NOAA Technical Memorandum OAR PMEL-121

ATLAS Module Temperature Bias Due to Solar

Heating

P.N. A’Hearn1, H.P. Freitag2 and M.J. McPhaden2

1Joint Institute for the Study of the Atmosphere and Ocean (JISAO)

University of Washington

Box 351640

Seattle, WA 98195

2Pacific Marine Environmental Laboratory

7600 Sand Point Way NE

Seattle, WA 98115

October 2002

Contribution 2486 from NOAA/Pacific Marine Environmental Laboratory

Contribution 939 from the Joint Institute for the Study of the Atmosphere

and Ocean (JISAO)
NOTICE

Mention of a commercial company or product does not constitute an endorsement by

NOAA/OAR. Use of information from this publication concerning proprietary products

or the tests of such products for publicity or advertising purposes is not authorized.

Contribution No. 2486 from NOAA/Pacific Marine Environmental Laboratory

Contribution 939 from the Joint Institute for the Study of the Atmosphere and Ocean (JISAO)

For sale by the National Technical Information Service, 5285 Port Royal Road

Springfield, VA 22161

ii
Contents iii

Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2. Sensor Description . . . . . . . . . . . . . . . . . . . . . . . . 1

3. Problem Description . . . . . . . . . . . . . . . . . . . . . . . 2

4. Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10

7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Appendix—Mooring sensor information . . . . . . . . . . . . . . . 13

List of Figures

1 Schematic drawing (a) and cross section (b) of a “fast response” NX

ATLAS module, and cross section (c) of the original NX ATLAS

module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Temperature time series from 4 Seacats and 2 NX ATLAS modules

deployed at 8◦N, 125◦W. . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 Temperature time series from a 1 m Seacat, NX Modules at 1 m and

10 m, and downwelling solar radiation from an Eppley PSP radiometer deployed near 8◦N, 167◦E. . . . . . . . . . . . . . . . . . . . . . . 4

4 Salinity error (psu) due to temperature biases at temperatures of

15◦C and 30◦C and salinities of 34 psu and 36 psu. . . . . . . . . . . 7

List of Tables

1 Observed temperature biases, shown as peak values for a given day. . 6
iv Contents
ATLAS Module Temperature Bias Due to Solar Heating

P.N. A’Hearn

1

, H.P. Freitag

2 and M.J. McPhaden2

Abstract. Some near-surface temperature measurements from NextGeneration Autonomous

Temperature Line Acquisition Systems (NX ATLAS) moorings between 1996 and 2001 have been

found to be at times biased by solar heating. The bias is maximum near the sea surface around noon

local time and has been observed at depths down to 75 m. Sea surface temperature sensors mounted

immediately beneath the buoy at 1 m are not exposed to direct sunlight and thus not subject to

similar solar heating. The bias is estimated to have a typical maximum of about 0.13

◦C at 20 m,

the depth of the shallowest sensor on most moorings. Temperature sensors at 5 m and 10 m on some

specially instrumented moorings may have larger biases. Modifications to the instrumentation and

deployment procedures have reduced solar heating bias to 0.01

◦C or less. These improvements were

first introduced in April 2000 and have been used on all moorings deployed since January 2001. The

recovery of potentially biased instrumentation was completed in December 2001. A list of when and

where data may be biased is given in the appendix.

1. Introduction

NX ATLAS moorings were developed by NOAA’s Pacific Marine Environmental Laboratory (PMEL) to measure meteorological and oceanographic

parameters in tropical latitudes. These moorings were developed in the mid1990s and were first deployed in 1996 as part of the Tropical AtmosphereOcean (TAO) array (McPhaden et al., 1998). They gradually replaced the

original Standard ATLAS moorings in the array and occupied all locations

by the end of 2001. NX ATLAS moorings have also been deployed in the

Pilot Research Moored Array in the Tropical Atlantic (PIRATA) since its

inception in 1997 (Servain et al., 1998) and at other sites in the South China

Sea and the North Pacific. Triangle Trans-Ocean Buoy Network (TRITON)

moorings (http://www.jamstec.go.jp/jamstec/TRITON/), which replaced

TAO moorings west of 165◦E in late 2000, are maintained by the Japan Marine Science and Technology Center (JAMSTEC), and make measurements

similar to those made by NX ATLAS moorings, using commercially available

instruments. TRITON instrumentation is not discussed in this report.

It was discovered in 1998 that subsurface temperature measurements

from NX ATLAS systems could be biased toward higher temperatures when

exposed to sunlight. In this paper we describe the problem, and present

solutions that have been developed to address it.

2. Sensor Description

NX ATLAS moorings use self-contained, internally recording subsurface

sensor modules designed by PMEL’s Engineering Development Division to

record water properties. Each module can be configured to measure tempera1

Joint Institute for the Study of the Atmosphere and Ocean (JISAO), University of

Washington, Box 351640, Seattle, WA 98195

2NOAA/Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle,

WA 98115
2 P.N. A’Hearn et al.

34 cm

Line Shedding

Clamp

1.3 cm

Diameter

Plastic

Jacketed

Mooring Line

6.7cm Dia

PET Housing

and Endcap

Rated to 500m

Inductive

Coupler

(b)

5 mm

Thermistor

Titanium

Temperature

Probe Case

Brass Shield

and Anti-foul

Guard

Data Logger / Modem

(a) (c)

8mm

(End of Thermistor

to Top Surface of Cap)

Thermistor

Figure 1: Schematic drawing (a) and cross section (b) of a “fast response” NX ATLAS module, and cross

section (c) of the original NX ATLAS module.

ture alone, temperature and conductivity, or temperature and pressure. The

pressure housing for the modules is machined from polyethylene terepthalate (PET) in two pieces: an end cap to which the sensors and circuitry are

attached, and a hollow cylindrical pressure case (Fig. 1a).

As originally designed, the PET had a small amount of carbon black

added for UV resistance, and was black to dark grey in color. The thermistor

used to measure water temperature in these modules was 8 mm from the

outside surface of the end cap at the end of a blind hole drilled from the

interior (Fig. 1c). The module surface nearest to the thermistor was deployed

toward the sea surface when attached to the mooring wire, and therefore

this surface received the most direct sunlight. Later versions of the module

design involved elimination of the carbon black from the PET to produce

white cases, and end cap modifications to provide better exposure of the

thermistor to sea water temperatures (Fig. 1b). These design modifications

are described in more detail below.

3. Problem Description

In some cases, additional instruments are attached to ATLAS moorings for

specific experiments. In one such case, SeaBird SBE-16’s (Seacats) were

attached to an NX ATLAS mooring at 8◦N, 125◦W in 1997. Temperature
ATLAS Module Temperature Bias 3

Figure 2: Temperature time series from 4 Seacats and 2 NX ATLAS modules

deployed at 8◦N, 125◦W.

measurements from Seacats are believed to have minimal bias attributable

to solar heating because the thermistor in these instruments is mounted in

a thin titanium probe extending outside a titanium end cap, which provides

rapid heat conductance to the surrounding water. Assuming that Seacat

data are unbiased, differences between Seacat and NX ATLAS module temperatures may be used to quantify NX ATLAS module bias due to solar

heating. In this case, NX ATLAS modules recorded significantly higher temperatures during daylight hours on some days. An example of solar heating

was observed on 16 May 1997 when the temperature from an NX module at

20 m depth rose above temperatures from Seacats located between 5 m and

15 m (Fig. 2). At local noon the module temperature reached a maximum

for the day and was 0.13◦C above the temperature from a Seacat at 15 m.

Real temperature inversions can occur in the ocean when salinity variations

due to rainfall events or lateral intrusions stabilize the water column (e.g.,

McPhaden, 1985; Cronin and Kessler, 2002). The inversion shown in Fig. 2

and others like it in the NextGeneration temperature records are clearly

instrumental in origin, however.

This diurnal temperature bias of near-surface NX modules is typically

synchronous with shortwave solar radiation measured by Eppley PSP radiometers, which are mounted on some buoys. Recorded water temperature

often peaks around local noon, rather than in the mid-afternoon as would

be expected of typical warming of the water column. For example, on 11
4 P.N. A’Hearn et al.

Figure 3: Temperature time series from a 1 m Seacat, NX Modules at 1 m and

10 m, and downwelling solar radiation from an Eppley PSP radiometer deployed

near 8◦N, 167◦E.

August 1999 near 8◦N, 167◦E, the Sea Surface Temperature (SST) nominally

measured at 1 m depth was highest around 1500 LMT. SST measurements

are presumably unbiased due to shading by the surface buoy (see below). In

contrast, the temperature from an NX module at 10 m began rising above

the 1 m temperature at sunrise (0600 LMT, as indicated by the PSP) and

reached a maximum bias of 0.15◦C at 1100 LMT (Fig. 3). After 1100 LMT

the 10 m temperature was less than that at 1 m. Nevertheless, some solarheating bias undoubtedly remained (given the observed solar radiation), although it was smaller than the temperature gradient between 1 m and 10 m.

Temperature bias similar to this has been observed at many sites in both

TAO and PIRATA arrays at depths as great as 75 m.

The dip in 10 m temperature at noon (Fig. 3) is a feature commonly observed in other near-surface NX module time series biased by solar heating

and is thought to be due to the buoy shading the module when the sun is directly overhead. Module SST measurements are not thought to be strongly

affected by solar heating, as the instrument is mounted directly underneath

the surface float, and is shaded from direct sunlight throughout the day.

Differences between module SST and co-located Seacat measurements support this idea, in that they do not show diurnal bias similar to that observed

deeper in the water column (Fig. 3). SST differences between the Seacat and

ATLAS module are due to differences in sensor time constants and small-
ATLAS Module Temperature Bias 5

scale temperature differences over the finite vertical distance (about 0.1 m)

between instruments.

To estimate the relative heating of NX modules from sunlight, we apply tropical Pacific chlorophyll values (Strutton and Chavez, 2000) to the

chlorophyll/light-attenuation relationship of Morel (1988), yielding light attenuation coefficients (KPAR) for the tropical Pacific in the range 0.03 to

0.09 m−1, typically being around 0.06 m−1. Typical noon peak irradiance

for cloudless days as measured from TAO array buoys instrumented with Eppley PSP radiometers is around 1100 W m−2

, approximately half of which

(550 W m−2) is in the visible frequency band (Siegel et al., 1995; Mobley,

1994). Visible light, rather than ultraviolet or infrared, which are attenuated

strongly in seawater, is assumed to be the source of the heating. Assuming

a worst-case scenario of low chlorophyll levels (KPAR = 0.03 m−1), a sea

surface albedo of 0.03 (typical of tropical, clear-sky conditions near noon,

Payne, 1972), no shadowing by the surface buoy, and only downwelling light,

the upper bounds on solar radiation would be approximately 400 W m−2 at

10 m and 120 W m−2 at 50 m. The upward facing surface of the instrument

pressure case has an area of 3.56 × 10−3 m2. Assuming complete absorption

of incoming light by the instrument, an upper bound for the estimate of

radiant flux into the top of the instrument from solar radiation could be as

much as 1.4 W at 10 m.

Modeling the measured temperature increase caused by this flux is relatively complicated and was not done for this study. We can however observe

its effects, as illustrated by examples of peak temperature biases in the table

below. Biases are typically largest around noon when the sun is near its

zenith. They are generally lower in the morning and afternoon, and absent

at night.

Table 1 lists peak bias for a number of modules, typically estimated by

daytime comparison with measurements from a module 20 to 25 m deeper or

shallower (but possibly still upwardly biased) for which nighttime temperatures indicated both modules were in a well-mixed layer. At shallow depths

(where irradiance is greater) the water column typically heats up during the

day. No attempt was made to account for such a vertical temperature gradient, as it is impossible to accurately separate solar heating of the module

from actual increases in water temperature. Thus the heating bias could be

overestimated or underestimated in some cases. The observed temperature

biases listed in Table 1 are meant to give an idea of the range of values,

but should not be considered uniformly applicable, as the bias is dependant

on many factors such as cloudiness, sea surface albedo, solar elevation, and

water clarity. As expected, the larger biases were nearest the surface. On

the majority of ATLAS moorings the uppermost modules are placed at 20 m

or 25 m. The largest bias observed from a 20 m black module was 0.13◦C.

Therefore, we conclude that 0.13◦C represents a realistic upper bound on

heating bias for modules typically deployed within the TAO and PIRATA

mooring arrays. At depths of 50 m and below the observed bias in some

instances approached the accuracy of the instrument, namely 0.01◦C.

In a few special cases, modules have been placed shallower than 20 m.

These include current meter moorings along the equator in the Pacific at
6 P.N. A’Hearn et al.

Table 1: Observed temperature biases, shown as peak values for a given day.

Location Depth Temperature

Mooring Name (Latitude Longitude) (m) Bias

PM121 10◦N 95◦W 5 0.42

PM121 10◦N 95◦W 10 0.20

PM092 8◦300N 167◦200E 10 0.15

PM016 8◦N 125◦W 20 0.13

PM035 0◦35◦W 20 0.10

PM037 8◦N 38◦W 40 0.04

MOMMA 35◦N 165◦W 50 0.01

PM029 8◦N 110◦W 60 0.04

PM073 15◦N 38◦W 60 0.02

PM070 11◦300N 38◦W 60 0.01

PM093 8◦N 165◦E 75 0.03

PMEL laboratory — — 0.08

110◦W, 140◦W, 170◦W, and 165◦E; two moorings deployed for about 6 weeks

in the summer of 1999 near Kwajalein Island as part of the KWAJEX experiment (data from which are shown in Fig. 3); moorings deployed since fall of

1999 along 95◦W for the Eastern Pacific Investigation of Climate Processes

(EPIC); and three moorings deployed in the North Pacific between fall 1998

and summer 2000. The largest observed bias listed in Table 1 (0.42◦C) from

these shallower-than-normal modules was from a white module placed at

5 m on an EPIC mooring.

Daily averaged temperature, as reported in real-time data or derived

from internally stored RAM data, will have a slight positive bias when this

problem is present. Modeling the heating bias as the positive half of a sine

wave for half the day produces a conservative upper bound on the daily

mean bias of a factor of π

−1

, or about one third, the daytime maximum.

Thus heating bias of daily averaged temperature would be limited to about

0.04◦C at typical module depths, and about 0.14◦C for the shallower modules

deployed in the special cases described above.

For NX ATLAS modules equipped with SeaBird conductivity cells, temperature bias will affect salinity measurements. Assuming that water within

the conductivity cell is not significantly above ambient temperature, the

error produced in the conductivity measurement from applying the biased

thermistor temperature is insignificant (3.25 × 10−6 mS cm−1 ◦C

−1

, based

upon SeaBird calibration equations). However, salinity calculated using a

temperature higher than that in the conductivity cell will be substantially

biased downwards. At 30◦C and 34 psu, a salinity error of –0.07 psu would

result from a temperature bias of +0.1◦C (Fig. 4). As for temperatures, daily

averaged salinity bias would be roughly one third of the maximum daytime

salinity bias.
ATLAS Module Temperature Bias 7

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

0.20

0.18

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

 0.00

Temperature Measurement Error (

oC)

Calculated Salinity Error (psu)

15o, 34 psu

15o, 36 psu

30o, 34 psu

30o, 36 psu

Figure 4: Salinity error (psu) due to temperature biases at temperatures of 15◦C

and 30◦C and salinities of 34 psu and 36 psu.

4. Solutions

In response to this problem, near-surface (upper 50 m), black modules were

attached on some moorings in an inverted, “top down” configuration beginning in September 1998. This reduced the heating of the end cap immediately surrounding the thermistor by orienting it away from direct sunlight.

The quantitative effect of this change is difficult to calculate exactly, since

it depends on several unknowns such as the thermal behavior of the entire

pressure case, and irradiance as a function of direction. An empirical estimate of the effect of inverting the modules was obtained through PMEL

laboratory tests. Incident radiation of order 120 W m−2(as measured by a

Biospherical Instruments QSP-200 radiometer) was produced by two 500 W

floodlamps over a constant-temperature water bath. Mean temperature increases of 0.077◦C were observed in upright modules exposed to the light,

while mean increases in inverted modules were limited to 0.003◦C. If similar results occur in the field, then mounting the instruments upside down

should reduce the heating problem by approximately 96%. In this simple

test, neither the lighting nor water flow in the bath were strictly uniform,

therefore the results should be considered approximate.

While providing a rather simple solution to the module heating problem,

inversion of the modules was not considered to be completely satisfactory,

because the modules were more susceptible to being caught on fishing line
8 P.N. A’Hearn et al.

or nets when inverted. Beginning in 1999 new instruments were constructed

using white PET pressure case material. As it was assumed that module

heating would be reduced significantly in white modules, those initially deployed (beginning in July 1999) were oriented in an upright position. It

was soon discovered that the change to white PET did not eliminate the

problem of module heating. For example, the data from a white module at

10 m shown in Fig. 3 have a 0.15◦C bias relative to the SST. In a laboratory test (similar to that described above) the temperature increase when

exposed to light was 0.045◦C on a white case compared to 0.062◦C on a

black case. Thus the substitution of white PET was much less effective than

inverting the modules as a method of reducing solar heating bias. Beginning

in February 2000, all modules in the upper 50 m (both black and white) were

again deployed inverted. In January 2001 the depth of inverted modules was

extended to 75 m.

Beginning in April 2000, modules were modified to place the thermistor

inside a titanium probe which is exposed to sea water (Fig. 1b). The modification served two purposes; to decrease the thermal response time of the

instruments (which improved salinity measurements1), and to decrease the

solar heating effect. The modified instruments shade the thermistor from

sunlight coming from directly above, as it is recessed within the side of the

pressure case and is surrounded by a brass sleeve. Moreover, the titanium

probe conducts heat more rapidly to the ambient water and thus is less prone

to temperature bias. The effectiveness of these modifications is somewhat

dependant on the speed at which water flows past the probe. Laboratory

tests indicated a mean decrease in heating of 88% for upright, fast-response

modules compared to the original black modules when upright. When inverted in the laboratory test, the mean heating in fast-response modules was

limited to less than 0.002◦C, a decrease of about 98% when compared to the

original upright modules.

All modules deployed in the upper 75 m since January 2001 are fastresponse modules. In addition, all new end caps and pressure cases are

constructed from white PET material, and all instruments deployed at 75 m

or shallower are inverted on the mooring line. Slow-response modules have

been modified to the fast-response, titanium thermistor probe, and those

which have black end caps or pressure cases are deployed at depths below

100 m. This combination of improvements should reduce the heating problem to about 2% of the value seen in the original black modules, for maximum

1

In addition to reducing solar-heating bias, the fast-response modules have the added

benefit of more closely matched temperature and conductivity response times. The original modules with thermistors inside the PET end cap (Fig. 1c) had a temperature time

constant (e−1) of order 800 s. The fast-response modules have a temperature time constant

of order 30 s. The in situ time response of the conductivity sensor is strongly dependant

upon mooring motion and ocean currents, which force sea water through the cell. PMELdesigned anti-foulant attachments to the conductivity cells were purposely constructed to

slow the flow of water through the cell in order to extend the effective life of the antifoulant and to better match the temperature and conductivity time response. Laboratory

experiments indicate that in the presence of 2.7 m high waves of 7.5 s period, the time

constant of the conductivity cell is of the same order as the fast-response temperature

sensor (30 s).
ATLAS Module Temperature Bias 9

daytime biases of ∼0.01◦C or less for modules deployed at 5 m or deeper in

the water column.

5. Summary

Measurements of high-resolution (10-min sample rate), near-surface temperature on NX ATLAS buoys deployed at standard depths (20 m and deeper)

in the TAO and PIRATA Arrays may have positive daytime biases up to

0.13◦C due to solar heating. These modules were first introduced into the

TAO Array in 1996. The magnitude of the problem is proportional to incident solar radiation, and therefore greatest at shallow depths (but not SST

measurements due to shading by the buoy), under clear skies, and in clear

water conditions. Efforts to reduce the bias were begun in September 1998

by inverting the module orientation. Later improvements included changing

to white case material and improving the thermistor mounting system. Instruments deployed in 2001 and thereafter are of the modified type. Solar

heating, while potentially present in these new modules, should be less than

0.010◦C, which is the accuracy of the instrument.

No corrections have been made to NX ATLAS data which are potentially

biased due to solar heating. For standard deployment depths, data from NX

ATLAS moorings deployed before 1999 have the greatest potential for solar

heating bias. Between July 1999 and April 2000, upright modules were

deployed at some mooring sites shallower than the 20 m standard depth,

during which period a worst case bias of 0.42◦C was observed. Thereafter, all

modules in the upper 50 m (later 75 m) were inverted. Details on the color,

orientation, and time response of near-surface modules deployed before the

introduction of inverted, fast-response modules are listed in the appendix.

General criteria for determining the potential for data biased by solar

heating are:

1. Near surface modules were biased more than deeper modules.

2. Black, slow-response, upward modules were most biased.

3. Black modules were biased more than white modules.

4. Upright modules were biased more than inverted modules.

5. Fast response, inverted modules (of either color) are the least biased.

Laboratory tests indicated the following reductions in the bias relative

to the original black, slow response, upwardly oriented modules:

White, slow-response, upward ∼27%

White, fast-response, upward ∼88%

Black, slow-response, inverted ∼96%

White, fast-response, inverted ∼98%

White, fast-response, inverted modules are not included in the appendix,

as they represent the present ATLAS configuration and are considered to
10 P.N. A’Hearn et al.

be effectively unbiased. Black, fast-response, inverted modules are likewise

omitted from the appendix, as it is assumed their performance is similar if

not equal to white, fast-response, inverted modules, and better than black,

slow-response, inverted modules which had a 96% reduction in bias. Black,

slow-response, inverted modules are included in the appendix because they

are not the type and orientation of module used at present, although they

have substantially less bias than upright modules.

Due to the diurnal nature of the solar bias, daily mean bias values from

NX modules should be about one third the peak bias observed in the 10-min

data. For the bulk of TAO and PIRATA moorings, with the first subsurface

temperature module located at 20 m depth, this bias should be about 0.04◦C

or less. On specially instrumented moorings with modules placed between

5 m and 10 m, daily mean biases could be as large as 0.13◦C.

Standard ATLAS moorings, used from the inception of the array in 1984

until retired in 2001, reported daily means only. Temperature sensors on

these moorings were constructed of grey (rather than black) plastic and the

thermistors were not near the upper surface of the instrument or in direct

contact with the case. Thus, bias due to solar heating is expected to be

less than that of NX modules and the potential bias due to solar heating

in Standard ATLAS daily-mean measurements would be substantially lower

than their accuracy of 0.09◦C (Freitag et al., 1994).

6. Acknowledgments

We would like to thank Chris Meinig, Engineering Development Division Leader at

PMEL, for the design and development of improvements to the NX temperature

modules. Also, special thanks to Meghan Cronin for comments on an earlier version of this report. This work was supported by NOAA’s Office of Oceanic and

Atmospheric Research, and by the Joint Institute for the Study of the Atmosphere

and Ocean (JISAO under NOAA Cooperative Agreement No. NA17RJ11232, Contribution #939. This is PMEL Contribution #2486.

7. References

Cronin, M.F., and W.S. Kessler (2002): Seasonal and interannual modulation of

mixed layer variability at 0◦, 110◦W. Deep-Sea Res., 49(1), 1–7.

Freitag, H.P., Y. Feng, L.J. Mangum, M.P. McPhaden, J. Neander, and L.D. Stratton (1994): Calibration procedures and instrumental accuracy estimates of

TAO temperature, relative humidity and radiation measurements. NOAA Tech.

Memo. ERL PMEL-104, 32 pp.

McPhaden, M.J. (1985): Fine-structure variability observed in CTD measurements

from the central equatorial Pacific. J. Geophys. Res., 90, 11,726–11,740.

McPhaden, M.J., A.J. Busalacchi, R. Cheney, J.R. Donguy, K.S. Gage, D. Halpern,

M. Ji, P. Julian, G. Meyers, G.T. Mitchum, P.P. Niiler, J. Picaut, R.W.

Reynolds, N. Smith, and K. Takeuchi (1998): The Tropical Ocean-Global Atmosphere (TOGA) observing system: A decade of progress. J. Geophys. Res.,

103, 14,169–14,240.

Mobley, C.D. (1994): Light and Water; Radiative Transfer in Natural Waters.

Academic Press, 592 pp.
ATLAS Module Temperature Bias 11

Morel, A. (1988): Optical modeling of the upper ocean in relation to its biogenous

content (Case I Waters). J. Geophys. Res, 93, 10,749–10,768.

Payne, R.E. (1972): Albedo of the sea surface. J. Atmos. Sci., 29, 959–970.

Servain, J., A.J. Busalacchi, M.J. McPhaden, A.D. Moura, G. Reverdin, M. Vianna,

and S.E. Zebiak (1998): A Pilot Research Moored Array in the Tropical Atlantic

(PIRATA). Bull. Am. Meteorol. Soc., 79, 2019–2031.

Siegel, D.A., J.C. Ohlmann, L. Washburn, R.R. Bidigare, C.T. Nosee, E. Fields,

and Y. Zhou (1995): Solar radiation, phytoplankton pigments, and the radiant

heating of the equatorial Pacific warm pool. J. Geophys. Res., 100(C3), 4485–

4891.

Strutton, P.G., and F.P. Chavez (2000): Primary productivity in the equatorial

Pacific during the 1997–98 El Ni ̃no. J. Geophys. Res, 105, 26,089–26,101.
12 P.N. A’Hearn et al.
ATLAS Module Temperature Bias 13

Appendix

Mooring sensor information
14 P.N. A’Hearn et al.

PIRATA (Eastern Atlantic)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

0

◦

, 0◦ PM038 02/01/98 11/08/98 20 B S U

40 B S U

60 B S U

PM066 11/04/98 01/12/99 20 B S *

40 B S *

60 B S *

PM160 08/08/00 12/10/01 20 W F *

40 W F *

60 W F *

2

◦N, 10◦W PM111 11/01/99 03/06/00 20 * S *

40 * S *

60 * S *

PM133 03/10/00 07/30/00 20 W S I

40 W S I

60 B S U

0

◦

, 10◦W PM031 09/14/97 11/20/97 25 B S U

50 B S U

75 B S U

PM068 01/28/99 03/11/00 20 B S I

40 B S I

60 B S U

PM134 03/11/00 11/22/00 20 W S I

40 W S I

60 B S I

2

◦S, 10◦W PM110 11/02/99 03/12/00 20 * S *

40 * S *

60 B S *

5

◦S, 10◦W PM067 01/27/99 03/13/00 20 B S I

40 B S I

60 B S U

PM135 03/14/00 11/25/00 20 W S I

40 W S I

60 * S I

10◦S, 10◦W PM030 09/10/97 11/04/98 20 B S U

40 B S U

60 B S U

PM063 11/04/98 10/30/99 20 B S *

40 B S *

60 B S *

PM109 10/30/99 11/27/00 20 * S U

40 B S U

60 B S U

* = unknown
ATLAS Module Temperature Bias 15

PIRATA (Western Atlantic)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

0

◦

, 23◦W PM078 03/06/99 02/23/00 20 B S I

40 B S I

60 B S U

PM128 02/24/00 05/07/01 20 W S I

40 W S I

60 W S U

0

◦

, 35◦W PM035 01/21/98 02/23/99 20 B S U

40 B S U

60 B S U

PM077 02/23/99 03/28/00 20 B S I

40 B S I

60 B S U

PM140 03/28/00 05/03/01 20 W S I

40 W S I

60 W S U

15◦N, 38◦W PM036 01/27/98 02/05/99 20 B S U

40 B S U

60 B S U

PM073 02/05/99 03/14/00 20 B S I

40 B S I

60 B S U

PM136 03/15/00 04/16/01 20 W S I

40 W S I

60 B S U

11◦300N, 38◦W PM070 02/03/99 03/16/00 20 B S I

40 B S I

60 B S U

PM137 03/16/00 01/15/01 20 W S I

40 W S I

60 B S U

8

◦N, 38◦W PM037 01/30/98 02/08/99 20 B S U

40 B S U

60 B S U

PM074 02/08/99 03/18/00 20 B S I

40 B S I

60 B S U

PM138 03/18/00 04/19/01 20 W S I

40 W S I

60 B S U

4

◦N, 38◦W PM076 02/20/99 03/19/00 20 B S I

40 B S I

60 B S U

PM139 03/19/00 04/20/01 20 W S I

40 W S I

60 B S U
16 P.N. A’Hearn et al.

TAO (95◦W)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

12◦N, 95◦W PM123 12/02/99 04/20/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

10◦N, 95◦W PM122A 12/01/99 04/21/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

PM122B 04/21/00 11/11/00 60 B S U

8

◦N, 95◦W PM028 08/05/97 11/10/98 20 B S U

40 B S U

60 B S U

PM121A 11/30/99 04/23/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

PM121B 04/23/00 11/10/00 60 B S U

5

◦N, 95◦W PM087 05/25/99 04/23/00 20 B S I

40 B S I

60 B S U

PM181 11/09/00 11/23/01 60 W F U

3

◦

300N, 95◦W PM120 11/28/99 04/24/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

2

◦N, 95◦W PM065 11/08/98 07/20/99 20 B S U

40 B S U

60 B S U

PM086 05/24/99 11/27/99 20 B S I

40 B S I

60 B S U

PM118A 11/27/99 04/25/00 5 W S U

10 W S U

20 W S U

40 W S U

60 W S U

PM118B 04/25/00 07/11/00 60 W S U
ATLAS Module Temperature Bias 17

TAO (95◦W cont.)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

0

◦

, 95◦W PM064 11/06/98 05/22/99 20 B S U

40 B S U

60 B S U

PM085 05/23/99 11/26/99 20 B S I

40 B S I

60 B S U

PM117A 11/26/99 04/26/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

PM117B 04/26/00 11/05/00 60 B S U

2

◦S, 95◦W PM116A 11/25/99 04/27/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

PM116B 04/27/00 11/04/00 60 B S U

5

◦S, 95◦W PM084 05/20/99 04/28/00 20 B S I

40 B S I

60 B S U

8

◦S, 95◦W PM007 05/13/96 08/11/97 20 B S U

40 B S U

60 B S U

PM115A 11/23/99 04/30/00 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

PM115B 04/30/00 11/12/00 60 B S U
18 P.N. A’Hearn et al.

TAO (110◦W)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

8

◦N, 110◦W PM029 08/22/97 10/23/98 20 B S U

40 B S U

60 B S U

PM112A 11/11/99 05/12/00 20 * S U

40 W S U

60 * S U

PM112B 05/12/00 10/21/00 60 * S U

2

◦N, 110◦W PM113A 11/13/99 05/09/00 20 * S U

40 * S U

60 * S U

PM113B 05/09/00 10/23/00 60 * S U

0

◦

, 110◦W PM062 10/27/98 05/11/99 20 B S U

40 B S U

60 B S U

PM083 05/11/99 11/15/99 10 B S U

20 B S I

25 B S U

40 B S I

60 B S U

PM114 11/15/99 05/07/00 20 W S I

40 W S I

60 W S U

8

◦S, 110◦W PM008 05/16/96 08/15/97 20 B S U

40 B S U

60 B S U

* = unknown
ATLAS Module Temperature Bias 19

TAO (125◦W)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

8

◦N, 125◦W PM044 04/25/98 09/14/98 20 B S U

40 B S U

60 B S U

PM107 10/06/99 02/24/00 20 B S *

40 * S *

60 * S *

PM129 02/25/00 09/08/00 20 W S I

40 W S I

60 B S U

PM161 09/08/00 02/07/01 60 W F U

5

◦N, 125◦W PM017 04/03/97 04/26/98 20 B S U

40 B S U

60 B S U

PM045B 08/09/98 09/16/98 20 B S U

40 B S U

60 B S U

2

◦N, 125◦W PM075 02/13/99 10/02/99 20 B S *

40 B S *

60 B S U

PM106 10/03/99 09/12/00 20 B S *

40 B S *

60 B S *

0

◦

, 125◦W PM009 06/24/96 04/06/97 20 B S U

40 B S U

60 B S U

PM018 04/08/97 04/28/98 20 B S U

40 B S U

60 B S U

PM046 04/29/98 09/18/98 20 B S U

40 B S U

60 B S U

PM058 09/18/98 10/01/99 20 B S I

40 B S I

60 B S U

PM105 10/01/99 02/21/00 20 B S *

40 W S *

60 B S *

PM127 02/21/00 02/04/01 20 W S I

40 W S I

60 B S U

* = unknown
20 P.N. A’Hearn et al.

TAO (140◦W)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

9

◦N, 140◦W PM102 09/15/99 09/26/00 20 B S I

40 B S I

60 B S U

5

◦N, 140◦W PM061 10/01/98 01/31/99 20 B S I

40 B S I

60 B S U

PM069B 09/17/99 02/09/00 20 B S *

40 B S *

60 B S U

PM124 02/10/00 01/22/01 20 B S I

40 W S I

60 W S U

2

◦N, 140◦W PM060 09/30/98 02/03/99 20 B S I

40 B S I

60 B S U

PM071 02/04/99 09/14/99 20 B S *

40 B S *

60 B S U

PM103 09/18/99 02/11/00 20 B S I

40 B S I

60 B S U

PM125 02/11/00 01/23/01 20 W S I

40 W S I

60 B S U

0

◦

, 140◦W PM072 02/05/99 09/19/99 20 B S *

40 B S *

60 B S U

PM104 09/21/99 02/12/00 20 * S *

40 * S *

60 * S *

PM126 02/12/00 09/23/00 20 * S I

40 * S I

60 * S U

* = unknown
ATLAS Module Temperature Bias 21

TAO (155◦W, 170◦W, 180◦)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

8

◦N, 155◦W PM148 06/19/00 06/02/01 25 W S I

50 * S I

75 * S I

2

◦N, 155◦W PM088 07/07/99 06/22/00 25 W S U

50 W S U

75 B S U

PM149 06/22/00 06/06/01 25 W S I

50 W S I

75 * S I

0

◦

, 155◦W PM108 10/27/99 10/21/00 25 W S U

50 W S U

75 B S U

2

◦S, 155◦W PM150 06/23/00 06/08/01 25 W S I

50 W S I

75 W S I

5

◦N, 170◦W PM013 07/26/96 05/26/97 25 B S U

50 B S U

75 B S U

PM022 05/27/97 06/25/98 25 B S U

50 B S U

75 B S U

PM050 06/26/98 07/22/99 25 B S U

50 B S U

75 B S U

PM090 07/23/99 07/05/00 25 W S U

50 W S U

75 B S U

PM152 07/06/00 06/20/01 25 W S I

50 W S I

75 * S I

2

◦N, 180◦ PM011 06/29/96 06/24/97 25 B S U

50 B S U

75 B S U

PM027 06/25/97 07/22/98 25 B S U

50 B S U

75 B S U

PM056 07/23/98 07/25/99 25 B S U

50 B S U

75 B S U

PM100 08/21/99 08/02/00 25 W S *

50 W S *

75 B S *

0

◦

, 180◦ PM119 11/28/99 11/30/00 25 W S U

50 W S U

75 B S U

PM191 11/30/00 11/14/01 75 B S U

2

◦S, 180◦ PM190 11/29/00 07/19/01 50 W S I

75 B S U

* = unknown
22 P.N. A’Hearn et al.

TAO (KWAJEX)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

8

◦N, 168◦E PM091 07/29/99 09/14/99 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

8

◦N, 167◦E PM092 07/30/99 09/13/99 5 W S U

10 W S U

20 W S U

40 W S U

60 B S U

TAO (165◦E)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

8

◦N, 165◦E PM023 06/09/97 07/07/98 25 B S U

50 B S I

75 B S U

PM051 07/08/98 08/05/99 25 B S U

50 B S U

75 B S U

PM093 08/06/99 07/18/00 25 B S I

50 B S I

75 B S U

5

◦N, 165◦E PM024 06/11/97 07/09/98 25 B S U

50 B S U

75 B S U

PM052 07/09/98 08/07/99 25 B S U

50 B S U

75 B S U

PM094 08/07/99 07/19/00 25 W S U

50 B S I

75 B S U

PM184 11/18/00 11/06/01 75 W S U

2

◦N, 165◦E PM032 01/06/98 03/20/99 25 B S U

50 B S U

75 B S U

PM082 03/21/99 08/08/99 25 B S I

50 B S I

75 B S U

PM095 08/09/99 02/27/00 25 B S I

50 B S I

75 B S U

PM130 02/28/00 04/20/00 25 W S I

50 W S U

75 W S U
ATLAS Module Temperature Bias 23

TAO (165◦E cont.)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

0

◦

, 165◦E PM081 03/20/99 08/10/99 25 B S I

50 B S I

75 B S U

PM096 08/11/99 10/21/99 25 B S I

50 B S I

75 B S U

PM131 02/29/00 07/22/00 25 W S I

50 W S I

75 W S U

PM185 11/20/00 07/09/01 75 * F U

2

◦S, 165◦E PM025 06/15/97 07/11/98 25 B S U

50 B S U

75 B S U

PM054 07/12/98 08/11/99 25 B S U

50 B S U

75 B S U

PM097 08/12/99 07/23/00 25 B S I

50 B S I

75 B S U

5

◦S, 165◦E PM012 07/09/96 02/01/97 25 B S U

50 B S U

75 B S U

PM034 01/10/98 03/13/99 25 B S U

50 B S U

75 B S U

PM080 03/14/99 03/01/00 25 B S I

50 B S I

75 B S U

PM132 03/02/00 11/21/00 25 W S I

50 W S I

75 W S I

PM186 11/22/00 07/11/01 75 W S U

8

◦S, 165◦E PM026 06/17/97 07/14/98 25 B S U

50 B S U

75 B S U

PM055 07/14/98 03/12/99 25 B S U

50 B S U

75 B S U

PM079 03/13/99 07/26/00 25 B S I

50 B S I

75 B S U

TAO (156◦E)

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

0

◦

, 156◦E PM057 08/21/98 10/06/99 25 B S U

50 B S U

75 B S U

* = unknown
24 P.N. A’Hearn et al.

South China Sea

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

18◦N, 116◦E PM020 04/27/97 04/09/98 25 B S U

50 B S U

75 B S U

PM041 04/10/98 04/09/99 25 B S U

50 B S U

75 B S U

PM098 08/19/99 05/07/00 25 * S *

50 * S *

75 B S *

15◦N, 115◦E PM042 04/11/98 04/10/99 25 B S U

50 B S U

75 B S U

PM099 08/20/99 05/04/00 25 * S *

50 * S *

75 * S *

13◦N, 114◦E PM043 04/12/98 04/11/99 25 B S U

50 B S U

75 B S U

PM101 08/21/99 05/05/00 25 * S *

50 * S *

75 * S *

North Pacific

Latitude Mooring Deployment Recovery

Longitude Name Date Date Depth Color Response Orientation

(Degrees) (Mo/Da/Yr) (Mo/Da/Yr) (m) Black/White Slow/Fast Upright/Inverted

50◦N, 145◦W PAPA1 09/28/98 06/08/99 6 B S U

10 B S U

15 B S U

20 B S U

30 B S U

40 B S U

50 B S U

60 B S U

PAPA2 10/10/99 08/12/00 5 W S U

10 W S U

15 * S U

20 W S U

30 B S U

40 W S U

50 * S U

60 W S U

35◦N, 165◦W MOMMA 09/28/99 10/01/00 5 W S U

10 W S U

15 W S U

20 B S U

30 W S U

40 B S U

50 W S U

60 B S U

* = unknown