Values Of Specific Humidity Research Articles

Water vapor transport in the NCAR CCM2

The NCAR Community Climate Model, Version 2, uses the spectral transform method for the underlying dry dynamical fluid flow component, and a monotonic, semi-Lagrangian transport algorithm for water vapor specific humidity. The reasons for this choice of 2 different approaches for these different components are reviewed, and the details of the implementation of the transport algorithm are presented. The properties of the transport scheme are described in the context of a 20-year control simulation. This simulation is also compared to one using the spectral transform method for water vapor transport. Neither numerical approach is perfect. The semi-Lagrangian method requires arbitrary corrections to conserve mass, and the spectral method requires the filling of nonphysical negative values of specific humidity. The analysis shows that the balance of processes that produces the climate of CCM2 is very sensitive to the discrete water vapor transport algorithm. The spectral transport method clearly has shortcomings. The negative filler is a dominant process in significant regions and leads to an incorrect balance of the moisture budget. The mass conservation adjustment of the semi-Lagrangian method seems to be cosmetic and has no identified adverse effect on the simulation. DOI: 10.1034/j.1600-0870.1994.00004.x

Above-Inversion Profiles of Moisture and Ozone Observed during FIRE

Data from the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE) were combined with NOAA synoptic products, a trajectory analysis scheme, and satellite imagery to document the existence and causes of layers of air characterized by high ozone concentrations and low specific-humidity values, as well as layers of air characterized by high specific-humidity values and low ozone concentrations above the summertime marine stratocumulus cloud deck off the coast of California. The ozone concentrations and specific-humidity values observed were larger than those expected in the region just above the subsidence inversion off the California coast. The layers with high ozone concentrations appear to be extruded from the middle or upper troposphere. The layers with high specific-humidity values result from frontal lifting associated with surface cyclones upstream of the marine stratocumulus cloud regime. The impact of these layers on the marine stratocumulus cloud regime is also analyzed using boundary-layer model simulations. 16 refs., 11 figs.

Conditions over the equatorial area during the period of monsoon experiment (Monex) 1973

The surface and upper air observations recorded by the two Russian ships, viz., Okean (EREI) and Voekov (UAAX) at different locations over the equator and by the observatories over Kenya during the monsoon experiment 1973, have been examined in detail to get an idea about the conditions over the equator during southwest monsoon. Comparative study of the observations over the equator, at Long. 60° and 50°E and of observations recorded at Garissa and Nairobi during the period 27 May to 4 June and 24 June to 2 July, has been made and presented in this paper. The observations of the ship Okean over the equator on its cruise from about Long 45.0°E to 70.0°E during the period from 16 to 22 June have also been critically examined.
 The following salient features are revealed in this study:
 (a) The southerly component in the wind direction and its depth increase as one moves wast of Long. 60°E southerly jet speed winds even being noticed near 40°E between about 850 and 700mb.
 (b) The high humidities are noticed in the western Indian Ocean west of 50°E upto about 500 mb, indicating considerable transport of moisture across the equator over this area.
 (c) An area of maximum dryness in levels above about 850 mb is noticed near Long. 60°E compared to other longitudes to the east and west. The difluence at the we3tern end (near 60°E) of the equatorial trough may also, to some extent, be responsible for relatively greater dryness at that longitude in levels above about.850 mb.
 (d) The inverions or isothermal conditions seen in some of the tephigrams would not appear to be due to any mass subsidence over the equatorial area, but mainly due to the presence of district airmasses, as is evident from the variations of specific humidity values and the lapse rates.
 (e) There would not appear presence of a deep layer of westerlies at all the longitudes over the equator.
 (f) The upper level easterlies would appear to begin at lower heights over the eastern regions than over the western regions of the equator, the jet speeds occurring near about 150 mb.
 (g) As at result of difference in circulation round 'highs' and 'lows' in the two hemispheres, it is difficult to trace systematic movements of pressure systems over the equator either from east to west or from west to east.
 From the present study, it would appear that for a proper understanding of transport of air and moisture across the equator in the western Indian Ocean and the adjoining land areas, it is necessary to have rawin and radiosonde observations at intervals of about 1 degree between Long. 37° and 45°E. Such observations alone will enable us to understand the characteristics of southwest monsoon current over the Arabian Sea and predictions of its activity over the west coast of India in terms of rainfall.

A Diagnostic Study of a Non-Deepening Disturbance in the Caribbean Sea

Abstract This paper discusses the results obtained from a study of a non-deepening disturbance which developed and dissipated in the Caribbean Sea. Careful analyses Of the temperature moisture, and wind fields Were performed at six levels for a two-day, period while the disturbance was dissipating. The data were used to compute vertical motions from a nonlinear balance model for the purpose of diagnosing the reasons for decay of the disturbance. The vertical motions that were derived from the diagnostic computations compared favorably with the synoptic-scale cloud distribution. The results suggested that the presence of clouds within the disturbance on the first day was attributed to 1) frictionally induced ascending motions in the lower troposphere where there were large values of specific humidity, 2) the Laplacian of thermal advection which produced rising motions in the lower and upper troposphere where there were weak, though significant, temperature gradients, and 3) ascending motions in the upper t...