Mesoscale Parameters Research Articles

Linkage of scaling and thermodynamic parameters of rainfall: Results from midlatitude mesoscale convective systems

In this paper we explore the possibility of establishing predictive relationships between statistical characteristics of rainfall at the mesoscale (approximately 102 to 104 km2) and representative meteorological parameters of the storm environment. To increase the usefulness of these relationships and, in particular, to explore their use in subgrid‐scale rainfall parameterization, special attention is given to statistical characteristics of rainfall that are scale invariant, i.e., are constant at least within a significant range of scales. The main contributions of this paper are the following: (1) we establish the presence of statistical (simple) scaling in “standardized rainfall fluctuations” (derived from rainfall intensities via an orthogonal wavelet transform and normalization by local means) and (2) we establish empirical connections between statistical and physical storm characteristics by quantifying relations between the scaling parameters and kinematic and thermodynamic indices of the prestorm environment. The data used for this analysis are rainfall events and corresponding soundings observed during the PRE‐STORM experiment (May and June 1985) over Oklahoma and Kansas. The developed relationships are applicable to midlatitude mesoscale convective systems, which are the major rainfall producers over most of the Global Energy and Water Cycle Experiment (GEWEX) Continental International Project (GCIP) region, and are envisioned to play a key role in disaggregating rainfall (predicted by mesoscale numerical models) to subgrid scales for runoff prediction and other hydrologic applications.

The relationship between synoptic, mesoscale and microscale meteorological parameters during poor air quality events in Athens, Greece

This paper presents an analysis of some aspects of the ambient carbon monoxide (and some other pollutants) data from 1984–1993 recorded at 10 appropriately distributed locations in the Athens Basin. A major purpose of this study is to assess the influence of meteorological conditions on the concentrations of pollutants. Appropriate statistical methods have been applied which relate CO to wind speed and traffic patterns. In addition, an analysis of the meteorological conditions during days in which concentration levels exceed standards is given. The main characteristics of the results are: (i) The variation of CO, O 3, NO x concentrations are strongly affected by traffic, wind speed and height of the inversion. (ii) It is difficult to define a firm urban rate of change for CO since it varies considerably from year to year, and it is not possible to unequivocally attribute the entire observed decrease to emission limitations and meteorological influences. An analysis of the seasonal, weekday and weekend diurnal variations is also presented. (iii) Surface ozone, NO x and other pollutant data at several urban and suburban stations in Athens with variable record lengths, all show a slight increasing trend.

Numerical Forecasting of Radiation Fog. Part II: A Comparison of Model Simulation with Several Observed Fog Events

Abstract A 1D model adapted for forecasting the formation and development of fog, and forced with mesoscale parameters derived from a 3D limited-area model, was used to simulate three fog event observations made during the Lille 88 campaign. The model simulation correctly reproduced the time of fog formation and its vertical development when forcing terms derived from observations were used. It determined the influence of different physical processes and in particular that of dew deposition. The initial conditions deduced from the 3D model proved to be correct in two of the three events. On the other hand, the prediction of advection terms necessary for forecasting the vertical growth of fog was a more delicate matter.

On the determination of parameters of mesoscale eddies from remote sensing data

In the real case, the steady estimates of mesoscale eddy parameters can be obtained by integrating three types of remote data: measurement of kinematics of IR tracers, integral characteristics of scales, and local estimates of the SST partial derivatives. An appropriate analytical model of the eddy is selected based on the data of numerical modelling. A method for the estimation of the drift current velocity is suggested on the basis of the discrimination of the ageostrophic components of the tracer's translation.

Correlations between Maximum Rate of Precipitation and Mesoscale Parameters

Daily 5, 10 and 30 min maxima of precipitation rate determined from a raingage network and radar were correlated with parcel convective energies, upper air humidity, height of parcel convection and maxima of surface conditions. After a selection of 54 well-documented cases the correlation coefficient between the maximum of rain rate over 5 min and the maximum convective energy was ρ = 0.79 for all cases and ρ = 0.89 for 15 air mass cases. Introducing the upper air humidity further improves the correlations.