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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

A study of the influence of satellite data on GLA analyses over the Atlantic Ocean during a period of blocking anticyclone development

This paper presents a statistical diagnosis of the differences between two Goddard Laboratory for Atmospheres analysis representations of temperature and wind speed, one containing satellite data influences (SAT analyses) and one without (NOSAT analyses), for a case of oceanic blocking anticyclone development. Results, obtained using area means and standard deviations of the two fields and correlation coefficients and root-mean-square differences between the two fields, indicate that the inclusion of satellite data can have significant impact on ocean-domain analyses. This is especially evident if one examines higher-order fields that represent gradients in the basic variable fields or contain covariances between two different variables (e.g., advections). More specifically, the inclusion of satellite data resulted in a cold (warm) temperature bias at low (high) levels and weaker temperature gradients, stronger winds, weaker vertical wind shears, and a warm-air advection bias at most levels. The SAT analyses also exhibited larger standard deviations than the NOSAT for wind speed, relative vorticity, vorticity advection, temperature advection, and 500-mb height tendencies, suggesting that for this case the spatial variability of the circulation features were enhanced by the inclusion of satellite data. Even so, since height tendencies forced by vorticity and temperature advection were less sensitive to the addition of satellite data than were the advection quantities themselves, the dynamics of the blocking system was apparently less influenced by the presence of satellite data than was the structure of the system.

Lamberty, Gregory L.↗
NASA NTRSDate not supplied

Trends in Asian Summer Monsoon Anticyclone Dynamical Diagnostics in Reanalyses

The area of the Asian summer monsoon anticyclone (ASMA), as defined by contours of Montgomery stream function (MSF) on isentropic surfaces, has been increasing over at least the last four decades. Here we analyze the relationship of the trend in ASMA area to trends in dynamical diagnostics in the ASM region, both inside and outside the ASMA, for 1979 through 2020 in the MERRA-2, JRA-55, and ERA5 reanalyses. Trends in geopotential height (GPH) and temperature (from which MSF is calculated) indicate that MSF increases are dominated by increasing temperature (GPH) at levels that are primarily in the troposphere (stratosphere). Trends in MSF, GPH, and temperature are much less clear within the ASMA circulation than those for the entire ASM region, suggesting that other mechanisms, besides the direct effects of increasing tropospheric temperatures, are at play. To further explore these results, we present trends in lapse rate and dynamical tropopause altitudes, easterly and westerly windspeeds bounding the ASMA, and potential vorticity. Overall, weak or inconsistent trends inside the ASMA in most diagnostics likely arise from a complex interplay of mechanisms in this region (which spans tropospheric/stratospheric and tropical/midlatitude conditions), and suggest that the previously reported area trends do not necessarily indicate an increase in “intensity" of the ASMA. In regions both with and without robust trends in dynamical diagnostics, trend results are typically consistent between the three reanalyses studied even when there are biases in the magnitudes of those diagnostics. This generally good agreement indicates that these reanalyses are suitable for more detailed studies needed to fully understand the mechanisms for trends in the ASMA.

Gloria Manney↗
NASA NTRS1993

The life cycles of intense cyclonic and anticyclonic circulation systems observed over oceans

Full attention was now directed to the blocking case studies mentioned in previous reports. Coding and initial computational tests were completed for a North Atlantic blocking case that occurred in late October/early November 1985 and an upstream cyclone that developed rapidly 24 hours before block onset. This work is the subject of two papers accepted for presentation at the International Symposium on the Lifecycles of Extratropical Cyclones in Bergen, Norway, 27 June - 1 July 1994. This effort is currently highlighted by two features. The first is the extension of the Zwack-Okossi equation, originally formulated for the diagnosis of surface wave development, for application at any pressure level. The second is the separation of the basic large-scale analysis fields into synoptic-scale and planetary-scale components, using a two-dimensional Shapiro filter, and the corresponding partitioning of the Zwack-Okossi equation into synoptic-scale, planetary-scale, and synoptic/planetary-scale interaction terms. Preliminary tests suggest substantial contribution from the synoptic-scale and interaction terms.

Smith, Phillip J.↗
NASA NTRS1994

The life cycles of intense cyclonic and anticyclonic circulation systems observed over oceans

The work over the past six months has focused on the October/November 1985 blocking case study noted in the last progress report. A summary of the results of this effort is contained in the attached preprint papers for the Symposium on the Life Cycles of Extratropical Cyclones. Using this case study as a model, Ph.D. student Anthony Lupo is now initiating the multiple-case diagnosis by first examining two more fall 1985 blocking episodes. In addition, two secondary efforts have been completed, as summarized in the attached M.S. thesis abstracts. Both studies, which were primarily funded by a fellowship and a teaching assistantship, complement the objectives of this study by providing diagnoses of additional cyclone cases to serve as a comparative base for the pre-blocking cyclones to be studied in the multiple-case blocking diagnosis.

Smith, Phillip J.↗
NASA NTRS1996

The Life Cycles of Intense Cyclonic and Anticyclonic Circulation Systems Observed over Oceans

This report presents a summary of research accomplished over the past four years under the sponsorship of NASA grant #NAG8-915. Building on previously funded NASA grants, this part of the project focused on the following specific goals relative to cyclone/anticyclone systems: the jet streak link between block formation and upstream cyclone activity; the role of northward warm air advection in block formation; the importance of cooperative participation of several forcing mechanisms during explosive cyclone development; and the significance of the vertical distribution of forcing processes during cyclone/anticyclone development.

Smith, Phillip J.↗
NASA NTRS1973

An investigation of the Sutcliffe development theory

Two case studies were used to test the Sutcliffe-Peterssen development theory for both cyclonic and anticyclonic development over the eastern United States. Each term was examined to determine when and where it made a significant contribution to the development process. Results indicate the advection of vorticity at the level of non-divergence exerts the dominant influence for initial cyclone development, and that the thermal terms (advection of thickness, stability, and diabatic influence) become important after development has begun. Anticyclonic development, however, depends primarily on the stability term throughout the life cycle of the anticyclone. Simple procedures for forecasting the development and movement of cyclones and anticyclones are listed. These rules indicate that routine National Meteorological Center analyses may be used to locate areas where the positive advection of 500-mb vorticity, indicative of cyclonic development, coincides with regions of severe weather activity. The development of anticyclones also is predicted easily. Regions of increasing stability, indicating anticyclonic development, may be located by use of National Meteorological Center radar summaries and analyses for 1000-500-mb thickness. A test of these techniques found them to be satisfactory for the case examined.

Dushan, J. D.↗
NASA NTRS2001

The Continuation of Cloud Statistics for NASA Climate Change Studies

The weather systems, cyclones, and anticyclones, along with air trajectories and cloud forms, are compared to past studies of the Arctic to assess compatibility of the four month study of the Arctic Cloud Experiment flights of the First ISCCP Regional Experiment (FIRE/ACE) with past climatologies. The frequency and movement of cyclones (lows) and anticyclones (highs) followed the general eastward and northeastward directions indicated by past studies. Most cyclones (lows) came from eastern Siberia and the Bering Sea to the south and moved north across the Bering Straight or Alaska into the Arctic Ocean. They generally weakened in central pressure as they moved poleward. Anticyclones (highs) were most common in the eastern Beaufort Sea near Canada in June and July as predicted from previous studies. However, many cyclones and anticyclones moved in westward directions which is rare in other latitudes. Erratic changes in shape and intensity on a daily basis also were observed. The National Center for Environmental Prediction (NCEP) analysis generally reflected the Surface Heat Budget in the Arctic (SHEBA) Ship World Meteorological Organization (WMO) observations which it used. However, NCEP temperatures were biased warm by 1.0 to 1.5 C in April and early May. In July when the surface temperature were at the freezing/thawing point, the NCEP analysis changed to a cold bias of -1.0 C. Dew points had smaller biases except for July where they were biased cold by -1.4 C. Wind speeds had a -2 m/s low bias for the six windiest days. Surface barometric pressures had consistently low biases from -1.2 to -2.8 hPa in all four months. Air parcel historical trajectories were mainly from the south or from local anticyclonic gyres in the Beaufort Sea. Most air came to the SHEBA Ship from the north Pacific Ocean or from Alaska and Canada and occasionally from eastern Siberia. Very few trajectories traced back across the pole to Europe and Central Asia. Cloud cover was high, as expected, from 69-86% of the time. Satellite data also indicate frequent stratus, altostratus, and cirrus clouds (occurring 61% of the time) above the expected boundary layer fog and Arctic stratus clouds.

Wylie, Donald P.↗
NASA NTRSDate not supplied

Summer Monsoons in the UTLS as Observed By Recent NASA Airborne Campaigns.

During boreal summer, the circulation of the northern hemisphere upper troposphere and lower stratosphere (UTLS) is dominated by two quasi-stationary anticyclonic eddies driven by latent heat released in the troposphere: the Asian Monsoon Anticyclone (AMA) and the North American Monsoon Anticyclone (NAMA). Deep convection rapidly transports boundary layer air to the UTLS, and the monsoon anticyclones act to partially confine and isolate air from the surrounding atmosphere. The interactions between chemistry and circulation within these systems are crucial for understanding the sensitivity of these regions to changes in climate and air quality. Satellite observations show that within the summer monsoon anticyclones is a region of enhanced water vapor, aerosol, and trace gases of boundary layer origin near the tropopause level. However, satellite data do not provide necessary details for process studies and for diagnosing their representations in models. In response to this need, NASA conducted two airborne missions to investigate these summer monsoon systems and their roles in climate. NASA Earth Venture Suborbital 3 (EVS-3) mission called Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) completed two deployments in Salina, Kansas during summers 2021 and 2022 to study the NAMA. The Asian Summer Monsoon Chemical and Climate Impact Project (ACCLIP) was a multi-agency effort to investigate the AMA from Osan, South Korea in summer 2022.

Summer↗
NASA NTRS1986

Observed aspects of atmospheric blocking

An important problem in large-scale atmospheric dynamics is understanding the evolution of these blocking systems. Inspection of a large number of cases of 500 mb cyclonic and anticyclonic blocking vortices during recent winter seasons reveals that the occurrence of these systems is preceded by high amplitude (but not necessarily stationary) planetary waves at 500 mb and by intense synoptic-scale surface cyclone activity. A possible relationship between the cyclones and planetary waves during block evolution is thus hypothesized. Detailed diagnostic study of blocking cases during January 1977, February 1978 and November 1980 discloses that the development of 500 mb anticyclonic blocking vortices is preceded in time by the intense surface cyclogenesis between 500 mb planetary scale troughs and ridges, whereas blocking cyclonic vortices form following cyclogenesis near the axes of 500 mb troughs. A positive feedback between the cyclone and planetary waves is thus implied. The 500 mb height changes accompanying the above processes were analyzed in terms of quasi-geostrophic potential vorticity. During anticyclonic vortex development, there are spatially and temporally persistent calculated quasi-geostrophic height rises due to anticyclonic potential vorticity advections occurring near the cyclone track. Similarly, during cyclonic vortex development, there are spatially and temporally persistent calculated quasi-geostrophic height falls due to cyclonic potential vorticity advections occurring near the cyclone track.

Colucci, S. J.↗
NASA NTRS1987

Simulated sudden stratospheric warming - Synoptic evolution

An analysis is presented of a sudden stratospheric warming event which occurred spontaneously during a general circulation model simulation of the global atmospheric circulation. Two separate warming pulses exhibit the same dynamical evolution with a 'cycle' of about two weeks. Two distinct phases of the warming cycle are apparent: (1) the generation of an intense localized warm cell in conjunction with significant adiabatic heating associated with cross-isobar flow which has been induced by vertically propagating long wave disturbances; and (2) the northward transport of that warm cell via advection by the essentially geostrophic windfield corresponding to an intense, offset polar cyclone, in conjunction with a strong Aleutian anticyclone. During the first warming pulse in January, a moderate Aleutian anticyclone was in place prior to the warming cycle and was intensified by interaction with an eastward traveling anticyclone induced by the differential advection of the warm cell. The second warming pulse occurred in early February with a strong Aleutian anticyclone already established. In contrast to the January event, the warming in February culminated with reversal of the zonal westerlies to easterlies over a significant depth of the stratosphere.

Blackshear, W. T.↗
NASA NTRS1991

Rapid 500-mb cyclogenesis and anticyclogenesis

The process of intensification of 500-mb cyclones and anticyclones as represented in NMC's 500-mb analyses is investigated, using a sample of records for 500-mb cyclones and anticyclones drawn from the cool season of September 1983 through May 1984 to determine the statistically large intensification rates and thus to establish criteria for rapid intensification. From the catalog of all rapidly intensifying 500-mb cyclones and anticyclones defined by these criteria, seasonal and geographical frequency distributions of cyclogenesis and anticyclogenesis is constructed. It is shown that, for the data sample used in this analysis, the operational forecast models tend to underpredict rapid developments of 500-mb cyclones and anticyclones.

Alberta, Timothy L.↗
NASA NTRS1974

Results of the US contribution to the joint US/USSR Bering Sea experiment

The atmospheric circulation which occurred during the Bering Sea Experiment, 15 February to 10 March 1973, in and around the experiment area is analyzed and related to the macroscale morphology and dynamics of the sea ice cover. The ice cover was very complex in structure, being made up of five ice types, and underwent strong dynamic activity. Synoptic analyses show that an optimum variety of weather situations occurred during the experiment: an initial strong anticyclonic period (6 days), followed by a period of strong cyclonic activity (6 days), followed by weak anticyclonic activity (3 days), and finally a period of weak cyclonic activity (4 days). The data of the mesoscale test areas observed on the four sea ice option flights, and ship weather, and drift data give a detailed description of mesoscale ice dynamics which correlates well with the macroscale view: anticyclonic activity advects the ice southward with strong ice divergence and a regular lead and polynya pattern; cyclonic activity advects the ice northward with ice convergence, or slight divergence, and a random lead and polynya pattern.

Campbell, W. J.↗
NASA NTRS1994

Warm core ring dynamics derived from satellite imagery

A reinterpretation of the life history of warm core ring 82-b is constructed from drifter trajectories, hydrographic profiles, and satellite-derived sea surface temperature fields. An analysis of the observations strongly suggests this ring is fundamentally a dipole structure for much of its existence. The dipole has unequal strength vortices, with the cyclone being the weaker component. Quantification of the dipole indicates the anticyclonic is oval shaped and rotates at approximately 7.7 deg per day, while the cyclone revolves around the anticyclone at about 14.5 deg per day, yielding an orbit period of approximately 25 days for the cyclone. The elusive part of the dipole explanation is in interpreting its surface signature as a function of time, as the cyclone appears to disappear when in proximity to the steep continental slope. Vortex modeling suggests that when the weaker cyclonic eddy is placed close to a boundary, the cyclone is drawn into a filament as it is advected through the gap between the anticyclone and the boundary. This means the cyclone is either in a filamentation state or undergoing the straining associated with filamentation approximately three fourths of this time, which is in complete agreement with the satellite imagery. In addition, the 82-B dipole configuration is sufficiently robust to survive continuous interaction with the continental slope and the onset of a Gulf Stream interaction. Although only warm core ring 82-B is analyzed in detail (and found to be a vortex pair), dipole configurations are found in the warm core ring 81-F time series as well.

Hooker, Stanford B.↗
NASA NTRS2000

Intrinsic Coupled Ocean-Atmosphere Modes of the Asian Summer Monsoon: A Re-assessment of Monsoon-ENSO Relationships

Using global rainfall and sea surface temperature (SST) data for the past two decades (1979-1998), we have investigated the intrinsic modes of Asian summer monsoon (ASM) and ENSO co-variability. Three recurring ASM rainfall-SST coupled modes were identified. The first is a basin scale mode that features SST and rainfall variability over the entire tropics (including the ASM region), identifiable with those occurring during El Nino or La Nina. This mode is further characterized by a pronounced biennial variation in ASM rainfall and SST associated with fluctuations of the anomalous Walker circulation that occur during El Nino/La Nina transitions. The second mode comprises mixed regional and basin-scale rainfall and SST signals, with pronounced intraseasonal and interannual variabilities. This mode features a SST pattern associated with a developing La Nina, with a pronounced low level anticyclone in the subtropics of the western Pacific off the coast of East Asia. The third mode depicts an east-west rainfall and SST dipole across the southern equatorial Indian Ocean, most likely stemming from coupled ocean-atmosphere processes within the ASM region. This mode also possesses a decadal time scale and a linear trend, which are not associated with El Nino/La Nina variability. Possible causes of year-to-year rainfall variability over the ASM and sub-regions have been evaluated from a reconstruction of the observed rainfall from singular eigenvectors of the coupled modes. It is found that while basin-scale SST can account for portions of ASM rainfall variability during ENSO events (up to 60% in 1998), regional processes can accounts up to 20-25% of the rainfall variability in typical non-ENSO years. Stronger monsoon-ENSO relationship tends to occur in the boreal summer immediately preceding a pronounced La Nina, i.e., 1998, 1988 and 1983. Based on these results, we discuss the possible impacts of the ASM on ENSO variability via the west Pacific anticyclone and articulate a hypothesis that anomalous wind forcings derived from the anticyclone may be instrumental in inducing a strong biennial modulation to natural ENSO cycles.

Lau, K.-M.↗