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- Author or Editor: Frank L. Martin x
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Abstract
Over an area spanning the North American Continent from tropical to polar latitudes, and between 40W and 135W, four consecutive days of the NIMBUS II Medium Resolution Infrared (MRIR) five-channel equivalent blackbody temperatures and of 1000-mb geopotential fields were used to specify the 500-mb field of geopotential. Three of the four days were reserved for dependent data, the fourth day being reserved for independent test-case data. The data samples were stratified into “extratropical” and subtropical-tropical areas, and then pooled three-day stepwise, with screening regression equations being developed by areas. In the lower latitude stratifications, the 500-mb regression equations were only of marginal significance, but in the extratropical zone (latitudes 32–64N), the regressions have 500-mb height specifications with multiple correlation coefficients of 0.95. Moreover, in the independent-data test case, no shrinkage of explained variances occurred in these extratropical latitudes. Here the most important predictors for Z 5(I, J) were the equivalent blackbody temperatures (TBB ) in the 14–16 μ and 10–11 μ channels, the 1000-mb geopotential, and finally an effective TBB associated with the solar-reflectance channel.
Abstract
Over an area spanning the North American Continent from tropical to polar latitudes, and between 40W and 135W, four consecutive days of the NIMBUS II Medium Resolution Infrared (MRIR) five-channel equivalent blackbody temperatures and of 1000-mb geopotential fields were used to specify the 500-mb field of geopotential. Three of the four days were reserved for dependent data, the fourth day being reserved for independent test-case data. The data samples were stratified into “extratropical” and subtropical-tropical areas, and then pooled three-day stepwise, with screening regression equations being developed by areas. In the lower latitude stratifications, the 500-mb regression equations were only of marginal significance, but in the extratropical zone (latitudes 32–64N), the regressions have 500-mb height specifications with multiple correlation coefficients of 0.95. Moreover, in the independent-data test case, no shrinkage of explained variances occurred in these extratropical latitudes. Here the most important predictors for Z 5(I, J) were the equivalent blackbody temperatures (TBB ) in the 14–16 μ and 10–11 μ channels, the 1000-mb geopotential, and finally an effective TBB associated with the solar-reflectance channel.
Abstract
Based upon four years of complete data spanning 1957 through 1960 at Ship P, “clear-sky” multiple regression equations were obtained relating computed long-wave flux from water vapor over Ship P to shipboard measurements of the black-body flux and the square root of vapor pressure, as the two independent variables. The water-vapor radiative flux computations were made using the “total water vapor” flux table in the recent Elsaaser-Culbertson Meterological Monograph. In order to limit the noise, only those clear-sky cases synoptic with the filing time of radiosondes were selected. The multiple correlation coefficient was of the order of 0.95. Statistical tests indicate, at high confidence levels, that both independent variables gave significant contributions to the explained variance.
Abstract
Based upon four years of complete data spanning 1957 through 1960 at Ship P, “clear-sky” multiple regression equations were obtained relating computed long-wave flux from water vapor over Ship P to shipboard measurements of the black-body flux and the square root of vapor pressure, as the two independent variables. The water-vapor radiative flux computations were made using the “total water vapor” flux table in the recent Elsaaser-Culbertson Meterological Monograph. In order to limit the noise, only those clear-sky cases synoptic with the filing time of radiosondes were selected. The multiple correlation coefficient was of the order of 0.95. Statistical tests indicate, at high confidence levels, that both independent variables gave significant contributions to the explained variance.
Abstract
A sample of 60 individual cases of southwesterly jet-stream maxima located over the continental United States during the Nimbus II period is studied in relation to the MRIR characteristics surrounding the jet. The analysis has been conducted primarily from a statistical point-of-view applied to the equivalent black-body temperature (TBB ) patterns of channels 1, 2 and 4, and to hypsometric combinations of these TBB values representing layer-mean temperatures. It was found that certain grow features of the fields of convergence and divergence associated with the moisture distribution in certain quadrants surrounding the jet are consistently indicated in these patterns. A stepwise, multiple regression analysis for specification of the maximum wind speeds gives predictive skill in several channels, particularly in the 5–30 μ channel, indicating that baroclinic effects can be discerned by MRIR observations applied to suitably stratified data samples.
Abstract
A sample of 60 individual cases of southwesterly jet-stream maxima located over the continental United States during the Nimbus II period is studied in relation to the MRIR characteristics surrounding the jet. The analysis has been conducted primarily from a statistical point-of-view applied to the equivalent black-body temperature (TBB ) patterns of channels 1, 2 and 4, and to hypsometric combinations of these TBB values representing layer-mean temperatures. It was found that certain grow features of the fields of convergence and divergence associated with the moisture distribution in certain quadrants surrounding the jet are consistently indicated in these patterns. A stepwise, multiple regression analysis for specification of the maximum wind speeds gives predictive skill in several channels, particularly in the 5–30 μ channel, indicating that baroclinic effects can be discerned by MRIR observations applied to suitably stratified data samples.
Abstract
Stepwise linear regressions for the specification of blackbody surface radiances are computed using a set of 103 model atmospheres chosen originally by Wark et al. and the corresponding simulated values of Nimbus 2 window-channel (10–11 µ) radiances. Two stratifications are considered: (a) precipitable water vapor, u>1, and (b) u<1 gm cm–2. For each of five zenith angles considered, significant contributions are made in both regression formulas by inclusion of parameters representing the radiative transfer effects of water vapor and ozone. This regression formulation makes use of empirically derived expressions related to these effects over long atmospheric paths. The specification of the sample of surface radiances is in accordance with a multiple correlation coefficient, exceeding 0.990 and 0.995 in the respective stratifications. Corrections for atmospheric effects to be applied to Nimbus 2 window-channel radiances in estimating the corresponding surface values are displayed in nomogramic as well as analytic forms.
Abstract
Stepwise linear regressions for the specification of blackbody surface radiances are computed using a set of 103 model atmospheres chosen originally by Wark et al. and the corresponding simulated values of Nimbus 2 window-channel (10–11 µ) radiances. Two stratifications are considered: (a) precipitable water vapor, u>1, and (b) u<1 gm cm–2. For each of five zenith angles considered, significant contributions are made in both regression formulas by inclusion of parameters representing the radiative transfer effects of water vapor and ozone. This regression formulation makes use of empirically derived expressions related to these effects over long atmospheric paths. The specification of the sample of surface radiances is in accordance with a multiple correlation coefficient, exceeding 0.990 and 0.995 in the respective stratifications. Corrections for atmospheric effects to be applied to Nimbus 2 window-channel radiances in estimating the corresponding surface values are displayed in nomogramic as well as analytic forms.
Abstract
Uncertainty in radiative forcing caused by aerosol–cloud interactions is about twice as large as for CO2 and remains the least well understood anthropogenic contribution to climate change. A major cause of uncertainty is the poorly quantified state of aerosols in the pristine preindustrial atmosphere, which defines the baseline against which anthropogenic effects are calculated. The Southern Ocean is one of the few remaining near-pristine aerosol environments on Earth, but there are very few measurements to help evaluate models. The Antarctic Circumnavigation Expedition: Study of Preindustrial-like Aerosols and their Climate Effects (ACE-SPACE) took place between December 2016 and March 2017 and covered the entire Southern Ocean region (Indian, Pacific, and Atlantic Oceans; length of ship track >33,000 km) including previously unexplored areas. In situ measurements covered aerosol characteristics [e.g., chemical composition, size distributions, and cloud condensation nuclei (CCN) number concentrations], trace gases, and meteorological variables. Remote sensing observations of cloud properties, the physical and microbial ocean state, and back trajectory analyses are used to interpret the in situ data. The contribution of sea spray to CCN in the westerly wind belt can be larger than 50%. The abundance of methanesulfonic acid indicates local and regional microbial influence on CCN abundance in Antarctic coastal waters and in the open ocean. We use the in situ data to evaluate simulated CCN concentrations from a global aerosol model. The extensive, available ACE-SPACE dataset (https://zenodo.org/communities/spi-ace?page=1&size=20) provides an unprecedented opportunity to evaluate models and to reduce the uncertainty in radiative forcing associated with the natural processes of aerosol emission, formation, transport, and processing occurring over the pristine Southern Ocean.
Abstract
Uncertainty in radiative forcing caused by aerosol–cloud interactions is about twice as large as for CO2 and remains the least well understood anthropogenic contribution to climate change. A major cause of uncertainty is the poorly quantified state of aerosols in the pristine preindustrial atmosphere, which defines the baseline against which anthropogenic effects are calculated. The Southern Ocean is one of the few remaining near-pristine aerosol environments on Earth, but there are very few measurements to help evaluate models. The Antarctic Circumnavigation Expedition: Study of Preindustrial-like Aerosols and their Climate Effects (ACE-SPACE) took place between December 2016 and March 2017 and covered the entire Southern Ocean region (Indian, Pacific, and Atlantic Oceans; length of ship track >33,000 km) including previously unexplored areas. In situ measurements covered aerosol characteristics [e.g., chemical composition, size distributions, and cloud condensation nuclei (CCN) number concentrations], trace gases, and meteorological variables. Remote sensing observations of cloud properties, the physical and microbial ocean state, and back trajectory analyses are used to interpret the in situ data. The contribution of sea spray to CCN in the westerly wind belt can be larger than 50%. The abundance of methanesulfonic acid indicates local and regional microbial influence on CCN abundance in Antarctic coastal waters and in the open ocean. We use the in situ data to evaluate simulated CCN concentrations from a global aerosol model. The extensive, available ACE-SPACE dataset (https://zenodo.org/communities/spi-ace?page=1&size=20) provides an unprecedented opportunity to evaluate models and to reduce the uncertainty in radiative forcing associated with the natural processes of aerosol emission, formation, transport, and processing occurring over the pristine Southern Ocean.
