The authors document the interaction of the atmosphere and ocean during the formation and passage of an Extra-Tropical Cyclone, which is a Nor-Easter, winter storm that formed in the southern apex of the Middle Atlant...The authors document the interaction of the atmosphere and ocean during the formation and passage of an Extra-Tropical Cyclone, which is a Nor-Easter, winter storm that formed in the southern apex of the Middle Atlantic Bight near Cape Hatteras North Carolina, between February 15 and 18, 1996. While Nor-Easters per se, which have formed along the Atlantic Eastern Seaboard of the United States have been studied for decades, the actual atmospheric-oceanic mechanics and thermodynamics in the formation of a Nor-Easter has never been documented. We report on having done so with in-situ observations and data-based calculations and a numerical model. The in-situ observations were made via a Control Volume consisting of an array of Eulerian Oceanic-Atmospheric Moorings with current meters, temperature and salinity sensors and meteorological towers. We find that Gulf Stream waters were located surrounding the mooring array, and that with the invasion of cold dry atmospheric air, there was a rapid loss of heat from the ocean to the atmosphere via latent and sensible surface heat flux during the cyclogenesis onset of the storm. A unique feature of this storm was that neither satellite nor buoy data showed significant sea surface cooling in the control volume. The findings indicate that storm winds drove warm saline waters from the Gulf Stream across the continental shelf into the control volume, accounting for a 51 cm rise in water level along the coast. This lateral heat advection provided heat to the control volume of 3.4e+18 Joules. On average, the heat loss at the surface of the control volume, via sensible and latent heat fluxes and radiation, was 0.7e+18 Joules, corresponding to a surface heat flux of -600 Watts per Meter2 (W/m<sup>2</sup>). However, the heat lost by the control volume as latent and sensible heat fluxes was less than the heat it received via lateral heat advection, resulting in the lack of an often-observed sea surface cooling during other winter storms. The serendipitous and detailed observations and展开更多
The study presented herein is the analysis of Sodar based instrument measurements of air temperature, dew point, and vertical wind speed and direction, recorded at two South Carolina sites, Waties Island in North Myrt...The study presented herein is the analysis of Sodar based instrument measurements of air temperature, dew point, and vertical wind speed and direction, recorded at two South Carolina sites, Waties Island in North Myrtle Beach and in Sumter, and at three atmospheric ground stations. Two of the ground stations are National Weather Service stations near the Sodars and one is a Coastal Carolina University Sea-Econet, as a part of the National Oceanic & Atmospheric Administration, MESO program, weather-sensor site on the Coastal Carolina University campus in Conway South Carolina. Objectives of this study are to establish specific values of winds, land and sea temperatures, precipitation and dew points associated with the changes induced by passages of the Sea Breeze Front, and to examine differences in the station-to-station incarnation of the Sea Breeze circulation. Variability from station to station in the nature and timing of Sea Breeze Front passage is found to be a function of relative proximity to the coast with Sea Breeze Front passage occurring earliest at the North Myrtle Beach site (the station at the coast), then at Sumter (~100 km inland) and finally Aiken at >100 km inland. Satellite based estimates of the percentages of onshore penetration distances from the coast are depicted. Wind vectors and air temperatures associated with onsets and passages of the Sea Breeze display robust wind fields directed onshore perpendicular to the coastline. Kinematical descriptors of the Sea Breeze wind particle motions are presented and display coherent stable elliptical motions during the late summer to early fall but are absent during the winter.展开更多
文摘The authors document the interaction of the atmosphere and ocean during the formation and passage of an Extra-Tropical Cyclone, which is a Nor-Easter, winter storm that formed in the southern apex of the Middle Atlantic Bight near Cape Hatteras North Carolina, between February 15 and 18, 1996. While Nor-Easters per se, which have formed along the Atlantic Eastern Seaboard of the United States have been studied for decades, the actual atmospheric-oceanic mechanics and thermodynamics in the formation of a Nor-Easter has never been documented. We report on having done so with in-situ observations and data-based calculations and a numerical model. The in-situ observations were made via a Control Volume consisting of an array of Eulerian Oceanic-Atmospheric Moorings with current meters, temperature and salinity sensors and meteorological towers. We find that Gulf Stream waters were located surrounding the mooring array, and that with the invasion of cold dry atmospheric air, there was a rapid loss of heat from the ocean to the atmosphere via latent and sensible surface heat flux during the cyclogenesis onset of the storm. A unique feature of this storm was that neither satellite nor buoy data showed significant sea surface cooling in the control volume. The findings indicate that storm winds drove warm saline waters from the Gulf Stream across the continental shelf into the control volume, accounting for a 51 cm rise in water level along the coast. This lateral heat advection provided heat to the control volume of 3.4e+18 Joules. On average, the heat loss at the surface of the control volume, via sensible and latent heat fluxes and radiation, was 0.7e+18 Joules, corresponding to a surface heat flux of -600 Watts per Meter2 (W/m<sup>2</sup>). However, the heat lost by the control volume as latent and sensible heat fluxes was less than the heat it received via lateral heat advection, resulting in the lack of an often-observed sea surface cooling during other winter storms. The serendipitous and detailed observations and
文摘The study presented herein is the analysis of Sodar based instrument measurements of air temperature, dew point, and vertical wind speed and direction, recorded at two South Carolina sites, Waties Island in North Myrtle Beach and in Sumter, and at three atmospheric ground stations. Two of the ground stations are National Weather Service stations near the Sodars and one is a Coastal Carolina University Sea-Econet, as a part of the National Oceanic & Atmospheric Administration, MESO program, weather-sensor site on the Coastal Carolina University campus in Conway South Carolina. Objectives of this study are to establish specific values of winds, land and sea temperatures, precipitation and dew points associated with the changes induced by passages of the Sea Breeze Front, and to examine differences in the station-to-station incarnation of the Sea Breeze circulation. Variability from station to station in the nature and timing of Sea Breeze Front passage is found to be a function of relative proximity to the coast with Sea Breeze Front passage occurring earliest at the North Myrtle Beach site (the station at the coast), then at Sumter (~100 km inland) and finally Aiken at >100 km inland. Satellite based estimates of the percentages of onshore penetration distances from the coast are depicted. Wind vectors and air temperatures associated with onsets and passages of the Sea Breeze display robust wind fields directed onshore perpendicular to the coastline. Kinematical descriptors of the Sea Breeze wind particle motions are presented and display coherent stable elliptical motions during the late summer to early fall but are absent during the winter.
