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- Author or Editor: Roland A. Madden x
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Abstract
An examination of 30 mb data from eight winter seasons reveals that out-of-phase temperature oscillations occur regularly on either side of 60°N. The typical time scale of these oscillations is 1–3 weeks. Evidence is presented indicating that these out-of-phase oscillations occur because fluctuations in horizontal eddy heat transport across 60°N are a dominant mechanism controlling zonal mean temperature variations in this period range. The interaction between quasi-stationary and transient planetary-scale waves is shown to be capable of producing a large fraction of these fluctuations in eddy transport.
Abstract
An examination of 30 mb data from eight winter seasons reveals that out-of-phase temperature oscillations occur regularly on either side of 60°N. The typical time scale of these oscillations is 1–3 weeks. Evidence is presented indicating that these out-of-phase oscillations occur because fluctuations in horizontal eddy heat transport across 60°N are a dominant mechanism controlling zonal mean temperature variations in this period range. The interaction between quasi-stationary and transient planetary-scale waves is shown to be capable of producing a large fraction of these fluctuations in eddy transport.
Abstract
Estimates of the natural variability of monthly-mean sea-level pressure are made based on a 74-year, grid-point data set. The natural variability of monthly means is defined as those interannual fluctuations that can be ascribed to the effects of statistical sampling alone. That is, the natural variability of monthly means is that variability resulting from the variance and autocorrelation associated with daily weather fluctuations. The natural variability does not reflect a “climate change,” but rather it is the variability within an “unchanging climate.” As such it is a measure of the “climatic noise.” Comparisons between natural and actual interannual variability are discussed in the context of potential long-range predictability. A characteristic time between independent estimates is determined.
Abstract
Estimates of the natural variability of monthly-mean sea-level pressure are made based on a 74-year, grid-point data set. The natural variability of monthly means is defined as those interannual fluctuations that can be ascribed to the effects of statistical sampling alone. That is, the natural variability of monthly means is that variability resulting from the variance and autocorrelation associated with daily weather fluctuations. The natural variability does not reflect a “climate change,” but rather it is the variability within an “unchanging climate.” As such it is a measure of the “climatic noise.” Comparisons between natural and actual interannual variability are discussed in the context of potential long-range predictability. A characteristic time between independent estimates is determined.
Abstract
The possible relation between blocking-type flow patterns in the atmosphere and large-scale traveling waves has been investigated. A 30-yr time series of observational 500-hPa geopotential-height data was used to study the relation between westward-moving planetary-scale waves 1 and 2 and blocked flow. It was found that, depending on longitude, 20%–40% of blocks were related to traveling wave 1, whereas the percentage was smaller for wave 2. The study confirms results of earlier studies that suggest a possible important role for large-scale, westward-moving waves in many blocking episodes.
Abstract
The possible relation between blocking-type flow patterns in the atmosphere and large-scale traveling waves has been investigated. A 30-yr time series of observational 500-hPa geopotential-height data was used to study the relation between westward-moving planetary-scale waves 1 and 2 and blocked flow. It was found that, depending on longitude, 20%–40% of blocks were related to traveling wave 1, whereas the percentage was smaller for wave 2. The study confirms results of earlier studies that suggest a possible important role for large-scale, westward-moving waves in many blocking episodes.
Abstract
We describe the global correlations between a measure of the Southern Oscillation and sea level pressure and surface air temperature in the northern winter. The stability of these correlations were tested on the Northern Hemisphere for an 80-year period, and it turned out that most stable correlation coefficients were found over India, the North Pacific Ocean, the Rocky Mountains, and the central and western North Atlantic Ocean. On the Southern Hemisphere most records are too short for a similar test, but the following may tentatively be said about the Southern Oscillation in middle and high southern latitudes: when pressure is low in lower latitudes over the South Pacific Ocean it tends to be high at higher latitudes of that ocean, high over East Antarctica and low in the belt of westerlies in the Indian and South Atlantic oceans. In the zonal average on both hemispheres the pressure gradients in this extreme of the oscillation tend to be steeper at lower latitudes and flatter at higher latitudes than in the other extreme. The apparent large-scale sympathetic variations between the SO and temperature are shown to occur over the relatively wide range of periods dust have been attributed to the SO itself.
Abstract
We describe the global correlations between a measure of the Southern Oscillation and sea level pressure and surface air temperature in the northern winter. The stability of these correlations were tested on the Northern Hemisphere for an 80-year period, and it turned out that most stable correlation coefficients were found over India, the North Pacific Ocean, the Rocky Mountains, and the central and western North Atlantic Ocean. On the Southern Hemisphere most records are too short for a similar test, but the following may tentatively be said about the Southern Oscillation in middle and high southern latitudes: when pressure is low in lower latitudes over the South Pacific Ocean it tends to be high at higher latitudes of that ocean, high over East Antarctica and low in the belt of westerlies in the Indian and South Atlantic oceans. In the zonal average on both hemispheres the pressure gradients in this extreme of the oscillation tend to be steeper at lower latitudes and flatter at higher latitudes than in the other extreme. The apparent large-scale sympathetic variations between the SO and temperature are shown to occur over the relatively wide range of periods dust have been attributed to the SO itself.
Abstract
Estimates of the natural variability of monthly mean temperature data from 107 U.S. stations are made. The natural variability of monthly means is defined as those interannual fluctuations that can be attributed to the effects of statistical sampling alone. It is variability resulting from the variance and autocorrelation associated with daily weather fluctuations. It does not indicate “climate change” but rather it is the variability within an “unchanging climate”; as such it is a measure of unpredictable “climatic noise”. Comparisons between the natural and actual interannual variability are discussed in the context of potential long-range predictability. The natural variability is proposed as a lower limit for the standard error of estimate for any long-range prediction. A characteristic time between independent estimates is computed.
Abstract
Estimates of the natural variability of monthly mean temperature data from 107 U.S. stations are made. The natural variability of monthly means is defined as those interannual fluctuations that can be attributed to the effects of statistical sampling alone. It is variability resulting from the variance and autocorrelation associated with daily weather fluctuations. It does not indicate “climate change” but rather it is the variability within an “unchanging climate”; as such it is a measure of unpredictable “climatic noise”. Comparisons between the natural and actual interannual variability are discussed in the context of potential long-range predictability. The natural variability is proposed as a lower limit for the standard error of estimate for any long-range prediction. A characteristic time between independent estimates is computed.
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.
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.
Abstract
Observational aspects of the 40–50-day oscillation are reviewed. The oscillation is the result of large-scale circulation cells oriented in the equatorial plane that move eastward from at least the Indian Ocean to the central Pacific. Anomalies in zonal winds and the velocity potential in the upper troposphere often propagate the full circumference of the globe. Related, complex convective regions also show an eastward movement. There is a zonally symmetric component to the oscillation. It is manifest in changes in surface pressure and in the relative atmospheric angular momentum. The oscillation is an important factor in the timing of active and break phases of the Indian and Australian monsoons. It affects ocean waves, currents, and air-sea interaction. The oscillation was particularly active during the First GARP (Global Atmospheric Research Program) Global Experiment year, and some features that were evident during the Monsoon Experiment are described.
Abstract
Observational aspects of the 40–50-day oscillation are reviewed. The oscillation is the result of large-scale circulation cells oriented in the equatorial plane that move eastward from at least the Indian Ocean to the central Pacific. Anomalies in zonal winds and the velocity potential in the upper troposphere often propagate the full circumference of the globe. Related, complex convective regions also show an eastward movement. There is a zonally symmetric component to the oscillation. It is manifest in changes in surface pressure and in the relative atmospheric angular momentum. The oscillation is an important factor in the timing of active and break phases of the Indian and Australian monsoons. It affects ocean waves, currents, and air-sea interaction. The oscillation was particularly active during the First GARP (Global Atmospheric Research Program) Global Experiment year, and some features that were evident during the Monsoon Experiment are described.
Abstract
Two patterns dominate changes of monthly mean temperature and pressure-height in the stratosphere. In the one, the middle latitudes vary oppositely to low and high latitudes, and in the other the changes at higher latitudes are out of phase with those at lower latitudes.
A shorter trend consisting of opposite changes at middle and high latitudes is superposed on the above variations which a cross-spectrum analysis shows has a preferred time scale of one to three weeks. The contrast between middle and high latitudes thus undergoes a series of corresponding fluctuations and we show that these are associated with amplitude changes in waves 1 and 2 in that the meridional contrast decreases when the amplitude of one or both waves is large, and vice versa.
Abstract
Two patterns dominate changes of monthly mean temperature and pressure-height in the stratosphere. In the one, the middle latitudes vary oppositely to low and high latitudes, and in the other the changes at higher latitudes are out of phase with those at lower latitudes.
A shorter trend consisting of opposite changes at middle and high latitudes is superposed on the above variations which a cross-spectrum analysis shows has a preferred time scale of one to three weeks. The contrast between middle and high latitudes thus undergoes a series of corresponding fluctuations and we show that these are associated with amplitude changes in waves 1 and 2 in that the meridional contrast decreases when the amplitude of one or both waves is large, and vice versa.
