Search Results

You are looking at 31 - 40 of 46 items for

  • Author or Editor: JAY S. WINSTON x
  • Refine by Access: All Content x
Clear All Modify Search
Jay S. Winston and Lloyd Tourville

The cloud structure of an occluded cyclone and its environs over the Gulf of Alaska is revealed in detail by a series of TIROS pictures. The pictures clearly portray:

  • (1) the nature and extent of dense cloudiness around the inner core of the cyclone;

  • (2) a broad band of cloudiness associated with the main polar front;

  • (3) the pattern of overrunning cloudiness marking a newly developing wave south of the main storm;

  • (4) a previously undetected, old cyclonic vortex in mid-troposphere; and

  • (5) the striking cellular arrangement of cumuliform clouds in the cyclonic flow to the rear of the storm.

These features are related to the conventional meteorological data and analyses over this area and are found in many places to corroborate them rather well. On the other hand, there are several places, particularly in view of the sparsity of conventional data, where the cloud pictures suggest that improvements could be made in the map analyses and numerically computed vertical motions on the basis of the TIROS cloud information.

Full access
WILLIAM H. KLEIN and JAY S. WINSTON

Abstract

The geographical frequencies of occurrence of troughs and ridges on both 5-day and 30-day mean 700-mb. charts for the Northern Hemisphere during a long period of record are presented for individual months. Many regions of maximum and minimum frequency show a close relationship to trough and ridge positions on long-period mean, or normal 700-mb. charts. However, even a cursory inspection of these frequency charts shows that they yield considerably more information for both the practicing forecaster and the research worker than can be derived solely from normal maps. Preferred trough and ridge locations and their seasonal changes appear to be related largely to land-sea boundaries with their associated thermal influences and also to prominent orography.

Full access
Eugene J. Aubert and Jay S. Winston

Abstract

By a study of heat sources and sinks, an attempt is made to further the knowledge of energy changes associated with the general circulation. The average monthly heating and cooling of the air between sea level and 10,000 ft is computed for individual and normal months. The heating and cooling regions show sizeable departures from normal and considerable monthly variations, both in magnitude and location. The absolute magnitudes of heating and cooling are greater in the colder seasons and at middle and high latitudes. At low latitudes, where the magnitudes are small, adiabatic motions are predominant. Attempts are made to determine the contributions of the various heat-exchange processes to the net heating. Certain relationships between the heating fields and the lO,OOO-ft monthly mean jet-stream are presented. The jet axis is usually found in the region of maximum transition of the heating field, with heating to the north and cooling to the south. Heat energy and kinetic energy appear to reach their longitudinal maxima at the same location along the jet.

Full access
Carl O. Erickson and Jay S. Winston

Abstract

Satellite photographs have revealed the occasional existence of broad and extensive cloud bands reaching from tropical storms northeastward into the westerlies of middle latitudes. Fourteen well-defined cases of such cloud connections from western North Pacific tropical storms in the autumns of 1967, 1968 and 1969 are examined with respect to the large-scale circulation. The composited data show that the 300-mb westerlies over the North Pacific increase for several days following the onset of the cloud-band connections. Hemispheric kinetic energy for the whole troposphere tends to increase in similar fashion. These associations suggest that the injection of heat and moisture from tropical cyclones into the middle latitudes plays a significant role in the autumnal buildup of the planetary-scale circulation.

Full access
Philip F. Clapp and Jay S. Winston

Abstract

This is the second report on a continuing project designed to investigate quantitatively the confluence process and associated changes in the strength and location of the mid-tropospheric jet stream. An empirical study has been made of a case of large-scale confluence as observed on a sequence of 5-day mean charts. It is found that the local change in wind speed is related to the relative advection of cold and warm air on either side of the jet axis and also to the advection of wind speed along the axis. Tentative estimates of vertical motion indicate sinking motion in the cold air north of the jet axis and rising motion in the warm air to the south.

Full access
Eugene J. Aubert and Jay S. Winston

Abstract

No Abstract Available

Full access
Arthur F. Kruger and Jay S. Winston

Abstract

The authors have been monitoring the large-scale circulation over the tropics since 1968 through use of operational tropical wind analyses prepared by the National Meteorological Center. Seasonal and monthly anomaly charts of the tropical circulation at 700 and 200 mb have been prepared using four-year seasonal and monthly means as a preliminary “normal” A sequence of seasonal anomaly charts is used here to describe the highly anomalous tropical circulation during the northern summer of 1972 and its antecedents. During this season the trades were weaker than “normal” over most of the Pacific with both the North and South Pacific anticyclones displaced poleward. In the upper troposphere the anomalous flow was anticyclonic over the Central Pacific reflecting the weakness of the mid-oceanic troughs north and south of the equator. From the eastern Pacific eastward across the Atlantic, Africa, and the Indian Ocean the flow at upper levels north of the equator was westerly relative to normal, signifying a notable reduction in the strength of the summertime “monsoon” easterlies over Africa and the Indian Ocean. The evolution of these striking circulation anomalies from a substantially different initial state a year earlier and their association with sea-surface temperature variations over the equatorial Pacific are discussed.

Full access
JAY S. WINSTON and ARTHUR F. KRUEGER

Abstract

A large-scale cycle of available potential energy in the Northern Hemisphere over a period of about two weeks during late December 1958 and early January 1950 has been investigated in some detail. During this cycle the zonal available potential energy first built up strongly to a maximum, and then when it began to decline, increases in eddy available and eddy kinetic energy took place. These changes in the energy parameters were well related to variations in the poleward heat transport, large values of which signify substantial conversions from zonal to eddy available potential energy, and to variations in the conversion between potential and kinetic energy. Furthermore some estimates of the generation of available potential energy show good consistency with the available potential energy variations. Examination of this cycle of available potential energy on a regional basis indicates that it was almost completely dominated by developments over North America and vicinity. The synoptic events associated with this energy cycle are also illustrated.

Full access
Arthur F. Krueger and Jay S. Winston

Abstract

The contrasting circulation and cloudiness over the tropics during two extremes of the zonally oriented Walker circulation are described. During February 1971 the trade winds over the Pacific Ocean were very strong with fast upper tropospheric westerlies superimposed. This was associated with well-developed, high-level oceanic troughs over the east central Pacific both north and south of the equator. Tropical convection was largely confined to the three tropical continental areas, while the ITCZ over the Pacific was very weak.

During February 1969 the Walker circulation was considerably weaker. Tropical convection was more extensive over the central and eastern Pacific. The high-level mid-oceanic troughs were also weaker and even replaced by weak anticyclonic flow over the convective regions. Associated with this the sub-tropical jet stream was very much stronger over the eastern Pacific, North America and the Atlantic, but weaker near Japan.

It is suggested that dynamic instability in the westerlies of the subtropical jet stream plays an important role in regulating the intensity of the tropical circulation.

Full access
P. Krishna Rao and Jay S. Winston

Abstract

Several samples of infrared radiation measurements in the 8–13 micron water-vapor “window” made by TIROS II are studied in relation to conventionally observed information on pressure systems, cloudiness and temperature These cases demonstrate further the synoptic capabilities, as well as some of the limitations, of these data for cloud detection; determination of cloud-top height; and observation of spatial gradients and temporal changes in the temperature of water-, land-, and snow-covered surfaces.

Full access