Search NASA⌕ Search

SEARCH · Search NASA

Results for “Diabatization”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

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

Research on diabatic initialization

The objective of this research is to contribute to the improvement of the analyses of irrotational wind and moisture fields in the tropics through advancement in the technique of initialization, incorporating diabatic effects and use of satellite-derived, radiometric imagery data that are not used currently by operational centers. Significant accomplishments during the period of May 1991 - April 1992 in research involving the following are presented: impact of tropical initialization upon the spin-up of precipitation forecasts; and a unified approach to diabatic initialization for improvement in the analysis of divergence and water vapor fields in the tropics. Focus of current research and plans for next year are discussed with respect to the topics of controlling the precipitation over shoot during the early part of a numerical forecast and the use of satellite imagery data for improvement of the tropical analysis.

Kashara, Akira↗
NASA NTRS1993

Diabatic dynamic initialization

A version of the dynamical adjustment procedure is generalized in order to make the procedure applicable to a diabatic model. In this new initialization procedure, backward adiabatic model integration is followed by forward diabatic model integration, with a high-frequency (low-pass) time filter in the form of the Euler backward time-differencing scheme applied throughout the integration. The new procedure was applied to the Goddard Laboratory for Atmospheres 4D data-assimilation system. It was found that, right from the beginning of the forecast integration, the forecast tendencies (and fields) were free of any noise due to imbalance in initial conditions, and the shocks related to an initial imbalance between model physics and dynamics, or the initial spinup effect, were practically removed.

Fox-Rabinovitz, Michael S.↗
NASA NTRS1991

Scale interactions and diabatic processes during the development of an Atlantic blocking event

Results of a case study of the development of a major blocking event over the North Atlantic Ocean are reported with emphasis on the potential roles of interactions between synoptic-scale systems and diabatic processes in the large-scale development. The approach used here involves the analysis of the evolution of the potential temperature on a constant potential vorticity (PV) surface, where the value of PV is chosen to be representative of that of the tropopause. The approach is shown to provide a simple way to qualitatively identify significant features in the development of the block, including scale interactions and diabatic processes.

Morgan, Michael C.↗
NASA NTRS1994

An assessment of satellite temperature distributions used to derive the net diabatic transport for zonally averaged models of the middle atmosphere

Determinations of the zonally averaged and diabatically derived residual mean circulation (RMC) are particularly sensitive to the assumed zonal mean temperature distribution used as input. Several different middle atmosphere satellite temperature distributions have been employed in models and are compared here: a 4-year (late 1978 to early 1982) National Meteorological Center (NMC) climatology, the Barnett and Corney (or BC) climatology, and the 7 months of Nimbus 7 limb infrared monitor of the stratosphere (LIMS) temperatures. All three climatologies are generally accurate below the 10 hPa level, but there are systematic differences between them of up to +/-5 K in the upper stratosphere and lower mesosphere. The NMC/LIMS differences are evaluated using time series of rocketsonde and reconstructed satellite temperatures at station locations. Much of those biases can be explained by the differing vertical resolutions for the satellite-derived temperatures; the time series of reconstructed LIMS profiles have higher resolution and are more accurate. Because the LIMS temperatures are limited to just two full seasons, one cannot obtain monthly RMCs from them for an annual model calculation. Two alternate monthly climatologies are examined briefly: the 4-year Nimbus 7 stratospheric and mesospheric sounder (SAMS) temperatures and for the mesosphere the distribution from the Solar Mesosphere Explorer (SME), both of which are limb viewers of medium vertical resolution. There are also differences of the order of +/-5 K for those data sets. It is concluded that a major source of error in the determination of diabatic RMCs is a persistent pattern of temperature bias whose characteristics vary according to the vertical resolution of each individual climatology.

Remsberg, Ellis E.↗
NASA NTRS1997

The Effect of Enhanced Diabatic Heating on Stratospheric Circulation

The objective of this research focuses on the stratospheric dynamical response to the increase in aerosol loading and subsequent enhanced diabatic heating resulting from the eruption of Mt. Pinatubo. The Langley research Center three dimensional general circulation model and modifications made to that model for this study are described (addition of hydrogen fluoride tracer and diabatic heating enhancement). Unperturbed hydrogen fluoride distribution is compared to the hydrogen fluoride distribution measured by HALOE. A comparison of control and perturbed model runs is presented.

Kleb, Mary M.↗
NASA NTRS2003

Diabatic Initialization of Mesoscale Models in the Southeastern United States: Can 0 to 12h Warm Season QPF be Improved?

It is well known that numerical warm season quantitative precipitation forecasts lack significant skill for numerous reasons. Some are related to the model--it may lack physical processes required to realistically simulate convection or the numerical algorithms and dynamics employed may not be adequate. Others are related to initialization-mesoscale features play an important role in convective initialization and atmospheric observation systems are incapable of properly depicting the three-dimensional stability structure at the mesoscale. The purpose of this study is to determine if a mesoscale model initialized with a diabatic initialization scheme can improve short-term (0 to 12h) warm season quantitative precipitation forecasts in the Southeastern United States. The Local Analysis and Prediction System (LAPS) developed at the Forecast System Laboratory is used to diabatically initialize the Pennsylvania State University/National center for Atmospheric Research (PSUNCAR) Mesoscale Model version 5 (MM5). The SPORT Center runs LAPS operationally on an hourly cycle to produce analyses on a 15 km covering the eastern 2/3 of the United States. The 20 km National Centers for Environmental Prediction (NCEP) Rapid Update Cycle analyses are used for the background fields. Standard observational data are acquired from MADIS with GOES/CRAFT Nexrad data acquired from in-house feeds. The MM5 is configured on a 140 x 140 12 km grid centered on Huntsville Alabama. Preliminary results indicate that MM5 runs initialized with LAPS produce improved 6 and 12h QPF threat scores compared with those initialized with the NCEP RUC.

Lapenta, William M.↗
NASA NTRS1984

Analysis of Diabatic Heating During FGGE

The objective is to examine the maintenance of momentum and thermal fields in the Southern Hemisphere and the diabatic heating and generation of available potential energy of the entire global atmosphere. The data generated by the Goddard Laboratory for Atmospheric Sciences First GARP Global Experiment (FGGE) III-b analysis for SOP1 and SOP2 are used for this effort. It is observed that the atmospheric circulation of the Southern Hemisphere exhibits a double jet structure (subtropical jet and polar jet) in winter and a single jet in summer during the FGGE year. The geographic distribution of standard deviation in the height field at 500 mb indicates that the major eddy activities occur in the downstream side of the polar jet and poleward side of the subtropic jet in winter. However, the major eddy activites go hand-in-hand with the jet stream in summer. The momentum transport is essentially carried out by the transient eddies in both seasons. The distribution of the temperature field is more axisymmetric in the Southern Hemisphere than in the Northern Hemisphere. The sensible heat is mainly transported poleward by transient eddies along the strong baroclinic zone where the jet streams are located. In other seasons, it is shown from the geographic distribution of the divergence of transient eddy sensible heat flux that the Antarctic continent acts as a heat sink to consume the sensible heat converged toward the polar area from the middle and low latitudes.

Chen, T. C.↗
NASA NTRS1986

Tracer transport by the diabatic circulation deduced from satellite observations

Nimbus-7 sensor data were used to track the diabatic circulation in the stratosphere to study the advective transport of CH4 and N2O as tracer species. Advective transport by the mean circulation was found to be a function of the temperature field and associated deviations from radiative equilibrium. A photochemical model was applied to account for the disappearance of the tracer species from the stratosphere. Comparisons between the SAMS data and modeling on the basis of the chemical loss rates of the tracers and the LIMS circulation data showed that the model predictions underestimated the resident abundances, although the global distributions and circulations exhibited a good match.

Solomon, S.↗
NASA NTRS1988

Diabatic initialization for a mesoscale model simulation experiment

A mesoscale model simulation of a 'surrogate' atmosphere designed for the evaluation of adiabatic initialization and moisture enhancement techniques is briefly described. The simulation provides mesoscale precipitation rates and associated diabatic heating fields which are known exactly and are internally consistent within the context of the model. The advantage of this approach is that a numerical model can easily serve as a source of mesoscale data in the usual absence of internally consistent mesoscale observed data sets.

Kalb, Michael W.↗
NASA NTRS1989

Global distribution of moisture, evaporation-precipitation, and diabatic heating rates

Global archives were established for ECMWF 12-hour, multilevel analysis beginning 1 January 1985; day and night IR temperatures, and solar incoming and solar absorbed. Routines were written to access these data conveniently from NASA/MSFC MASSTOR facility for diagnostic analysis. Calculations of diabatic heating rates were performed from the ECMWF data using 4-day intervals. Calculations of precipitable water (W) from 1 May 1985 were carried out using the ECMWF data. Because a major operational change on 1 May 1985 had a significant impact on the moisture field, values prior to that date are incompatible with subsequent analyses.

Christy, John R.↗
NASA NTRS1989

Evidence for diabatic cooling and poleward transport within and around the 1987 Antarctic ozone hole

Atmospheric dynamics at altitudes of 17.5-19 km were analyzed using measurements of N2O, total water, total odd-nitrogen species, and potential vorticity (derived from pressures, temperatures, and wind speeds) obtained aboard the ER-2 aircraft flown in the period between August 23 and September 22 during the Airborne Antarctic Ozone Experiment. Results indicated a consistent gradual poleward movement of air, extending from about 10 deg in latitude outside the boundary of the ozone hole to about 5 deg inside. Evidence is presented of ongoing diabatic cooling throughout this zone, both inside and outside the chemically perturbed region.

Profitt, M. H.↗
NASA NTRS1989

The role of diabatic heating in maintaining the upper-tropospheric baroclinic zone in the South Pacific

The four-dimensional structure of the region in the South Pacific convergence zone (SPCZ) during January 10-18, 1979 is studied using a modified set of ECMWF FGGE level III-b analyses. The effects of kinematic and thermodynamic processes on maintaining the upper baroclinic region corresponding with the subtropical jet are analyzed. The role of adiabatic and diabatic processes in the maintenance of baroclinicity in the area of the SPCZ is examined using the frontogenetical function. It is observed that the processes affecting the evolution of baroclinicity in the SPCZ region differ from those in the middle latitude; possible reasons for these differences are proposed.

Robertson, Franklin R.↗
NASA NTRS1990

Global-scale, intraseasonal fluctuations of diabatic forcing of the atmosphere

Fields of diabatic heating rate estimates (H) for 5-day periods were calculated from the European Center for Medium Weather Forecasts (ECMWF) analyses since 1985 as the residual of the dry thermodynamic equation. Included in these fields are the horizontal and vertical divergences of heat for both mean and eddy statistics. Previous work dealt with 4-day periods, however, with the emphasis in the Global Precipitation Climatology Project (GPCP) for 5-day period totals the change was made to accommodate the GPCP product. H has long been associated with cold tropical cloud-top temperatures as measured by polar orbiting outgoing longwave radiation (OLR) sensors. Correlations between H and OLR fields on three time scales indicate a moderate amount of agreement. For periods less than 90 days, significant negative correlations are found between H and OLR for (1) tropical and NH midlatitude oceanic areas, and (2) for zonal and hemispheric mean values. Positive correlations are seen in NH mean and continental areas of N. Africa, N. America, N. Asia and Antarctica. These latter results reflect seasonal heating and cooling. Comparisons have been made between H as H as calculated from the ECMWF analyses and output from the CCM1 T42 simulations. The CCM1 tends to have a more cellular structure with more heating (precipitation) over land versus that observed (ECMWF) over oceans.

Christy, John R.↗
NASA NTRS1991

Research on diabatic initialization

The objective was to contribute to the improvement of the analyses of irrotational wind and moisture fields in the trophics through advancement in the technique of initialization by incorporating diabatic effects. Significant accomplishments made during the period May 1990 to April 1991 in the following areas are presented: (1) estimation of the uncertainty of daily synoptic analyses in the tropics; (2) normal modes of Laplace's tidal equations for zonal wavenumber zero; and (3) tropical initialization to ameliorate the spin-up problem of precipitation forecasts. The focus of current research and plans for next year are also presented.

Kasahara, Akira↗
NASA NTRS1991

Diabatic heating rate estimates from European Centre for Medium-Range Weather Forecasts analyses

Vertically integrated diabatic heating rate estimates (H) calculated from 32 months of European Center for Medium-Range Weather Forecasts daily analyses (May 1985-December 1987) are determined as residuals of the thermodynamic equation in pressure coordinates. Values for global, hemispheric, zonal, and grid point H are given as they vary over the time period examined. The distribution of H is compared with previous results and with outgoing longwave radiation (OLR) measurements. The most significant negative correlations between H and OLR occur for (1) tropical and Northern-Hemisphere mid-latitude oceanic areas and (2) zonal and hemispheric mean values for periods less than 90 days. Largest positive correlations are seen in periods greater than 90 days for the Northern Hemispheric mean and continental areas of North Africa, North America, northern Asia, and Antarctica. The physical basis for these relationships is discussed. An interyear comparison between 1986 and 1987 reveals the ENSO signal.

Christy, John R.↗