Rn-Rz

 

RNODC

Abbreviation for Responsible National Oceanographic Data Center, a facility established within the framework of the IOC IODE structure to take on the responsbility of assisting the WDCs. This scheme was developed to enable to international exchange system to cope with an increasing variety and volume of oceanographic data being collected by providing special data processing and compilation support for specific programs and certain areas. See the IODE Web site.

 

RNODC-SOC

Abbreviation for RNODC from the Southern Oceans, a data center commissioned in 1988 within IODE to acquire the physical and chemical data obtained by the international scientific community in cruises and research programs carried out in the Southern Oceans, control their quality, store them in standard format, and distribute them upon request. This center is a part of CEADO. See the RNODC-SOC Web site.

 

roaring forties

The region between 40 and 50 S latitude where the prevailing westerly winds blow largely unobstructed by land over the open oceans, and also the winds themselves. They are constant and of great velocity, whence comes the term "roaring". The weather is stormy, rainy, and comparatively mild in the wake of constantly appearing depressions. The land areas that do obstruct them, the western mountainous coasts of southern Chile, Tasmania and New Zealand, experience tremendous rainfall through the year on the western sides (up to 100 in.) and much less on the eastern sides (around 20 in.). These are also known as brave west winds.

 

robust

See statistically robust.

 

rocketsonde

An instrument for measuring and transmitting upper-air meteorological data. It is borne on a rocket (whence comes the name) and takes data samples up to 76,000 meters, well above the 30,000 meter limit of the similiar and complementary radiosonde instrument.

 

ROSCOP

Acronym for Reports of Oceanographic Cruises and Oceanographic Programs, a program conceived by the IOC in the late 1960s to provide a low level inventory for tracking oceanographic data collected on research vessels. It is a form to be completed by a scientist on each cruise that provides various metadata about what kinds of data were taken on the cruise. It was renamed the Cruise Summary Report (CSR) in 1990 but the acronym ROSCOP persists. See the ROSCOP Web site where digitized forms of collected ROSCOP info from the 1960s through the present can be obtained.

 

ROSIS

Acronym for Reflective Optics System Imaging Spectrometer, a compact airborne imaging spectrometer. This device was designed for the detection of spectral fine structure in coastal waters. See the ROSIS Web site.

 

Ross, James Clark

More later.

 

Ross Sea

See Jacobs et al. (1970).

 

Rossby, Carl-Gustav Arvid (1898-1957)

Rossby was born in Sweden and joined a group studying under V. Bjerknes in 1918 after receiving his ``Kandidat'' in theoretical mechanics. There he started his career in meteorology as well as his interest in oceanography. In 1921 he followed Bjerknes to the University of Leipzig for a year and then returned to Stockholm in 1922 to a position with the Swedish Meteorological Hydrologic Service. Over the next three years he accompanied, as a meteorologist, oceanographic expeditions to Jan Mayen in the Nordic Seas, around the British Isles, and to Portugal and Madeira. He also studied mathematical physics at the University of Stockholm during this time and received his ``Licentiat'' in 1925.

In 1926 Rossby moved to the United States and continued his research at the only extent meteorological center, the Government Weather Bureau in Washington, D.C. He wrote several significant papers on atmospheric turbulence and stratospheric dynamics during this period and also organized the first airway meterological service on an experimental basis in California which provided the pattern for future systems. In 1928 he organized the first university level meteorological program in the United States at the Massachusetts Institute of Technology 9MIT), in which he soon became a full professor.

He spent eleven years at MIT and contributed to such areas as the thermodynamics of air masses, turbulence in the atmosphere and in the oceans, lateral mixing, and the interaction of the ocean-atmosphere boundary layers. He gradually turned his attentions to large-scale motions and the general circulation of the atmosphere, to which he began to apply the concepts of vorticity and momentum that permeate the field today. In 1939 he became the assistant chief of research at the U.S. Weather Bureau and in 1940 the chairman of the Department of Meteorology at the University of Chicago, during which time he developed his theory for the long waves in the atmosphere that later came to be called Rossby waves.

During World War II he organized the training of military meteorologists and continued his research on long waves in the atmosphere. After the war he recruited many outstanding future researchers for the University of Chicago and played a significant role in the development of equations for the prediction of weather using electronic computers. In 1947 he became the director of the newly formed Institute of Meteorology in Stockholm and divided his time between there and Chicago (although, for convenience, his American affiliation was transferred to Woods Hole in the early 1950s.

At Stockholm Rossby's principal activities were concerned with developing numerical prediction systems for European weather. He also founded the geophysical journal Tellus. In 1954 he turned his attention to the field of geochemistry and also became interested in deep circulation processes in the ocean. He worked in these areas until his death in 1958.

 

Rossby-gravity wave

See Yanai wave.

 

Rossby number

A non-dimensional number expressing the ratio of inertial to Coriolis forces in the atmosphere or oceans. The Rossby number is defined by

where U is a characteristic velocity scale, f the Coriolis parameter, and L a characteristic length scale. If the Rossby number is large, then the effect of the Earth's rotation on the phenomenon in question can be neglected. This is also called the Kibel number.

 

Rossby radius of deformation

The fundamental horizontal length scale in fluids that are affected by both gravity and rotation. It is the length scale at which rotation effects become as important as buoyancy effects. In transient problems an initial disturbance at a scale small compared to the Rossby radius will result in an adjustment process about the same as would occur in a nonrotating system. If the disturbance is on a scale comparable to the Rossby radius, the Coriolis acceleration becomes as important as the pressure gradient term and the response is markedly different than would be seen in the nonrotating system.

In a homogeneous layer of fluid the barotropic Rossby radius is given by

where c is the gravity wave propagation velocity , g the gravitational acceleration, H the water depth, and f the Coriolis parameter. In the deep ocean where H is 4 or 5 km, the baroclinic radius is around 2000 km, but on the continental shelves with depths closer to 50 to 100 m it is around 200 km.

In a stratified fluid the baroclinic Rossby radius is similarly computed, except that c is now the wave speed of the nth baroclinic mode as would be found in a normal mode decomposition of the system. The baroclinic radius is a natural scale in the ocean associated with boundary phenomena such as boundary currents, fronts, and eddies. The first mode baroclinic radius is typically around 10-30 km in the ocean. See Gill (1982).

 

Rossby wave

Large scale waves in the ocean or atmosphere whose restoring force is the -effect of latitudinal variation of the local vertical component of the earth's angular rotation vector, i.e. the Coriolis force. In the atmosphere they are easily observed as the large-scale meanders of the mid-latitude jet stream that are responsible for prevailing seasonal (via blocking) and day-to-day weather patterns. They are more difficult to detect in the ocean as their sea surface height signature is on the order of 10 cm, their propagation speeds of order 10 cm/s, and their wavelengths hundreds to thousands of kilometers.

Rossby waves in the ocean are responsible for establishing the westward intensification of circulation gyres, the Gulf Stream being one example of this. They are also the dynamic mechanism for the transient adjustment of the ocean to changes in large-scale atmospheric forcing, e.g. information is transmitted from the tropical oceans to mid- and high-latitudes via Rossby waves acting in concert with coastal trapped waves. They are generated by wind and buoyancy forcing at the eastern boundaries and over the ocean interior. They are also known to be generated by perturbations along the eastern boundaries caused by coastal trapped waves originating at low latitudes. They subsequently freely propagate away from their source regions.

Standard theory derives the properties of freely propagating Rossby waves from the linearized equations of motion for large-scale, low-frequency motion about a state of rest, which yields an equation for normal modes. These normal modes can be found by specifying surface and bottom boundary conditions and solving an eigenvalue problem that depends only on the local stratification. There are an infinite number of wave modes ordered by decreasing phase speed, which are westward for all modes. Solutions for low frequencies and long wavelengths are zonally nondispersive, i.e. the phase speed is independent of the wavelength.

The lowest mode is the barotropic mode. It is uniform vertically and propagates across an ocean basin in about a week. The next gravest, or first baroclinic, mode is surface intensified, depends strongly on the stratification profile, has a velocity profile that changes sign at the depth of the thermocline, and takes months to cross the same basin as the first mode does in a week. The surface height variations of this mode are mirrored as thermocline depth variations of the opposite sign, which are also about three orders of magnitude larger, i.e. a 5 cm surface elevation variation would correspond to a 50 m depression in the thermocline. See Platzman (1968), Dickinson (1978) and Kuo (1973).

 

Rothamsted model

A soil turnover model used to explore the time lags involved in soil carbon sequestration and to link CO2-induced effects on plant productivity with decomposition. Plant residues are divided into two components, the first being decomposable plant matter (DPM) which includes simple compounds subject to rapid uptake, transformation, and mineralization by decomposers and with a turnover time of 0.1 year. The second is recalcitrant plant matter (RPM), containing components such as lignin that are not easily decomposed and having a turnover time of 3 years. Soil humus is divided into three components. The first is soil biomass (BIO), with a turnover time of 1.5 years and composed of mostly live microbes and microbial products such as extracellular enzymes. The second is active soil humus (HUM), with a turnover time of 50 years and consisting of organic compounds that are either protected physically or exist in forms that are biologically resistant to decomposition. The final component is inert soil organic matter (IOM), consisting of chemically refractory and physically protected froms with turnover times of 1000 years or more. See Jenkinson (1990).

 

roughness height

In atmospheric boundary layer dynamics, the height above a surface where the wind speed reaches zero. This is used when surface irregularities are larger than the 1 mm depth of the layer where molecular diffusion dominates and an analogous ``turbulent'' diffusion depth is needed. It is a constant in expressions used to find the logarithmic velocity profiles in boundary layers, and ranges from about a millimeter for average seas to more than a meter for cities with tall buildings. See Hartmann (1994).

 

ROWS

Acronym for Remote Ocean Wave Spectrometer, an instrument which uses the specular backscatter from a rotating near-nadir radar to estimate the two-dimensional ocean surface wave spectrum. See Jackson (1987).

 

Royal Greenwich Observatory (RGO)

A observatory founded in Greenwich, England in 1675 by Charles II. During most of its history its main aim has been to provide fundamental astrometric measures, and accurate time service, and almanacs and predictions for use by navigators and surveyors. The development of astrophysics in the last century has changed its emphasis to that of investigative science, with its present role being the provision, operation and maintenance of the main optical telescopes for British, Dutch, Irish and Spanish astronomers (with the telescopes now located on the island of La Palma in the Canaries). At the main RGO center (now at Cambridge) teams design and supervise the building of telescopes and the complex auxiliary instrumentation used to analyze the faint light coming from distant astronomical objects. See the RGO Web site.

 

Royal Meteorological Society

An organization founded in 1850 under a Royal Charter for the advancement of meteorological science. It does so by publishing journals and other publications, holding meetings, offering field courses, giving grants, and offering professional accreditation. Further details can be found at their Web site.

 

rrashaba

See reshabar.

 

RSMAS

Abbreviation for Rosensteil School and Marine and Atmospheric Sciences. See the RSMAS Web site.

 

RSS

See Regional Stratigraphic Scale.

 

Rumford, Count

See Benjamin Thompson.

 

Rupelian

The first of two ages in the Oligocene epoch (coincidental with the Early Oligocene), lasting from 36.6 to 30.0 Ma. It is preceded by the Priabonian age of the Eocene epoch and followed by the Chattian age.

 

RV

Abbreviation for research vessel.

 

RVTEC

Abbreviation for Research Vessel Technical Enhancement Committee.