Showing papers in "Monthly Weather Review in 1978"
TL;DR: In this paper, the authors investigated the well-known tendency for winter temperatures to be low over northern Europe when they are high over Greenland and the Canadian Arctic, and conversely, they found that these pressure anomalies are so distributed that the pressure in the region of the Icelandic low is negatively correlated with the pressure over the North Pacific Ocean and over the area south of 50°N in the North Atlantic Ocean, Mediterranean and Middle East.
Abstract: We have investigated the well-known tendency for winter temperatures to be low over northern Europe when they are high over Greenland and the Canadian Arctic, and conversely. Well-defined pressure anomalies over most of the Northern Hemisphere are associated with this regional seesaw in temperature, and these pressure anomalies are so distributed that the pressure in the region of the Icelandic low is negatively correlated with the pressure over the North Pacific Ocean and over the area south of 50°N in the North Atlantic Ocean, Mediterranean and Middle East, but positively correlated with the pressure over the Rocky Mountains. The composite patterns of pressure anomalies in the seesaw are almost identical to the fist eigenvector in the monthly mean pressure, but the standard deviations of pressure anomalies in seesaw mouths are as large as the standard deviations of monthly means in general. Since 1840 the seesaw, as defined by temperatures in Scandinavia and Greenland, occurred in more than 40%...
905 citations
TL;DR: In this paper, an inexpensive method of computing θE to include the beat capacities of water substance is presented aid the results compared with those derived from several tephigrams which ignore this contribution, which may he an acceptable practice for temperatelatitude usages but a questionable one when applied in the tropics where lower layers, rich in moisture, may he several; degrees warmer and the vertical gradient larger when this factor is included.
Abstract: The computation of θE, the pseudo-quivalent potential temperature, ordinarily omits the contribution due to specific heats of water vapor. This may he an acceptable practice for temperate-latitude usages but a questionable one when applied in the tropics where lower layers, rich in moisture, may he several; degrees warmer and the vertical gradient larger when this factor is included. An inexpensive method of computing θE to include the beat capacities of water substance is presented aid the results compared with those derived from several tephigrams which ignore this contribution.
649 citations
TL;DR: In this article, the authors describe the development of a general, predictive, hydrostatic meteorological model, which is suitable for a wide variety of problems, ranging from the synoptic scale to the small end of the mesoscale.
Abstract: We describe the development of a general, predictive, hydrostatic meteorological model. The model is three-dimensional and is suitable for a wide variety of problems, ranging from the synoptic scale to the small end of the mesoscale. The model contains provisions for variable terrain, a moisture cycle, sensible heat addition at the earth's interface, and high- and low-resolution boundary layer physics. This paper presents the mathematical and numerical formulation used in the various options of the model. First we write the basic equations on a Lambert conformal projection. Then we describe the horizontal and vertical grid structure, the finite-difference equations, and the energetics of the three-dimensional model and its two-dimensional analog. We consider the role of the lateral boundary conditions for limited area forecasts, with emphasis on their effect on the mean motion over the domain. Two options for including the frictional and diabatic effects at the earth's surface are presented. Thes...
398 citations
TL;DR: In this paper, a diagnostic method to estimate rainfall over large space and time scales by the use of geosynchronous visible or infrared satellite imagery has been derived and tested based on the finding that arms of active convection and rainfall in the tropics are brighter or colder on the satellite visible and infrared photographs than inactive regions, ATS-3 and SMS/GOES images were calibrated with gage adjusted 10 cm radar data over south Florida.
Abstract: A diagnostic method to estimate rainfall over large space and time scales by the use of geosynchronous visible or infrared satellite imagery has been derived and tested. Based on the finding that arms of active convection and rainfall in the tropics are brighter or colder on the satellite visible or infrared photographs than inactive regions, ATS-3 and SMS/GOES images were calibrated with gage-adjusted 10 cm radar data over south Florida. The resulting empirical relationships require a time sequence of cloud area, measured from the satellite images at a specified threshold brightness or temperature to calculate rain volume over a given period. Satellite rain estimates were made for two areas in south Florida that differ in size by an order of magnitude (1.3×104km2 vs 1.1×105km2) and verified by a combined system of gages and radar. Contrary to our expectations, the rain estimates for the smaller area agreed better with the raingage-radar groundtruth than the satellite rain estimates for the large...
279 citations
TL;DR: In this article, the tropical Atlantic surface features were located/centered 300-500 km further south in the deficient sub-Saharan rainy season (July-September) of 1968 than the more abundant 1967 rainy season.
Abstract: Sub-Saharan West Africa (10–20°N) receives moisture from the tropical Atlantic via low-level south-westerly flow across the southwestern coast of West Africa. This paper utilizes a 1arge data set to identify the tropical Atlantic (30°N–30°S) surface atmospheric and oceanic patterns for two years when sub-Saharan West Africa experienced anomalous weather. Comparison is made with 60-year (1911–70) average fields. The following tropical Atlantic surface features were located/centered 300–500 km further south in the deficient sub-Saharan rainy season (July-September) of 1968 than the more abundant 1967 rainy season— the kinematic axis between the Northern and Southern Hemisphere trades, the near-equational convergence tune, the near-equatorial pressure trough, the zone of maximum sea surface temperature (SST), the mid-Atlantic maxima of precipitation frequency and total cloudiness, and the center of the North Atlantic subtropical high. Sixty-year mean positions of these features were generally interm...
258 citations
TL;DR: A survey of the literature dating back to the early 1920's along with some appropriate statistical studies delineate an atmospheric-oceanic phenomenon of considerable interest as mentioned in this paper, which is known as the Southern Oscillation.
Abstract: A survey of the literature dating back to the early 1920’s along with some appropriate statistical studies delineate an atmospheric-oceanic phenomenon of considerable interest. The Southern Oscillation—an oscillatory exchange of atmospheric mass between the eastern south Pacific and Indonesia—and the Walker Circulation—its counterpart in wind circulation—have a time-scale of years and are manifestations of a near-global variation in circulation, clouds and precipitation, centered in the equatorial eastern Pacific. Ocean surface temperatures in this region are intimately involved; in their warmest phase these variations are known as El Nino events. Some evidence that the strength of the Northern Hemisphere subtropical jet stream varies in conjunction with this phenomenon is given. Since a fully coupled atmosphere-ocean model is presently impractical, a set of general circulation model experiments using altered ocean boundary temperatures has been performed with the NCAR 5° global atmospheric model...
226 citations
TL;DR: The severe 1976-77 winter over eastern North America and the drought in the west are related to contemporary and antecedent atmospheric, oceanic and cryospheric factors.
Abstract: The severe 1976–77 winter over eastern North America and the drought in the west are related to contemporary and antecedent atmospheric, oceanic and cryospheric factors. Although greatly amplified, the atmospheric flow pattern was in phase with the normal winter pattern so that the seasonal forcing by mountains, coastlines, etc., did not oppose the anomalous pattern. The autumn pattern of southerly air flow over the eastern North Pacific reduced heat losses from the ocean, induced advection of warmer waters, and reduced coastal upwelling. Meanwhile, the cold sea surface temperatures generated in spring and summer over the central North Pacific persisted. These cold waters seem to have been generated by the persistently strong Aleutian low which, following Bjerknes’ hypothesis, was associated with a persistent El Nino which began several months before and lasted through the abnormal winter. The atmospheric baroclinicity from the strong sea surface temperature gradient near 140°W strengthened front...
223 citations
TL;DR: In this paper, a unique tornadic vortex signature (TVS) was discovered in the field of mean Doppler velocity data, and its association with the tornado was verified using a model that simulates Dopperler velocity measurements through a tornado.
Abstract: Doppler radar measurements in the Union City, Okla., tornadic storm of 24 May 1973 led to discovery of a unique tornadic vortex signature (TVS) in the field of mean Doppler velocity data. The distinct character of this signature and its association with the tornado are verified using a model that simulates Doppler velocity measurements through a tornado. Temporal and spatial variations of the TVS reveal previously unknown tornado characteristics. The TVS originates at storm mid-levels within a parent mesocyclone, descends to the ground with the tornado (extending vertically at least 10 km), and finally dissipates at all heights when the tornado dissipates. NSSL Doppler radar data from 1973 through 1976 reveal 10 signatures; eight were associated with tornadoes or funnel clouds, while no reports are available for the other two. Since the TVS first appears aloft tens of minutes before tornado touchdown, the signature has decided potential for real-time warning.
157 citations
TL;DR: In this article, the combined use of the equations of cloud dynamics, and the observed wind, will permit a unique determination of the density and pressure fluctuations, which is crucial for severe storm observations where very often the boundary conditions are not those of the larger scale environment.
Abstract: An algorithm is proposed, whereby the combined use of the equations of cloud dynamics, and the observed wind, will permit a unique determination of the density and pressure fluctuations. The algorithm has several unique features. First, it involves the use of only the momentum equations without resorting to any thermodynamical (microphysical) parameterizations. Second, there is no need to make any artificial assumptions about the boundary conditions. Instead, the algorithm determines (from wind observations) its own optimal boundary conditions. This latter feature is crucial for severe storm observations where very often the boundary conditions are not those of the larger scale environment. The viability of the method is tested with data generated by a numerical model. From these data the wind and its time derivative are estimated and used to calculate the density and pressure fluctuations. These calculations are then compared to the originally given density and pressure. The sensitivity of the m...
147 citations
TL;DR: In this paper, meteorological conditions that produced devastating flash floods in the Big Thompson Canyon on 31 July 1976 and in the Black Hills on 9 June 1972 were analyzed and described, and a set of meteorological features were defined for the purpose of identifying the potential for this type flash flood along the eastern slopes of the Rocky Mountains.
Abstract: Analyses and descriptions of the meteorological conditions that produced devastating flash floods in the Big Thompson Canyon on 31 July 1976 and in the Black Hills on 9 June 1972 are presented. The storms developed when strong low-level easterly winds pushed moist, conditionally unstable air masses upslope into elevated, mountainous terrain. Orographic uplift released the convective instability and light winds aloft allowed the storm complexes to remain nearly stationary. Meteorological conditions that produced these flash floods were found to have been very similar. A set of meteorological features is defined for the purpose of identifying the potential for this type flash flood along the eastern slopes of the Rocky Mountains.
139 citations
TL;DR: In this paper, the authors compared the 200 mb flow regimes during a drought year (1972) with those during a normal rainfall year (1967) over the global tropics for the northern summer months.
Abstract: We contrast the 200 mb flow regimes during a drought year (1972) with those during a normal rainfall year (1967) over the global tropics for the northern summer months. It is shown that the deficient rainfall over central India and western Africa during 1972 may be related to the following: 1) warm sea surface temperatures over the equatorial Pacific; 2) excessive number of typhoon days over the western Pacific; 3) strong east-northeasterlies over the equatorial eastern Indian ocean (related to upper level outflows from typhoons); 4) weaker tropical easterly jet; 5) weaker meridional pressure gradient over India; 6) weaker Tibetan high; 7) a southeastward shift of the major circulation patterns as well as of several dynamical parameters; 8) weaker vertical wind shear and a weaker measure of the combined barotropic-baroclinic instability over West Africa; and 9) weaker westward steering for rain-producing disturbances over India and a consequent stronger influence of the mountains. A sequential in...
TL;DR: There were 14 409 tornadoes for which both intensity and path length estimates were made as discussed by the authors, of which 61.7% were weak (<112 mph), 36% strong (113-206 mph), and only 2.3% violent (207-318 mph).
Abstract: Careful screening of the National Severe Storms Forecast Center's tornado log eliminated almost 20% of the reports as doubtful, leaving 17 659 tornadoes during 27 years, 1950–76 (654 annually). Newspaper accounts and other local information provided intensifies (Fujita wale) for all but 2346 tornadoes and path lengths for all but 2011 tornadoes. There were 14 409 tornadoes for which both intensity and path length estimates were made. Of these, 61.7% were weak (<112 mph), 36% strong (113–206 mph), and only 2.3% violent (207–318 mph). However, the 340 violent tornadoes caused 68% of the 3070 fatalities attributed to tornadoes for which force estimates could he made (113.7 annually). Most violent tornadoes came in swarms except in southeastern United States, where no day had mart than one. Some 61% of the violent tornadoes had intermediate paths (3.2–31 mi), while 73% of weak and strong tornadoes had short paths. Violent tornadoes occurred at all times of day and night, while weak and strong tornado...
TL;DR: In this paper, the correlation between seasonal mean temperatures and precipitation is computed at some 98 North American and European stations and it is shown that negative correlation is most frequent in summers, while negative and positive correlation appear about equally in other seasons.
Abstract: The correlation between seasonal mean temperatures and precipitation totals is computed at some 98 North American and European stations. Negative correlation is most frequent in summers, while negative and positive correlation appear about equally in other seasons. Normalized cospectra show that these correlation do not, in general, reflect a relationship common to a single time scale but rather one that is prevalent at all time scales.
TL;DR: In this article, it is proposed that the non-conservative property o@ potential vorticity permits air parcels to enter the stratosphere by direct transport across the potential Vorticity discontinuity in the layer of maximum wind, in agreement with earlier isentropic trajectory calculations.
Abstract: Recent aircraft observations of the mesoscale and turbulent structure of upper level frontal zone-jet stream systems provide further evidence of stratosperic mesoscale cyclonic wind shear and associated anomalously high values of potential vorticity in the layer of maximum wind. Measurements of turbulent heat flux in regions of clear air turbulence above and below the layer of maximum wind (LMW) document the first-order importance of turbulent-scale processes in the generation and dissipation of potential vorticity. Ozone concentration measurements illustrate the intrusion of stratospheric air into the troposphere and give evidence of the effect of turbulent mixing processes in the LMW. It is proposed that the nonconservative property o@ potential vorticity permits air parcels to enter the stratosphere by direct transport across the potential vorticity discontinuity in the LMW, in agreement with earlier isentropic trajectory calculations.
TL;DR: In this paper, departure maps of sea level pressure (SLP), wind speed and sea surface temperature (SST) in March/April are presented for composite of ten extreme years of either regime.
Abstract: Atmospheric–oceanic departure patterns in the tropical Atlantic and eastern Pacific associated with the Ecuador/Peru El Ninno and its antithesis are studied on the basis of long-term ship observations during 1911–71. Departure maps of sea level pressure (SLP), wind speed and sea surface temperature (SST) in March/April are presented for composite of ten extreme years of either regime. The evolution of SLP anomalies from the preceding to the event year is traced for large ocean areas. Gaussian and binomial probabilities are calculated as a measure of the importance of SLP departures. El Nino years are characterized by abnormally low SLP over the eastern South Pacific and positive SLP anomalies over the Atlantic; winds are weaker than normal over the Pacific, and stronger over the Atlantic; SST anomalies are positive in the Pacific, but negative in a band of the Atlantic extending from West Africa toward the South American coast. During counter-El Nino years, departure patterns am approximately inv...
TL;DR: In this article, the parent mesocirculation exhibits an apparent "breakdown", i.e., a transition from single-cell to two-cell axial flow structure.
Abstract: Updraft mesocyclones in tornado-producing thunderstorms form along convergent and cyclonically sheared boundaries that separate inflow air entering forward and rear storm quadrants. Maximum tangential flow resides in girding wind bands, averaging usually less than 3 km in radius (depending upon the development stage), that strengthen near ground during toradogenesis. Strong inflow, concentrated at or below cloud base, is maintained throughout the intensification period. During the tornadic phase the parent mesocirculation exhibits an apparent “breakdown", i.e., a transition from single-cell to two-cell axial flow structure. At this critical period small eddies may appear within an elongated mesocyclone core and some may become tornado and/or grow to large proportions. Tornado dissipation may result from cyclonic rotation of the major mesocyclone horizontal axis which chokes the supply of inflow air and detaches the tornado from the principal updraft. Another apparent mechanism for dissipation inv...
TL;DR: In this article, an unusually cloud-ftee nighttime thermal infrared image of the midwestern and northeastern United States from the NOAA 5 satellite enabled detection of more than 50 urban beat islands.
Abstract: On 28 July 1977 an unusually cloud-ftee nighttime thermal infrared image of the midwestern and northeastern United States from the NOAA 5 satellite enabled detection of more than 50 urban beat islands. Analysis of digital data from the satellite for selected cities yielded maximum urban-rural temperature differences ranging from 2.6 to 6.5°C. Through computer enhancement and enlargement of the satellite imagery, the urban beat islands of St. Louis, Washington, DC and Baltimore can be depicted at a usable scale as large as 1:500 000. A comparison of the enhanced thermal infrared imagery with the 1970 U.S. Census maps of urbanized areas for the three cities indicates the extent of possible urbanization changes in the last seven years.
TL;DR: In this paper, upstream interpolation with a cubic spline is used to integrate the advective terms in a two-dimensional hydrostatic primitive equation model to study the problems of air flow over a mountain, and sea and land breezes.
Abstract: Upstream interpolation with a cubic spline is used to integrate the advective terms in a two-dimensional hydrostatic primitive equation model. The model is applied to study the problems of air flow over a mountain, and sea and land breezes. Results are compared against existing numerical models and against an identical model which uses a simple upstream differencing scheme for the advective terms. It was found that under certain atmospheric conditions, where the atmosphere is being continuously forced, accurate results may be obtained near the surface even with the simple upstream scheme. Also it is shown that a sophisticated planetary boundary layer parameterisation is needed in order to obtain accurate results in both the lower and upper troposphere.
TL;DR: In this paper, an alternative interpretation of the quasi-geostrophic omega equation can be found, and an alternative but complementary approach is suggested, in which upward motion is shown to be the consequence of cyclonic advection of vorticity by the thermal wind.
Abstract: The usual interpretation of the quasi-geostrophic omega equation can be ambiguous, and an alternative but complementary approach is suggested. In the middle troposphere, upward motion is shown to he the consequence of the cyclonic advection of vorticity by the thermal wind. This relates to several empirical-dynamical rules of synoptic meteorology.
TL;DR: In this article, the phase and normalized amplitude of the diurnal variations in convective activity and precipitation during phases II and III of GATE were determined using harmonic analysis, and the longterm representativeness of the results for the land areas was judged by comparing them with the results obtained from analysis of data presented by Burpee (1976) on the frequencies of occurrence of thunder, moderate to heavy precipitation and light precipitation during the period June-September 1966-69.
Abstract: Harmonic analysis is used to determine the phase and normalized amplitude of the diurnal variations in convective activity and precipitation during phases II and III of GATE. Satellite results are based on the percent coverage of squares, 3° of latitude and longitude in dimensions, by convective clouds, as estimated subjectively from SMS-1 infrared images. Rainfall results are based on hourly precipitation records for 33 land stations and hourly or 3-hourly rainfall amounts from 13 ships in the A/B-scale networks. The rainfall data for the land stations were combined into four geographically distinct groups and the ship data into a single group before making the harmonic analyses. The long-term representativeness of the results for the land areas is judged by comparing them with the results obtained from analysis of data presented by Burpee (1976) on the frequencies of occurrence of thunder, moderate to heavy precipitation and light precipitation during the period June-September 1966–69. The main...
TL;DR: In this paper, a set of numerical experiments conducted with the Goddard (formerly GISS) general circulation model were designed to test the model atmospheric response to a single fixed and specified parameter, the total ice cover in the Davis Strait, Barents Sea, East Greenland Sea, Sea of Okhotsk and Bering Sea.
Abstract: Results are presented for a set of numerical experiments conducted with the Goddard (formerly GISS) general circulation model. The experiments were designed to test the model atmospheric response to a single fixed and specified parameter, the total ice cover in the Davis Strait, Barents Sea, East Greenland Sea, Sea of Okhotsk and Bering Sea. Margin variations are considered that are substantially smaller than those involved in ice age or ice-free Arctic simulations. Anomaly is defined as the mean of two runs corresponding to climatological maximum sea ice conditions. Model results indicate that the ice margin anomalies are capable of altering local climates in certain regions of high and middle latitudes. Possible interactions between high latitudes and subtropical regions are suggested.
TL;DR: A long rainfall series for the contiguous Indian region for the summer monsoon season (June-September) has been constructed by considering the rainfall data of a very large number of raingages since 1841 to present as mentioned in this paper.
Abstract: A long rainfall series for the contiguous Indian region for the summer monsoon season (June-September), when more than 75% of the annual rainfall occurs over large parts of the country, has been constructed by considering the rainfall data of a very large number of raingages since 1841 to present. The series from 1866–1970 has been found to be homogeneous. The statistical properties of this homogeneous time series have been investigated. The average monsoon rainfall of India is 88.75 cm with a standard deviation of 7.64 cm. Fisher's statistics g1, g2 and the chi-square statistic indicate that the that series is normally distributed. The years 1877, 1899, 1918, 1920, 1951 and 1965 were very bad monsoon years when the rainfall was below the 5th percentile of the distribution. The increase of 4.6% in the 30-year average from 1901–30 to 1931–60 is significant at the 5% level. The mean for the period 1931–60 is also significantly higher than the overall mean for the period 1866–1970 at the 5% level. D...
TL;DR: In this article, an additional source of semidiurnal forcing due to daily variations in tropical rainfall was suggested to correct the discrepancy between the calculated phase (boned onforcing due to insulation absorption by ozone and water vapor) and that observed for the surface pressure oscillation, and it was shown that the 180° phase shift in horizontal wind oscillations at 28 km which current calculations predict, but which is not observed, would he eliminated by the proposed additional forcing.
Abstract: It is suggested that an additional source of semidiurnal forcing due to daily variations in tropical rainfall could correct the discrepancy between the calculated phase (boned on forcing due to insulation absorption by ozone and water vapor) and that observed for the surface pressure oscillation. It is also shown that the 180° phase shift in horizontal wind oscillations at 28 km which current calculations predict, but which is not observed, would he eliminated by the proposed additional forcing. The magnitude and phase of the required rainfall oscillation is calculated and found to be consistent with existing observations. Finally, it is shown that the convergence field due to the tide could not directly account for the rainfall oscillation.
TL;DR: In this article, a variable-mesh model is used with several grid configurations, each having uniform high resolution over a specified area of interest and lower resolution elsewhere to produce short-term forecasts over this area without the necessity of high resolution everywhere.
Abstract: A barotropic primitive-equation model using the finite-element method of space discretization is generalized to allow variable resolution. The overhead incurred in going from a uniform mesh to a variable mesh having the same number of degrees of freedom is found to be approximately 20% overall. The variable-mesh model is used with several grid configurations, each having uniform high resolution over a specified area of interest and lower resolution elsewhere to produce short-term forecasts over this area without the necessity of high resolution everywhere. It is found that the forecast produced on a uniform high-resolution mesh can be essentially reproduced for a limited time over the limited area by a variable-mesh model having only a fraction of the number of degrees of freedom and requiring significantly less computer time. As expected, the period of validity of forecasts on variable meshes can be lengthened by refining the mesh in the outer region. It is concluded that from the point of view ...
TL;DR: In this article, the stability of the semi-implicit method of time integration of the primitive equations is examined when the actual temperature deviates from the reference profile about which the implicitly treated gravity wave terms are linearized.
Abstract: The stability of the semi-implicit method of time integration of the primitive equations is examined when the actual temperature deviates from the reference profile about which the implicitly treated gravity wave terms are linearized. The stability criterion is shown in general to be much more stringent than might he assumed from a simple analytical solution. Instability may occur when there exists a region in which the static stability of the actual atmosphere differs significantly from that of the reference atmosphere, and for realistic actual profiles and commonly chosen reference profiles it is likely to arise at vertical resolutions that are little higher than those used in previous tests of the scheme. Stabilization is achieved either by an appropriate change of reference profile or by a modification of the time-averaging of gravity wave terms. Both may result in a small further reduction in gravity wave phase speeds. Alternatives are mentioned which give better phase speeds at the expense ...
TL;DR: The relationship between meteorological factors, measured at Barrow, Alaska, and summertime Beaufort Sea ice conditions along the shipping route between Pt. Barrow and Prudhoe Bay was investigated using data available from 1953-1975.
Abstract: The relationship between meteorological factors, measured at Barrow, Alaska, and summertime Beaufort Sea ice conditions along the shipping route between Pt. Barrow and Prudhoe Bay was investigated using data available from 1953–1975. Light-ice summers are associated with higher than normal sea level pressure (SLP) northeast of the Beaufort Sea (centered on 80°N, 120°W), lower than normal SLP over the east Siberian Sea and with more frequent surface winds primarily from the directions 135–195°. A reversal in this pressure and wind direction pattern occurs during heavy-ice summers. Air temperature, in the form of thawing degree days (TDD's), is the parameter most highly correlated with the summertime ice margin distance (r = 0.815) and it is highly correlated with SLP and wind direction. Correlation coefficients between these meteorological factors and ice margin distance increase during the summer suggesting their increasing importance to melt processes with time. The amount of open water by late ...
TL;DR: In this paper, a set of differential equations representing a system of postulated interactions between the ocean and the atmosphere can reproduce certain hitherto unexplained aspects of atmospheric and oceanic behavior in the Indonesia-North Australia region.
Abstract: Solutions to a set of differential equations representing a system of postulated interactions between the ocean and the atmosphere can reproduce certain hitherto unexplained aspects of atmospheric and oceanic behavior in the Indonesia-North Australia region. These solutions also represent a biennial oscillation and it is concluded that the postulated air-sea interaction could be the source of the tropospheric quasi-biennial oscillation.
TL;DR: A mid-season test of a synoptic model for typhoon development (Sadler, 1976a) was conducted for July 1972 during an outbreak of four simultaneous typhoons as mentioned in this paper.
Abstract: A mid-season test of a synoptic model for typhoon development (Sadler, 1976a) was conducted for July 1972 during an outbreak of four simultaneous typhoons. In agreement with the model, the rapid deepening phase of typhoons Rita, Phyllis and Tess was associated with multi-directional outflow channels to the large-scale flows of the upper troposphere. The depressions were positioned beneath the subequatorial ridge with normal outflow to the south into the equatorial easterlies. Vigorous outflow to the north was initiated by the proper positioning, through relative motion, of intense cells in the tropical upper tropospheric trough. Each storm, filled to minimal typhoon strength when either of these efficient outflow channels was denied to it. Susan was a study in contrasts. She spent most of her lifetime under large-scale unidirectional northeast flow aloft and attained doubtful minimal typhoon intensity for a few hours. The upper flow became favorable for intensification just prior to landfall.
TL;DR: In this article, total ozone variations have been updated into 1976 for five data regions in north temperate latitudes, as well as for the five climatic zones, both hemispheres, and the world.
Abstract: Total ozone variations have been updated into 1976 for five data regions in north temperate latitudes, as well as for the five climatic zones, both hemispheres, and the world. In the Northern Hemisphere we find a significant (at the 95% level) 5% increase in total O3 between the early 1960's and 1970, an apparent decrease of 1–2% between 1970 and 1972, and no appreciable change thereafter, though relatively low values were observed in early 1976. In the Southern Hemisphere there was perhaps a 2% increase in total O3 between 1960 and 1968, and a 1% decrease thereafter, but because of the small data sample neither trend approaches significance. The out-of-phase relation between the quasi-biennial oscillation in total O3 in the tropics and midlatitudes persists, with the biennial oscillation particularly clearcut in south temperate latitudes (except after the eruption of Mt. Agung). Umkehr data suggest about an 8% increase in ozone in the 32–46 km layer in north temperate latitudes between 1962 and ...
TL;DR: In this article, a time-averaging operator is proposed to integrate the primitive equations of motion, which allows for a timestep increment up to twice that of the conventional leapfrog scheme.
Abstract: A simple method for integrating the primitive equations is presented which allows for a timestep increment up to twice that of the conventional leapfrog scheme. It consists of a time-averaging operator, which incorporates three consecutive time levels, on the pressure gradient terms in the equations of motion. An attractive feature of the method is its case in programming, since the resulting finite-difference equations can he solved explicitly. Presented here are linear analyses of the method applied to the barotropic and two-layer baroclinic gravity waves. Also presented is an analysis of the method with a time-damping device incorporated, which is an alternative in controlling linearly amplifying computational modes.