Responses by marine top predators to environmental variability have previously been almost impossible to observe directly. By using animal-mounted instruments simultaneously recording movements, diving behavior, and in situ oceanographic properties, we studied the behavioral and physiological responses of southern elephant seals to spatial environmental variability throughout their circumpolar range. Improved body condition of seals in the Atlantic sector was associated with Circumpolar Deep Water upwelling regions within the Antarctic Circumpolar Current, whereas High-Salinity Shelf Waters or temperature/salinity gradients under winter pack ice were important in the Indian and Pacific sectors. Energetic consequences of these variations could help explain recently observed population trends, showing the usefulness of this approach in examining the sensitivity of top predators to global and regional-scale climate variability.body condition ͉ ocean observation ͉ oceanography ͉ elephant seals

Abstract. The increasing need for continuous monitoring of the world oceans has stimulated the development of a range of autonomous sampling platforms. One novel addition to these approaches is a small, relatively inexpensive datarelaying device that can be deployed on marine mammals to provide vertical oceanographic profiles throughout the upper 2000 m of the water column. When an animal dives, the CTD-Satellite Relay Data Logger (CTD-SRDL) records vertical profiles of temperature, conductivity and pressure. Data are compressed once the animal returns to the surface where it is located by, and relays data to, the Argos satellite system. The technical challenges met in the design of the CTD-SRDL are the maximising of energy efficiency and minimising size, whilst simultaneously maintaining the reliability of an instrument that cannot be recovered and is required to survive its lifetime attached to a marine mammal. The CTD-SRDLs record temperature and salinity with an accuracy of better than 0.005 • C and 0.02 respectively. However, due to the limited availability of reference data, real-time data from remote places are often associated with slightly higher errors. The potential to collect large numbers of profiles cost-effectively makes data collection using CTD-SRDL technology particularly beneficial in regions where traditional oceanographic measurements are scarce or even absent. Depending on the CTD-SRDL configuration, it is possible to sample and transmit hydrographic profiles on a daily basis, providing valuable and often unique information for a real-time ocean observing system.

Models of the Venus neutral upper atmosphere, based on both in-situ and remote sensing measurements, are provided for the height interval from 100 to 3,500 km.The general approach in model formulation was to divide the atmosphere into three regions: 100 to 150 km, 150 to 250 km, and 250 to 3,500 km.Boundary conditions at 150 km are consistent with both drag and mass spectrometer measurements.A paramount consideration was to keep the models simple enough to be used conveniently.Available observations are reviewed. Tables are provided for density, temperature, composition (C0 2, 0, CO, He, N, N2, and H), derived quantities, and day-to-day variability as a function of solar zenith angle on the day-and nightsides.Estimates are made of other species, including 02 and D.Other tables provide corrections for solar activity effects on temperature, composition, and density. For the exosphere, information is provided on the vertical distribution of normal thermal components (H, 0, C, and He) as well as the hot components (H, N, C, 0) on the day-and nightsides.1.

Abstract. The increasing need for continuous monitoring of the world oceans has stimulated the development of a range of autonomous sampling platforms. One novel addition to these approaches is a small, relatively inexpensive data-relaying device that can be deployed on marine mammals to provide vertical oceanographic profiles throughout the upper 2000 m of the water column. When an animal dives, the CTD-Satellite Relay Data Logger (CTD-SRDL) records vertical profiles of temperature, conductivity and pressure. Data are compressed once the animal returns to the surface where it is located by, and relays data to, the Argos satellite system. The technical challenges met in the design of the CTD-SRDL are the maximising of energy efficiency by minimising size, whilst simultaneously maintaining the reliability of an instrument that cannot be recovered and is required to survive its lifetime attached to a marine mammal. The CTD-SRDLs record temperature and salinity with an accuracy of better than 0.005°C and 0.02 respectively. However, due to the limited availability of reference data for post-processing, data are often associated with slightly higher errors. The potential to collect large numbers of profiles cost-effectively makes data collection using CTD-SRDL technology particularly beneficial in regions where traditional oceanographic measurements are scarce. Depending on the CTD-SRDL configuration, it is possible to sample and transmit hydrographic profiles on a daily basis, providing valuable and often unique information for a real-time ocean observing system.

From analysis of the orbiter atmospheric drag (OAD) data obtained from the orbital decay of the Pioneer Venus orbiter from December 9, 1978, to August 7, 1979, atmospheric densities have been determined and tabulated near 16°N latitude between 140 and 190 km for all times of day. Maximum daytime densities on Venus are approximately 8 × 10−13 g cm−3 at an altitude of 150 km (dropping by a factor of 24 at night) and 7 × 10−14 g cm−3 at 170 km (dropping by a factor of 82 at night). Comparative atmospheric densities on earth at 150 km are a factor of 3.5 higher during the day with only a 1% diurnal variation. An atmospheric composition, temperature, and density model based on OAD vertical structure measurements is presented. The inferred exospheric temperatures and atomic oxygen concentrations are surprisingly insensitive to model assumptions. This model indicates that atomic oxygen is the major species in the Venus atmosphere above 145 km at night and above 160 km during the day with mixing ratios near 140 km in excess of 0.1. Atomic oxygen concentrations determined from drag measurements near 170 km range from 1 × 109 cm−3 during the day to 3 × 107 cm−3 at night. Exospheric temperatures inferred from OAD measurements are found to vary from 100°K at night to approximately 300°K during the day. The very low exospheric temperatures discovered at night, lower than temperatures near 100 km, are inconsistent with the concept of a planetary thermosphere, in which temperature increases with altitude. We have adopted the term ‘cryosphere’ to define this region of cooling where temperature decreases with altitude. The phase of the diurnal temperature variation is consistent with theoretical models of an atmosphere with mean motion to the west more rapid than planetary rotation superimposed on solar‐antisolar motion. The very low nighttime temperatures and our observation of an absence of the predicted nighttime atomic oxygen bulge suggest substantial downward eddy transport of heat as well as of atomic oxygen. Finally, the OAD data indicate that the neutral upper atmosphere of Venus is unexpectedly insensitive to both solar extreme ultraviolet variations and variations in the solar wind. Thus, the Venus upper atmosphere may not be controlled by the major heating mechanisms generally assumed for planetary thermospheres.