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Abstract
A comparison of diurnal cycles in high clouds (<440 hPa) measured by the Geostationary Operational Environmental Satellite Visible Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (GOES-VAS) and the International Satellite Cloud Climatology Project (ISCCP) was made. The GOES-VAS longwave infrared data allow uniform detection of upper-tropospheric cirrus clouds from daylight into night without effects from solar reflections. It is sensitive to thin cirrus, which are difficult to detect. But it is not available globally because the sounder instrument is flown only on geostationary satellites operated by the United States. The ISCCP, however, is a global dataset using five to seven geostationary satellites.
Large diurnal cycles were found in the Rocky Mountains and along the northern coast of the Gulf of Mexico mainly in the summer season. In the Tropics substantial diurnal cycles also were found in central Brazil and the Atlantic ITCZ. In the winter over the continental United States, diurnal cycles were very small or nearly absent.
The ISCCP found similar diurnal cycles over land. The amplitudes of the cycles were about 1.5 times larger in the VAS data than the ISCCP (IR only) data over land because of the former's sensitivity to thin cirrus. The phase relationships were very similar. In the western tropical Atlantic ITCZ, the VAS found dual maxima in the diurnal cycle (morning and later afternoon), which the ISCCP could not detect. These changes in high cloud cover probably were driven by radiative cooling of the cloud tops over the ocean. Over land the obvious cause of diurnal cycles in high clouds is deep convection from solar surface heating.
Abstract
A comparison of diurnal cycles in high clouds (<440 hPa) measured by the Geostationary Operational Environmental Satellite Visible Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (GOES-VAS) and the International Satellite Cloud Climatology Project (ISCCP) was made. The GOES-VAS longwave infrared data allow uniform detection of upper-tropospheric cirrus clouds from daylight into night without effects from solar reflections. It is sensitive to thin cirrus, which are difficult to detect. But it is not available globally because the sounder instrument is flown only on geostationary satellites operated by the United States. The ISCCP, however, is a global dataset using five to seven geostationary satellites.
Large diurnal cycles were found in the Rocky Mountains and along the northern coast of the Gulf of Mexico mainly in the summer season. In the Tropics substantial diurnal cycles also were found in central Brazil and the Atlantic ITCZ. In the winter over the continental United States, diurnal cycles were very small or nearly absent.
The ISCCP found similar diurnal cycles over land. The amplitudes of the cycles were about 1.5 times larger in the VAS data than the ISCCP (IR only) data over land because of the former's sensitivity to thin cirrus. The phase relationships were very similar. In the western tropical Atlantic ITCZ, the VAS found dual maxima in the diurnal cycle (morning and later afternoon), which the ISCCP could not detect. These changes in high cloud cover probably were driven by radiative cooling of the cloud tops over the ocean. Over land the obvious cause of diurnal cycles in high clouds is deep convection from solar surface heating.
Abstract
An analysis technique for Geostationary Operational Environmental Satellite-VISSR (Visible and Infrared Spin Scan Radiometer) Atmospheric Sounder (GOES-VAS) sounder data was developed to extract cloud and clear radiance information. This technique employed many of the concepts used in the International Satellite Cloud Climatology Project (ISCCP) such as spatial and time comparisons of neighboring satellite pixels. It improved upon the previous studies that used VAS data by using all available VAS data at full time and space resolution. The previous studies utilized <10% of the original data.
The GOES-VAS cloud and clear radiance statistics compared well with rawinsondes and the ISCCP cloud analysis. The best agreement between the ISCCP and this GOES-VAS cloud analysis was for upper-tropospheric clouds (<440 hPa) in both cloud frequency and infrared emissivity. The two cloud datasets agreed to within 2% for both parameters. A comparison of the GOES-VAS clear radiance data to National Weather Service (NWS) rawinsondes showed agreement within 1.7 K (blackbody radiances). The upper-tropospheric VAS channels were warmer than the rawinsondes. The VAS water vapor channels suggested that the NWS rawinsondes have a dry bias in the upper troposphere.
Abstract
An analysis technique for Geostationary Operational Environmental Satellite-VISSR (Visible and Infrared Spin Scan Radiometer) Atmospheric Sounder (GOES-VAS) sounder data was developed to extract cloud and clear radiance information. This technique employed many of the concepts used in the International Satellite Cloud Climatology Project (ISCCP) such as spatial and time comparisons of neighboring satellite pixels. It improved upon the previous studies that used VAS data by using all available VAS data at full time and space resolution. The previous studies utilized <10% of the original data.
The GOES-VAS cloud and clear radiance statistics compared well with rawinsondes and the ISCCP cloud analysis. The best agreement between the ISCCP and this GOES-VAS cloud analysis was for upper-tropospheric clouds (<440 hPa) in both cloud frequency and infrared emissivity. The two cloud datasets agreed to within 2% for both parameters. A comparison of the GOES-VAS clear radiance data to National Weather Service (NWS) rawinsondes showed agreement within 1.7 K (blackbody radiances). The upper-tropospheric VAS channels were warmer than the rawinsondes. The VAS water vapor channels suggested that the NWS rawinsondes have a dry bias in the upper troposphere.
Abstract
Fourteen HASP and two ARCAS rockets, carrying WOX-1A and Arcasonde 1A instrumentation, respectively, were launched at Wallops Island during a 39-hr period in September 1965 to gain information regarding 1) the daily variation of temperature and wind within the 30- to 50-km layer, and 2) the compatibility between temperatures measured nearly simultaneously by the rocketsondes and by supporting balloon-borne radiosondes. Analysis of the observed rocketsonde temperatures indicates a diurnal variation ranging from about 3C at 30 km to 9C at 48 km. Marked differences in the temperatures measured by rocketsondes launched prior and subsequent to sunrise and sunset suggest that a portion of the variation may not be real, but is possibly a, function of instrumental error. Support for this inference is provided by computations utilizing the rocketsonde winds as an independent means of determining the diurnal temperature wave. The results yield an amplitude about half that of the observed variation in the 35- to 45-km layer.
Temperatures obtained from several rockets launched within a short time interval disclose that the HASP (WOX-1A) system is capable of reproducing a given temperature profile with relatively small random error. In addition, ARCAS (Arcasonde 1A) measurements appear compatible with those of the HASP. However, a definite discrepancy was found to exist between rocketsonde temperatures and these reported by the supporting rawinsonde observations. Additional experiments are suggested as a means of determining the errors inherent in measurement of temperature by the various systems.
Abstract
Fourteen HASP and two ARCAS rockets, carrying WOX-1A and Arcasonde 1A instrumentation, respectively, were launched at Wallops Island during a 39-hr period in September 1965 to gain information regarding 1) the daily variation of temperature and wind within the 30- to 50-km layer, and 2) the compatibility between temperatures measured nearly simultaneously by the rocketsondes and by supporting balloon-borne radiosondes. Analysis of the observed rocketsonde temperatures indicates a diurnal variation ranging from about 3C at 30 km to 9C at 48 km. Marked differences in the temperatures measured by rocketsondes launched prior and subsequent to sunrise and sunset suggest that a portion of the variation may not be real, but is possibly a, function of instrumental error. Support for this inference is provided by computations utilizing the rocketsonde winds as an independent means of determining the diurnal temperature wave. The results yield an amplitude about half that of the observed variation in the 35- to 45-km layer.
Temperatures obtained from several rockets launched within a short time interval disclose that the HASP (WOX-1A) system is capable of reproducing a given temperature profile with relatively small random error. In addition, ARCAS (Arcasonde 1A) measurements appear compatible with those of the HASP. However, a definite discrepancy was found to exist between rocketsonde temperatures and these reported by the supporting rawinsonde observations. Additional experiments are suggested as a means of determining the errors inherent in measurement of temperature by the various systems.
Abstract
Meteorological data from the NASA Mobile Launch Expedition aboard USNS Croatan are utilized to investigate the early autumn stratospheric circulation of the Southern Hemisphere. Time-height and cross-section analyses indicate the vertical and areal extent of the developing wintertime polar vortex. A comparison is made between this cyclone and that of the Northern Hemisphere at a similar stage of development. Additional sets of analyses illustrate segments of the circulation patterns in both hemispheres along the 78th meridian at the time period of the Croatan observations.
Abstract
Meteorological data from the NASA Mobile Launch Expedition aboard USNS Croatan are utilized to investigate the early autumn stratospheric circulation of the Southern Hemisphere. Time-height and cross-section analyses indicate the vertical and areal extent of the developing wintertime polar vortex. A comparison is made between this cyclone and that of the Northern Hemisphere at a similar stage of development. Additional sets of analyses illustrate segments of the circulation patterns in both hemispheres along the 78th meridian at the time period of the Croatan observations.
Abstract
A method is presented for deducing lower troposphere moisture fields from radiances measured by the operational polar orbiting NOAA satellites. Statistical evaluation of the technique demonstrates the viability of the approach. A case study with TIROS-N observations shows substantial improvement over current operational methods, and a qualitatively reasonable product. High moisture gradients are clearly defined and horizontal consistency is achieved. The technique appears useful for the initialization of subsynoptic forecast models.
Abstract
A method is presented for deducing lower troposphere moisture fields from radiances measured by the operational polar orbiting NOAA satellites. Statistical evaluation of the technique demonstrates the viability of the approach. A case study with TIROS-N observations shows substantial improvement over current operational methods, and a qualitatively reasonable product. High moisture gradients are clearly defined and horizontal consistency is achieved. The technique appears useful for the initialization of subsynoptic forecast models.
Abstract
This paper describes a statistical regression technique for specifying the vertical temperature profile above 10 mb from satellite radiances simulated for the Satellite Infrared Spectrometer B (SIRS B) instrument when the temperature profile up to 10 mb is known. Sensitivity of the radiance information to temperature at the high atmospheric levels is attained by subtracting, from the total radiance, that part of the radiance emanating from the known temperature profile below 10 mb. The remainder is that portion of the radiance representative of the temperature profile above 10 mb. Statistics are derived using a sample of 50 carefully selected temperature profiles representative of worldwide atmospheric conditions above 30 km during all times of the year. Regression equations are developed relating temperature at 10 pressure levels between 10 and 0.5 mb to a set of predictors [temperature at 50, 30, and 10 mb and radiance information derived from SIRS B channels 7 (679.8 cm−1) and 8 (668.7 cm−1)]. For an independent data set, root-mean-square errors in specification ranged from 2.1°C at 9 mb to 8.8°C at 0.5 mb, with the shapes of all profiles very well distinguished. Regression-specified temperatures above 10 mb are then used as first guess in simulated retrievals of complete atmospheric temperature profiles. These regression results are shown to significantly increase the accuracy of temperature retrievals at tropospheric as well as stratospheric levels over those retrievals derived using a climatological first guess.
Abstract
This paper describes a statistical regression technique for specifying the vertical temperature profile above 10 mb from satellite radiances simulated for the Satellite Infrared Spectrometer B (SIRS B) instrument when the temperature profile up to 10 mb is known. Sensitivity of the radiance information to temperature at the high atmospheric levels is attained by subtracting, from the total radiance, that part of the radiance emanating from the known temperature profile below 10 mb. The remainder is that portion of the radiance representative of the temperature profile above 10 mb. Statistics are derived using a sample of 50 carefully selected temperature profiles representative of worldwide atmospheric conditions above 30 km during all times of the year. Regression equations are developed relating temperature at 10 pressure levels between 10 and 0.5 mb to a set of predictors [temperature at 50, 30, and 10 mb and radiance information derived from SIRS B channels 7 (679.8 cm−1) and 8 (668.7 cm−1)]. For an independent data set, root-mean-square errors in specification ranged from 2.1°C at 9 mb to 8.8°C at 0.5 mb, with the shapes of all profiles very well distinguished. Regression-specified temperatures above 10 mb are then used as first guess in simulated retrievals of complete atmospheric temperature profiles. These regression results are shown to significantly increase the accuracy of temperature retrievals at tropospheric as well as stratospheric levels over those retrievals derived using a climatological first guess.
Abstract
A physical model is presented for calculating the total ozone amount from HIRS radiance measurements from TIROS-N/NOAA satellites. Simulations and retrievals indicate that the total ozone amount can be retrieved with an accuracy better than 5%. Comparisons are presented of analyses of real data physical ozone retrievals from HIRS observations with analyses of regression ozone retrievals from HIRS observations obtained operationally by NOAA/NESDIS, and with analyses of ozone measurements from the Nimbus-G satellite by the Total Ozone Mapping Spectrometer(TOMS). Comparisons of these analyses show that small scale ozone features not resolved by operational regression retrievals are resolved quite well by the higher spatial resolution HIRS retrievals using the physical algorithm.
Abstract
A physical model is presented for calculating the total ozone amount from HIRS radiance measurements from TIROS-N/NOAA satellites. Simulations and retrievals indicate that the total ozone amount can be retrieved with an accuracy better than 5%. Comparisons are presented of analyses of real data physical ozone retrievals from HIRS observations with analyses of regression ozone retrievals from HIRS observations obtained operationally by NOAA/NESDIS, and with analyses of ozone measurements from the Nimbus-G satellite by the Total Ozone Mapping Spectrometer(TOMS). Comparisons of these analyses show that small scale ozone features not resolved by operational regression retrievals are resolved quite well by the higher spatial resolution HIRS retrievals using the physical algorithm.
Abstract
A theoretical analysis is performed to evaluate the accuracy and vertical resolution of atmospheric profiles obtained with the HIRS/2, GOES I/M, and HIS instruments. In addition, a linear simultaneous retrieval algorithm is used with aircraft observations to validate the theoretical predictions. Both theoretical and observational results clearly indicate that the accuracy and vertical resolution of the retrieval profile would be improved by high spectral resolution and broad spectral coverage of infrared radiance measurements.
The HIS is found to possess the equivalent of 11 pieces of temperature-and 9 pieces of water vapor-independent precise measurements. The characteristics for temperature include a vertical resolution of 1–6 km with an accuracy of 1 K and for water vapor a vertical resolution of 0.5–3.0 km with an accuracy of 3 K in dewpoint temperature. The HIS is a factor of 2–3 times better in vertical resolution and a factor of 2 times better in accuracy than the GOES 1/M and HIRS/2 filter radiometers.
Abstract
A theoretical analysis is performed to evaluate the accuracy and vertical resolution of atmospheric profiles obtained with the HIRS/2, GOES I/M, and HIS instruments. In addition, a linear simultaneous retrieval algorithm is used with aircraft observations to validate the theoretical predictions. Both theoretical and observational results clearly indicate that the accuracy and vertical resolution of the retrieval profile would be improved by high spectral resolution and broad spectral coverage of infrared radiance measurements.
The HIS is found to possess the equivalent of 11 pieces of temperature-and 9 pieces of water vapor-independent precise measurements. The characteristics for temperature include a vertical resolution of 1–6 km with an accuracy of 1 K and for water vapor a vertical resolution of 0.5–3.0 km with an accuracy of 3 K in dewpoint temperature. The HIS is a factor of 2–3 times better in vertical resolution and a factor of 2 times better in accuracy than the GOES 1/M and HIRS/2 filter radiometers.
Abstract
Geostrophic angular momentum transport at 500 mb has been computed as a function of latitude and zonal wave number for a 10-yr period. The record has been inspected for evidence of periodic variations at latitudes 17.5N, 27.5N, 42.5N, and 57.5N. A quasi-biennial cycle is most prominent in the case of the planetary waves, with wave numbers 1 and 3 out of phase with wave number 2. The cyclone waves display a phase shift with time that implies a varying scheme of interaction with the long waves.
Monthly average values of the 500-mb mean zonal wind, based on the same 10-yr record, do not indicate any strong periodicity.
Abstract
Geostrophic angular momentum transport at 500 mb has been computed as a function of latitude and zonal wave number for a 10-yr period. The record has been inspected for evidence of periodic variations at latitudes 17.5N, 27.5N, 42.5N, and 57.5N. A quasi-biennial cycle is most prominent in the case of the planetary waves, with wave numbers 1 and 3 out of phase with wave number 2. The cyclone waves display a phase shift with time that implies a varying scheme of interaction with the long waves.
Monthly average values of the 500-mb mean zonal wind, based on the same 10-yr record, do not indicate any strong periodicity.
A method for displaying sounding and cloud information in a composite image is described. Examples are shown to illustrate how a forecaster may use a time sequence of these images to monitor changes in atmospheric moisture and stability antecedent to convective weather and at the same time monitor the cloud developments resulting from these atmospheric moisture and stability tendencies. The image products are now being produced in real time at the University of Wisconsin for an assessment of their operational utility as a part of the NOAA Operational VAS Assessment (NOVA) program. It is likely that the sounding/cloud imagery product will be available to all forecast centers in 1986, after the VAS data acquisition and processing system becomes fully operational.
A method for displaying sounding and cloud information in a composite image is described. Examples are shown to illustrate how a forecaster may use a time sequence of these images to monitor changes in atmospheric moisture and stability antecedent to convective weather and at the same time monitor the cloud developments resulting from these atmospheric moisture and stability tendencies. The image products are now being produced in real time at the University of Wisconsin for an assessment of their operational utility as a part of the NOAA Operational VAS Assessment (NOVA) program. It is likely that the sounding/cloud imagery product will be available to all forecast centers in 1986, after the VAS data acquisition and processing system becomes fully operational.
