Monthly Mean Sea Surface Temperature Research Articles

Reproduction and recruitment patterns of the surf clam Donax serra (Bivalvia, Donacidae) on two Namibian sandy beaches

Reproduction and recruitment of the surf clam Donax serra on two Namibian beaches were studied over a period of two years. Histological examination of the gonads indicated a discontinous annual reproductive cycle, related to monthly mean sea surface temperature. The spawning season lasted from August/September to February, but juveniles (2–6 mm anterior-posterior shell length) were only present for three months in the intertidal zone. The condition index indicates that the species spawns during autumn and summer, but histological validation is needed. The period when juveniles are abundant is decoupled from the spawning period and therefore cannot be predicted clearly, even if the spawning period is known. Starvation, hydrodynamic processes, chemical parameters and different release times during the spawning period are thought to cause the differences in settlement time and recruitment strength between locations. Keywords: condition index, Donax serra , histology, Namibia, recruitment, reproduction, sandy beach ecology African Journal of Marine Science 2001, 23: 53–60

The Correlation between U.S. Tornadoes and Pacific Sea Surface Temperatures

Abstract The correlation between tornadic activity in several regions of the United States and the monthly mean sea surface temperature over four zones in the tropical Pacific Ocean is examined. Tornadic activity is gauged with two mostly independent measures: the number of tornadoes per month, and the number of tornadic days per month. Within the assumptions set forth for the analysis, it is found that there appears to exist a statistically significant but very weak correlation between sea surface temperature in the Pacific Ocean and tornadic activity in the United States, with the strength and significance of the correlation depending on the coordinates at which the sea surface temperatures are assessed and the geographic region of the United States. The strongest evidence found is for the correlation between the number of days with strong and violent (F2 and greater) tornadoes in an area that runs from Illinois to the Atlantic Coast, and Kentucky to Canada and a cool sea surface temperature in the cent...

The relationships between variations of sea surface temperature anomalies in the key ocean areas and the precipitation and surface air temperature in China

The relationships between variations of sea surface temperature anomalies (SSTVA) in the key ocean areas and the precipitation / temperature anomalies in China are studied based on the monthly mean sea surface temperature data from January 1951 to December 1998 and the same stage monthly mean precipitation/ temperature data of 160 stations in China. The purpose of the present study is to discuss whether the relationship between SSTVA and precipitation / temperature is different from that between sea surface temperature anomalies (SSTA) and precipitation/ temperature, and whether the uncertainty of prediction can be reduced by use of SSTVA. The results show that the responses of precipitation anomalies to the two kinds of tendency of SSTA are different. This implies that discussing the effects of two kinds of tendency of SSTA on precipitation anomalies is better than just discussing the effects of SSTA on precipitation anomalies. It helps to reduce the uncertainty of prediction. The temperature anomalies have more identical re-sponses to the two kinds of tendency of SSTA than the precipitation except in the western Pacific Ocean. The response of precipitation anomalies to SSTVA is different from that to SSTA, but there are some similarities.

The Relationships between Tropical Pacific and Atlantic SST and Northeast Brazil Monthly Precipitation

The monthly patterns of northeast Brazil (NEB) precipitation are analyzed in relation to sea surface temperature (SST) in the tropical Pacific and Atlantic Oceans, using singular value decomposition. It is found that the relationships between precipitation and SST in both basins vary considerably throughout the rainy season (February–May). In January, equatorial Pacific SST is weakly correlated with precipitation in small areas of southern NEB, but Atlantic SST shows no significant correlation with regional precipitation. In February, Pacific SST is not well related to precipitation, but south equatorial Atlantic SST is positively correlated with precipitation over the northern Nordeste, the latter most likely reflecting an anomalously early (or late) southward migration of the ITCZ precipitation zone. During March, equatorial Pacific SST is negatively correlated with Nordeste precipitation, but no consistent relationship between precipitation and Atlantic SST is found. Atlantic SST–precipitation correlations for April and May are the strongest found among all months or either ocean. Precipitation in the Nordeste is positively correlated with SST in the south tropical Atlantic and negatively correlated with SST in the north tropical Atlantic. These relationships are strong enough to determine the structure of the seasonal mean SST–precipitation correlations, even though the corresponding patterns for the earlier months of the season are quite different. Pacific SST–precipitation correlations for April and May are similar to those for March. Extreme wet (dry) years for the Nordeste occur when both Pacific and Atlantic SST patterns for April and May occur simultaneously. A separate analysis reinforces previous findings in showing that SST in the tropical Pacific and the northern tropical Atlantic are positively correlated and that tropical Pacific–south Atlantic correlations are negligible. Time-lagged analyses show the potential for forecasting either seasonal mean or monthly precipitation patterns with some degree of skill. In some instances, individual monthly mean SST versus seasonal mean (February–May) precipitation relationships differ considerably from the corresponding monthly SST versus monthly precipitation relationships. It is argued that the seasonal mean relationships result from the relatively strong monthly relationships toward the end of the season, combined with the considerable persistence of SST in both oceans.

ENSO Seasonality: 1950–78 versus 1979–92

ENSO-related seasonal-to-interannual variability in the Pacific basin is documented, based on marine surface observations of monthly mean sea surface temperature, sea level pressure, and wind, together with satellite-based estimates of rainfall and mean tropospheric temperature. Anomalies in these fields are linearly regressed onto simultaneous values of an index of equatorial Pacific SST anomalies. The analysis is performed separately on the data for earlier (1950–78) and later (1979–92) epochs of the record. The analyses are further stratified in terms of the climatological-mean warm and cold seasons in the equatorial Pacific, which correspond to January–May and July–November, respectively. Composite SST, wind, and rainfall fields for he warm and cold seasons that fall within typical warm and cold ENSO episodes are also presented. Despite the dramatic differences in the sequencing of ENSO warm episodes with respect to the annual march in the two epochs, the anomaly patterns are found to be remarkably similar and generally consistent with the Rasmusson and Carpenter composite. SST and zonal wind anomalies were quite comparable in strength in the warm and cold seasons, although the distributions were somewhat different. Rainfall anomalies and the associated anomalies in surface wind convergence and mean tropospheric temperature were much stronger during the warm season (and particularly during January–February) than during the cold season. Some aspects of the observed rainfall anomaly seasonality can be explained on the basis of simple thermodynamical considerations.

The relationship between sea surface temperature anomalies and atmospheric circulation in GCM experiments

Several 19-year integrations of the Hamburg version of the ECMWF/T21 general circulation model driven by the monthly mean sea surface temperature (SST) observed in 1970–1988 were examined to study extratropical response of the atmospheric circulation to SST anomalies in the Northern Hemisphere in winter. In the first 19-years run SST anomalies were prescribed globally (GAGO run), and in two others SST monthly variability was limited to extratropical regions (MOGA run) and to tropics (TOGA run), respectively. A canonical correlation analysis (CCA), which select from two time-dependent fields optimally correlated pairs of patterns, was applied to monthly anomalies of SST in the North Alantic and Pacific Oceans and monthly anomalies of sea level pressure and 500 hPa geopotential height in the Northern Hemisphere. In the GAGO run the best correlated atmospheric pattern is global and is characterized by north-south dipole structures of the same polarity in the North Atlantic and the North Pacific sectors. In the MOGA and TOGA experiments the atmospehric response is more local than in the GAGO run with main centers in the North Atlantic and North Pacific, respectively. The extratropical response in the GAGO run is not equal to the sum of the responses in the MOGA and TOGA runs. The artificial meridional SST gradients at 25°–30°N probably influence the results of the MOGA and TOGA runs. The atmopsheric modes found by the CCA were compared with the normal modes of the barotropic vorticity equation linearized about the 500 hPa. winter climate. The normal modes with smallest eigenvalues are similar to the model leading variability modes and canonical patterns of 500 hPa geopotential height. The corresponding eigenvectors of the adjoint operator, which represent an external forcing optimal for exciting normal modes, have a longitudinal structure with maxima in regions characterized by enhanced high frequency baroclinic activity over both oceans.

The relationship between sea surface temperature anomalies and atmospheric circulation in GCM experiments

Several 19-year integrations of the Hamburg version of the ECMWF/T21 general circulation model driven by the monthly mean sea surface temperature (SST) observed in 1970–1988 were examined to study extratropical response of the atmospheric circulation to SST anomalies in the Northern Hemisphere in winter. In the first 19-years run SST anomalies were prescribed globally (GAGO run), and in two others SST monthly variability was limited to extratropical regions (MOGA run) and to tropics (TOGA run), respectively. A canonical correlation analysis (CCA), which select from two time-dependent fields optimally correlated pairs of patterns, was applied to monthly anomalies of SST in the North Alantic and Pacific Oceans and monthly anomalies of sea level pressure and 500 hPa geopotential height in the Northern Hemisphere. In the GAGO run the best correlated atmospheric pattern is global and is characterized by north-south dipole structures of the same polarity in the North Atlantic and the North Pacific sectors. In the MOGA and TOGA experiments the atmospehric response is more local than in the GAGO run with main centers in the North Atlantic and North Pacific, respectively. The extratropical response in the GAGO run is not equal to the sum of the responses in the MOGA and TOGA runs. The artificial meridional SST gradients at 25°–30°N probably influence the results of the MOGA and TOGA runs. The atmopsheric modes found by the CCA were compared with the normal modes of the barotropic vorticity equation linearized about the 500 hPa. winter climate. The normal modes with smallest eigenvalues are similar to the model leading variability modes and canonical patterns of 500 hPa geopotential height. The corresponding eigenvectors of the adjoint operator, which represent an external forcing optimal for exciting normal modes, have a longitudinal structure with maxima in regions characterized by enhanced high frequency baroclinic activity over both oceans.

Correlation analyses between sea surface temperature anomalies in the eastern equatorial Pacific and the world ocean

Based on data from the Comprehensive Ocean-Atmosphere Data Set (COADS), objective analyses of the monthly mean sea surface temperature (SST) were prepared at GFDL for each month of the 110-year period 1870–1979. Time series of various indices characterizing the SST anomalies averaged over the eastern equatorial Pacific (EEP), the tropical oceans and the world ocean are presented for monthly, yearly and decadal time-averaging periods. Global correlations maps are given for each decade of the 1870–1979 period. They show the spatial connections between the monthly SST anomalies in the EEP and in other parts of the world ocean and how these connections vary for the different decades. On the intermonthly time scale the SST anomalies in the EEP and those in the tropical and world oceans are found to be highly correlated, with maximum correlations values of 0.91 at zero lag for the tropical oceans during the 1950–1959 decade and 0.81 for the world ocean during the 1970–1979 decade. Positive correlation values of r⩾0.36 persist on average from about 4 months before to about 8 months after the EEP anomalies occur. There is a clear tendency for the tropical and world ocean anomalies to lag behind the EEP anomalies. Comparing different oceans, we find the tendency for the tropical SST anomalies in the Indian and Atlantic Oceans to lag behind those in the EEP region by about 1 and 3 months, respectively. On the interannual time scale the EEP anomalies are also well correlated with those in the other regions, having an average correlation of 0.84 for the tropical oceans and of about 0.7 for the world ocean.

The Response of a Linear Model of the Tropical Pacific to Surface Winds from the NCAR General Circulation Model

Abstract An experiment in which surface wind stress data from the National Center for Atmospheric Research global circulation model (GCM) was used to drive a simple model of the tropical Pacific is described. First, a 15-year integration of the GCM was conducted, forcing the model with observed sea surface temperatures (SSTs) for the period 1958–72 (the FORCED case). A parallel integration was conducted using long-term monthly mean SSTs (the CONTROL case). All other boundary forcing in both GCM simulations was identical. Surface wind stress date from each GCM integration were then used to drive the Florida State University 1½ layer, reduced gravity model of the tropical Pacific. A separate integration of the ocean model was conducted using observed wind stress for the period 1961–72 (the OBSTRESS case). The goal of this research was to evaluate the response of a sophisticated GCM to tropical Pacific SST variability in terms of the surface wind stress field, and to investigate the sensitivity of a simple w...

Interannual Variations of Sea Surface Temperature over the Arabian Sea and the Indian Monsoon: A New Perspective

Abstract The interannual variation of surface fields over the Arabian Sea and Bay of Bengal are studied using data between 1900 and 1979. It is emphasized that the monthly mean sea surface temperature (SST) over the north Indian Ocean and monsoon rainfall are significantly affected by synoptic systems and other intraseasonal variations. To highlight the interannual signals it is important to remove the large-amplitude high-frequency noise and very low frequency long-term trends, if any. By suitable spatial and temporal averaging of the SST and the rainfall data and by removing the long-term trend from the SST data, we have been able to show that there exists a homogeneous region in the southeastern Arabian Sea over which the March–April (MA) SST anomalies are significantly correlated with the seasonal (June–September) rainfall over India. A potential of this premonsoon signal for predicting the seasonal rainfall over India is indicated. It is shown that the correlation between the SST and the seasonal mon...

El Nino/Southern oscillation signals in the global tropical ocean

The monthly mean sea surface temperature data of 6 areas are used to study the El Nino/Southern Oscillation signals in the global tropical ocean. These areas are in the 5°N-5°S latitude zone at 1) eastern Pacific (110°-140°W), 2) western Atlantic (30°-50°W), 3) eastern Atlantic (10°W-10°E), 4) western Indian Ocean (30°-50°E), 5) central Indian Ocean (70°-90°E) and 6) far western Pacific (120°-140°E), and the data cover the 120-month period of December 1968 to November 1978.

Statistical estimation of Cloudiness parameters

An attempt has been made to use satellite radiation measurements for the determination of the temporal and spatial variability of two cloudiness parameters, which are closely related with the radiation budget of the Earth-atmosphere system. On the basis of two sets of experimentally determined values of the planetary albedo the monthly mean cloud amount distribution has been estimated in the latitudinal belt between 60°N and 60°S. For this purpose the realistic values of the ground albedo have been used, and the cloud albedo was assumed to be dependent only on the solar zenith angle. A harmonic analysis has been undertaken for the cloud amount distribution over the latitudinal belt from 30°N to 30°S. It has been shown that nine harmonics can be used for an adequate description of the temporal-spatial variability of cloudiness. The mean monthly zonal values of cloud top temperature and of the cloud top height over the tropical oceans have been estimated on the basis of the experimental values of outgoing longwave flux. For this task the monthly mean sea surface temperatures have been used. The transfer of longwave radiation has been described by means of the integral transmission functions for water vapour and carbon dioxide.

Air-sea interaction on a seasonal scale over north Indian Ocean-Part I: Inter-annual variations of sea surface temperature and Indian summer monsoon rainfall

Monthly mean sea surface temperature (SST) obtained from ship observations have been studied for two 'selected representative areas' (SRA) in the Arabian Sea and one in the Bay of Bengal for the 13-year period 1961 to 1973. Each SRA is 3 degrees longitude X 2 degrees latitude. They are centred, A at 11 deg, 00’N, 59 deg. 30'E, Bat 14 deg. 00'N, 71 deg. 30'E and C at 11 deg. 00' N, 83 deg. 30' E. 12 monthly running means of the monthly mean SST of each SRA shows a pronounced three-year oscillation, during the whole period. The series of monthly anomalies of SST for A, Band C were subjected to harmonic an power spectrum analyses, which also show a apart, from the annual variation, the only prominent periodicity is the 3-year variation. For the 9-year period 1965 to 1973, five-degree square averages of monthly mean SST have been worked out for the Indian. Ocean area north to 15 deg. S. It is found that the 3-year oscillation in SST covers a large area of north Indian Ocean, where power spectrum analysis of SST monthly anomalies shows significant peaks at confidence level 95% for this oscillation.
 
 Correlations between monsoon rainfall of India and the SST anomalies at A, Band C have been worked out using data of 1961 to 1973. It is found that the SST of pre-monsoon months is positively correlated with the following monsoon rainfall, but the correlation is low and not statistically significant. However, the monsoon rainfall is significantly negatively correlated with the post-monsoon SST of areas A, Band C.

Propagation of the Seasonal Upwelling in the Eastern Equatorial Atlantic

Several mechanisms have been proposed to explain the coastal and equatorial upwelling in the eastern Atlantic (Guinea Gulf). The most controversial is the mechanism of remote wind forcing in the western equatorial Atlantic suggested by Moore et al. (1978). Most of the possible explanations for the upwelling and their relative importance are discussed in view of recent observations. Detailed analysis of daily sea surface temperature (SST) collected at 16 coastal stations along the northern coast of the Guinea Gulf reveals that the upwelling event propagates westward along this coast at a mean speed of 0.7 m s−1. Similar analysis of historical monthly mean SST data shows that the coastal upwelling event propagates poleward from 1°S to at least 13°S at the same phase speed. Furthermore, the Northern Hemisphere and Southern Hemisphere coastal upwelling signals seem to start at the same time from the equator. The same kind of analysis applied to hydrographic data from a station situated 41 km off Abidjan, reveals an upward phase propagation of the upwelling event at 7 m day−1 from 300 m to the surface. These results and those of Servain et al. (1982) suggest that remote wind forcing west of the Gulf of Guinea is an important factor affecting the temperature in the Gulf.

The variation of sea surface temperature in 1976 and 1977 1: The data analysis

To study the spatial distribution of the sea surface temperature (SST) for the years of 1976 and 1977, ship and satellite data at 1° quadrangles were collected. Two points were investigated: (1) the difference of monthly mean SST data between the two sources, and (2) map analyses over the globe. The study shows that without satellite data, an adequate coverage of world ocean is not possible and that there is a large difference in values between the ship and satellite data. The standard deviation of the difference between the satellite and merchant ship SST data for monthly and 1° quadrangle mean was ±1.49°C, where the sampling errors were not subtracted. Using these data, analyses were created and compared with independent analyses. The comparisons included large‐scale analyses and two small‐scale analyses. Attention was focussed specially on (1) the utility of the satellite SST data and (2) the data quality control. The large‐scale analyses agreed well with the independent analyses. However, both of the small‐scale analyses did not compare well.

Regular Monthly Mean Temperatures of Earth's Oceans from Satellites

Abstract Comparisons of satellite-derived monthly mean sea surface temperature anomalies with National Marine Fisheries Service (NMFS) ship-derived monthly mean sea surface temperature anomalies over the North Pacific Ocean reveal some encouraging results. Although still far from perfect, correlation coefficients for linear fits of 0.34, 0.49, 0.50, and 0.55 are observed for the winter months of November 1977, December 1977, January 1978, and February 1978, respectively. The standard error of estimate remained close to ±0.6°C and the satellite-ship temperature difference between the overall monthly mean anomaly vacillated between +0.31°C (December 1977) and −0.30°C (February 1978). Several other comparisons are presented. If the encouraging results of this study can be improved using improved sensor systems on the NOAA satellites, in addition to incorporating improved processing procedures, it would seem that we are now on the threshold of a more complete Earth monitoring system for at least one aspect of...

A Note Comparing Historical Sea Surface Temperature Observations at Ocean Station P

Abstract Two series of sea surface temperature observations reported for Station P (50°N, 145°W) during the period 1952–65 are compared. One series consists of either engine intake or surface bucket temperature measurements (TS) and the other consists of surface bathythermograph temperatures (TB). Estimates of the monthly mean sea surface temperature from these two series differ by up to 1.04°C. The difference (Ts−TS) is time dependent, changing from positive during 1952–53 to negative in 1954–56. Only since 1956 have the annual mean differences been less than the accepted accuracy of the measurements (±0.2°C). The minimum difference occurs in summer with the maximum in winter. There are occasional significant effects on the annual mean difference due to the type of ship operations, that is, whether hydrographic observations are carried out.

A quasi-biennial standing wave in the Southern Hemisphere and interrelations with sea surface temperature

An empirical orthogonal function analysis is performed on monthly mean sea level pressure (SLP) deviations from normal (anomalies) in the Australasian area and monthly mean sea surface temperature (SST) anomalies in the Tasman Sea for 14 years of data. Only the five components of each that explain most of the variance appear to be significant. Spectral and cross-spectral analysis of the time series of the coefficients reveals significant relations at a quasi-biennial periodicity. An empirical model of the SLP and SST fields for this period is constructed and the amplitudes of the oscillation are found to be about 2 1/2 mb in the monthly mean SLP anomaly field and 0·4 degC in the monthly mean SST anomaly field. Physical and statistical indications are that the SST field is largely caused by the SLP field but some interdependence is present. The quasi-biennial SLP oscillation is related to Pittock's L-index and appears to correspond to a change in wavenumber 3 in the Southern Hemisphere atmospheric circulation. A phase change occurred at the end of 1970, but in even years prior to 1971, and in odd years since 1970, there were increased meridional transports throughout the troposphere and lower stratosphere by the large-scale eddies. A suggestion is made that changes in land–sea heating contrasts may be an important part of the mechanism.

A quasi‐biennial standing wave in the Southern Hemisphere and interrelations with sea surface temperature

AbstractAn empirical orthogonal function analysis is performed on monthly mean sea level pressure (SLP) deviations from normal (anomalies) in the Australasian area and monthly mean sea surface temperature (SST) anomalies in the Tasman Sea for 14 years of data.Only the five components of each that explain most of the variance appear to be significant. Spectral and cross‐spectral analysis of the time series of the coefficients reveals significant relations at a quasi‐biennial periodicity. An empirical model of the SLP and SST fields for this period is constructed and the amplitudes of the oscillation are found to be about 2 1/2 mb in the monthly mean SLP anomaly field and 0·4 degC in the monthly mean SST anomaly field. Physical and statistical indications are that the SST field is largely caused by the SLP field but some interdependence is present.The quasi‐biennial SLP oscillation is related to Pittock's L‐index and appears to correspond to a change in wavenumber 3 in the Southern Hemisphere atmospheric circulation. A phase change occurred at the end of 1970, but in even years prior to 1971, and in odd years since 1970, there were increased meridional transports throughout the troposphere and lower stratosphere by the large‐scale eddies. A suggestion is made that changes in land–sea heating contrasts may be an important part of the mechanism.

Sea surface temperatures and atmospheric circulation anomalies south of New Zealand during 1957 to 1966

Abstract Sea surface temperatures (SSTs) observed near 60°S, 170°E during the spring and summer each year from 1957 to 1966 showed large year‐to‐year variations. The monthly mean SSTs in the springs of 1958, 1963, and 1964 were comparatively cold, but those in 1961 and 1966 were comparatively warm. Much smaller magnitude, nearly 2‐yearly variations occurred in the monthly mean SSTs at Campbell Island (52° 40’ S, 169° E) also. Surface pressure data were used to compute the geostrophic wind, wind‐stress and wind‐drift convergence and their yearly anomalies for the same periods. Theoretical transverse circulation models of the Antarctic Circumpolar Current applied to the observed wind distributions, provided plausible explanations of the yearly differences of the SSTs near 60° S. The largest SST and atmospheric circulation anomalies within the 10‐year period occurred in the springs of 1963 and 1964. The nature of the anomalies suggested that they were indirectly related to the increase of atmospheric turbidi...