Showing papers in "Journal of Applied Meteorology in 1990"
TL;DR: In this article, a simple model of evaporation from a bare soil surface is developed, which combines two processes of water vapor transport: one is the vapor transport in air expressed by the bulk formula, and the other is molecular diffusion of vapor in the surface soil pore with the vapor being carried from the interior of the soilpore to the land surface.
Abstract: A simple model of evaporation from a bare soil surface is developed. This model combines two processes of water vapor transport: one is the vapor transport in air expressed by the bulk formula, and the other is molecular diffusion of vapor in the surface soil pore with the vapor being carried from the interior of the soil pore to the land surface. The resistance to the vapor diffusion in the soil pore is expressed using a new parameter, estimated by experimental means. General formulation of the so-called “surface moisture availability” is expressed with this model. The formulation shows that the “surface moisture availability” depends not only on volumetric soil moisture, but also on wind velocity, and on the ratio of the specific humidity of the air to that of the saturation value at the soil surface temperature. This dependence agrees with experiments performed with loam and sand under various conditions. In the evaporation parameterization used in current numerical simulations, the humidity o...
268 citations
TL;DR: The mass, dimensions, and habits of over 2800 natural ice particles precipitating from orographic winter storms in the central Sierra Nevada were obtained using photomicrographs as discussed by the authors.
Abstract: The masses, dimensions, and habits of over 2800 natural ice particles precipitating from orographic winter storms in the central Sierra Nevada were obtained using photomicrographs. Ice particles that could be unambiguously classified were used to generate empirical expressions relating snow particle masses and dimensions. Many of the ice particle types had not been investigated previously. The influence of riming and aggregation on ice particle masses was examined. When possible, comparisons are made between these results and those of other experimental observations. By incorporating these mass-dimensional relationships into an expression for the ice mass content in a snowstorm, it was possible to estimate the mass fraction of the fresh snowpack resulting from accreted supercooled cloud water. The results from two storms analyzed suggest that about 30 to 40 percent of the deposited snow is composed of accreted cloud water during moderately rimed snowfall.
231 citations
TL;DR: A review of existing literature is made to determine typical values for the physical properties of cirrus clouds as mentioned in this paper, with typical values and measured ranges of cloud-center altitude (9 km, 4 to 20 km), cloud thickness (1.5 km, 0.1 to 8 km), crystal number density (30 L−1, 10−4 to 10−5 L−4 L− 1), condensed water content (0.025 g m −3), and crystal size (250 μm, 1 to 8000 μm).
Abstract: A review of existing literature is made to determine typical values for the physical properties cirrus clouds. The properties examined (with typical values and measured ranges) are cloud-center altitude (9 km, 4 to 20 km), cloud thickness (1.5 km, 0.1 to 8 km), crystal number density (30 L−1, 10−4 to 10−4 L−1), condensed water content (0.025 g m −3, 10−4 to 1.2 g m −3), and crystal size (250 μm, 1 to 8000 μm). A typical crystal size distribution is also reported.
192 citations
TL;DR: In this paper, three different longwave broadband radiation parameterization schemes were tested against a reference narrow-band model in clear sky conditions and the three schemes gave rather similar results and the emissivity dependence on water vapor path length was tuned to give best fit to the reference.
Abstract: Three fast and simple longwave broadband radiation parameterization schemes were tested against a reference narrow-band model in clear sky conditions. The three schemes gave rather similar results. The emissivity dependence on water vapor path length was tuned to give best fit to the reference. The smaller other gas, aerosol and continuum circus were added in a simple fashion both to the radiative cooling and to the longwave downward flux at the surface. Clouds are handled as blackbodies. In the shortwave scheme the attenuation of solar radiation due to variable water vapor and gray clouds, but average ozone and other gas absorption, aerosols and Rayleigh scattering are taken into account and tuned by surface observations of solar flux. The water vapor absorptivity for solar heating was fitted by line-by-line model results.
187 citations
TL;DR: In this article, the activities of nearly monodisperse soot particles as ice nuclei at temperatures below −20°C were examined in a short series of experiments, where a continuous slow expansion cloud chamber was used to cause cloud formation and growth on soot during simulations of adiabatic cooling by expansion.
Abstract: The activities of nearly monodisperse soot particles as ice nuclei at temperatures below −20°C were examined in a short series of experiments. A continuous slow expansion cloud chamber was used to cause cloud formation and growth on soot during simulations of adiabatic cooling by expansion. Soot was generated using an acetylene burner operating near the sooting limit. Activity as ice nuclei was measured as clouds cooled to the apparent homogeneous-freezing temperatures of the cloud droplets. Immersion-freezing nucleation appears to be a particularly dominant heterogeneous mode for these particles. The preliminary results suggest that activity by immersion-freezing increases with particle size.
179 citations
TL;DR: In this paper, one-and two-layer resistance models are developed to account for some of the factors causing the poor agreement between computed and measured evapotranspiration values.
Abstract: One of the applications of remotely sensed surface temperature is to determine the latent heat flux (LE) or evapotranspiration (ET) from held to regional scales A common approach has been to use surface-air temperature differences in a bulk resistance equation for estimating sensible beat flux, H, and to subsequently solve for LE as a residual in the one-dimensional energy balance equation This approach has been successfully applied over uniform terrain with nearly full, actively transpiring vegetative cover; however, serious discrepancies between estimated and measured ET have been observed when there is partial canopy cover In an attempt to improve the estimates of H and as a result compute more accurate values of ET over partial canopy cover, one- and two-layer resistance models are developed to account for some of the factors causing the poor agreement between computed and measured ET The utility of these two approaches for estimating ET at the field scale is tested with remotely sensed a
172 citations
TL;DR: In this paper, a heat balance model was developed to predict the snow surface temperature and freezing depth. But, the model is not suitable for the use of incident radiation data, which is required for operation of the model.
Abstract: A snowmelt model based on a heat balance method has been developed. This model takes into account both the heat balance at the snow surface and that of the entire snow cover and simultaneously predicts the snow surface temperature and freezing depth. Observed or estimated incident radiation data are required for operation of the model. Calculated amounts of snowmelt and snow surface temperatures were in agreement with those observed. Dependency of snowmelt on several parameters including maximum liquid water content, thermal conductivity and albedo of the snow was examined. It was found that as liquid water content or thermal conductivity increases, snowmelt decreases. Albedo is very influential in evaluating snowmelt. Runoff from a basin having an area of 583 km2 was estimated using the present model, and was verified by the inflow data to a dam.
138 citations
TL;DR: In this paper, exact analytical solutions of the Monin-Obukhoy stability parameters ζ=z/L, in terms of gradient Richardson number and bulk Richardson number (Rib), respectively, are obtained.
Abstract: Analytical solutions Of surface layer similarity equations are presented for the nondimensional profile functional forms suggested by Businger et al. For stable atmospheric conditions, exact analytical solutions of the Monin-Obukhoy stability parameters ζ=z/L, in terms of gradient Richardson number (Ri) and bulk Richardson number (Rib), respectively, are obtained. For unstable atmospheric conditions, an exact solution of the same in terms of Ri is found. An approximate relationship between ζ and Rib, for an unstable surface layer, based on the solution of ζ in terms of Ri, is suggested. The proposed analytical solutions can replace costly numerical iterative methods as well as some of the ad hoc parameterizations used for estimating surface fluxes and related turbulence characteristics.
129 citations
TL;DR: In this paper, a multispectral technique was developed and evaluated for discriminating between clouds, snow-covered land and snow-free land in satellite image data, based primarily on the derived channel 3 reflectance.
Abstract: An algorithm is developed and evaluated for discriminating between clouds, snow-covered land and snow-free land in satellite image data. The multispectral technique uses daytime images of NOAA AVHRR channels 1 (0.63 μm), 3 (3.7 μm), and 4 (11.0 μm). Reflectance is derived for channel 3 by using the channel 4 emission temperature to estimate and remove the channel 3 thermal emission. Separation of clouds from snow and land is based primarily on the derived channel 3 reflectance. Observed reflectance in channel 3 is 0.02 to 0.04 for snow, 0.03 to 0.10 for land, 0.02 to 0.27 for ice clouds and 0.08 to 0.36 for liquid clouds. These ranges overlap for thin cirrus and snow, so the routine attempts analysis of cirrus based on differences in transmission between channels 3 and 4. Six case were analyzed and the total cloud cover was verified against a total of 110 surface observations in the standard categories of clear, scattered, broken and overcast. One of the cases is presented in detail to illustrate...
127 citations
TL;DR: In this article, a two-channel radiometer is proposed to estimate atmospheric total water vapor amounts from space, which consists of viewing the Earth's surface in two spectral channels, one narrow, the other wide, centered on the same wavelength at the water vapor absorption maximum near 940 nm.
Abstract: A new technique is proposed to estimate atmospheric total water vapor amounts from space. The technique consists of viewing the Earth's surface in two spectral channels, one narrow, the other wide, centered on the same wavelength at the water vapor absorption maximum near 940 nm. With these characteristics, the ratio of the solar radiance measured in the two channels is independent of the surface reflectance and yields a direct estimate of the water vapor amount integrated along the optical path. To test the technique, we designed and built a two-channel radiometer based on the above concept. Airborne experiments carried out with the new device demonstrate the technique's feasibility under clear sky conditions over both sea and land. Over the ocean and in the presence of thick aerosol layers, however, total water vapor amounts may be underestimated by as much as 20%. Compared to satellite microwave techniques, which are applicable under most weather conditions, the proposed technique has the adva...
124 citations
TL;DR: In this article, a computationally turbulence closure scheme is formulated and evaluated using a mesoscale model containing prognostic equations for mean momentum, heat and turbulent kinetic energy, and a one-dimensional version of this highly simplified scheme is evaluated against turbulence measurements from stable, neutral and convective atmospheric boundary layer.
Abstract: A computationally turbulence closure scheme is formulated and evaluated. The scheme includes a correction to the redistribution terms in order to account for the influence of the underlying surface. Care is taken in order to ensure realizability in simulated fields. The formulation is implemented in a mesoscale model containing prognostic equations for mean momentum, heat and turbulent kinetic energy. All other second moments are obtained through diagnostic expressions. A one-dimensional version of this highly simplified scheme is evaluated against turbulence measurements from stable, neutral and convective atmospheric boundary layer. Inclusion of wall effects is shown to improve the performance of the closure when applied to the atmospheric boundary layer. It gives a better prediction of ratios between velocity variances, of importance particularly for air pollution applications. Discrepancies found in the upper 40% of the convective boundary layer suggest that the additional computational effor...
TL;DR: In this article, a simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometeor profiles is proposed, which is based on output generated by a nonhydrostatic cloud model with parameterized microphysical processes.
Abstract: A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometeor profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a nonhydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algoritm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.
TL;DR: In this article, an effort is made to determine relationships between reflectivity (Z) and rain rate (R) which are tuned to the local climatology, where the relation is tuned so that the probability distribution of reflectivity, P(Z), replicates that of R over some predetermined space-time climatic domain.
Abstract: An effort is made to determine relationships between reflectivity (Z) and rain rate (R) which are tuned to the local climatology. The development of such relations was motivated by the need to understand the role of precipitation in controlling general circulation and in affecting such phenomena as ENSO. Attention is given to methods of deriving such relations and how they are linked to area integral rainfall measurements. In essence, the relation is tuned so that the probability distribution of reflectivity, P(Z), replicates that of R over some predetermined space-time climatic domain. Thus, the accurate measurement of the average R over any smaller domain depends on how closely the sampled P(Z) approximates the climatic P(Z). The probability matching method used is a modification of the approach of Calheiros and Zawadzki (1987) and Rosenfeld (1980). The technique is applied to data from Germany and the eastern tropical Atlantic (GATE).
TL;DR: In this article, a new IGMK model was developed to explicitly account for multiple reflections between surface and atmospheric layers, which is most important for the diffuse component of global radiation.
Abstract: For a better understanding, of climate, as well as all kinds of solar power applications it is necessary to know about incoming solar radiation at the surface (global radiation) and its partition into disuse and direct components Over the last ten years, several studies have been undertaken to demonstrate the capability of satellite-based methods for analyzing the downward solar radiation at the surface. At the University of Koin the so-called IGMK model was developed by Moser and Raschke to determine global radiation from geostationary satellite data. We now present some improvements of this IGMK model. These improvements include a totally new treatment of cloud transmittance in combination with the clear-sky atmospheric state. In this new algorithm we now explicitly account for multiple reflections between surface and atmospheric layers, which is most important for the diffuse component of global radiation. Thus, one additional major advantage of the new IGMK model is that the diffuse component...
TL;DR: The split window technique as discussed by the authors makes use of two differentially absorbing channels in the 11 μm region to remove the attenuating effects of atmospheric absorption so as to achieve a better estimate of the underlying skin temperature than could be produced by a single channel measurement.
Abstract: The split window technique makes use of two differentially absorbing channels in the 11 μm region to remove the attenuating effects of atmospheric absorption so as to achieve a better estimate of the underlying skin temperature than could be produced by a single channel measurement. Since the primary absorber in this region is water vapor, it follows that split window measurements should be able to produce bulk water vapor retrievals as well. When observations are made with split window channels under conditions where the surface contribution to measured radiance changes, but the atmospheric contribution does not, it is possible to estimate the ratio of the transmittance of the two split window channels. This transmittance ratio is inversely related to precipitable water. This paper applies this technique to observations from the Advanced Very High Resolution Radiometer, and the VISSR Atmospheric Sounder, and demonstrates the capability of both instruments to determine precipitable water under tw...
TL;DR: In this article, a best-fit power-law relationship between 1-minute integrated averages of snowfall rate and radar reflectivity factor (Z) was determined on the basis of observations made by using high sensitivity snow gauges (accuracy 0.03 mm h−1) and a radar (wavelength 3.2 cm, beamwidth 1.1°) of three 1987 Sapporo snowstorms.
Abstract: A best-fit power-law relationship (Z = 427 R1.09) between 1-minute integrated averages of snowfall rate (R) and radar reflectivity factor (Z) was determined on the basis of observations made by using high sensitivity snow gauges (accuracy 0.03 mm h−1) and a radar (wavelength 3.2 cm, beamwidth 1.1°) of three 1987 Sapporo snowstorms. The relationship Z = 554R0.88, using 30-minute integrated averages of Z and R, produced the best radar estimate of total snowfall. The ratio of the estimated to the observed amount of snowfall decreased with increasing density of new fallen snow ρ, the ratio roughly equaling 1, when ρ ≈ 0.05 g cm−3.
TL;DR: In this article, it was shown that the area-average rain rate and the fractional area covered by rain rate exceeding a fixed threshold are highly correlated; that is, are highly linearly related.
Abstract: Experimental evidence shows that the area-average rain rate and the fractional area covered by rain rate exceeding a fixed threshold are highly correlated; that is, are highly linearly related. A precise theoretical explanation of this fact is given. The explanation is based on the observation that rain rate has a mixed distribution, one that is a mixture of a discrete distribution and a continuous distribution. Under a homogeneity assumption, the slope of the linear relationship depends only on the continuous part of the distribution and as such is found to be markedly immune to parameter changes. This is illustrated by certain slope surfaces obtained from three specific distributions. The threshold level can be chosen in an optimal way by minimizing a certain distance function defined over the threshold range. In general, the threshold level should be not too far from the mean rain rate conditional on rain. The so-called threshold method advocates measuring rainfall from fractional area exploiting the observed linear relationship of the later with the area average rain rate. The method is potentially useful for the estimation of rainfall from space via satellites.
TL;DR: In this paper, a technique that uses the spatial variance of image brightness temperature to derive total column precipitable water is applied to high-resolution multispectral aircraft scanner data for the June 19, 1986 COHMEX day.
Abstract: A technique that uses the spatial variance of image brightness temperature to derive total column precipitable water is applied to high-resolution multispectral aircraft scanner data for the June 19, 1986 COHMEX day. The technique has several advantages over other approaches in that it requires only relative calibration accuracy, is less susceptible to instrument error, and does not directly use a priori information. Results indicate significant horizontal variability of precipitable water at the mesoscale. Precipitable water gradients of 6 mm per 10 km are not uncommon. The results verify well against special rawinsonde measurements and the ensuing cloud field development. While only applied to this specialized aircraft data, the applicability of the technique to operational AVHRR and VAS data is discussed.
TL;DR: A survey of pilots, air traffic controllers and meteorologists was conducted in Australia from 1 November 1987 to 31 January 1988 to test the hypothesis that a necessary condition for the formation of dust devils is −h/L⩾50, where h is the convective boundary layer height and L the Obukhov length.
Abstract: Following a suggestion by Deardorff, Hess et al. have proposed that a necessary condition for the formation of dust devils is −h/L⩾50, where h is the convective boundary layer height and L the Obukhov length. A survey of pilots, air traffic controllers and meteorologists was conducted in Australia from 1 November 1987 to 31 January 1988 to test this hypothesis. The results of the survey showed that this criterion was satisfied for each dust devil event. Furthermore, the results were consistent with the idea that convective downdrafts play an important role in initiating dual devils. In strongly convective conditions there were two preferred heights attained by the dust—one at ≈0.09h(the height of the convergence wall between cells) and the other ≈0.51h(the height at which the vertical divergence of the updraft changes sign). The number density in these conditions is ≈4 per area of h2. The survey showed that dust devils on density currents have a different geometry; they have diameters five times ...
TL;DR: In this paper, large (128 × 128 cm) pieces of chemically treated blotting paper were exposed to rain and both the size and position of the drops were determined, indicating that the spatial distribution is fractal.
Abstract: Large (128 × 128 cm) pieces of chemically treated blotting paper were exposed to rain and both the size and position of the drops were determined. Analyses were performed indicating that the spatial distribution is fractal. This implies that drops cluster over all the observed scales and, hence, that backscattered microwave radiation from weather radars will have a degree of coherent scattering and a systematic dependence on the measurement resolution not accounted for in the standard theory. This was quantified by two scaling exponents, and a scheme to correct radar measurements for these fractal effects was developed.
TL;DR: In this paper, the initialization and forecast fields from the National Weather Service's (NWS) Nested Grid Model (NOM) were archived on the 90 km calculational grid at 2-hour intervals out to 12 hours twice per day, for the 3-month period of January-March 1987.
Abstract: Initialization and forecast fields from the National Weather Service's (NWS) Nested Grid Model (NOM) were archived on the 90 km calculational grid at 2-hour intervals out to 12 hours twice per day, for the 3-month period of January–March 1987. The resulting time series of meteorological data were used to determine the sensitivity of calculated trajectories to changes in temporal and spatial density of meteorological data during a wide range of synoptic conditions. Trajectories were started from 63 evenly spaced locations, twice per day, for a duration of 4 days each over the 74-day period. The 9324 separate trajectories were computed using the meteorological data at 90, 180, and 360 km grid spacing and at 2-, 4-, 6-, and 12-hour time intervals. Calculated trajectories were compared with the base “truth” case of 2-hour data on the 90 km grid. Trajectories were most sensitive to changes in temporal resolution when the grid resolution was 90 and 180 km. Trajectories computed on the coarser 360 km gr...
TL;DR: In situ snow particle size spectra measured by Particle Measuring Systems probes near the downwind shore of Lake Michigan during lake-effect snow storms are presented and discussed in this article, where evidence of particle aggregation at −25°C.
Abstract: In situ snow particle size spectra measured by Particle Measuring Systems probes near the downwind shore of Lake Michigan during lake-effect snow storms are presented and discussed. Ice water contents ranged from 0.002 to 0.264 g m−3. Concentrations of sizes larger than 1 mm were generally exponentially distributed; however, concentrations of smaller particles usually were greater than suggested by the exponential fitted to concentrations of sizes larger than 1 mm. Exponential distribution parameters (N0 and λ) are consistent with previously reported values. There is evidence of particle aggregation at −25°C.
TL;DR: In this paper, a high spectral resolution interferometer sounder (GHIS) was designed for flight on future geostationary meteorological satellites and demonstrated the capability to observe the earth-emitted radiance spectrum with high accuracy.
Abstract: A high spectral resolution interferometer sounder (GHIS) has been designed for flight on future geostationary meteorological satellites. It incorporates the measurement principles of an aircraft prototype instrument, which has demonstrated the capability to observe the earth-emitted radiance spectrum with high accuracy. The aircraft results indicate that the theoretical expectation of 1°C temperature and 2°–3°C dewpoint retrieval accuracy will be achieved. The vertical resolution of the water vapor profile appears good enough to enable moisture tracking in numerous vertical layers thereby providing wind profile information as well as thermodynamic profiles of temperature and water vapor.
TL;DR: In this paper, the authors show that the presence of thermal effects is necessary to correctly interpret the physical processes involved in the generation or suppression of Reynolds stress and turbulent kinetic energy inside a form canopy.
Abstract: This paper shows that the inclusion of thermal effects is necessary to correctly interpret the physical processes involved in the generation or suppression of Reynolds stress and turbulent kinetic energy inside a form canopy. In both of thew budgets, thermal effects are largest in the upper third of the canopy where the foliage is densest and the radiation load highest. The magnitude of the buoyant production term in both these budgets increases almost linearly with instability in the upper region of the canopy. The onset of stability exerts a strong influence on the behavior of the shear production in both the budgets of Reynolds stress and turbulent kinetic energy. In strong thermal stratification, the shear production term becomes a sink of Reynolds stress and turbulent kinetic energy in the lower half of the canopy.
TL;DR: In this paper, the authors used high-spatial-resolution Landsat MSS imagery, the cumulus cloud morphology, cloud nearest-neighbor distributions, and cloud clumping scales were investigated.
Abstract: Using high-spatial-resolution Landsat MSS imagery, the cumulus cloud morphology, cloud nearest-neighbor distributions, and cloud clumping scales were investigated. It is shown that the cloud-size distribution can be represented by a mixture of two power laws; clouds of diameters less than 1 km have power-law slope range of 1.4-2.3, while larger clouds have slopes from 2.1 to 4.75. The break in power-law slope occurs at the cloud size that makes the largest contribution to cloud cover. Results suggest that larger clouds grow at the expense of smaller clouds. It was also found that the cloud inhomogeneities have significant impact on radiative fluxes.
TL;DR: In this paper, the effects of echo shape and radar viewing angle on detecting small thunderstorms with the NEXRAD storm identification algorithms are examined, and a new algorithm based on the analysis of 15 storms observed in Florida, Alabama, and New Mexico is proposed that would identify storms as having lightning if 40 dBZ reflectivity is present at the -10 C level and the echo top exceeds 9 km.
Abstract: The effects of echo shape and radar viewing angle on detecting small thunderstorms with the NEXRAD storm identification algorithms are examined. The amorphous low-level echo shapes are modeled as ellipses with major axes ranging from 5-15 km and minor axes varying between 2-5 km. The model echoes are then used to create a 'probability of detection' chart that demonstrates the impact of storm asymmetry on cell identification. The algorithm performance on small thunderstorms observed near Huntsville, Alabama and Kennedy Space Center, Florida is examined. A new algorithm based on the analysis of 15 storms observed in Florida, Alabama, and New Mexico is proposed that would identify storms as having lightning if 40 dBZ reflectivity is present at the -10 C level and the echo top exceeds 9 km. This algorithm would have a 100 percent probability of detecting lightning producing storms 4-33 min before the first flash, a 7 percent false alarm rate and a critical success index of 93 percent.
TL;DR: A series of observations of the three-dimensional wind and thermal structure of the boundary layer was carried out during each summer season from 1986 to 1988 over the western portion of the Kanto plain this article.
Abstract: A series of observations of the three-dimensional wind and thermal structure of the boundary layer was carried out during each summer season from 1986 to 1988 over the western portion of the Kanto plain. The data obtained during five selected days were analyzed, focusing on the sea breeze system which advances north-westward from Tokyo Bay through the Tokyo metropolitan area. A distinct sea breeze front was found on three of the days examined, whereas no front was observed during the remaining two days. The difference in the synoptic weather conditions between the frontal and non-frontal days was small, although a definite difference was found in the convective-scale thermal structure. Temporal and spatial interpolation methods followed by an adjustment using a variational analysis technique were applied to analyze the three-dimensional wind distribution. Trajectories of air parcels wore examined, based on the interpolated wind held. As a result, it was found that, for the frontal case, the upwar...
TL;DR: In this paper, a simulation is performed for the time variation in depth of seasonal snow with variable air temperature and precipitation in Japan, and the calculated snow depth is well fitted to the observed snow depth using the same parameters over eight years.
Abstract: A simulation is performed for the time variation in depth of seasonal snow with variable air temperature and precipitation in Japan. Processes of snow densification and snowmelt are considered for snow depth calculation. The using parameters are a precipitation gage deficiency parameter b, the solid/liquid precipitation portion of total precipitation at air temperature Tc1, temperature dependence of the compactive viscosity factor, the snowmelt at surface of snowcover, and snowmelt at the bottom of the snowcover. The calculated snow depth is well fitted to the observed snow depth using the same parameters over eight years. The characteristics of the parameters are discussed. The value of b is found to be 0.6–1.0. The Tc1 is 0°C at Hokkaido (northern Japan) and 2°–3°C at Honshu (central Japan). The melting index for calculating surface snowmelt is larger in Honshu than in Hokkaido. The viscosity factor takes a low value when the snowcover warms or becomes wet. If air temperature shifts ±2°C, the p...
TL;DR: In this article, the authors used high spectral resolution Interferometer Spectrometer (HIS) data with simultaneous airborne lidar data to investigate the accuracy of cloud height determinations using the COz slicing method.
Abstract: High Spectral Resolution Interferometer Spectrometer (HIS) data are used with simultaneous airborne lidar data to investigate the accuracy of cloud height determinations using the 'COz slicing method'. It is shown that the accuracy of cirrus cloud heights are greatly improved as the spectral resolution and coverage is increased. Since next generation infrared temperature and moisture sounders will yield high spectral resolution with quasicontinuous spectral coverage, improved cloud height accuracies achieved from these sensors will improve soundings in clouded areas and will also improve our global cloud climatology.
TL;DR: In this paper, the amount of dewfall and dewrise to a corn canopy has been estimated over 7 nights by using the Bowen ratio energy balance technique and the soil diffusivity technique, respectively.
Abstract: The amount of dewfall and dewrise to a corn canopy has been estimated over 7 nights by using the Bowen ratio energy balance technique and the soil diffusivity technique, respectively. In addition, the distribution of free liquid water within the plant community has been measured by using Leick plates. By combining the Leick plate results with the foliage area distribution of the plant canopy, the total amount of dew deposition within the plant canopy can also be estimated. On average, both techniques did not show a systematic difference and agreed to within 10%. Moreover, it appeared that the nondimensionized dew profiles within the stand showed a more or less similar shape for all nights. The potential dew formation was calculated for all nights. On average, the potential dew was 30% higher than the actual dew. This offers the opportunity to make reliable total dew estimates, and also, due to similarity, dew profile estimates for a corn canopy from simple micrometeorological data. Model calculat...