Sea Surface Pressure Research Articles

Some relationships between sea surface temperature anomalies and surface pressure anomalies

Possible relationships between sea surface temperature anomalies in the tropical east Atlantic and surface pressure anomalies in the Atlantic-European sector are investigated. From principal component analysis of the sea surface temperature time series in conjunction with the mean surface pressure anomaly distribution, it is deduced that there is a long-term change in tropical sea surface temperatures associated with variations in westerly component in higher latitudes. Variations of sea surface temperature are shown to be related, through spatial surface pressure eigenvectors, to the surface pressure distribution in most months of the year. Indications are that the atmosphere initially drives the ocean and that the two media subsequently vary in phase. A method of making quantitative forecasts of the sea surface temperature effect on surface pressure is suggested with special reference to the winter season.

Some relationships between sea surface temperature anomalies and surface pressure anomalies

AbstractPossible relationships between sea surface temperature anomalies in the tropical east Atlantic and surface pressure anomalies in the Atlantic‐European sector are investigated. From principal component analysis of the sea surface temperature time series in conjunction with the mean surface pressure anomaly distribution, it is deduced that there is a long‐term change in tropical sea surface temperatures associated with variations in westerly component in higher latitudes. Variations of sea surface temperature are shown to be related, through spatial surface pressure eigenvectors, to the surface pressure distribution in most months of the year. Indications are that the atmosphere initially drives the ocean and that the two media subsequently vary in phase. A method of making quantitative forecasts of the sea surface temperature effect on surface pressure is suggested with special reference to the winter season.

Effect of Arabian Sea-Surface Temperature Anomaly on Indian Summer Monsoon: A Numerical Experiment with the GFDL Model

The global general circulation model of the Geophysical Fluid Dynamics Laboratory has been integrated with and without a cold sea surface temperature (SST) anomaly over the Somali coast and the western Arabian Sea. The temperature anomaly is −3°C near the Somali coast and linearly decreases eastward having zero anomaly at about 1500 km east of the coast. Comparison of the mean of the two model states indicates that the rainfall over India and the adjoining region is drastically reduced due to the colder SST anomaly over the western Arabian Sea. The other associated features due to the cold anomaly are an increase in sea surface pressure over the Arabian Sea, a decrease in local evaporation, and a reduction in the cross equatorial component of the wind at the surface and hence a reduction in the cross equatorial moisture flux. Statistical analysis of the results has been done by comparing the difference between the two mean states (“signal”) and the standard deviation of the errors (“noise”) in estimating the mean due to the finiteness of the averaging period. It is found that the results of the present numerical experiment are statistically significant.

Characteristics and circulation of deep and abyssal waters

The deep and abyssal potential temperature and salinity of the major areas of the world ocean have been re-examined in the hope that recent data may extend the conventional concepts of the formation and circulation of the deeper waters. In addition to these properties, which have been considered before, the potential density (δϑ) has been included. Potential denstity, in which density is calculated from the in situ temperature and salinity values moved adiabatically to sea-surface pressure, has been useful in defining mixing surfaces for shallow water. A peculiarity of this quantity in the western Atlantic Ocean is that it has a maximum above the bottom (though the column is stable) between about 40°N and 35°S. These high values originate from the Greenland-Norwegian Sea area and represent the lower North Atlantic Deep Water. This distribution suggests that δϑ surfaces at great depth cannot be interpreted as surfaces of mixing or flow but that δϑ can be interpreted as a conservative quantity whose extreme values can represent areas of water-mass formation and paths of flow. The lower North Atlantic Deep Water is a very good example of such a water mass: it can be traced by the maximum in δϑ to 35°S at least. Beyond there the δϑ maximum is either too weak to be followed or disappears entirely; some other quantity must be used if it is to be followed farther. If we wish to follow deeper water we can calculate density using a deeper reference pressure, for example 4000 dbars. This new quantity increases monotonically downward at great depth. An isopycnal of this quantity can be chosen to represent a mixing surface for the lower North Atlantic Deep Water and to trace this water much farther south.