Showing papers in "Journal of Applied Meteorology and Climatology in 1983"
TL;DR: In this paper, a two-dimensional, time-dependent cloud model was used to simulate a moderate intensity thunderstorm for the High Plains region, where six forms of water substance (water vapor, cloud water, cloud ice, rain, snow and hail) were simulated.
Abstract: A two-dimensional, time-dependent cloud model has been used to simulate a moderate intensity thunderstorm for the High Plains region. Six forms of water substance (water vapor, cloud water, cloud ice, rain, snow and hail, i.e., graupel) are simulated. The model utilizes the “bulk water” microphysical parameterization technique to represent the precipitation fields which are all assumed to follow exponential size distribution functions. Autoconversion concepts are used to parameterize the collision-coalescence and collision-aggregation processes. Accretion processes involving the various forms of liquid and solid hydrometeors are simulated in this model. The transformation of cloud ice to snow through autoconversion (aggregation) and Bergeron process and subsequent accretional growth or aggregation to form hail are simulated. Hail is also produced by various contact mechanisms and via probabilistic freezing of raindrops. Evaporation (sublimation) is considered for all precipitation particles outsi...
3,300 citations
TL;DR: In this paper, a global vegetation and land-use data base (1° latitude by 1° longitude resolution) was compiled in digital form drawing upon approximately 100 published sources complemented by a large collection of satellite imagery.
Abstract: Global vegetation and land-use data bases (1° latitude by 1° longitude resolution), designed for use in studies of climate and climate change, were compiled in digital form drawing upon approximately 100 published sources complemented by a large collection of satellite imagery. The vegetation data were encoded using the UNESCO classification system; land-use data were encoded using a classification system developed by the author. The vegetation and land-use data were then integrated into a land-cover data base. Areal estimates for most ecosystems from the land-cover data base were found to be significantly different from areal estimates derived from two other global land-cover sources. Possible explanations for discrepancies among these data bases include differences in ecosystem definitions and source material used in compilation. From areal estimates of major ecosystems, derived from the new vegetation and land-cover data bases it is estimated that the total ecosystem reduction caused by agricu...
948 citations
TL;DR: The interactive Barnes scheme allows real-time assessments both of the quality of the resulting analyses and of the impact of satellite-derived data upon various meteorological data sets.
Abstract: The Barnes (1973) objective map analysis scheme is employed to develop an interactive analysis package for assessing the impact of satellite-derived data on analyses of conventional meteorological data sets. The method permits modification of the values of input parameters in the objective analysis within objectively determined, internally set limits. The effects of the manipulations are rapidly displayed, and methods are included for assimilating the spatially clustered characteristics of satellite data and the various horizontal resolutions of the data types. Data sets from the SESAME rawinsonde wind data with uniform spatial distribution, with the same data set plus satellite cloud motion data, and a data set from the atmospheric sounder radiometer on the GOES satellite were analyzed as examples. The scheme is demonstrated to recover details after two iterations through the data.
446 citations
TL;DR: In this article, a simple empirical scheme is presented, which gives hourly estimates of the surface fluxes of heat and momentum from routine weather data during daytime, but it is designed for grass surfaces, and it contains parameters which take account of surface properties in general.
Abstract: In this paper a simple empirical scheme is presented, which gives hourly estimates of the surface fluxes of heat and momentum from routine weather data during daytime. The scheme is designed for grass surfaces, but it contains parameters which take account of the surface properties in general. The required input weather data are no more than a single wind speed, air temperature at screen height and total cloud cover. The output of the scheme is in terms of the Monin-Obukhov similarity parameters; it is obtained by using estimates for the mean values of the surface radiation and energy budget. For the climate of the Netherlands good agreement is found between a full year of observations and estimates made with the scheme. For all data it appears that root-mean-square errors are σ = 90 W m−2 for the incoming solar radiation, σ = 63 W m−2 for the net radiation, σ = 34 W m−2 for the sensible heat flux, σ = 0.01 m s−1 for the friction velocity and σ = 0.67 × 10−3 for the similarity ratio between the s...
376 citations
TL;DR: In this paper, a CO2 cloud tracking technique to determine simultaneous heights and velocities of cloud motion winds is presented using animated CO2 channel imagery from VAS, multi-level cloud situations are separated into high, middle and low level cloud motion wind vectors by the CO2 slicing method.
Abstract: A CO2 cloud tracking technique to determine simultaneous heights and velocities of cloud motion winds is presented. Using animated CO2 channel imagery from VAS, multi-level cloud situations are separated into high, middle and low level cloud motion wind vectors by the CO2 slicing method. The VAS CO2 channel radiometric values are used in the CO2 absorption method to assign quantitative heights to the cloud vectors; cloud top pressures are determined from the ratio of the deviations in cloud produced radiances and the corresponding clear air values for three CO2 channels in a radiative transfer equation formulation. Two case studies are presented that show CO2 cloud-motion wind vectors to be in good agreement with radiosonde wind observations and CO2 cloud heights to be within a 50 mb rms deviation of radiosonde, bispectral and stereo height determinations.
288 citations
TL;DR: In this article, the velocity covariance above and within a plant canopy (Zea mays L) was examined using the technique of quadrant analysis to separate the momentum transport into events classified as sweep, ejection and outward and inward interactions.
Abstract: The u, w velocity covariance above and within a plant canopy (Zea mays L) was examined using the technique of quadrant analysis to separate the momentum transport into events classified as sweep, ejection, and outward and inward interactions. A hyperbolic hole of variable size acted as an excluded region in the u, w domain to asses the relative importance of short-lived events of large magnitude. The results of the analysis were a reasonably close match to rough-wall wind tunnel studies but differed in some respects from a similar experiment performed elsewhere in a flexible wheat canopy. Generally, sweeps exceeded ejections in their contribution to the Reynolds stress, especially at mid-canopy, while the interaction events were of minor importance. Sweeps that were large in magnitude relative to the time-averaged stress were evident at all levels and were intermittent in character. Compared with the layers above, the effect of the canopy was to increase the dominance of sweeps over ejections and...
237 citations
TL;DR: The sensitivity of the PDSI was tested in relation to changes of derived and prescribed parameters in order to determine their effect on the spatial characteristics of drought duration as discussed by the authors, and the sensitivity tests indicated a negligible effect.
Abstract: By using the Palmer Drought Severity Index (PDSI) as calculated from state averages of temperature and precipitation and from numerous single station analyses, it has been demonstrated that droughts (as defined by the PDSI) persist longer in the interior of the United States than in areas farther east or west. The question arises whether this is merely an artifact of the PDSI calculations, or whether there is actually more persistence of abnormally dry (wet) weather in the interior. The sensitivity of the PDSI was tested in relation to changes of derived and prescribed parameters included in the PDSI calculations in order to determine their effect on the spatial characteristics of drought duration. The sensitivity tests indicated a negligible effect. Contingency tables which use the PDSI as the predictor for the following one-month, six-month and 12-month precipitation anomalies (and also anomalies of precipitation minus potential evapotranspiration) however, are generally characterized by signif...
216 citations
TL;DR: In this paper, the behavior of the Priestley-Taylor parameter α was investigated using a simplified atmospheric boundary-layer model coupled to the Penman-Monteith equation, and it was found that under conditions typical for a sunny summer day in the mid-latitudes, α is primarily determined by the surface resistance r3.
Abstract: The behavior of the Priestley-Taylor parameter α is investigated using a simplified atmospheric boundary-layer model coupled to the Penman-Monteith equation. It is found that under conditions typical for a sunny summer day in the mid-latitudes, α is primarily determined by the surface resistance r3, (α ≈ 1.3 when r3 = 0, α ≈ 1 when r3 ≈ 60 s m−1, and α ≈ 0.6 when r3 ≈ 250 s m−1). This is in good agreement with, experimental values reported in literature. The model is an extension of the models by McNaughton (1976) and Perrier (1980).
210 citations
TL;DR: In this article, an instrument that remotely senses the integrated amounts of water vapor and liquid on a path through the atmosphere is discussed, which is used for weather forecasting, weather modification, solar-radiation studies and instrumentation for geodetic metrology.
Abstract: An instrument that remotely senses the integrated amounts of water vapor and liquid on a path through the atmosphere is discussed. The vapor and liquid are measured simultaneously but independently by microwave radiometers. Comparison of the accuracy in measurement of vapor is made with radiosondes, and of liquid with an independent method employing transmission from a geosynchronous satellite. The instrument is designed for unattended operation; examples of measured data are given. Applications including observations for weather forecasting, weather modification, solar-radiation studies, and instrumentation for geodetic metrology are also discussed.
209 citations
TL;DR: In this paper, a direct method was described to determine the complete mineral size distribution in aerosol and soils (water-insoluble component) covering a size range from 0.01 up to 100 μm and 1000 μm, respectively, by using a combination of a scanning electron microscope, optical microscope and sieving.
Abstract: A direct method will be described to determine the complete mineral size distribution in aerosol (xylene-insoluble component) and soils (water-insoluble component) covering a size range from 0.01 up to 100 μm and 1000 μm radius, respectively, by using a combination of a scanning electron microscope, optical microscope and sieving. Aerosol and soil samples from the Sahara have been investigated. All mineral aerosol size distributions indicate a maximum between 0.06 and 0.08 μm radius and mineral particles have been found in the Aitken size range down to 0.02 μm radius. The concentration decrease toward larger particles is not uniform and shows considerable variations below 0.5 μm and above 5 μm radius. Volume distributions show a fairly stable mode around 3 μm and a highly variable mode around 30 μm radius. Particles below 5 μm radius can be considered as a well mixed mineral background aerosol, traveling long distances, whereas larger particles seem to be of local origin, activated under strong w...
163 citations
TL;DR: Using state monthly values of the Palmer Drought Index from January 1895 through April 1981, the spatial and temporal features of dry and wet episodes over the contiguous United States were analyzed.
Abstract: Using state monthly values of the Palmer Drought Index from January 1895 through April 1981, thespatial and temporal features of dry and wet episodes over the contiguous United States were analyzed. Thevariance spectrum of the area under both drought and wet spells in the western United States (17 westernmoststates) was also investigated. The main results are as follows. Consistent with the findings of previous investigators, the interior andwestern portions of the United States are found to be more drought-prone than other parts of the country.By contrast, the likelihood of drought occurrence in states near coastal areas is considerably less. Prolongedmoisture abnormalities also tend to occur over the more drought-prone states indicating a tendency towardbimodality (either too dry or too wet). The variance spectrum of the area under drought in the western United States exhibits a red-type spectrum,whereas the wet spell area exhibits relatively greater variance at the highest and intermediate fre...
TL;DR: The Boulder Atmospheric Observatory (BAO) as mentioned in this paper is a unique research facility for studying the planetary boundary layer and for testing and calibrating atmospheric sensors, which includes a 300 m tower instrumented with fast and slow-response sensors, a variety of remote sensing systems, and a real-time processing and display capability that greatly reduces analysis time for scientists working with current or archived data.
Abstract: The Boulder Atmospheric Observatory (BAO) is a unique research facility for studying the planetary boundary layer and for testing and calibrating atmospheric sensors. The facility includes a 300 m tower instrumented with fast- and slow-response sensors, a variety of remote sensing systems, and a real-time processing and display capability that greatly reduces analysis time for scientists working with current or archived data. In the past four years of operation the BAO has been the site of several large cooperative experiments and numerous smaller ones. Details of the data acquisition, processing and archiving schemes are presented. Results of studies conducted and opportunities for future investigations are also described.
TL;DR: In this paper, an air-motion sensing technique for measurement of attack and sideslip angles and dynamic pressure was described, which consists of an array of five pressure holes in the standard radome of a twin-jet research aircraft.
Abstract: An air-motion sensing technique is described for measurement of attack and sideslip angles and dynamicpressure. The sensing probe consists of an array of five pressure holes in the standard radome of a twin-jetresearch aircraft. Comparisons are made with air motion measurements (angle of attack and dynamic pressure) obtained from a conventional differential pressure flow angle sensor at the tip of a nose boom 1.5fuselage diameters ahead of the aircraft body. The results indicate that the radome system works well downto scale sizes slightly larger than the fuselage diameter. (Finer scale measurements were limited by pressuretransducer response.) An insitu calibration technique is described for the determination of the empiricalradome angle-pressure difference sensitivity factor k, as a function of aircraft Mach number. The value ofk, so determined at low Mach numbers, is in approximate agreement with that calculated for potential flowfor a spherical radome. The in-situ technique applied to the con...
TL;DR: Some physical causes of United States drought are outlined in this paper, including subsidence, either in the upper level anticyclones or to the south of strong jets, or sometimes under prevailing northerly components of upper level flow.
Abstract: Some physical causes of United States drought are outlined. Among the associated factors is subsidence,either in the upper level anticyclones or to the south of strong jets, or sometimes under prevailing northerlycomponents of upper level flow. These conditions are engendered by abnormal forms of the atmosphere'sgeneral circulation. Causative factors vary in kind and degree according to area, so that droughts over theFar West differ from those of the Great Plains or the East. Examples of each of these are shown as well astreatment of a rapidly developing drought. It should be obvious from this report that a successful numerical(dynamical) solution of the drought problem should be high on meteorologists' agendas.
TL;DR: In this paper, the authors used satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes and investigated the optical thickness of aerosol from the surface and found that first eigenvalue of the covariance matrix of all observations accounts for 99% of the trace of the matrix.
Abstract: In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band λ440–870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99% of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 μm. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend an several aerosol parameters, but it is difficult to ...
TL;DR: A 248-year reconstruction of the low-flow (July, August and September) period of the Potomac River indicates that the prolonged drought of the 1960s may have been the most severe since 1730 as mentioned in this paper.
Abstract: A 248-year reconstruction of the low-flow (July, August and September) period of the Potomac River indicates that the prolonged drought of the 1960s may have been the most severe since 1730. However, there appear to have been several long periods of about 50 years in length when flow was generally above or below the long-term median flow. The period from 1900 through 1950, which comprises most of the measured flow period, was generally above median. Long-period climatic shifts can have important water resource implications. The Potomac River streamflow at Point of Rocks, Maryland was reconstructed by using tree-ring chronologies from sites in or near the river basin. Canonical regression analysis was used to reconstruct simultaneously July, August and September discharge after screening all the tree-ring predictors. Verification statistics and cross-spectral analysis indicate that the average reconstruction of these three months is most reliable for periods longer than about six years and shorter...
TL;DR: In this article, the snow cover extent during the autumn months in both North America and Eurasia has been related to the ensuing winter temperature as measured at several locations near the center of each continent.
Abstract: In this study the snow cover extent during the autumn months in both North America and Eurasia has been related to the ensuing winter temperature as measured at several locations near the center of each continent. The relationship between autumn snow cover and the ensuing winter temperatures was found to be much better for Eurasia than for North America. For Eurasia the average snow cover extent during the autumn explained as much as 52 percent of the variance in the winter (December-February) temperatures compared to only 12 percent for North America. However, when the average winter snow cover was correlated with the average winter temperature it was found that the relationship was better for North America than for Eurasia. As much as 46 percent of the variance in the winter temperature was explained by the winter snow cover in North America compared to only 12 percent in Eurasia.
TL;DR: In this paper, an empirical formula is suggested to predict the hourly average lateral turbulence intensity as a function of wind speed and hour-to-hour variation in wind direction, and it is suggested that nighttime diffusion cannot be accurately predicted using onsite observations of wind fluctuations.
Abstract: There is much evidence in the literature for the presence of mesoscale lateral meanders in the stable nighttime boundary layer. These meanders result in relatively high lateral turbulence intensities and diffusion rates when averaged over an hour. Anemometer data from 17 overnight experiments at Cinder Cone Butte in Idaho are analyzed to show that the dominant period of the mesoscale meanders is about two hours. Lidar cross-sections of tracer plumes from these same experiments show that the hourly average σ y is often dominated by meandering. Since meandering is not always observed for given meteorological conditions, it is suggested that nighttime diffusion cannot be accurately predicted without using onsite observations of wind fluctuations. In case no turbulence data are available, an empirical formula is suggested that predicts the hourly average lateral turbulence intensity as a function of wind speed and hour-to-hour variation in wind direction.
TL;DR: In this paper, a model is described which simulates icing on an unheated, non-rotating cylinder and the model computes the thermodynamic conditions and initial icing rate as a function of angle around the upstream face of the cylinder.
Abstract: A model is described which simulates icing on an unheated, non-rotating cylinder. Both rime and glaze ice can be accounted for. The model computes the thermodynamic conditions and the initial icing rate as a function of angle around the upstream face of the cylinder. Although the model is not time-dependent, the initial icing rate can be used to compute local ice thickness after a specified time interval, and these in turn allow one to plot the ice accretion profile in either a single-step or multi-step fashion. Thus it is possible to predict total ice accretion cross-sectional area and mass for ice grown under varying conditions of airspeed, air temperature and pressure, cloud liquid water content, droplet size distribution, and cylinder size. Results are presented on the stagnation line growth rate as a function of liquid water content and airspeed, and examples of accretion profiles over a range of environmental conditions are provided. Although the model may be applied quite generally, the mo...
TL;DR: In this article, a vertically scanning, airborne, pulse-Doppler radar is described and an intercomparison with a ground-based Doppler network is conducted.
Abstract: A vertically scanning, airborne, pulse-Doppler radar is described. Data processing methods to yield pseudo-dual-Doppler horizontal winds are presented. Results of an intercomparison with a ground-based dual-Doppler network are presented and discussed. These results indicate that the accuracy of the Doppler estimates are not seriously degraded by the aircraft's motion in a nonturbulent environment. Reasonable wind velocities were obtained in a stratiform precipitation (pre-warm-frontal) regime despite relatively long time periods for data gathering (∼20 min). Potential error sources are discussed, with the principal conclusion being that the uncertainty in the airborne Doppler mean velocity estimates are slightly larger than would be expected for a ground-based Doppler. However, the time period over which data are gathered is much longer than for a ground-based dual-Doppler network. Potential modifications to the antenna and data system to improve data quality are also discussed.
TL;DR: In this paper, a remote sensing system for continuously profiling the troposphere is discussed; the prototype Profiler utilizes radio wavelengths, thereby achieving essentially all-weather operation, and it employs radiometric and Doppler radar technology.
Abstract: A remote-sensing system for continuously profiling the troposphere is discussed; the prototype Profiler utilizes radio wavelengths, thereby achieving essentially all-weather operation. Designed for unattended operation, the Profiler employs radiometric and Doppler radar technology. Design, construction and calibration of the instruments composing the Profiler system are described along with some of the physics and mathematics upon which their operation is based. Examples of profiles and other variables of meteorological interest are given, and comparisons are made with simultaneous data from colocated operational (NWS) sondes. An algorithm based on climatological statistics of measurements by radiosonde is used in the radiometric retrieval process, but there is no reliance of the products of the Profiler upon any current radiosonde data. The role of the Profiler in mesoscale and synoptic weather forecasting and its relationship to systems employing sounders on satellite platforms are also discussed.
TL;DR: In this paper, a specific study was made of the effect of two different climate scenarios on crop yields in England and Wales with regression models constructed using a principal components regression technique, with most crops showed a decrease in yield for both warm-world scenarios, with largest decreases for hay yield and least effect on wheat yield.
Abstract: Scenarios for Europe in a warmer world, such as may result from increased atmospheric carbon dioxide levels, have been constructed using the early 20th century warming as an analogue. The climate scenarios are used to construct scenarios of the impact of a global warming on energy consumption and agriculture. Cool winters alone would imply greater energy demand for space heating, but this is largely offset by warmer temperatures in spring and autumn which reduce the length of the heating season. Increased temperature variability combined with a general cooling during winter over north and northwestern Europe suggests a greater frequency of severe winters, and thus larger fluctuations in the demand for heating energy. The impact on agriculture is difficult to assess because of the complexity of crop-climate relationships and because of the importance of nonclimatic factors associated with technological change and perhaps, with enhanced photosynthesis due to increased carbon dioxide concentrations. In northern latitudes, the increase in the length of the growing season would appear to be favorable for agriculture, but warmer summers, drier springs and wetter autumns would be less favorable. A specific study was made of the effect of two different climate scenarios on crop yields in England andmore » Wales with regression models constructed using a principal components regression technique. Most crops showed a decrease in yield for both warm-world scenarios, with largest decreases for hay yield and least effect on wheat yield. A similar regression analysis of French wine-quality showed an improvement in the quality of Bordeaux and Champagne in a warmer world. 52 references, 5 figures, 2 tables.« less
TL;DR: In this article, the results of a surface-layer experiment near the Cabauw meteorological mast were discussed, where the authors measured momentum, heat and moisture fluxes at two heights, namely, 3.5 and 22.5 m. The measurements also included the mean wind speed and mean temperature profiles.
Abstract: This paper discusses the results of a surface-layer experiment near the Cabauw meteorological mast. We measured momentum, heat and moisture fluxes at two heights, namely, 3.5 and 22.5 m. The measurements also include the mean wind speed and mean temperature profiles. The purpose was to investigate surface-layer similarity laws under nonideal fetch conditions. We found that under such conditions, the shell stress increases with height because of obstacles upstream. As a consequence flux-profile relationships differ from those over uniform terrain. It is shown that these deviations imply a slow relaxation in the exchange coefficient for heat and momentum over a terrain with changing surface roughness. Furthermore, we found that horizontal velocity fluctuations scale on a friction velocity representative of a large area. On the other hand, vertical velocity fluctuations scale on the local friction velocity.
TL;DR: In this paper, total ozone variations have been updated through 1981 for four regions in north temperate latitudes, the five climatic zones, both hemispheres, and the world.
Abstract: Total-ozone variations have been updated through 1981 for four regions in north temperate latitudes, the five climatic zones, both hemispheres, and the world. Also updated through 1981 are ozone values in height layers 32–48 km, 24–32 km, 16–24 km, 8–16 km and 2–8 km, based on Umkehr and ozonesonde observations mainly in north temperate latitudes. The data are presented in terms of year-average values and smoothed seasonal values. On the basis of linear regression applied to year-average values, between 1970 and 1981 the change in total ozone was −0.5% in north temperate latitudes, −1.2% in the Northern Hemisphere, and −0.4% for the world, none significant at the 5% level. Between 1958 and 1981 the respective values were 1.3%, 1.0% and 0.6%, none significant. We find little evidence of a decrease in total ozone following the large nuclear explosions in 1961 and 1962. In the 32–48 km layer sensitive to anthropogenic effects, Umkehr observations suggest an ozone decrease in north temperate latitude...
TL;DR: In this article, a semi-physical model based on standard meteorological data was developed to estimate solar radiation received at the earth's surface, including the effects of Rayleigh scattering, absorption by water vapor and permanent gases, and absorption and scattering by aerosols and clouds.
Abstract: Solar radiation information is used in crop growth, boundary layer, entomological and plant pathological models, and in determining the potential use of active and passive solar energy systems. Yet solar radiation is among the least measured meteorological variables. A semi-physical model based on standard meteorological data was developed to estimate solar radiation received at the earth's surface. The radiation model includes the effects of Rayleigh scattering, absorption by water vapor and permanent gases, and absorption and scattering by aerosols and clouds. Cloud attenuation is accounted for by assigning transmission coefficients based on cloud height and amount. The cloud transmission coefficients for various heights and coverages were derived empirically from hourly observations of solar radiation in conjunction with corresponding cloud observations at West Lafayette, Indiana. The model was tested with independent data from West Lafayette and Indianapolis, Madison, WI, Omaha, NE, Columbia,...
TL;DR: In this paper, droplets freely suspended in the air stream of a wind tunnel were nucleated with dedicated bacterial cells in either the contact or immersion mode, and the temperature ranges over which droplets froze by either mode of nucleation were closer to 0°C than those so far published for nonbiogenic ice nuclei of natural origin.
Abstract: Droplets freely suspended in the air stream of a wind tunnel were nucleated with dedicated bacterial cells in either the contact or immersion mode. Immersion freezing seemed to give a noncontinuous frequency distribution of freezing with temperature whereas the corresponding curve for contact was monotonic. Although the latter nucleation mode was more efficient by ∼2°C, the temperature ranges over which droplets froze by either mode of nucleation were closer to 0°C than those so far published for nonbiogenic ice nuclei of natural origin.
TL;DR: In this article, it was shown that very cold brightness temperature cases all coincided with heavy thunderstorm rainfall, with the cold temperatures being attributable to scattering by a layer of ice hydrometeors in the upper parts of the storms.
Abstract: Brightness temperatures obtained through examination of microwave data from the Nimbus 7 satellite are noted to be much lower than those expected on the strength of radiation emanating from rain-producing clouds. Very cold brightness temperature cases all coincided with heavy thunderstorm rainfall, with the cold temperatures being attributable to scattering by a layer of ice hydrometeors in the upper parts of the storms. It is accordingly suggested that brightness temperatures observed by satellite microwave radiometers can sometimes distinguish heavy rain over land.
TL;DR: A detailed size calibration of the Forward Scattering Spectrometer Probe (FSSP) over the size ranges of interest to cloud physics (2-47 μm) is presented in this paper.
Abstract: A detailed size calibration of the Forward Scattering Spectrometer Probe (FSSP) over the size ranges of interest to cloud physics (2–47 μm), is presented. The calibration includes laboratory tests with glass spheres, Mie scattering calculations and airborne cloud measurements. Each size bin of the FSSP was found to have errors of 0–5 μm in diameter. The magnitude and sign of the errors were dependent on airspeed for airspeeds greater than 55 m s−1. This sizing error can lead to errors of 70% or more in derived cloud liquid water content. In addition, a concentration algorithm was derived from laboratory tests with pseudo-random pulse generators which properly corrects for probe dead time. After application of both calibration algorithms the instrument is capable of yielding mean diameters that agree with predicted mean diameters to within a few tenths of a micron and liquid water contents which are in good agreement with an independent liquid water measurement. Even after corrections, the instrum...
TL;DR: The Man Computer Interactive Data Access System (McIDAS) as mentioned in this paper allows remote and local access to a wide range of data from satellites and conventional observations, time lapse displays of imagery data, overlaid graphics, and current and past meteorological data.
Abstract: A powerful facility for meteorological analysis called the Man Computer Interactive Data Access System (McIDAS) was designed and implemented in the early 1970's at the Space Science and Engineering Center of the University of Wisconsin-Madison. Hardware and software experience gained via extensive use of that facility and its derivatives have led to a newer implementation of McIDAS on a larger computer with significant enhancements to the supporting McIDAS software. McIDAS allows remote and local access to a wide range of data from satellites and conventional observations, time lapse displays of imagery data, overlaid graphics, and current and past meteorological data. Available software allows one to perform analysis of a wide range of digital images as well as temperature and moisture sounding data obtained from satellites. McIDAS can generate multicolor composites of conventional and satellite weather data, radar and forecast data in a wide variety of two- and three-dimensional displays as well as time lapse movies of these analyses. These and other capabilities are described in this paper.
TL;DR: In this article, a collection of experimental data concerning turbulent characteristics of the convective boundary layer is presented, including vertical turbulent fluxes of sensible and latent heat, second-order moments of vertical wind component, potential temperature and humidity, dissipative and spectral characteristics and length scales.
Abstract: We present a collection of experimental data concerning turbulent characteristics of the convective boundary layer. These data were obtained by means of instrumented aircraft during numerous experiments carried out above five flight areas from 1973 to 1978. Only dry convective conditions with weak dynamic instability are contained in this report. The computed quantities are vertical turbulent fluxes of sensible and latent heat, second- and third-order moments of vertical wind component, potential temperature and humidity, dissipative and spectral characteristics and length scales. All these quantities are normalized using the convective similarity hypothesis of Deardorff. A particular case is considered for humidity where it is necessary to choose between the two boundary conditions: evaporation and entrainment flux. The latter is chosen.