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At least 19 records

High resolution marine meteorological analysis utilizing Seasat data

Seasat scatterometer (SASS) wind data was combined with surface meteorological readings to generate maps of lows, highs, ridges, and fronts. The SASS microwave radar permits all-weather surface wind observations with a 50 km resolution to within 2 m/sec or 10%. The scan area comprised the northern Pacific off the west coast of North America and southward from Alaska. Emphasis was placed on surface pressure analyses alone and in combination with the SASS data. Standard modeling of the existing weather systems was found to be unaltered by addition of the SASS data, although improvements were evident in the accuracy of delineating significant meteorological features and quantifying pressure gradients. Scale eddies and circulations were defined and cols were identified (by low wind speeds).

Peteherych, S.↗

Ocean Surface Vector Wind: Research Challenges and Operational Opportunities

The atmosphere and ocean are joined together over seventy percent of Earth, with ocean surface vector wind (OSVW) stress one of the linkages. Satellite OSVW measurements provide estimates of wind divergence at the bottom of the atmosphere and wind stress curl at the top of the ocean; both variables are critical for weather and climate applications. As is common with satellite measurements, a multitude of OSVW data products exist for each currently operating satellite instrument. In 2012 the Joint Technical Commission on Oceanography and Marine Meteorology (JCOMM) launched an initiative to coordinate production of OSVW data products to maximize the impact and benefit of existing and future OSVW measurements in atmospheric and oceanic applications. This paper describes meteorological and oceanographic requirements for OSVW data products; provides an inventory of unique data products to illustrate that the challenge is not the production of individual data products, but the generation of harmonized datasets for analysis and synthesis of the ensemble of data products; and outlines a vision for JCOMM, in partnership with other international groups, to assemble an international network to share ideas, data, tools, strategies, and deliverables to improve utilization of satellite OSVW data products for research and operational applications.

Joint Technical Commission on Oceanography and Mar↗

Climatological perspectives, oceanographic and meteorological, on variability in the subtropical convergence zone in the northwestern Atlantic

The large-scale climatological environment of the Frontal Air-Sea Interaction Experiment (FASINEX) is described, with emphasis on the largest scales. Both long-term and annual sea surface temperature (SST) variability is discussed; a climatology of the west-central North Atlantic, derived from various sets of data obtained during the intensive phases of January-March, is presented, and the meteorological and oceanographic context for FASINEX is thus established. Surface marine observations and SST variability are discussed, and the marine meteorology of the FASINEX area is examined in terms of the surface pressure and winds, the sea-air temperature difference, and the cloud cover. Near 28 deg N in February is found to be a favorable time and place to observe large mean temperature gradients and downward Ekman pumping. The large-scale processes that set up the favorable environment for frontal activity are not limited to the winter months.

Hanson, Howard P.↗

Satellite sensing capabilities for surface temperature and meteorological parameters over the ocean

Remote meteorological measurements over the oceans have been used extensively for weather forecasting, ship safety, and global-scale studies of climate and sea conditions. A review is conducted regarding the satellite-sensing capabilities for sea-surface temperature and tropospheric marine meteorological mesurements. The tropospheric measurements are concerned with vertical temperature profiles, integrated water vapor and liquid water, rain, aerosols and surface winds. Attention is also given to several environmental-monitoring applications where satellite sensed synoptic data might be combined with ground and airborne chemical measurements to provide improved assessments of regional and global ennvironmental quality and climatology. Special emphasis is given to current satellite measurement accuracies (errors) and to programs involving U.S. technology. Aspects of sea-surface temperature are treated in detail in connection with extensive studies concentrated in this area.

Darnell, W. L.↗

Space Shuttle - A new era in terrestrial remote sensing

The Space Shuttle will carry its first scientific cargo into orbit on its second test flight. The seven experiments to be conducted during this flight - investigations related to continental geology, atmospheric chemistry, meteorology, marine biology, and plant physiology - will demonstrate the potential usefulness of the Shuttle for research in the earth and life sciences.

Taranik, J. V.↗

El Nino and the Global Ocean Observing System

Until a decade ago, an often-quoted expression in oceanography is that very few observations are recorded throughout the ocean. Now, the sentiment is no longer valid in the uppermost 10% of the tropical Pacific Ocean nor at the surface of the global ocean. One of the remarkable legacies of the 1985-1994 Tropical Oceans Global Atmosphere (TOGA) Program is an in situ marine meteorological and upper oceanographic measurement array throughout the equatorial Pacific to monitor the development and maintenance of El Nino episodes. The TOGA Observing System, which initially consisted of moored- and drifting-buoy arrays, a network of commercial ships, and coastal and island stations, now includes a constellation of satellites and data-assimilating models to simulate subsurface oceanographic conditions. The El Nino and La Nina tropical Pacific Ocean observing system represents the initial phase of an integrated global ocean observing system. Remarkable improvements have been made in ocean model simulation of subsurface currents, but some problems persist. For example, the simulation of the South Equatorial Current (SEC) remains an important challenge in the 2S-2N Pacific equatorial wave guide. During El Nino the SEC at the equator is reduced and sometimes the direction is reversed, becoming eastward. Both conditions allow warm water stored in the western Pacific to invade the eastern region, creating an El Nino episode. Assimilation of data is a tenet of faith to correct simulation errors caused by deficiencies in surface fluxes (especially wind stress) and parameterizations of subgrid-scale physical processes. In the first of two numerical experiments, the Pacific SEC was simulated with and without assimilation of subsurface temperature data. Along the equator, a very weak SEC occurred throughout the eastern Pacific, independent of assimilation of data. However, as displayed in the diagram, in the western Pacific there was no satisfactory agreement between the two simulations. To help determine reliability of the simulated SEC in the western Pacific, current measurements recorded during the 9-19 October 1994 voyage of the French research vessel L'Atalante are also shown in the diagram. With data assimilation, the simulated SEC was in much better agreement with L'Atalante observations. The simulated SEC with data assimilation was far from perfect, in part because of the sparsity of subsurface temperature observations. In the next experiment, TOPEX/POSEIDON sea surface height data in combination with subsurface temperatures will be assimilated to assess further improvement of the simulation of the SEC.

Halpern, David↗

Identifying Meteorological Influences on Marine Low Cloud Mesoscale Morphology Using Satellite Classifications

Marine low cloud mesoscale morphology in the southeastern Pacific Ocean is analyzed using a large dataset of machine-learning generated classifications spanning three years. Meteorological variables and cloud properties are composited 10by mesoscale cloud type, showing distinct meteorological regimes of marine low cloud organization from the tropics to the midlatitudes. The presentation of mesoscale cellular convection, with respect to geographic distribution, boundary layer structure, and large-scale environmental conditions, agrees with prior knowledge. Two tropical and subtropical cumuliform boundary layer regimes, suppressed cumulus and clustered cumulus, are studied in detail. The patterns in precipitation, circulation, column water vapor, and cloudiness are consistent with the representation of marine shallow mesoscale convective 15 self-aggregation by large eddy simulations of the boundary layer. Although they occur under similar large-scale conditions, the suppressed and clustered low cloud types are found to be well-separated by variables associated with low-level mesoscale circulation, with surface wind divergence being the clearest discriminator between them, whether reanalysis or satellite observations are used. Clustered regimes are associated with surface convergence and suppressed regimes are associated with surface divergence.

Johannes Mohrmann↗

The spatial and seasonal distribution of Martian clouds and some meteorological implications

All Mariner 9 and Viking Orbiter images of Martian atmospheric clouds were analyzed to obtain temporal meteorological characteristics of Mars. The data comprised over 57,000 images which were separated into seven categories of surface obscuration. The classes included: lee waves, waves, plumes, streak clouds, cloud streets, localized fogs and hazes and were associated with particular formation mechanisms, probabilities of wind shear, static stability and surface shear stress and composition. Near surface winds followed the cap edges except in summer. Hemispheric asymmetries were attributed to the hydration state and global dust storm effects. Static stability was regionally and seasonally variable. Finally, clouds formed more easily in the northern than in the southern hemisphere in all corresponding seasons.

Kahn, R.↗

Quantifying the Turbulent Entrainment‐Mixing Processes Based on Z ‐LWC Relationships of Cloud Droplets

Abstract Turbulent entrainment‐mixing processes profoundly influence the relationship between radar reflectivity factor and liquid water content ( Z ‐LWC) of cloud droplets. However, quantification of the entrainment‐mixing mechanisms based on the Z ‐LWC relationship is still lacking. To address this gap, 12,218 entrainment‐mixing cases are simulated using the Explicit Mixing Parcel Model. We examine the variations of the parameters in the power‐law relationship Z = a LWC b , and the relationship between parameter b and homogeneous mixing degree ( ψ ), a measure quantifying entrainment‐mixing processes. The results indicate that parameter b distributes within the range of 1–2, with a positive correlation between parameter b and ψ . The b ‐ ψ relationship is fitted, which connects the Z ‐LWC relationship for various entrainment‐mixing types. The results suggest the potential for employing a remote sensing approach to investigate the entrainment‐mixing mechanisms of non‐precipitating small cumulus/stratocumulus clouds, thereby overcoming the limitations of traditional observational studies that rely solely on aircraft observations.

54 ENVIRONMENTAL SCIENCES↗