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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 379 records · Page 21
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NASA NTRS1987

Relating multitemporal meteorological satellite data to climatological data for Africa

The questions of surface-atmosphere interaction and effects of land surface changes have been investigated by studying the energy balance over Africa. The energy and mass balance model being developed is an adaptation of the Lettau climatonomy model. The climatonic approach is a systems approach which encompasses: (1) a process, (2) an input to the process (forcing function), (3) an output from the process (response function), (4) feedback, and (5) control or management of the system. Steady-state climate is described and parametrized using a series of one-dimensional differential continuity and balance equations for energy and mass.

Nicholson, Sharon E.↗
NASA NTRS1986

The First International Satellite Land Surface Climatology Project (ISLSCP) field experiment FIFE

The purpose of ISLSCP is to verify the use of satellite data for the estimation of land-surface properties. This is to be done through a series of field experiments using a combination of point measurements on the ground and areal measurements from aircraft overflights. In addition to validating satellite estimates of surface properties, approaches for obtaining areal averages of the radiation, moisture, and heat fluxes from remotely sensed data are to be studied. The procedure for doing this is to combine the surface point measurements of the fluxes with the aircraft areal observations using a surface-energy-balance model. This should make it possible to interpolate between the point estimates of these fluxes and calculate area-averaged quantities. The surface parameters to be estimated from aircraft observations include: surface radiation temperature, albedo, land-cover or vegetation index, and surface soil moisture.

Schmugge, T. J.↗
NASA NTRS1986

Constructing a coherent long-term global total ozone climatology from the BUV, MFR, and SBUV/TOMS data sets

Multichannel Filter Radiometer (MFR) data are intercompared with Solar Backscattered Ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) data during a five-month period of their data overlap in order to determine the usefulness of MFR data to represent the SBUV/TOMS and backscatter ultraviolet spectrometer data during their data gap period. Total ozone differences found were latitudinally and monthly dependent. Average differences between the TOMS and the MFR ozone data vary from -12.4 to +13.3 percent, with differences in the tropical to middle latitudes generally between + or - 4 percent. Biases between the data sets can be removed for certain latitude zones by applying an appropriate algorithm to the MFR ozone data.

Ellis, J. S.↗
NASA NTRS1987

Use of topographic and climatological models in a geographical data base to improve Landsat MSS classification for Olympic National Park

An unsupervised computer classification of vegetation/landcover of Olympic National Park and surrounding environs was initially carried out using four bands of Landsat MSS data. The primary objective of the project was to derive a level of landcover classifications useful for park management applications while maintaining an acceptably high level of classification accuracy. Initially, nine generalized vegetation/landcover classes were derived. Overall classification accuracy was 91.7 percent. In an attempt to refine the level of classification, a geographic information system (GIS) approach was employed. Topographic data and watershed boundaries (inferred precipitation/temperature) data were registered with the Landsat MSS data. The resultant boolean operations yielded 21 vegetation/landcover classes while maintaining the same level of classification accuracy. The final classification provided much better identification and location of the major forest types within the park at the same high level of accuracy, and these met the project objective. This classification could now become inputs into a GIS system to help provide answers to park management coupled with other ancillary data programs such as fire management.

Cibula, William G.↗
NASA NTRS1987

Cloud cover over the equatorial eastern Pacific derived from July 1983 International Satellite Cloud Climatology Project data using a hybrid bispectral threshold method

A set of visible and IR data obtained with GOES from July 17-31, 1983 is analyzed using a modified version of the hybrid bispectral threshold method developed by Minnis and Harrison (1984). This methodology can be divided into a set of procedures or optional techniques to determine the proper contaminate clear-sky temperature or IR threshold. The various optional techniques are described; the options are: standard, low-temperature limit, high-reflectance limit, low-reflectance limit, coldest pixel and thermal adjustment limit, IR-only low-cloud temperature limit, IR clear-sky limit, and IR overcast limit. Variations in the cloud parameters and the characteristics and diurnal cycles of trade cumulus and stratocumulus clouds over the eastern equatorial Pacific are examined. It is noted that the new method produces substantial changes in about one third of the cloud amount retrieval; and low cloud retrievals are affected most by the new constraints.

Minnis, Patrick↗
NASA NTRS1987

The stratosphere - Climatologies of the radiative heating and cooling rates and the diabatically diagnosed net circulation fields

Stratospheric solar, IR, and net radiative heating are calculated on a monthly basis using solar and IR radiative codes and satellite derived distributions of ozone, water vapor, and temperature. Divergence-free, zonally averaged, advective fields are diagnosed using the calculated diabatic heating; associated stream functions are derived. The stratospheric transport of inert tracers is studied. Analysis of the diagnosed advective fields reveal that: (1) entry into the mid- to upper stratosphere of tropospheric air is mainly from altitude regions of + or - 10 deg at the equatorial tropopause; (2) at latitudes poleward of + or - 15 deg, tracers transported from the troposphere into the stratosphere are transported toward the pole and then downward and out of the stratosphere; and (3) the presence of net cooling cells in the lower stratospheric polar regions is important. The interannual variability of the diabatic circulation is estimated using heating and advection fields derived from LIMS data.

Callis, Linwood B.↗
NASA NTRS1988

The GISS global climate-middle atmosphere model. I - Model structure and climatology

A coupled global climate/middle atmosphere model (GCMAM) is developed by extending the Hansen et al. (1983) GISS global climate model to include the middle atmosphere up to 85 km. The model includes numerical solutions of the primitive equations, calculations of the radiative and surface fluxes, and a complete hydrologic cycle with convective and cloud-cover parameterizations. In addition, a parameterized gravity wave drag cycle is incorporated, in which gravity-wave momentum fluxes due to flow over topography, wind shear, and convection are calculated at each grid box, using theoretical relationships between the grid-scale variables and expected source strengths. The results of the GCMAM demonstrate that the model produces a reasonable simulation of the stratosphere. It is shown that the improvements over the previous version were achieved largely through the incorporation of the parameterized gravity wave drag.

Rind, D.↗
NASA NTRS1988

Climatological aspects of Nimbus-7 SMMR data

An algorithm was developed for calculating simultaneously SSTs, SWs, and TAUs on a global basis using only the 6.6 and 18 GHz channels of the SMMR. Samples of the retrievals were calculated in each of eight of the SMMR years and found to produce independent results, consistent with weather charts and climatic records, even in the presence of high winds. Another new algorithm for calculating high-latitude scalar winds from Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) data was devised and tuned with surface observations from a number of documented Arctic Polar Low events. The algorithm utilizes the horizontally and vertically polarized radiances from the 0.8 and 1.7 cm wavelength channels of the ten-channel SMMR to retrieve near surface oceanic scalar winds and cloud water in the column, and takes advantage of the relatively small fluctuations in atmospheric water vapor at high latitudes. An advantage of this algorithm for high latitude winds from SMMR over the global algorithm is an inherently better spatial resolution as a result of the shorter wavelengths used.

Gloersen, P.↗
NASA NTRS1989

Observations of, and sources of the spatial and temporal variability of ozone in the middle atmosphere on climatological time scales (OZMAP) and equatorial dynamics: Seasonal variations of ozone trends

The long term trends (least square linear regression with time) of ozone content at seven European, seven North American, three Japanese and two tropical stations during 21 years (1964 to 1984) are analyzed. In all regions negative trends are observed during the 1970s, but are partly compensated by limited periods of positive trends during the late 1960s and late 1970s. Solely the North American ozone data show negative trends in all 10 year periods. When the long term ozone trends are evaluated for each month of the year separately, a seasonal variation is revealed, which in Europe and North America has largest negative trends in late winter and spring. While in Europe the negative trends in winter/spring are partly compensated by positive trends in summer, in North America the summer values reach only zero, retaining the significant negative trend in annual mean values. In contrast to the antarctic ozone hole, the spring reduction of ozone in Europe and in North America is associated with stratospheric temperatures increasing in the analyzed period and therefore is consistent with the major natural ozone production and loss processes.

Entzian, G.↗
NASA NTRS1988

Climatological observations and predicted sublimation rates at Lake Hoare, Antarctica

In December 1985, an automated meteorological station was established at Lake Hoare in the dry valley region of Antarctica. Here, the first year-round observations available for any site in Taylor Valley are reported. The mean annual solar flux at Lake Hoare was 92 W/sq m during 1986, the mean air temperature -17.3 C, and the mean 3-m wind speed 3.3 m/s. The local climate is controlled by the wind regime during the 4-month sunless winter and by seasonal and diurnal variations in the incident solar flux during the remainder of the year.

Clow, Gary D.↗
NASA NTRS1988

A study of cloud-generated radiative heating and its generation of available potential energy. I - Theoretical background. II - Results for a climatological zonal mean January

The effect of radiative heating and cooling by clouds on the available potential energy (APE) is theoretically discussed. It is shown that the cloud radiative contribution to the generation of APE is determined by the net cloud radiative heating and the efficiency factor, which is a function of the temperature distribution of the atmosphere. Results are presented for low and middle cloud effects for three atmospheric layers. Cloud radiative heating is found to be a single function of cloud optical thickness for all classes designed in terms of cloud top heights and optical thickness. Low clouds at low latitudes destroy APE an midclouds generate APE. A concept is developed to relate the cloud radiative heating to cloud heights and optical depths. Cloud-generated radiative heating is computed for January zonal mean conditions for low and midclouds. For both cases, the strongest influence is found in the low troposphere, with marked differences in signs and magnitudes. At extratropical latitudes, both cloud classes generate net radiative cooling. In the tropics, the effect of low cloud changes from net cooling to the net heating as the optical thickness increases, and midclouds cause net heating. A mechanism is described whereby this dependence produces a strong positive feedback effect on the development of SST anomalies in the tropical oceans.

Stuhlmann, R.↗
NASA NTRS1989

MISR - A multiangle imaging spectroradiometer for geophysical and climatological research from EOS

The scientific objectives, instrument concept, and data plan for the multiangle imaging spectroradiometer (MISR), an experiment proposed for the EOS (Earth Observing System) mission, are described. MISR is a pushbroom imaging system designed to obtain continuous imagery of the sunlit Earth at four different view angles (25.8, 45.6, 60.0, and 72.5 deg relative to the vertical at the earth's surface), in both the forward and aftward directions relative to nadir, using eight separate cameras. Observations will be acquired in four spectral bands, centered at 440, 550, 670, and 860 nm. Data analysis algorithms will be applied to MISR imagery to retrieve the optical, geometric, and radiative properties of complex, three-dimensional scenes, such as aerosol-laden atmospheres above a heterogeneously reflecting surface, nonstratified cloud systems, and vegetation canopies. The MISR investigation will address a number of scientific questions concerning the climatic and ecological consequences of many natural and anthropogenic processes, and will furnish aerosol information necessary for atmospheric corrections of surface images.

Diner, David J.↗
NASA NTRS1989

A climatology of gravity waves and other coherent disturbances at the Boulder Atmospheric Observatory during March-April 1984

Gravity waves and other coherent disturbances observed at the Boulder Atmospheric Observatory (BAO) during the period between mid-March and mid-April 1984 were studied using data collected by an array of microbarographs located around the 300-m meteorological tower, together with data from the tower. Five passbands were considered in the period range 1-20 min; it was found that, for most of the time, the atmospheric state at these passbands displayed highly coherent structure. For disturbances of up to 5-min periods, a relationship was found between the turbulent kinetic energy measured on the tower and the amplitude of the rms pressure field at the ground, but, for longer periods, no such relationship was found.

Einaudi, F.↗
NASA NTRS1989

The separated polar winter stratopause - A gravity wave driven climatological feature

An examination of satellite-derived temperatures reveals that the winter polar stratopause is usually elevated and warmer than the adjacent midlatitude stratopause. This separated stratopause occurs in both hemispheres, but is more pronounced and persistent in the southern winter. It descends with time towards spring and exhibits week-to-week variability. Observational diagnostics and results from a two-dimensional model suggest that gravity-wave driving can account for this separated polar stratopause by driving a meridional circulation, with downwelling over the winter pole. In the model, the solar heating pattern induces stronger winter westerlies than summer easterlies, which leads to a stronger gravity-wave-driven circulation in the winter hemisphere. Spherical geometry and the high latitude location of the winter westerly jet combine to yield a concentrated region of downwelling. Model results suggest that descent of the temperature maximum with time is probably caused by wave/mean-flow interaction.

Hitchman, Matthew H.↗
NASA NTRS1989

Climatology of nitric oxide in the upper stratosphere, mesosphere, and thermosphere - 1979 through 1986

The contents of NO in the upper stratosphere, mesosphere, and thermosphere were determined as a function of time and latitude, using spectral scan data for 1979 through 1986 from the solar backscattered UV instrument on Nimbus 7. In that period, the integrated column amount of NO near the equator decreased from 6.4 x 10 to the 14th molecules/sq cm to 3.3 x 10 to the 14th molecules/sq cm. The time dependence of the decrease in NO correlated with solar activity, following the decline in solar activity from a solar maximum in 1979 to solar minimum in 1985-86. At middle and high latitudes, on the other hand, the NO concentration was found to be maximal in 1982-1983, a few years after the solar cycle maximum, and declined thereafter.

Mcpeters, R. D.↗
NASA NTRS1988

Nimbus-7 global cloud climatology. I - Algorithms and validation

An improved version of the Nimbus-7 cloud retrieval algorithm was validated using data from Nimbus-7 Temperature Humidity Infrared Radiometer and Total Ozone Mapping Spectrometer to determine cloudiness parameters for the globe. Quantitative validation of total cloud amount was performed by comparing the algorithm results with estimates derived from GOES images and auxiliary meteorological data. The systematic errors of the Nimbus-7 total cloud-amount algorithm, relative to the GOES-derived estimates, were found to be less than 10 percent. The random errors of daily estimates ranged between 7 and 16 percent, day or night.

Stowe, L. L.↗
NASA NTRS1989

A global climatology of albedo, roughness length and stomatal resistance for atmospheric general circulation models as represented by the Simple Biosphere Model (SiB)

Components of the Simple Biosphere Model (SiB) of Sellers et al. (1986) were used to generate global monthly fields of surface albedo (0.4-4.0 microns), roughness length and minimum surface (stomatal) resistance. SiB consists of three submodels which describe the roles of radiative transfer, turbulent transfer and surface resistance in determining the energy balance of the vegetated land surface. These three submodels were detached from SiB and used on the SiB parameter set (total and green leaf area index, leaf angle orientation, canopy dimensions, etc.) to calculate global monthly fields of albedo, roughness length and minimum stomatal resistance at 1 x 1 deg resolution. Time series of various parameters are also displayed for each vegetation type for specified grid points. The SiB results compare reasonably well with appropriate measurements obtained from the literature and have the additional merit of being mutually consistent; the three submodels use many common parameters, which ensures that, for each grid area, the calculated surface properties are closely interrelated as is the case in nature. The derived fields provide a check on the operation of the submodels and the correctness of the parameter set. They can also be used as prescribed fields for GCMs that do not have biophysically based land surface parameterizations.

Dorman, J. L.↗