Morphology of an uncharted seamount from central Indian Basin

Abstract

The morphology of a seamount at 12°35'S and 76°16'E is studied. This conical seamount has a maximum height of 1275 m (water depth 4135 m) and covers an area of about 189 sq km. The maximum basal extension is about 24 km. The mount is gentler and lengthier on the western flank and steeper and shorter on the eastern flank. A conspicuous flat steplike feature is present on the western flank. Slope angles are high (up to 35°). The trend of the seamount is approximately NNE‐SSW. Dredging yielded basalts containing ferromanganese encrustations indicating its volcanic origin.     

Experimental investigation of water slamming loads on panels

Rigid-body slamming has become increasingly important as ships travel at higher speeds experiencing larger loads during hull impacts against surface water which can result in structural damage and crew injury. It is necessary to characterise the hydrodynamic loading during water impacts.We present a series of experiments conducted in order to study slamming force events seen by flat plates during free surface impacts. The experiments focus on the characterisation of the loads experienced by flat plates during the first phase of the slamming event, the water entry. They have been conducted in an especially designed test apparatus, the Slingshot Impact Testing System (SITS), which allows us launching objects against the free surface of an open channel, with the possibility of setting up different speeds and deadrise angles. We can study slamming with trapped air between the plate and the water free surface, at high impact speeds and small deadrise angles, allowing us to quantify the resulting cushioning effect. High velocity impacts up to 5 m/s were conducted at angles between 0.3° and 25°. It was found that the trapped air phenomenon significantly cushions flat plate impacts with angles less than 5° and impacts with larger angles adhere to Von Kármán's equations.     

Improved parabolic water wave transformation model

An improved parabolic water wave transformation model is developed based on generalized [1/1] Padé approximation. For forward scattered waves, the parabolic equation is solved using a marching scheme. The values of wave angles are calculated after the solution of each line; so that better [1/1] generalized Padé approximation is performed. The nonlinear effects are included using a modified dispersion equation. The model is easy to use and performs very well for complex bathymetry. The model is tested for cases of wave angles up to 70°. The numerical results show that for large wave angles, the new parabolic model is better than all the existing parabolic models based on rational approximation.     

Determining the weights of two types of artificial reefs required to resist wave action in different water depths and bottom slopes

The interaction between waves and artificial reefs (ARs; a hollow cube weighing 8.24 kN (0.84 t) and a water pipe weighing 1.27 kN (0.13 t)) in shallow waters was investigated with respect to variations in design weight, orientation (for cube; 45° and 90° angles, for pipe; 0°, 90°, and 180° angles to flow), depth (1–20 m), and bottom slope (10^?1, 30^?1, and 50^?1). Physics equations and FLUENT software were used to estimate resisting and mobilising forces, and drag coefficients. Drag coefficients for the hollow cube were 0.76 and 0.85 at 45° and 90° angles to the current, respectively, and 0.97, 0.38, and 1.42 for the water pipe at 0°, 90°, and 180° angles to the current, respectively. Deepwater offshore wave conditions at six stations were transformed into shallow nearshore waters representative of the artificial reef site. Waters deeper than 12 and 16 m are safe to deploy blocks with angles of 45° and 90°, respectively. However, water pipes constructed at angles of 90° and 180° to the current were estimated as being unstable for 365 out of 720 cases at all stations (only one station was stable for all cases). Water pipes angled at 0° were found to be stable in all 360 cases. Slope had a significant effect on weight and depth. Results from this study provide an important reference for engineers performing projects aiming to increase the performance and service life of ARs.     

Derivation of Bathymetry from High-resolution Optical Satellite Imagery and USV Sounding Data

Remote sensing bathymetry inversion can quickly obtain water depth data of large areas, but this process relies on a large number of in-situ depth data points. USV-based (Unmanned Surface Vehicle) technique can obtain the bathymetry data of shallow water where ordinary ships are inaccessible, but this technique is inefficient and generally only data along survey line can be collected. The combination of USV and high-resolution remote sensing provides a new solution for water depth surveying and mapping around an island. This paper focuses on the key techniques, using USV sounding data and GeoEye-1 multispectral remote sensing images covering the region of Wuzhizhou island in the experiment. The results show that the MAE (Mean Absolute Error) of USV sounding is 0.25 m, while the MRE (Mean Relative Error) is 1.41%, and the MRE of remote sensing bathymetry aided by USV sounding can be controlled within 20%. Errors are mainly from areas shallower than 5 m, and are also affected by the USV sounding position accuracy. It shows that it is feasible to combine the USV sounding and high-resolution remote sensing bathymetry, and this technique has broad application prospects in the field of bathymetry in large shallow areas.     

Limnology of Bird Pond,Ross Island,Antarctica

The physical, chemical and biological properties of Bird Pond, Cape Bird, Ross Island, Antarctica (77° 13’ 10” S, 166° 28’ 30” E), were investigated at weekly intervals for 2 months in the summer of 1970–71. The above properties were also investigated over a 24‐h period. Salinity and temperature tolerance of the rotifer Philodina gregaria were investigated in the laboratory at Cape Bird.

Bird Pond is characterised by a high conductivity and chloride ion concentration, and an alkaline pH. It has a water temperature as high as 15°c in mid summer, with the bottom water temperature often 3°c higher than the surface temperature. Diurnal measurements suggest a vertical movement of phytoplankton during a 24‐h period. P. gregaria survives ionic concentrations up to 250 000 g.m^‐3 Na⁺ + Cl^‐, and water temperatures up to 32°c.     

不同内倾角海螺笼对脉红螺的诱捕效果

作者对不同内倾角海螺笼对脉红螺(Rapana venosa)的诱捕效果进行了实验研究。在实验室水槽中,观察了4种不同内倾角(35°、45°、55°和65°)的海螺笼对脉红螺的诱捕效果,同时还研究了光照和温度对海螺笼诱捕效果的影响,为优化海螺笼捕捞技术提供理论依据。实验结果表明:在相同的实验条件下,不同的内倾角对海螺笼诱捕效果影响十分显著(P<0.01),其中内倾角为45°的海螺笼诱捕效果最好,内倾角为35°和55°的海螺笼较好,而内倾角为65°的海螺笼诱捕效果则最差。同时发现,内倾角对脉红螺的个体大小具有选择性,随着内倾角的增大,壳高<7cm的个体占相应笼诱捕总数的百分比越来越小。光照对海螺笼的捕捞效果有十分显著的影响,而温度的影响则不明显。     

Coastal Bathymetric Studies from Space Imagery

Abstract

Studies of coastal bathymetry are important where littoral drift has implications on the planning of fishing and dredging operations. Also, there is a possibility of finding hitherto unknown bottom features in relatively less explored regions of the shallow seas around the globe. High resolution satellite imagery over oceans provides us with quantitative methods for estimating depth in shallow parts of the seas. One of the methods is the analysis of the refraction of coastal gravity waves observed on satellite imagery. A panchromatic image acquired by SPOT with 10 m resolution on March 22, 1986, over Bay of Bengal near Madras Coast, was used for this analysis. The image was enhanced to clearly bring out the wave structure seen on the sea surface. The image was then superimposed with a 1 km × 1 km grid. For each grid cell, 64 × 64 pixels at the center were considered for getting a Fast Fourier Transform to determine the wave spectrum and the dominant wavelength present there. The classical theory of gravity waves was used to relate the shallow water wavelengths obtained as above with the corresponding wavelengths in the deep water. The deep‐water wavelength was estimated to be 110 m using the known chart depths at a set of control points. The resulting depth estimates, when compared with standard bathymetric charts, were found, in general, to be well in agreement up to a depth of 30 m in the sea, with an r.m.s. error of 2.6 meters. The method seems to be very useful for remotely sensed bathymetric work. However, further research is required to reduce the error margin and operationalize the method.     

Limnology of Lake Rotokawa and its outlet stream

Abstract

The water chemistry, flora, and fauna of Lake Rotokawa (38° 37.8’ S, 176° 11.2'E) was studied in 1975–76. The mean pH is 2.1 and thermal inflows may elevate the mean summer temperature of the surface waters 4.2°c above that of nearby cold water Lake Rotongaio (18.9°c). The temperature range of surface water was from 10.1 °c in winter to 23.1°c in summer. The major anions were SO₄ ^2? 679 g.m^?3, and Cl‐ 314 g.m^?3. Mean concentrations of major cations were Na⁺ 224 g.m^?3, K⁺ 28.9 g.m^?3, Ca²⁺ 13.3 g.m^?3, and Mg²⁺ 2.6 g.m^?3.

Two species of flagellate algae were recorded, of which Euglena anabaena was predominant. Only two benthic macroinvertebrates were found, larvae of Chironomus zealandicus, mean density 253 per square metre, and Helobdella sp., 1.3 per square metre.

The Parariki Stream was influenced by thermal springs in its upper and lower reaches, being cooler (24–25°c) about halfway along its length than near its source (27.8–39.0°c) or confluence (26.5°‐28.0°c) with the Waikato River. In the cooler stretch of the stream where unidentified benthic algae were not limited by high temperature, chlorophyll and total pigment increased from 3.9 to 377.9 mg.m^?3 and from 17.5 to 534.4 mg.m^?3 respectively, and nutrient levels fell (NO₃‐N, 22–10.5 mg.m^?3; NH₄‐N, 6440–230 mg.m^?3; and PO₄‐P, 51–19 mg.m^?3).     

Discretization of Complex Geometric Domain Through Computer-Based Stair-Step Representation Method for Estimating Water Levels Associated with A Storm

In this paper, an improvement has been made to the approximation technique of a complex domain through the stairstep approach to have a considerable accuracy, minimize computational cost, and avoid the hardship of manual work. A novel stair-step representation algorithm is used in this regard, where the entire procedure is carried out through our developed MATLAB routine. Arakawa C-grid is used in our approximation with (1/120)° grid resolution. As a test case, the method is applied to approximate the domain covering the area between 15°–23°N latitudes and 85°–95° E longitudes in the Bay of Bengal. Along with the approximation of the land-sea interface, coastal stations are also identified. Approximated land-sea interfaces and coastal stations are found to be in good agreement with the actual ones based on the similarity index, overlap fraction, and extra fraction criteria. The method can be used for approximating an irregular geometric domain to employ the finite difference method in solving problems related to long waves. As a test case, shallow water equations in Cartesian coordinates are solved on the domain of interest for simulating water levels due to the nonlinear tide-surge interaction associated with the storms April 1991 and AILA, 2009 along the coast of Bangladesh. The same input except for the discretized domain and bathymetry as that of Paul et al. (2016) is used in our simulation. The results are found to be in reasonable agreement with the observed data procured from Bangladesh Inland Water Transport Authority.

     

Analysis of submarine slumping in the continental slope off the southern coast of Israel

Abstract

The continental slope off the coast of Israel is riddled with numerous large slump scars at depths greater than 400 m. Recent scar slumps are situated in the steepest central portions of the continental slope (400–450 m depth, α=6°), frequently disfiguring older slump scars in its lower portions. The slumping materials were probably largely transported downslope in the form of density currents, and occasionally by sliding of large sediment chunks. Upslope retrogressive slumping phases progressively disfigure the shape of the slump scars until they totally disappear, causing net reduction of the thickness of the sedimentary column. To provide a basis for the quantitative analysis of slumping, laboratory vane tests, triaxial consolidated, undrained compression tests with pore‐pressure measurements, drained direct shear tests, and consolidation tests were performed oh undisturbed samples. Because the sediments consist of normally consolidated silty clays, the geotechnical properties measured on the core samples can be readily extrapolated for greater depths, assuming the sediments are homogeneous. Angles of internal friction measured by direct shearing under drained conditions are ?_d =24°‐25°, designating the maximum possible angle of a stable infinite slope. These angles are appreciably higher than the steepest slopes in the investigated area, and a drained slumping mechanism is therefore considered unlikely. The slopes of the slump scar walls are about 20°; therefore, in the absence of active erosional, sedimentological, or tectonic agents, these walls have long‐term stability (drained shear). Undrained shear failure resulting in slope instability may be attributable to rapid changes in slope geometry (undercutting or oversteepening of the slope), fluctuations in pore pressure, or accelerations associated with earthquakes. Undrained shear‐strength parameters were determined by both laboratory consolidated‐un‐drained triaxial tests and by miniature vane shear tests. The angles of internal friction that were measured are ?_cu =15°‐17°, and the c_u/p_o values range between 0.22 and 0.75. An analysis of the force equilibrium within the sediments leads to the conclusion that horizontal earthquake‐induced accelerations, as little as 5–6% of gravity, are sufficient to cause slope failure in the steepest slope zone (400–450 m depth, α = 6°, c_u /p_o =0.25). Collapse resulting from liquefaction is unlikely, as the sediments are normally consolidated silty clays with intermediate sensitivity, S_t =2–4.

The existence of slump scars in the lower portion of the continental slope, characterized by gentle slopes (α=1°‐3°) and sediments with high shear strength (c _u /p _o=0.30–0.50) is attributed to large horizontal accelerations(k=12–16% of gravity). Owing to the wide range of geotechnical properties of the sediments (c_u /p_o = 0.20–0.75) and the inclination of the continental slope (α=1°‐6°), the same earthquake may generate a wide range of horizontal accelerations in different portions of the continental slope, and slumping may occur wherever the stability equilibrium is disrupted.     

Analysis of submarine slumping in the continental slope off the southern coast of Israel

Abstract

The continental slope off the coast of Israel is riddled with numerous large slump scars at depths greater than 400 m. Recent scar slumps are situated in the steepest central portions of the continental slope (400–450 m depth, α = 6°), frequently disfiguring older slump scars in its lower portions. The slumping materials were probably largely transported downslope in the form of density currents, and occasionally by sliding of large sediment chunks. Upslope retrogressive slumping phases progressively disfigure the shape of the slump scars until they totally disappear, causing net reduction of the thickness of the sedimentary column. To provide a basis for the quantitative analysis of slumping, laboratory vane tests, triaxial consolidated, undrained compression tests with pore‐pressure measurements, drained direct shear tests, and consolidation tests were performed oh undisturbed samples. Because the sediments consist of normally consolidated silty clays, the geotechnical properties measured on the core samples can be readily extrapolated for greater depths, assuming the sediments are homogeneous. Angles of internal friction measured by direct shearing under drained conditions are ?_d =24°‐25°, designating the maximum possible angle of a stable infinite slope. These angles are appreciably higher than the steepest slopes in the investigated area, and a drained slumping mechanism is therefore considered unlikely. The slopes of the slump scar walls are about 20°; therefore, in the absence of active erosional, sedimentological, or tectonic agents, these walls have long‐term stability (drained shear). Undrained shear failure resulting in slope instability may be attributable to rapid changes in slope geometry (undercutting or oversteepening of the slope), fluctuations in pore pressure, or accelerations associated with earthquakes. Undrained shear‐strength parameters were determined by both laboratory consolidated‐un‐ drained triaxial tests and by miniature vane shear tests. The angles of internal friction that were measured are ?_cu =15°‐17°, and the c_u/p _o values range between 0.22 and 0.75. An analysis of the force equilibrium within the sediments leads to the conclusion that horizontal earthquake‐induced accelerations, as little as 5–6% of gravity, are sufficient to cause slope failure in the steepest slope zone (400–450 m depth, α=6°, c_u/p _o=0.25). Collapse resulting from liquefaction is unlikely, as the sediments are normally consolidated silty clays with intermediate sensitivity, S_t =2–4.

The existence of slump scars in the lower portion of the continental slope, characterized by gentle slopes (α=1°‐3°) and sediments with high shear strength (c_u/p _o=0.30–0.50) is attributed to large horizontal accelerations (k= 12–16% of gravity). Owing to the wide range of geotechnical properties of the sediments (c_u/p _o= 0.20–0.75) and the inclination of the continental slope (α=1°‐6°), the same earthquake may generate a wide range of horizontal accelerations in different portions of the continental slope, and slumping may occur wherever the stability equilibrium is disrupted.     

Unsteady RANS simulation of a surface piercing propeller in oblique flow

Conventional propellers might undergo severe cavitation at high speeds and this phenomenon not only affects the efficiency of the propeller, but also may result in serious damages in propulsion system. Due to their special geometries, surface piercing propellers (SPPs) overcome this problem and achieve high efficiencies in high speeds. Therefore, SPPs are one of the popular propulsors for high-speed crafts. The present research is aimed to pursue SPP's performance in the off-design conditions. URANS method was used to study the performance of the 841-B SPP (a case with some available experimental results; Olofsson, 1996) in several immersion ratios (I = 33%, 50%, 75% and 100%) and maneuvering conditions (incident angles of 0°, 10° and 20°). The free surface was simulated using VOF method. Off-design conditions might exert extra or less forces and torques on the propeller's blade. In the present research for 841-B SPP, it was found that a maneuver condition would increase the thrust and torque coefficient for some cases. The sliding mesh technique was utilized to simulate the 841-B SPP performance, which unlike the multiple reference frame (MRF) technique, this technique allows to capture the blades hit on the water surface in transient mode simulations.     

Pockmarks on either side of the Strait of Gibraltar: formation from overpressured shallow contourite gas reservoirs and internal wave action during the last glacial sea-level lowstand?

Integrating novel and published swath bathymetry (3,980 km²), as well as chirp and high-resolution 2D seismic reflection profiles (2,190 km), this study presents the mapping of 436 pockmarks at water depths varying widely between 370 and 1,020 m on either side of the Strait of Gibraltar. On the Atlantic side in the south-eastern Gulf of Cádiz near the Camarinal Sill, 198 newly discovered pockmarks occur in three well localized and separated fields: on the upper slope (n=14), in the main channel of the Mediterranean outflow water (MOW, n=160), and on the huge contourite levee of the MOW main channel (n=24) near the well-known TASYO field. These pockmarks vary in diameter from 60 to 919 m, and are sub-circular to irregularly elongated or lobate in shape. Their slope angles on average range from 3° to 25°. On the Mediterranean side of the strait on the Ceuta Drift of the western Alborán Basin, where pockmarks were already known to occur, 238 pockmarks were identified and grouped into three interconnected fields, i.e. a northern (n=34), a central (n=61) and a southern field (n=143). In the latter two fields the pockmarks are mainly sub-circular, ranging from 130 to 400 m in diameter with slope angles averaging 1.5° to 15°. In the northern sector, by contrast, they are elongated up to 1,430 m, probably reflecting MOW activity. Based on seismo-stratigraphic interpretation, it is inferred that most pockmarks formed during and shortly after the last glacial sea-level lowstand, as they are related to the final erosional discontinuity sealed by Holocene transgressive deposits. Combining these findings with other existing knowledge, it is proposed that pockmark formation on either side of the Strait of Gibraltar resulted from gas and/or sediment pore-water venting from overpressured shallow gas reservoirs entrapped in coarse-grained contourites of levee deposits and Pleistocene palaeochannel infillings. Venting was either triggered or promoted by hydraulic pumping associated with topographically forced internal waves. This mechanism is analogous to the long-known effect of tidal pumping on the dynamics of unit pockmarks observed along the Norwegian continental margin.     

Effect of angle between initial and cyclic shear stress on behaviors of marine clay

An angle exists between the initial static shear stress and cyclic shear stress when embankment and retaining walls are subjected to cyclic loadings. To investigate the influence of this angle on the dynamic properties of marine soft clay, tests were performed on Wenzhou soft clay. When the angle was varied from 0° to 90°, the shear strain and excess pore pressure decreased as θ increased while increased as θ increased from 120° to 180°. Shear strain developed more rapidly when θ was 120°, 150°, or 180° than that when θ was 0°, 30°, or 60°. These results indicate that the number of cycles to failure at the larger angles was greater than at the smaller angles. When θ was 90°, the strain in the x-axis direction increased as the number of cycles increased. The development of the excess pore pressure associated with specimen failure was different for different cyclic shear stress ratios and shearing angles. The effect of θ on the strain and excess pore pressure increased as the cyclic shear stress ratio increased.     

Intermediate Waters in the East/Japan Sea

Properties of the intermediate layer in the East/Japan Sea are examined by using CREAMS data taken mainly in summer of 1995. Vertical profiles of potential temperature, salinity and dissolved oxygen and relationships between these physical and chemical properties show that the dissolved oxygen concentration of 250 μmol/l, roughly corresponding to 0.6°C at the depth of about 400 db, makes a boundary between intermediate and deep waters. Water colder than 0.6°C has a very stable relationship between potential temperature and salinity while salinity of the water warmer than 0.6°C is lower in the western Japan Basin than that in the eastern Japan Basin. The low salinity water with high oxygen corresponds to the East Sea Intermediate Water (ESIW; <34.06 psu, >250 μmol/l and >1.0°C) which was previously identified by Kim and Chung (1984) and the high salinity water with high oxygen found in eastern Japan Basin is named as the High Salinity Intermediate Water (HSIW; >34.07 psu, >250 μmol/l and >0.6°C). Spatial distribution of salinity and acceleration potential on the surface of σ_ϑ = 27.2 kg/m³ shows that the ESIW prevailing in the western Japan Basin is transported eastward by a zonal flow along the polar front near 40°N and a cyclonic gyre in the eastern Japan Basin is closely related to the HSIW. This revised version was published online in August 2006 with corrections to the Cover Date.     

Developing empirical formulas for assessing the scour of vertical and inclined piers

Abstract

Because scour is one of the main reasons for bridge failure, this study focuses on accurately predicting the maximum scour depth around different vertical and inclined piers. Scouring is an issue of concern in the bridge design process, as most existing equations for predicting local scour near bridge piers suffer from over- or underprediction issues, resulting in higher foundation costs or bridge failure and inaccurate predictions of the scour around piers. The dimensionless maximum scour depths (y_s/D) of vertical and inclined piers were investigated for seven pier shapes with different L/D ratios and four inclination angles (θ) under shallow flow conditions. The inclined pier configuration reduced the y_s/D of the piers. The maximum y_s/D was observed for a rectangular pier with an L/D of 4.5 in both vertical and inclined configurations (θ of 10, 15 and 21°, respectively). The y_s/D was significantly decreased by increasing the angle of the pier from 10 to 30°. The y_s/D of the inclined rectangular piers decreased as θ decreased from 30 to 10° and the L/D ratio increased from 1 to 4.5. The best y_s/D results were obtained for inclined rectangular piers at a θ value of 30° and an L/D ratio of 7.5 compared to other shapes and inclination angles. New equations were developed to predict the local scour depth for circular, square and rectangular bridge piers. The equations yielded excellent results for predicting the maximum clear water scour depth around vertical and inclined piers with inclination angles of 10, 15, 21 and 30°, respectively.     

Marine Geodesy (1975–1979)— to the International Association of Geodesy,Section 1

Abstract

Geographic Information Systems (GIS) have been developed during the last decade. Their land‐based applications range from land information management, urban planning, and environmental research to engineering design and management in the utility and oil industries, geological subsurface analysis, and others. However, applications of GIS in the marine environment are still in the initial stages. This may be due to, among other things, the large marine data sets, the demands of 3D data processing, and the difficulty of ocean data acquisition.

This article presents the result of the development of an integrated Marine Geographic Information System (MGIS) for the exploration and development of the Exclusive Economic Zone (EEZ) in the U.S. Pacific Islands region by the Pacific Mapping Center, University of Hawaii. Features such as spatial marine data processing, integration of GIS and mapping systems, 3D data structures, and simulation and animation of marine operations are developed and applied in this system. Since MGIS applications in EEZ are related to many disciplines in marine sciences and engineering, an operational MGIS should be an integrated system in which both basic GIS and marine application systems are combined into a single geo‐referenced system, In addition to other applications, this MGIS has been used: (1) to select a potential deep‐water research site off the island of Hawaii for the State of Hawaii Department of Business, Economic, and Development (DBED); (2) to generate a three‐dimensional database and use it for the navigation and simulation of underwater operations of an underwater research vehicle; and (3) to produce two 2° × 2° mosaic sheets of sonar images, which meet the USGS standard for a sonar image atlas.     

斜向波浪作用下双层水平板式防波堤波浪荷载试验研究

In this study, systematic physical model tests were performed to investigate the wave forces on the twin-plate breakwater under irregular waves. Based on the experimental results, the effects of the relative plate width B/L,wave height Hs/D and incident angle θ0 on the wave forces were analyzed and discussed. The results showed that:(1) The envelopes of the total wave pressure were generally symmetrical along the direction of plate width under the incident angles(θ0) being 0°, 15°, 30°, 45° and 60°. In particular, the envelopes of wave pressure atθ0=30° were larger than all other cases.(2) The synchronous pressure distribution of the breakwater under oblique wave action was more complicated comparing to the normal incident waves.(3) Based on data analysis, an empirical formula was obtained to estimate the total vertical force of the twin-plate breakwater.This empirical formula can be a good reference for the design basis of engineering applications under specified wave conditions.     

Difference characteristics of sea surface temperature observed by GLI and AMSR aboard ADEOS-II

This study compares infrared and microwave measurements of sea surface temperature (SST) obtained by a single satellite. The simultaneous observation from the Global Imager (GLI: infrared) and the Advanced Microwave Scanning Radiometer (AMSR: microwave) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) provided an opportunity for the intercomparison. The GLI-and AMSR-derived SSTs from April to October 2003 are analyzed with other ancillary data including surface wind speed and water vapor retrieved by AMSR and SeaWinds on ADEOS-II. We found no measurable bias (defined as GLI minus AMSR), while the standard deviation of difference is less than 1°C. In low water vapor conditions, the GLI SST has a positive bias less than 0.2°C, and in high water vapor conditions, it has a negative (positive) bias during the daytime (nighttime). The low spatial resolution of AMSR is another factor underlying the geographical distribution of the differences. The cloud detection problem in the GLI algorithm also affects the difference. The large differences in high-latitude region during the nighttime might be due to the GLI cloud-detection algorithm. AMSR SST has a negative bias during the daytime with low wind speed (less than 7 ms⁻¹), which might be related to the correction for surface wind effects in the AMSR SST algorithm.