Richardson Philip L.

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Richardson

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Philip L.

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0000-0001-9115-2445

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Flight speed and performance of the wandering albatross with respect to wind

(BMC, 2018-03-07) Richardson, Philip L. ; Wakefield, Ewan D. ; Phillips, Richard A.

Albatrosses and other large seabirds use dynamic soaring to gain sufficient energy from the wind to travel large distances rapidly and with little apparent effort. The recent development of miniature bird-borne tracking devices now makes it possible to explore the physical and biological implications of this means of locomotion in detail. Here we use GPS tracking and concurrent reanalyzed wind speed data to model the flight performance of wandering albatrosses Diomedea exulans soaring over the Southern Ocean. We investigate the extent to which flight speed and performance of albatrosses is facilitated or constrained by wind conditions encountered during foraging trips.
Free drifting buoy trajectories in the Gulf Stream system : 1975-1978 : a data report

(Woods Hole Oceanographic Institution, 1979-01) Richardson, Philip L. ; Wheat, Jeffrey J. ; Bennett, Dolphus

From 1975 to 1978, thirty-one satellite-tracked free-drifting surface buoys were launched in the Gulf Stream system. Most of these buoys were launched in cyclonic rings, as part of an interdisciplinary Gulf Stream ring experiment, Other buoys were launched in anticyclonic rings and the Gulf Stream itself; one buoy was launched in a cyclonic Kuroshio ring. The basic data set consists of buoy trajectories and sea surface temperature and velocity measurements along trajectories. The main results consist of a series of 19 buoy trajectories in rings from which the movement of rings is inferred and a series of 20 buoy trajectories in the Gulf Stream. Rings frequently coalesced with the Gulf Stream, and some reformed as modified rings. The trajectories of buoys in the Stream reveal that at times surface currents are strongly influenced by topographic features such as seamounts and ridges. Most buoys in the Stream continued to move eastward until they reached the vicinity of the Grand Banks (50°W) where they rapidly fanned out, some moving northward, others eastward across the mid-Atlantic Ridge, still others southward and westward .
Gulf Stream ring trajectories

(Woods Hole Oceanographic Institution, 1980-11) Richardson, Philip L.

During the period 1976-78, the movement of 14 Gulf Stream rings, including two anticyclonic and 12 cyclonic rings, was measured with satellite-tracked free-drifting buoys. The buoys in the cyclonic rings showed a tendency to move out toward the high-velocity region of the ring and to remain there circling the center. One buoy stayed in a ring as long as 8 months and completed 86 loops. Periods of rotation ranged from less than 2 days up to 10 days. The movement of the rings was complicated and appears to be related to the Gulf Stream and strong topographic features such as the New England Seamounts . Rings that were not touching the Stream generally moved westward with typical speeds of 5 cm s-1. Rings that were attached to the Stream generally moved downstream in the Stream with speeds up to 75 cm s-1 . Frequently rings coalesced with the Gulf Stream and one of the following three things seemed to happen: I) the ring turned into an open meander of the Stream and was lost; 2) the ring was advected rapidly downstream in the Stream and was presumably lost; and 3) the ring became attached to the Gulf Stream and then split off again as a modified ring. The results of this study, that frequently strong interactions occur between rings and the Gulf Stream, are in contrast to my original view that rings slowly translate southwestward through the Sargasso Sea and gradually decay there.
SOFAR float Mediterranean outflow experiment : summary and data from 1986-88

(Woods Hole Oceanographic Institution, 1990-01) Zemanovic, Marguerite E. ; Richardson, Philip L. ; Price, James F.

In October, 1984, the Woods Hole Oceanographic Institution SOFAR float group began a three and a half year field program to measure the velocity field of the Mediterranean water in the eastern North Atlantic. The principal scientific goal was to learn how the Mediterranean salt tongue is produced by the general circulation and the eddy diffusion of the Canary Basin. Thirty-two floats were launched at depths near 1100 m: 14 in a cluster centered on 32°N, 24°W, with nearest neighbors at 20 km spacing, 10 at much wider spacing to explore regional variations of first order flow statistics, and 8 in three different Meddies (Mediterranean water eddies) in collaboration with investigators from Scripps Institution of Oceanography and the University of Rhode Island. The floats were launched in 1984 and 1985, and tracked with U.S. and French ALSs (moored listening stations) from October 1984 to June 1988. This report includes a summary of the whole three and a half year experiment, the final year and a half of data processed from the third ALS setting (October 1986-June 1988), and the first deep sea test of Bobber EB014 in the eastern subtropical North Atlantic (May 1986-May 1988). Approximately 60 years of float trajectories were produced during the three and a half years of the experiment.
Moored current meter data from the Atlantic north equatorial counter current near 6°N 28°W (February-September, 1983) : vol. XXXIV

(Woods Hole Oceanographic Institution, 1984-05) Levy, Ellen ; Richardson, Philip L.

This report presents current and wind data from the first of three surface mooring deployments in the Atlantic North Equatorial Countercurrent near 6°N and 28°W. A Vector Averaging Wind Recorder (VAWR) measured wind velocity, sea surface temperature and air temperature, barometric pressure and solar insolation. Four Vector Measuring Current Meters (VMCM) measured current velocity and temperature at depths of 20, 50, 75 and 150m. The mooring was deployed on February 25 and recovered (and replaced) on September 13, 1983 .
Nantucket whalers and the Franklin-Folger chart of the Gulf Stream

(Nantucket Historical Association, 2018-04) Richardson, Philip L. ; Adams, Nathan T.
Warm water pathways in the northeastern North Atlantic ACCE RAFOS float data report November 1996 - November 1999

(Woods Hole Oceanographic Institution, 2001-11) Furey, Heather H. ; Bower, Amy S. ; Richardson, Philip L.

This is the final data report of all acoustically tracked RAFOS float data collected by the Woods Hole Oceanographic Institution in 1996-1999 during the Atlantic Climate Change Experiment (ACCE). The RAFOS float component of ACCE, entitled "Warm Water Pathways and Intergyre Exchange in the Northeastern North Atlantic," was designed to measure the warm water currents entering the northeastern North Atlantic which become the source of intermediate and deep waters in the subpolar region. The experiment was comprised of three RAFOS float deployments on the R/V Knorr: the first in fall 1996 along the continental slope seaward of Porcupine Bank, the second in spring 1997 along the mid-Atlantic Ridge, and the final deployment in fall 1997 along both the Ridge and the Bank. Seventy floats were deployed, 13 RAFOS and 2 ALFOS in fall 1996, 14 RAFOS in spring 1997, and 41 RAFOS in fall 1997. The isobaric ALFOS floats were ballasted for 800 decibars and were launched to monitor the regions' sound sources during the experiment. The RAFOS floats were isopycnal and ballasted for the 27.5 sigma-t surface to target the intermediate-depth North Atlantic and Poleward Eastern Boundary Currents. The objectives of the Lagrangian float study were (1) to provide a quantitative description of the bifurcation of the North Atlantic Current east of the Mid-Atlantic Ridge, (2) to assess the importance of meridional eddy fluxes, compared to large-scale advection, in the northward flux of heat and salt in the northeastern North Atlantic, and (3) to establish the degree of continuity of the Poleward Eastern Boundary Current as it flows to the entrance of the Norwegian Sea and the fate of the Mediterranean Outflow Water carried by this current.
High-speed dynamic soaring

(B2Streamlines.com, 2012-04) Richardson, Philip L.

Dynamic soaring uses the gradient of wind velocity (wind shear) to gain energy for energy-neutral flight. Recently, pilots of radiocontrolled gliders have exploited the wind shear associated with fast winds blowing over mountain ridges to achieve very fast speeds, reaching a record of 487 mph in January 2012. A relatively simple two-layer model of dynamic soaring was developed to investigate factors that enable such fast speeds. The optimum period and diameter of a glider circling across a thin wind-shear layer predict maximum glider airspeed to be around 10 times the wind speed of the upper layer (assuming a maximum lift/drag of around 30). The optimum circling period can be small ~1.2 seconds in fast dynamic soaring at 500 mph, which is difficult to fly in practice and results in very large load factors ~100 times gravity. Adding ballast increases the optimum circling period toward flyable circling periods of 2-3 seconds. However, adding ballast increases stall speed and the difficulty of landing without damage. The compressibility of air and the decreasing optimum circling period with fast speeds suggest that record glider speeds will probably not increase as fast as they have during the last few years and will probably level out below a speed of 600 mph.
The physical structure and life history of cyclonic Gulf Stream ring, Allen

(Woods Hole Oceanographic Institution, 1980-11) Richardson, Philip L. ; Maillard, Catherine ; Sanford, Thomas B.

A cyclonic Gulf Stream ring, Allen, was followed over its life from September 1976 to April 1977 in the region north of Bermuda. Conductivity, temperature, and depth; expendable bathythermograph; and velocity profile measurements were made in Allen, and over the last 5 months of its life, satellite buoys were used to track continuously its movement. The measurements indicate that in December 1976 Allen split into two rings, a large one, Allen, and a small one, Arthur. Arthur moved rapidly eastward and coalesced with the Gulf Stream near the New England seamounts. Allen moved in a large clockwise loop; at the end of February 1977 it became attached to the Gulf Stream and reformed into a modified ring, smaller in size and faster in rotation . At the end of April 1977 the modified ring coalesced with the Gulf Stream and disappeared as it was advected downstream in the stream. The principal results of this study are that (I) the New England Seamount chain was a major influence in the genesis of Allen and on the trajectories of nearby rings; (2) while a free eddy, months after its formation, Allen evolved into a bi modal or peanut-shaped structure; (3) the bimodal structure ultimately bifurcated, spawning a new isolated eddy, denoted as Arthur, and a modified remnant, Allen; (4) the velocity field of Allen involved the whole water column, with bottom velocities of 10-15 em s- 1; (5) the barotropic velocity at the center of Allen (6 cm s-1 to NNW) was about equal to its translation velocity (4 cm s-1 to NW); (6) especially energetic inertial motions were seen at the center of Allen, and these may play a role in enhancing the stirring of water properties; (7) Allen survived several close encounters or entrainments with the Gulf Stream, proving that such encounters can be nonfatal to a ring; (8) the encounters appear to result in injections (exchanges) of water (momentum, heat, etc.) into the rings at an estimate rate of 106 m3 s-1 per ring; and (9) the behavior of Allen and Arthur was in contrast to the results of some other studies which have shown that rings generally drift slowly and passively southwestward.
Moored current meter data from the Atlantic north equatorial countercurrent near 6°N 28°W (September, 1983-March, 1984) : vol. XXXVI

(Woods Hole Oceanographic Institution, 1984-09) Levy, Ellen ; Richardson, Philip L.

This report presents current and wind data from the second of three surface mooring deployments in the Atlantic North Equatorial Countercurrent near 6°N and 28°W. A Vector Averaging Wind Recorder (VAWR) measured wind velocity, sea surface temperature, air temperature, barometric pressure and solar insolation. Four Vector Measuring Current Meters (VMCM) measured current velocity and temperature at depths of 20, 50, 75 and 150 m. The mooring was deployed on September 12,1983 and recovered (and replaced) on March 24,1984.
Reconstructing Columbus’s first transatlantic track and landfall using climatological winds and currents

(Woods Hole Oceanographic Institution, 1987-11) Goldsmith, Roger A. ; Richardson, Philip L.

An article in the November 1986 National Geographic magazine examined the question of Columbus's first landfall in the Americas. The author, Luis Marden, was the first to quantitatively include the effects of the winds and currents in reconstructing the transoceanic portion of the voyage. There seemed, however, to be two major weaknesses in his analysis. First, the leeway effect on the ship by the wind was ignored for that portion of the voyage west of 40W, the whole second half of the voyage. Second, currents from pilot charts were used with the corresponding speed determined by the prevailing current. We sought to reanalyze the track using the leeway effect for the whole transatlantic track and using more appropriate average vector velocities of the current. Using climatological winds and currents we found the island of San Salvador (Watling Island) to be the most likely site of the first landfall of Columbus. This paper discusses the effects of wind, current, leeway, and magnetic variation on the determination of the landfall.
Moored current meter data from the Canary Basin near 32°N, 24°W (1984-1986) Volume XL

(Woods Hole Oceanographic Institution, 1987-05) Tarbell, Susan A. ; Richardson, Philip L. ; Price, James F.

Data are shown from a two-year current meter mooring in the Canary Basin near 32°N, 24°W. Current meters were located at depths of 470 m, 970 m, 1070 m and 2970 m during the period October 19, 1984 to October 4, 1986. The mooring deployment is part of an 1984-1988 experiment to measure features of advection and diffusion of Mediterranean outflow water with neutrally buoyant SOFAR floats.
North Brazil Current Rings Experiment : RAFOS float data report : November 1998 – June 2000

(Woods Hole Oceanographic Institution, 2002-07) Wooding, Christine M. ; Richardson, Philip L. ; Pacheco, Marguerite A. ; Glickson, Deborah A. ; Fratantoni, David M.

Twenty-one RAFOS floats were tracked at depths of 200-1000 meters in and around several North Brazil Current Rings between November 1998 and June 2000. This was part of an experiment to study the role of these current rings in transporting upper level South Atlantic water across the equatorial-tropical gyre boundary into the North Atlantic subtropical gyre. The float trajectories in combination with surface drifters and satellite imagery reveal the sometimes complex life histories of several rings and their fate as they collide with the Lesser Antilles Islands. This report describes the float trajectories, the velocity, temperature, and depth time series, and a preliminary analysis of the float data.
On the history of meridional overturning circulation schematic diagrams

( 2007-07-23) Richardson, Philip L.

Recent global warming caused by humans and the prediction of a reduced Atlantic Ocean meridional overturning circulation in the future has increased interest in the role of the overturning circulation in climate change. A schematic diagram of the overturning circulation called the “Great Ocean Conveyor Belt,” published by Wallace Broecker in 1987, has become a popular image that emphasizes the inter-connected ocean circulation and the northward flux of heat in the Atlantic. This would appear to be a good time to review the development of the conveyor belt concept and summarize the history of overturning circulation schematics. In the nineteenth century it was thought that symmetric overturning circulation cells were located on either side of the equator in the Atlantic. As new hydrographic measurements were obtained in the late nineteenth century and early twentieth century, circulation schematics in the early twentieth century began to show the inter-hemispheric overturning circulation in the Atlantic. In the second half of the twentieth century schematics showed the global ocean overturning circulation including connections between the Atlantic and the Pacific and Indian Oceans. Some recent schematics of the overturning circulation show its complexities, but as more information is included these schematics have also become complex and not as easy to understand as the simple Broecker 1987 version.
A census of Gulf Stream rings, spring 1975

(Woods Hole Oceanographic Institution, 1979-02) Richardson, Philip L. ; Cheney, Robert E. ; Worthington, L. Valentine

During 1975 several shipboard expendable bathythermograph surveys plus satellite infrared imagery provided a nearly synoptic view of the distribution and number of Gulf Stream rings in the western North Atlantic. Twelve rings were identified; nine were cyclonic (cold core) rings and three were anticyclonic (warm core) rings. This is the largest number of rings ever observed during a short period of time (4 months). Evidence suggests that the mean movement of these rings was southwestward.
SOFAR float Mediterranean outflow experiment data from the second year, 1985-86

(Woods Hole Oceanographic Institution, 1988-09) Zemanovic, Marguerite E. ; Richardson, Philip L. ; Valdes, James R. ; Price, James F. ; Armi, Laurence

In October, 1984, the Woods Hole Oceanographic Institution SOFAR float group began a three-year-long field program to observe the low frequency currents in the Canary Basin. The principal scientific goal was to learn how advection and diffusion by these currents determine the shape and amplitude of the Mediterranean salt tongue. Fourteen floats were launched at a depth of 1100 min a cluster centered on 32°N, 24°W, and seven other floats were launched incoherently along a north/south line from 24°N to 37°N. At the same time investigators from Scripps Institution of Oceanography and the University of Rhode Island used four other SOFAR floats to tag a Meddy, a submesoscale lens of Mediterranean water. In October, 1985, seven additional floats were launched, four in three different Meddies, one of which was tracked during year 1. This report describes the second year of the floats launched in 1984 and the first year of the ones launched in 1985. Approximately 41 years of float trajectories were produced during the first two years of the experiment. One of the striking accomplishments is the successful tracking of one Meddy over two full years plus the tracking of two other Meddies during the second year.
Agulhas leakage into the Atlantic estimated with subsurface floats and surface drifters

( 2006-12-02) Richardson, Philip L.

Surface drifters and subsurface floats drifting at depths near 800 m were used to study the pathways of warm salty Indian Ocean water leaking into the South Atlantic that is a component of the upper limb of the Atlantic meridional overturning circulation. Four drifters and 5 floats drifted from the Agulhas Current directly into the Benguela Current. Others looped for various amounts of time in Agulhas rings and cyclones, which translated westward into the Atlantic contributing a large part of Indian Ocean leakage. Agulhas rings translated into the Benguela Current where they slowly decayed. Some large blob-like Agulhas rings with irregular shapes were found in the southeastern Cape Basin. Drifter trajectories suggest these rings become more circular with time eventually evolving into the circular rings observed west of the Walvis Ridge. Agulhas cyclones, which form on the north side of the Agulhas south of Africa, translated southwestward (to 6°E) and contributed water to the southern Cape Basin. A new discovery is a westward extension from the mean Agulhas retroflection measured by westward drifting floats near 41ºS out to at least 5ºW with some floats as far west as 25ºW. The Agulhas extension appears to split the South Atlantic Current into two branches and to transport Agulhas water westward where it is mixed and blended with eastward-flowing water from the western Atlantic. The blended mixture flows northeastward in the northern branch of the South Atlantic Current and into the Benguela Current. Agulhas leakage transport was estimated from drifters and floats to be at least 15 Sv in the upper 1,000 m, which is equivalent to the transport of the upper layer meridional overturning circulation. It is suggested that the major component of the upper layer overturning circulation in the Atlantic is Agulhas leakage.
How do albatrosses fly around the world (almost) without flapping their wings?

( 2010-08-26) Richardson, Philip L.

Albatrosses fly long distances over the Southern Ocean, even around the world (almost) without flapping their wings, which has raised interest in how they perform such a feat. On a cruise to the South Atlantic I observed albatrosses soaring in a characteristic swooping zigzag flight that appears to combine two soaring techniques to gain energy— wind-shear soaring (dynamic soaring) using the vertical gradient of wind velocity and wave-slope soaring using updrafts over waves. The observed characteristic swooping flight is shown in a new illustration and interpreted in terms of the two soaring techniques. The energy gain estimated for “typical conditions” in the Southern Ocean suggests that wind-shear soaring provides around 80-90% of the total energy required for sustained soaring. A much smaller percentage is provided by wind shear in light winds and significant swell when wave-slope soaring dominates. A simple dynamical model of wind-shear soaring is proposed based on the concept of a bird flying across a sharp windshear layer as first described by Lord Rayleigh in 1883 and later developed with Pennycuick’s (2002) description of albatrosses “gust soaring.” In gust soaring a bird exploits structures in the wind field, such as separated boundary layers and eddies in the lee of wave crests, to obtain energy by climbing headed upwind and descending headed downwind across a thin wind-shear layer. Benefits of the model are that it is simple to understand, it captures the essential dynamics of wind-shear soaring, and it provides reasonable estimates of the minimum wind shear required for travel velocity in different directions with respect to the wind. Travel velocities, given in a travel velocity polar diagram, can be combined with tacking to fly in an upwind direction faster than the wind speed located at the top of the wind-shear layer.
Gulf Stream trajectories measured with free-drifting buoys

(Woods Hole Oceanographic Institution, 1981-10) Richardson, Philip L.

During 1975-78, 35 free-drifting buoys measured surface currents in the Gulf Stream region. The buoy trajectories trace numerous paths of the Stream and show that the Stream is strongly influenced by the New England Seamounts. This influence is manifested as 1) a quasi-permanent, 100 km, southeastward deflection of the Stream and the frequent occurrence of a ring meander over the seamounts; 2) large-amplitude meanders beginning at the seamounts and extending eastward; and 3) small, 20 km diameter eddies which appear to be generated locally by individual seamounts. A chart of the mean temperature field at a depth of 450 m agrees with several of the patterns seen in the buoy trajectories. West of the seamounts, the mean path of the Gulf Stream is eastward; over the seamounts, the path turns sharply northeastward and the isotherms in the Stream abruptly diverge.
Surface drifter measurements in the Atlantic North Equatorial countercurrent 1983-1985

(Woods Hole Oceanographic Institution, 1985-09) Richardson, Philip L. ; Wooding, Christine M.

Thirty freely drifting drogued surface buoys were tracked by satellite in the vicinity of the Atlantic North Equatorial Countercurrent from February 1983 to February 1985 as part of the SEQUAL (Seasonal Equatorial Atlantic) Experiment. Buoys were launched at several different times of the year in order to sample the Countercurrent in different seasons. The purpose was to measure the seasonal variation of the Countercurrent in relation to wind forcing. The basic data set consists of buoy trajectories, and sea surface temperature, velocity, and wind speed along the trajectories. A comparison is made between the data from the buoys and from a current meter mooring near 6N, 28W. The main results presented here consist of the collection of figures which show trajectories and time series data along the Countercurrent, and in the North and South Equatorial Currents, Guinea Current and North Brazil Current.

Richardson Philip L.

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