Mixing Ratio Values Research Articles

Comparison between Global Latent Heat Flux Computed from Multisensor (SSM/I and AVHRR) and from In Situ Data

The accurate estimate of the latent heat flux (LHF) is important to understand better the coupling between the atmosphere and the ocean and their respective circulation. In the near future, the availability of satellite-derived datasets over long periods will allow us to perform studies that, so far, have only been possible with historic in situ datasets. Therefore, a natural issue to explore is how the computation derived from both data types agree on LHF estimates, Comprehensive Ocean-Atmosphere Data Set (COADS) on one hand and satellite-derived parameters on the other hand are input to a similarity theory-based model and treated in completely equivalent ways to compute global latent heat flux. In order to compute latent heat flux exclusively from satellite measurements, an empirical relationship (Q−W relationship) is used to compute the air mixing ratio from Special Sensor Microwave/Imager precipitable water W and a new one is derived to compute the air temperature also from retrieved W (T−W relationship). First analyses indicate that in situ and satellite LHF computations compare within 40%, but systematic errors increase the differences up to 100% in some regions. By investigating more closely the origin of the discrepancies, the spatial sampling of ship reports has been found to be an important source of error in the observed differences. When the number of in situ data records increases (more than 20 per month), the agreement is about 50 W m−2 rms (40 W m−2 rms for multiyear averages). Limitations of both empirical relationships and W retrieval errors strongly affect the LHF computation. Systematic LHF overestimation occurs in strong subsidence regions and LHF underestimation occurs within surface convergence zones and over oceanic upwelling areas. The analysis of time series of the different parameters in these regions confirms that systematic LHF discrepancies are negatively correlated with the differences between COADS and satellite-derived values of the air mixing ratio and air temperature. To reduce the systematic differences in satellite-derived LHF, a preliminary ship-satellite blending procedure has been developed for the air mixing ratio and air temperature. The T−W relationship is not used any more and the air temperature is computed by adding the 3-yr-averaged COADS air-sea temperature difference to the satellite SST maps. The method to get the air mixing ratio is based on a weighted combination of COADS and satellite values according to the number of COADS observations available. After the blending proem is applied, large improvements are observed in the Northern Hemisphere where both datasets are complementary. At midlatitudes, the blending procedure does not modify LHF values since satellite and COADS air mixing ratio do not differ by more than the expected satellite uncertainty (1 g kg−1). In the eastern and northern part of the basin, where the air mixing ratio difference is large and ship observations are numerous, blended LHF values are efficiently corrected toward in situ estimates compensating for the limitations of Q−W relationship. In the Southern Hemisphere, the number of in situ observations rarely exceeds four values per month, and without “ground truth,” more confidence is given to the satellite-derived values. Statistically, the rms difference drops to 28 W M−2 when 20 ship observations are available, which is likely a good approximation of the lowest bound of the blended LHF uncertainty compared with optimal in situ estimates. However, along the eastern boundaries in the southern oceans, local differences are expected to be much larger.

Millimeter‐wave measurements of chlorine monoxide at the Jungfraujoch Alpine Station

During the European Arctic Stratospheric Ozone Experiment (EASOE) in winter 91/92, first measurements with a new 204GHz radiometer were performed at the Jungfraujoch Alpine Station (7°59′E 46°33′N) in the Swiss Alps. The altitude of this site (3570m) allows detection of weak spectral lines like the ones of the chlorine monoxide J 11/2→9/2 rotational transition. At the end of January 1992, a large amount of ClO in the lower stratosphere was measured, indicating that highly perturbed airmasses had been transported towards mid latitudes. The maximum value of the ClO volume mixing ratio was about 1ppbv +/−0.4 ppbv in heights of 15–25km.

An Analysis of Daily Humidity Patterns at a Mountainous and Urban Site in a Tropical High-Altitude Region

Abstract Mixing ratio data of water vapor at different hours of the day in a high-altitude tropical plateau in Mexico are shown. The objective is to measure water vapor quantity in a mountainous zone, where no previous studies of this kind exist, and in an urban site. The selected mountain site is at 2700 m MSL about 70 km west southwest of Mexico City. The urban site is in Mexico City at 50 m above the city. Data for the 1989 rainy season (May–October) show that statistical differences in mixing ratio values from 0800 to 1200 LST and a regular increase were observed in the former place. A significant difference from 1400 to 1600 LST and a definite decrease during morning hours were observed in the latter. Explanations for these phenomena are given. The results indicate that in the absence of synoptic perturbations an analysis of the time elapsed between the beginning of mixing ratio increase and the beginning of rain can help to show the diurnal air circulation that controls rain cloud formation. Data al...

The tropopause cold trap in the Australian monsoon during STEP/AMEX 1987

The relationship between deep convection and tropopause cold trap conditions is examined for the tropical northern Australia region during the 1986–1987 summer monsoon season. Particular attention is paid to the Australian Monsoon Experiment (AMEX) period from January 10 through February 14 when the NASA Stratosphere‐Troposphere Exchange Project (STEP) was conducting aircraft investigations at Darwin. Time mean values of the saturation mixing ratio at the local temperature minimum or cold point at stations in the AMEX radiosonde network were everywhere below the global lower stratospheric average of ∼3.5 ppmv and in places substantially so, thus fulfilling the first of two conditions necessary for stratospheric dehydration. The cold point potential temperature Θcp in the region was anticorrelated both spatially and temporally with mesoscale convection. However, there was no direct connection between surface layer moist entropy and Θcp. Time mean Θcp ranged from 366 to 374 K at stations in the monsoon trough zone along the northern coast and in the northern Gulf of Carpentaria, while the time mean of the average equivalent potential temperature in the surface layer Θe was no greater than 356 K. This difference of at least 10 K between trough mean Θcp values and the maximum potential temperature achieved in undilute moist ascent from the surface layer indicates that rapid incorporation of tropospheric air into the stratosphere was occurring in monsoonal convective systems through a combination of cumulonimbus overshooting and anvil radiative heating. Over the continent, where mean Θe was 6–10 K lower, stratosphere‐troposphere exchange was less widespread but more vigorous. Here the average Θcp approached 380 K and was likely due to deeper tropopause penetrations produced by continental convective systems. This elevation of Θcp in continental systems relative to monsoon trough systems is evident in the Θcp of tropopause layers which had never passed over the continental interior: these were 8–13 K lower than their counterparts of continental origin. This elevating tendency accounts for the upward trends in cold point temperature, saturation mixing ratio and Θcp in the trough zone following monsoon onset in mid‐January. Before onset, tropopause air in the north coastal zone beyond the immediate vicinity of convective systems appeared to have originated in the tropics upstream of the continent. With the establishment of the monsoon continental‐scale upper‐level anticyclone, tropopause air entering the monsoon trough zone had more often been processed by systems of the continental interior. Nonetheless, the necessary conditions for stratospheric dehydration, i.e., cold point saturation mixing ratios below the global average and significant stratosphere‐troposphere exchange, remained in force throughout the monsoon period.

Dependence of the simulated seeding effects of Cb cloud on the types of the AgI agents

A one-dimensional kinematic model is used to investigate the effects of silver iodide seeding in the region of a Cb cloud between isotherms of −8°C and −12°C. The agent interaction with cloud atmosphere is simulated by an improved microphysical model version which includes phoretic processes. The behaviour of the different agent types is investigated using the maximum values of agent mixing ratios and corresponding agent particle masses and radii.

Voyager 2 ultraviolet spectrometer solar occultations at Neptune: Constraints on the abundance of methane in the stratosphere

Voyager 2 ultraviolet spectrometer (UVS) solar occultation lightcurves at wavelengths 125–138 nm acquired during the Neptune encounter are compared with one‐dimensional methane photochemical‐transport models. Photoabsorption by methane (the photochemical parent) is expected to be the major source of opacity at these wavelengths, in which case the UVS lightcurves can be used to infer the strength of eddy mixing at altitudes above the methane photolysis peak and compatible CH4mixing ratios in the lower stratosphere. For thep‐Tmodels adopted in this study, acceptable fits to the UVS lightcurves are obtained with eddy mixing coefficient values (K1/2) near the half‐light altitudes (placed 550–600 km above the respective 1 bar levels) of 2–15 × 106cm2s−1(ingress) and 4–35 × 106cm2s−1(egress) and lower stratospheric (p> 1.0 mbar) methane mixing ratio values (ƒT(CH4)) of 5 – 100 × 10−5(ingress and egress). The ranges in ƒT(CH4) andK1/2reflect uncertainties in the backgroundp‐Tstructure and the application of different criteria for deciding what constitutes a “good fit.” For the nominalp‐Tmodels and a criterion based on replicating the spacing in altitude of the 125–138 nm UVS lightcurves,K1/2values (near 0.2 μbar) of 107cm2s−1(ingress) and 1–2 × 107cm2s−1(egress) and ƒT(CH4) values of ∼1 × 10−4(ingress and egress) are indicated, with the egress results being more uncertain. These results are insensitive to photochemical details of the models.

Re-evaluation of surface ozone over Athens, Greece, for the period 1901–1940

Surface ozone mixing ratio was monitored in Athens, Greece from 1901 to 1940. This historic ozone series is unique for southeastern Europe. The series provides ozone mixing ratio values for that period and therefore allows comparison with recent ones. The measurements were obtained using the De James colometric papers, which scale from 0 to 21. A re-evaluation of the data is attempted considering the dependence of the measurements' conversion on both the relative humidity and the exposure time. The newly estimated surface daily ozone values in Athens (1901–1940) vary around 20 ppb and reach their maximum and minimum values during the periods April-June and October-December respectively.

A Lower-Tropospheric Thermodynamic Climatology for March through September: Some Implications for Thunderstorm Forecasting

Abstract A thermodynamic climatology was constructed to investigate source regions of low-level moist airmasses and lower mid-tropospheric dry airmasses that contribute to the production of convective instability, and thunder-storms, over the United States. Mean monthly 1200 UTC values of potential temperature, mixing ratio, and geopotential height were computed at the surface and 750 mb for March through September (1966–1980) for 69 upper-air stations in the continental United States and Mexico. Analyses indicated that the Gulf of Mexico is the most significant source of low-level moisture east of the Continental Divide for all months, but the Atlantic Ocean also becomes a significant source in summer. The Gulf of California was found to be the most important source of low-level moisture west of the Continental Divide in summer. A distinct synoptic scale dryline was found over west Texas from March to June and analyses suggested that the strongest drylines occur in April and May. Northwest Mexico and the...

Nuclear orientation study of the decay of204BiFe

The decay of204Bi nuclei (I π=6+, T1/2=11·22 h) oriented in an iron host was investigated on the JINR low-temperature nuclear orientation facility SPIN. The orientation parameterB 2=1·17 (6) was obtained from the analysis of six prominent E1 gamma-transitions. From the measured normalized intensities of the gamma-rays observed some 70 values of multipole mixing ratios δ for the gamma-transitions in204Pb nucleus were determined for the first time. The spins 6, 6, 5 and 4 could be uniquely assigned to the204Pb negative parity levels at 3891·5 keV, 3768·4 keV, 3301·5 keV and 2338·2 keV, respectively. The spin-parity assignments of the levels at 4183·8 keV, 4094·2 keV, 3782·0 keV, 2506·9 keV and 2065·1 keV were confirmed as 6−, 6−, 5−, 5− and 5+, respectively. For the level at 3105·1 keV spin-parity 5− was suggested and spinparity 7− of the level at 2696·4 keV was called in question. The possible placements of the gammatransitions 3 1351·7 keV and 1353·4 keV in the decay scheme is discussed. The reorientation parameters for the long-living levels at 2264·2 keV (T 1/2=0·45 μs) and 1273·9 keV (T 1/2= =265 ns) were determined asG 2=0·41 (14) andG 2=0·60 (17), respectively. For the isomeric level at 2185·7 keV (T 1/2=67·2 min) the value ofG 2=0·88 (49) was proposed.

Nuclear orientation study of the decay of $${}^{205}Bi\underline {Gd} $$

Angular distribution of gamma radiation from the decay of205Bi oriented at low temperatures in gadolinium host was investigated. The orientation parameters B2 and B4 were determined. The spin 9/2 could be uniquely assigned to the positive-parity level at 2252.3 keV. No attenuation was observed for the isomeric level at 1013.8 keV. Seven new values of multipole mixing ratios of E2/M1 gammatransitions in205Pb were determined, two earlier measured values were confirmed.

Sensitivity analysis of the 1-D convective cloud model outputs on the dynamical parameters

Forced 1-D time-dependent numerical model of Cb cloud is used to analyse the sensitivity of the model products on dynamical parameters. The model considers the processes of horizontal entrainment, forced lifting through the cloud base as well as the six forms of water substance: water vapour, cloud water, cloud ice, rain, snow and hail. Atmospheric soundings for deep storm situation are used as initial and evironmental conditions. The maxima model values of vertical velocity, cloud water, rain water and ice mixing ratios, temperature excess, cloud top height and radar reflectivity are under the strong influence of the parameters of entrainment, amplitude of initial vertical velocity and forced vertical velocity. The most visible influence is that of forced vertical velocity on the ice content. The model values agree well with observations in one case for selected dynamical conditions.

Coulomb excitation studies in antimony isotopes.

Various low-lying energy levels up to 1.145 MeV in {sup 121,123}Sb have been Coulomb excited using 3.0--4.0 MeV proton-beam energies. The reduced transition probabilities of the excited levels have been newly deduced from the measured yields of the deexcitation gamma rays. The values of mixing ratios for a few transitions and the removal of ambiguities in the spin values of some levels have been presented from the angular distribution analysis.

Nuclear orientation of 160Tb in Tb single crystal.

Nuclear orientation of {sup 160}Tb in a Tb single crystal has been carried out in order to obtain accurate values of multipole mixing ratios for 22 transitions in {sup 160}Dy. The experimental aspects are described in some detail as they form the basis for obtaining high quality data. Three different methods were used to extract the mixing ratios, and they are shown to agree very well. Our results for both {ital E}1/{ital M}2 and {ital E}2/{ital M}1 transitions are compared to other measurements. The signs and magnitude of the {ital E}1/{ital M}2 mixing ratios cannot be explained on the basis of Coriolis mixing of the {ital K}=0, 1, and 2 bands. Comparison of our results for the 299, 1178, and 1272 keV transitions with those from {gamma}-{gamma} directional correlation measurements indicate that some {ital E}3 admixture may be present in these transitions. The mixing ratios we obtained for the {ital E}2/{ital M}1 transitions are in reasonably good agreement with the predictions of the interacting-boson-approximation-1 model.

Correction of Negative Mixing Ratios in Spectral Models by Global Horizontal Borrowing

Abstract A method based on global horizontal borrowing would seem more appropriate than the current method of local vertical borrowing for the correction of negative values of mixing ratios arising in spectral models as a consequence of finite truncation. Two practical algorithms are proposed for the implementation of this new method in spectral models. A numerical experiment shows that this global horizontal scheme has a tendency to produce more horizontal smoothing on the humidity field than the local vertical scheme.

On-line nuclear orientation of Au isotopes at KOOL

On-line low temperature nuclear orientation measurements were performed on shortlived185Au,186Au,189mAu,191mHg implanted in an iron matrix. As decay products185IrFe and191mAuFe were studied too. Besides magnetic moment determinations spectroscopic information on spin values of excited levels and mixing ratios of transitions in the daughter nuclei Pt and Au are presented. The results are interpreted in a Nilsson + Coriolis + pairing model.

Monthly variation of the total mass of the atmosphere over India

A programme of work has been undertaken to study the role of atmospheric carboa dioxide (CO2) in the radiation budget over India. The total mass of air over India has been calculated monthwise. Adopting the mixing ratio values of CO2 over Mouna Loa (Hawaii), the likely monthly variation of the mass of CO2 over India has been estimated. The values obtained are presented.

Gamma-ray linear polarization and nuclear orientation experiments on oriented192, 194IrFe

The combined technique of gamma-ray linear polarization and directional distribution measurement from oriented nuclei (LPγON) has been applied to192IrFe. New polarization data are used to deduce values of mixing ratios in Β and γ transitions.

Linear polarization and directional distribution of gamma-rays from oriented172Lu

The gamma-ray linear polarization data in combination with the results of the directional distribution measurements were used to determine precise values of the multipole mixing ratios of the gamma-transitions in the172Yb nucleus. A detailed analysis of the deduced mixing ratios, supplemented by previous data, lends support to the following description of the two-quasiparticle excitations of192Yb (see also tab. 6): 2073 keVKπ = (4+) {p 4041 ↓ + p 411 ↓} + {n 514↓ − n 521↓} 1663 keVKπ = (3+) {n 514↓ − n 521↓} + {n 512↑ − n 521↓} 1172 keVKπ = 3+ {n 512↑ + n 521↓} + {p404↓ − P 411↓} A supporting evidence has also been given to the spin-parity assignments of the 1640 keV (Iπ = 4−) and 1706 keV (Iπ = 5−) members of theKπ = 4− band.

Numerical analysis of flow of binary gas mixture with large mass difference in rotating cylinder.

A numerical analysis is presented of the flow of a binary gas mixture of UF6 and N2 in a rotating cylinder. The equations for flow and the diffusion equation are solved simultaneously for the binary mixture in static state, taking account of viscosity and compressibility, using a modified version of the Newton method, commonly applied to rotating fluid flow. An appropriate model is assumed for a centrifuge provided with scoop and baffle plate. Computations are carried out with the N2 to UF6 mixing ratio adopted as parameter. At small values of mixing ratio, the pressure distribution of UFC in the radial direction is little influenced by the presence of N2. The N2 pressure distribution is close to that at equilibrium of N2 itself in zones inside cylinder of relatively slow gas travel. In the zones of faster gas travel, conversely, the N2 pressure distribution deviates from that of its equilibrium and approaches that of UF6. The pressure distribution of UF6, on the other hand, is strongly influenced by the presence of N2 when the mixing ratio is above 0.2. The resulting radial distribution along a section close to the exit scoop presents a peculiar concave configulation with a shallow valley appearing in the intermediate zone, and this significantly lowers the concentration of UF6 extracted through the scoop. The separation efficiency obtained between the two gases is extremely low, but this is due to the mass flow rate having been chosen to optimize the separation efficiency between UF6 isotopes.

Total precipitable water in the atmosphere over India

Electromagnetic radiation, in its passage through the atmosphere, is attenuated by absorption and scattering by atmospheric gases, dust and aerosols. The most important absorber is water vapour and the most significant parameter in atmospheric absorption studies is the total precipitable water in the atmosphere. The present paper summarises the results of a study made to compute the total precipitable water in the atmosphere over India using radiosonde and other data, as part of a programme for the computation of direct, global and diffuse solar radiation at the ground from the solar constant. Using values of air temperature and dew point from the ground up to 250 mb at 19 radiosonde stations and surface water vapour mixing ratio values at 105 surface observatories in India, precipitable water amounts have been computed for 124 stations, for each month and for the whole year. The paper describes the techniques used to extend the total precipitable water amounts derived from radiosonde data at 19 stations to 124 stations covering the major climatic zones in the country and presents the results in the form of 12 maps showing the spatial and temporal distribution of total precipitable water over India