: contains observed and standard level flagged data used to generate the WOA98 fields. WOD98 consists of 5 CD-ROMs;

 
• World Ocean Database 1998 atlas series, an eight volume series detailing the source of the WOD98 data and showing distribution plots for each variable as a function of year.

2. CONTENTS OF WOA98

The data on each WOA98 CD-ROM consists of:

• statistics of observed (vertically interpolated) data (unanalyzed) for one-degree squares and five-degree squares at standard depth levels (see table 1). The following statistics for each grid square are included: 1) number of observations, 2) mean, 3) standard deviation, 4) standard error of the mean. See table 2 for availability of statistics by variable;

 
• annual, seasonal, and monthly objectively analyzed mean fields by one-degree squares at standard depth levels. See table 2 for availability of objective analyses by variable;

• "interpolation error" of the objectively analyzed fields defined as fields of observed means minus annual objectively analyzed mean by one-degree squares at standard depth levels. See table 2 for availability of these fields by variable;

 
• seasonal and monthly objectively analyzed fields minus annual mean objectively analyzed fields by one-degree squares at standard depth levels. See table 3 for availability of these fields by variable;

 
• land/ocean-bottom mask used in the analyses at standard depth levels;

 
• definition of basins used in the objective analyses at standard depth levels (see table 4).

 

The seasons are defined as Winter (January-March), Spring (April-June), Summer (July-September), Fall (October-December) (based on the Northern Hemisphere). Table 1 lists the depths and Table 2 the available files for each variable in WOA98.
 

3. DATA STRUCTURE

This info is for the data served here. The simple differences available on the original CD-ROM are omitted because they can be easily computed, and the file formatting information is omitted because it is not relevent.

levels for which each numeric one degree value corresponds to the number given for the corresponding basin in Table 4, columns 1 and 4.

landsea.msk - bottom depth assigned to each one-degree latitude by one-degree longitude square. Numerical values correspond to the depth levels given in Table 1.

• Analyzed mean fields ( an) -

 

For temperature, salinity, and oxygen:
 

Each annual mean field is the average of the 12 analyzed monthly mean fields at and above 1500 meters. Below 1500 m the average of the four seasonal analyzed fields is used.

The seasonal mean fields above 1500 m are the average of the appropriate three monthly fields. Below 1500 m the seasonal analyzed mean fields are the all-data analyses of each season.

The monthly analyzed mean fields are all-data analyses.
 

For phosphate, nitrate, silicate, chlorophyll:
 
Each annual mean field is the average of the four analyzed seasonal mean fields at and above 500 meters (surface for chlorophyll). Below 500 m (0 m for chlorophyll) the annual fields are all-data analyses.

The seasonal mean fields are all-data analyses.

• Grid point fields (gp) - the number of grid points which contain data within the radius of influence for each grid box.

• Data distribution field (dd) - geographic distribution of data used in analysis

 
• Standard deviation field (sd) - standard deviation from the mean by one-degree squares

 
• Standard error of the mean (se) - standard error of the mean by one-degree squares

 
• Means (mn) - unanalyzed one-degree means for all data used in analysis

 

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 fields for each variable and the maximum depth for each data type. An X indicates that these files are not available for the specified variable.
 

Variable	Annual	Seasonal	Monthly
Temperature	5500	5500	1500
Salinity	5500	5500	1500
Dissolved Oxygen	5500	5500	1500
Apparent Oxygen Utilization	5500	5500	1500
Oxygen Saturation	5500	5500	1500
Phosphate	5500	500	X
Nitrate	5500	500	X
Silicate	5500	500	X
Chlorophyll	100	surface	X

Table 3. Availability of difference fields for each variable and the maximum depth available for each variable. An X indicates that these files are not available for the specified variable.
 

Variable	Seasonal	Monthly
Temperature	5500	1500
Salinity	5500	1500
Dissolved Oxygen	5500	1500
Apparent Oxygen Utilization	5500	1500
Oxygen Saturation	5500	1500
Phosphate	500	X
Nitrate	500	X
Silicate	500	X
Chlorophyll	surface	X

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