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- Author or Editor: George A. Maul x
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Abstract
The question of whether there is significant variation in precipitation in the United States at the lunar synodic period (29.531 days) has been examined, based on daily precipitation data for the period 1900–80. Our results confirm previous studies and indicate by a new method that there is statistically significant variation in precipitation at this lunar frequency. We also show for the first time that there is spatial progression over the United States in the phase of the lunar-precipitation relationship. During spring, a precipitation maximum occurs first when the moon is gibbous in the northwestern United States, progressively later during the lunar cycle in the Midwest, and, finally, about the time of the new moon in the East. The recognition of spatial progression in phase raises questions about the reality of previously proposed global, lunar-precipitation mechanisms. We suggest, instead, the actual cause-effect relationship may involve the long-wave circulation of the atmosphere.
Abstract
The question of whether there is significant variation in precipitation in the United States at the lunar synodic period (29.531 days) has been examined, based on daily precipitation data for the period 1900–80. Our results confirm previous studies and indicate by a new method that there is statistically significant variation in precipitation at this lunar frequency. We also show for the first time that there is spatial progression over the United States in the phase of the lunar-precipitation relationship. During spring, a precipitation maximum occurs first when the moon is gibbous in the northwestern United States, progressively later during the lunar cycle in the Midwest, and, finally, about the time of the new moon in the East. The recognition of spatial progression in phase raises questions about the reality of previously proposed global, lunar-precipitation mechanisms. We suggest, instead, the actual cause-effect relationship may involve the long-wave circulation of the atmosphere.
Abstract
Twelve years of monthly mean positions of the northern boundary of the Loop Current in the eastern Gulf of Mexico from satellite and in situ data have been compared with coincident 1977–1988 estimates of volume transport in the Straits of Florida in the subseasonal frequency band 15−1 to 5−1 cycles per month. Volume transport estimated from Cuba minus Florida sea level difference in this frequency band accounts for 69% of the variance in volume transport estimated from the Florida-Grand Bahama Island submarine cable. On average, the Loop Current has a dominant period of 11 months whereas the volume transport is dominated by annual spectral energy; little significant coherence squared occurs between them. The maximum northward penetration of the Loop Current occurs on average in winter when the volume transport is a minimum, but this is an artifact of the sampling epoch. This negative relationship is most pronounced for 1979–1981 when transport is characterized as unimodal, but for 1984–1985 and 1987 the Loop Current and volume transport are more in phase, bimodal, and transport and position tend to have more semiannual energy. In this subseasonal band, the volume transport undergoes a significant change in the phase of its annual cycle after 1985 as compared with 1977–1984. For the twelve years considered in this study, the ensemble correlation between monthly position of the Loop Current and volume transport is essentially zero.
Abstract
Twelve years of monthly mean positions of the northern boundary of the Loop Current in the eastern Gulf of Mexico from satellite and in situ data have been compared with coincident 1977–1988 estimates of volume transport in the Straits of Florida in the subseasonal frequency band 15−1 to 5−1 cycles per month. Volume transport estimated from Cuba minus Florida sea level difference in this frequency band accounts for 69% of the variance in volume transport estimated from the Florida-Grand Bahama Island submarine cable. On average, the Loop Current has a dominant period of 11 months whereas the volume transport is dominated by annual spectral energy; little significant coherence squared occurs between them. The maximum northward penetration of the Loop Current occurs on average in winter when the volume transport is a minimum, but this is an artifact of the sampling epoch. This negative relationship is most pronounced for 1979–1981 when transport is characterized as unimodal, but for 1984–1985 and 1987 the Loop Current and volume transport are more in phase, bimodal, and transport and position tend to have more semiannual energy. In this subseasonal band, the volume transport undergoes a significant change in the phase of its annual cycle after 1985 as compared with 1977–1984. For the twelve years considered in this study, the ensemble correlation between monthly position of the Loop Current and volume transport is essentially zero.
Abstract
Cold-domed cyclonic eddies juxtaposed to the cyclonic shear side of the Gulf Loop Current are observed in simultaneously obtained hydrographic, current meter mooring, and satellite infrared data. The cyclones are initially observed in the satellite data as cold perturbations on the northern extreme of the current and grow either into a cold tongue or a quasi-stable meander off the Dry Tortugas Florida. Areal shipboard surveys show closed isopleths of temperature and salinity, and surface geostrophic current speeds relative to 1000 db are in excess of 100 cm s−1. The diameter of the cold domes varied from 80 to 120 km. Separation of large anticyclonic rings is always observed to be preceded by cyclonic eddies in the transition zone between Campeche Bank and the West Florida Shelf, but only on the eastern side. Not every cyclonic eddy off Dry Tortups is associated with the separation of an anticyclonic ring; some are eroded away by the Florida Current, but they have never been observed in 10 years of satellite data to advect eastward through the Straits of Florida.
Abstract
Cold-domed cyclonic eddies juxtaposed to the cyclonic shear side of the Gulf Loop Current are observed in simultaneously obtained hydrographic, current meter mooring, and satellite infrared data. The cyclones are initially observed in the satellite data as cold perturbations on the northern extreme of the current and grow either into a cold tongue or a quasi-stable meander off the Dry Tortugas Florida. Areal shipboard surveys show closed isopleths of temperature and salinity, and surface geostrophic current speeds relative to 1000 db are in excess of 100 cm s−1. The diameter of the cold domes varied from 80 to 120 km. Separation of large anticyclonic rings is always observed to be preceded by cyclonic eddies in the transition zone between Campeche Bank and the West Florida Shelf, but only on the eastern side. Not every cyclonic eddy off Dry Tortups is associated with the separation of an anticyclonic ring; some are eroded away by the Florida Current, but they have never been observed in 10 years of satellite data to advect eastward through the Straits of Florida.
Abstract
Cross-stream profiles of ocean surface currents between Florida and the Bahamas are highly correlated with the cross-stream-averaged current. When the cross-stream averaged speed is high, the speed axis of the Florida Current is to the west, and when the cross-stream-averaged speed is low, the speed axis is near the center of the straits. Since sea level and weather along the Florida coast are routinely used to nowcast cross-stream-averaged speed, nowcasts of cross-stream surface current profiles and location of the speed axis can also be routinely reported. An improved algorithm using cross-stream sea level difference and local weather, and a description of the revised NOAA Gulf Stream product from the National Hurricane Center are presented.
Abstract
Cross-stream profiles of ocean surface currents between Florida and the Bahamas are highly correlated with the cross-stream-averaged current. When the cross-stream averaged speed is high, the speed axis of the Florida Current is to the west, and when the cross-stream-averaged speed is low, the speed axis is near the center of the straits. Since sea level and weather along the Florida coast are routinely used to nowcast cross-stream-averaged speed, nowcasts of cross-stream surface current profiles and location of the speed axis can also be routinely reported. An improved algorithm using cross-stream sea level difference and local weather, and a description of the revised NOAA Gulf Stream product from the National Hurricane Center are presented.
