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Abstract
Nimbus III carried a Satellite Infra-Red Spectrometer (SIRS) with which the temperature structure of the atmosphere can be observed. The most opaque spectral interval on SIRS was centered at 669.3 cm−1 (∼15 μ). At this frequency only the stratosphere essentially contributes to the outgoing radiation. A description of the measured radiances at 669.3 cm−1 is also a description of a weighted mean stratospheric temperature for the upper 100 mb of air. With the aid of additional spectral intervals, however, the temperature structure in thinner layers of the stratosphere can also be investigated.
Radiance measurements at 669.3 cm−1 are discussed in relation to several different stratospheric phenonmena. The phemomena discussed are:
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Moving and stationary “waves.” In May 1909, westward moving waves were discernible in the tropics. A stationary wavenumber 1 pattern was also seen. Wave motions were also shown at latitudes 60N and 60S.
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A stratospheric warming area was present in early May over the Indian Ocean area near 45S.
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A minimum of radiance was observed in July at the equator; the July minimum of stratospheric temperature above 10 mb was apparently responsible for the observed low radiance.
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Non-seasonal variations of radiance appear almost simultaneously over large areas of the world; although large-scale internal dynamical adjustments may account for the observations, extraterrestrial causes cannot be ruled out as contributing factors.
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The diurnal variation of stratospheric temperature (integrated in the vertical) is small. Observations which claim large stratosphere temperature variations between midnight and noon are probably erroneous.
Abstract
Nimbus III carried a Satellite Infra-Red Spectrometer (SIRS) with which the temperature structure of the atmosphere can be observed. The most opaque spectral interval on SIRS was centered at 669.3 cm−1 (∼15 μ). At this frequency only the stratosphere essentially contributes to the outgoing radiation. A description of the measured radiances at 669.3 cm−1 is also a description of a weighted mean stratospheric temperature for the upper 100 mb of air. With the aid of additional spectral intervals, however, the temperature structure in thinner layers of the stratosphere can also be investigated.
Radiance measurements at 669.3 cm−1 are discussed in relation to several different stratospheric phenonmena. The phemomena discussed are:
-
Moving and stationary “waves.” In May 1909, westward moving waves were discernible in the tropics. A stationary wavenumber 1 pattern was also seen. Wave motions were also shown at latitudes 60N and 60S.
-
A stratospheric warming area was present in early May over the Indian Ocean area near 45S.
-
A minimum of radiance was observed in July at the equator; the July minimum of stratospheric temperature above 10 mb was apparently responsible for the observed low radiance.
-
Non-seasonal variations of radiance appear almost simultaneously over large areas of the world; although large-scale internal dynamical adjustments may account for the observations, extraterrestrial causes cannot be ruled out as contributing factors.
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The diurnal variation of stratospheric temperature (integrated in the vertical) is small. Observations which claim large stratosphere temperature variations between midnight and noon are probably erroneous.
Abstract
TIROS II measured the emission from the planet Earth in the atmospheric water-vapor window near 10 microns. During carefully selected times, when no clouds were present near sunrise or near noon, the measurements served to estimate the change in temperature of the ground. Under these conditions, although the change in transmittance of the atmosphere can be neglected for the purpose of computing the ground temperature change, the transmittance through the atmosphere must still be evaluated.
During cloudless sky conditions over Wisconsin on 23 November 1960, the change in ground temperature from sunrise to noon was about 24C as estimated from satellite measurements. The change in shelter air temperature was less than 15C over the same time interval.
In overcast areas, the movement and development of the clouds determine the variation of the energy measured by the satellite.
Abstract
TIROS II measured the emission from the planet Earth in the atmospheric water-vapor window near 10 microns. During carefully selected times, when no clouds were present near sunrise or near noon, the measurements served to estimate the change in temperature of the ground. Under these conditions, although the change in transmittance of the atmosphere can be neglected for the purpose of computing the ground temperature change, the transmittance through the atmosphere must still be evaluated.
During cloudless sky conditions over Wisconsin on 23 November 1960, the change in ground temperature from sunrise to noon was about 24C as estimated from satellite measurements. The change in shelter air temperature was less than 15C over the same time interval.
In overcast areas, the movement and development of the clouds determine the variation of the energy measured by the satellite.
Abstract
A brief description of the basic method used to compute the absorption of solar energy in clouds is given. The numerical results of computations are presented. These include: 1. the absorption in thick clouds as a function of wavelength; 2. the total absorption in thick clouds as a function of certain cloud parameters; and 3. the absorption as a function of thickness for a particular cloud. The effect of the water vapor above the cloud on absorption in the cloud is discussed; the influence of the sun's zenith distance is indicated. For some cases, the albedo of the clouds is also given.
Abstract
A brief description of the basic method used to compute the absorption of solar energy in clouds is given. The numerical results of computations are presented. These include: 1. the absorption in thick clouds as a function of wavelength; 2. the total absorption in thick clouds as a function of certain cloud parameters; and 3. the absorption as a function of thickness for a particular cloud. The effect of the water vapor above the cloud on absorption in the cloud is discussed; the influence of the sun's zenith distance is indicated. For some cases, the albedo of the clouds is also given.
Abstract
For the case when absorption is negligible, the direct and scattered solar beams have been followed down into clouds of “large” spherical waterdrops, to calculate the distribution of the generation of diffuse energy in the cloud. The generated diffuse energy is considered to obey a simple diffusion equation, from which the cloud albedo has been computed as a function of the cloud thickness, the mean free path, and the sun's zenith distance. One of the main results is the marked variation of albedo with zenith distance, especially for “thin” clouds. The results are compared with observations, and it appears that the dissipation of stratus clouds is often accompanied by a reduction in the effective scattering radius of the cloud drops.
Abstract
For the case when absorption is negligible, the direct and scattered solar beams have been followed down into clouds of “large” spherical waterdrops, to calculate the distribution of the generation of diffuse energy in the cloud. The generated diffuse energy is considered to obey a simple diffusion equation, from which the cloud albedo has been computed as a function of the cloud thickness, the mean free path, and the sun's zenith distance. One of the main results is the marked variation of albedo with zenith distance, especially for “thin” clouds. The results are compared with observations, and it appears that the dissipation of stratus clouds is often accompanied by a reduction in the effective scattering radius of the cloud drops.
Abstract
The precipitation over northern Honduras in December was significantly correlated with 700 mb heights over Valencia, Ireland. (Measurements at Valencia were used to represent a more accurate indicator of the variations in the Icelandic Low than interpolated analyses in the Low over the Atlantic Ocean.) This relationship was suggested by a comparison between observed and theoretical “wave-trains” in the 700 mb height field. The observed 700 mb height wave train over the Atlantic was related to anomalies in the sea-surface temperature (SST) over the tropical Pacific Ocean; therefore, the northern Honduran rainfall was also significantly correlated with the tropical Pacific SST.
Abstract
The precipitation over northern Honduras in December was significantly correlated with 700 mb heights over Valencia, Ireland. (Measurements at Valencia were used to represent a more accurate indicator of the variations in the Icelandic Low than interpolated analyses in the Low over the Atlantic Ocean.) This relationship was suggested by a comparison between observed and theoretical “wave-trains” in the 700 mb height field. The observed 700 mb height wave train over the Atlantic was related to anomalies in the sea-surface temperature (SST) over the tropical Pacific Ocean; therefore, the northern Honduran rainfall was also significantly correlated with the tropical Pacific SST.
Abstract
Nimbus 3 and 4 satellites carried Satellite Infrared Spectrometers (SIRS-A and SIRS-B, respectively). One of the channels on each spectrometer measured the energy emitted from the stratosphere in a narrow wavelength interval in the middle of the 15-µm CO2 band. The measured radiance changes are indicative of temperature changes in the stratosphere.
In the tropics, the annual and semi-annual march of radiance (or temperature) depends on the variations of solar energy absorbed by ozone and on dynamical influences. The radiance changes produced by solar heating of ozone were computed. To do this the concept of “Newtonian cooling” was also utilized.
The computed solar radiances were then compared with the observed radiances; the difference was attributed to dynamical factors. The observed radiances for SIRS-A had a total annual range which did not exceed 6 mW per (m2 ster cm−1). Moreover, the north-south gradient of radiance was very small and there was a strong tendency for the radiances to have a minimum at the equator during much of the year, especially at the solstices. This produces north-south gradients with opposite signs in the Northern and Southern Hemisphere tropics. By contrast, the solar-induced radiances have large annual amplitudes away from the equator, and would produce large radiance (or temperature) gradients. Also, the solar radiance gradients have the same sign on both sides of the equator, especially during the solstices. This would introduce large wind shears in the vertical, and possibly large horizontal wind shears across the equator.
The observed radiance changes are often a residual between large solar radiance changes and large dynamical temperature changes. Near the equator the solar radiances agreed approximately with the observed radiances in the period April–July–October. But in November–January–March, dynamic factors dominated. At tropical latitudes away from the equator (e.g., at 2OS) dynamic factors almost completely balance the solar radiances in the annual cycle, leaving a small residual annual component in the observed radiances. The semi-annual amplitude at 20S is larger for the observed radiances than for the solar radiances; thus, the observed values are a combination of solar and dynamically induced temperature changes.
The dynamical radiance changes suggest that the air was sinking at 30° latitude in winter and rising there in summer. Also, at the equator, the air was rising in January 1970.
Abstract
Nimbus 3 and 4 satellites carried Satellite Infrared Spectrometers (SIRS-A and SIRS-B, respectively). One of the channels on each spectrometer measured the energy emitted from the stratosphere in a narrow wavelength interval in the middle of the 15-µm CO2 band. The measured radiance changes are indicative of temperature changes in the stratosphere.
In the tropics, the annual and semi-annual march of radiance (or temperature) depends on the variations of solar energy absorbed by ozone and on dynamical influences. The radiance changes produced by solar heating of ozone were computed. To do this the concept of “Newtonian cooling” was also utilized.
The computed solar radiances were then compared with the observed radiances; the difference was attributed to dynamical factors. The observed radiances for SIRS-A had a total annual range which did not exceed 6 mW per (m2 ster cm−1). Moreover, the north-south gradient of radiance was very small and there was a strong tendency for the radiances to have a minimum at the equator during much of the year, especially at the solstices. This produces north-south gradients with opposite signs in the Northern and Southern Hemisphere tropics. By contrast, the solar-induced radiances have large annual amplitudes away from the equator, and would produce large radiance (or temperature) gradients. Also, the solar radiance gradients have the same sign on both sides of the equator, especially during the solstices. This would introduce large wind shears in the vertical, and possibly large horizontal wind shears across the equator.
The observed radiance changes are often a residual between large solar radiance changes and large dynamical temperature changes. Near the equator the solar radiances agreed approximately with the observed radiances in the period April–July–October. But in November–January–March, dynamic factors dominated. At tropical latitudes away from the equator (e.g., at 2OS) dynamic factors almost completely balance the solar radiances in the annual cycle, leaving a small residual annual component in the observed radiances. The semi-annual amplitude at 20S is larger for the observed radiances than for the solar radiances; thus, the observed values are a combination of solar and dynamically induced temperature changes.
The dynamical radiance changes suggest that the air was sinking at 30° latitude in winter and rising there in summer. Also, at the equator, the air was rising in January 1970.
Abstract
This paper presents a method for using satellite measurements to interpolate vertical temperature soundings between radiosonde stations. The calculations presented show that especially in the 1000–800 mb layer, where linear methods of temperature retrieval usually contain large errors, the proposed method reduces the errors substantially.
The method finds a set of coefficients, which when multiplied by corresponding measured radiance quantities, yield zero temperature error at a radiosonde station. This derived set of coefficients is then applied to satellite radiance measurements at places between the radiosonde stations. The computations show, for example, that the average absolute error in the layer 1000–800 mb is only 0.3 K when the corresponding “minimum-information” method error was 2.9 K. The method may be most applicable to measurements from geostationary satellites, but should also be applicable to measurements from polar orbiting satellites under certain conditions.
Abstract
This paper presents a method for using satellite measurements to interpolate vertical temperature soundings between radiosonde stations. The calculations presented show that especially in the 1000–800 mb layer, where linear methods of temperature retrieval usually contain large errors, the proposed method reduces the errors substantially.
The method finds a set of coefficients, which when multiplied by corresponding measured radiance quantities, yield zero temperature error at a radiosonde station. This derived set of coefficients is then applied to satellite radiance measurements at places between the radiosonde stations. The computations show, for example, that the average absolute error in the layer 1000–800 mb is only 0.3 K when the corresponding “minimum-information” method error was 2.9 K. The method may be most applicable to measurements from geostationary satellites, but should also be applicable to measurements from polar orbiting satellites under certain conditions.
Abstract
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Abstract
When air stagnates in dark polar regions, an inversion forms. The change of the inversion magnitude is studied under the assumption that the snow surface radiates about as much energy as it receives from the atmosphere. It turns out that the inversion magnitude may either decrease or increase as the surface temperature falls, depending on the rate of change of atmospheric “emissivity” with air temperature.
Abstract
When air stagnates in dark polar regions, an inversion forms. The change of the inversion magnitude is studied under the assumption that the snow surface radiates about as much energy as it receives from the atmosphere. It turns out that the inversion magnitude may either decrease or increase as the surface temperature falls, depending on the rate of change of atmospheric “emissivity” with air temperature.
Abstract
The mean characteristics of the Aleutian low in January and February are compared. The comparison is made separately for years when the tropical Pacific sea surface temperature (SST) was anomalously high, and when the SST was low. It was found that when the SST was high, and the January sea level pressure (SLP) in the Aleutian low center was less than 990 mb, the center was east of the Dateline in both January and February; the February SLP also tended to be below normal. It is speculated that the characteristics of the Aleutian low in January and February under these conditions may be due to interaction between the influences of precipitation distribution over the tropical Pacific and the large-scale wind flow near the Asian coast.
Abstract
The mean characteristics of the Aleutian low in January and February are compared. The comparison is made separately for years when the tropical Pacific sea surface temperature (SST) was anomalously high, and when the SST was low. It was found that when the SST was high, and the January sea level pressure (SLP) in the Aleutian low center was less than 990 mb, the center was east of the Dateline in both January and February; the February SLP also tended to be below normal. It is speculated that the characteristics of the Aleutian low in January and February under these conditions may be due to interaction between the influences of precipitation distribution over the tropical Pacific and the large-scale wind flow near the Asian coast.
