Abstract A two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea. The domain includes a representation of part of Borneo as well as the sea so that the model can simulate the initiation of convection. Also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle. This allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck, which typically occupies several hundred kilometers of the domain. Frank and Cohen's cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area. The major conclusions are: Ice phase processes are important in determining the level of maximum large-scale heating and vertical motion because there is a strong anvil componen...

Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model [presentation]

https://hal.archives-ouvertes.fr/jpa-00239583/document

Il nuovo cimento

Wind speed and wind energy forecast through Kalman filtering of Numerical Weather Prediction model output

A finite element model for the Venice Lagoon. Development, set up, calibration and validation

An air-sea interaction theory for tropical cyclones [presentation]

This paper investigates the mean spatial features of the winds in the Mediterranean and Black Seas using the wind fields observed by the SeaWinds scatterometer. Five years (2000–04) of data have been analyzed on annual and seasonal basis, with particular attention paid to the meso- and local scales. The fields show the existence of structured regional wind systems—in particular, the mistral in the western Mediterranean and the etesians in the Levantine Basin, which are characterized, respectively, by high wind variability and moderate steadiness and by low wind variability and high steadiness. Estimated seasonal mean wind stress τ fields show that the values falling in the top range 0.15 < τ < 0.20 N m−2 affect a large portion of the Mediterranean Basin in winter, in the belt extending from the Gulf of Lion up to the Levantine Basin and the northern Black Sea. In the other seasons, only few regions experience such high values of τ. The analysis of the wind vorticity shows and quantifies the main ...

Sea Surface Winds over the Mediterranean Basin from Satellite Data (2000–04): Meso- and Local-Scale Features on Annual and Seasonal Time Scales

Surface wind forecasts from a limited-area model [the Quadrics Bologna Limited-Area Model (QBOLAM)] covering the entire Mediterranean area at 0.1° grid spacing are verified against Quick Scatterometer (QuikSCAT) wind observations. Only forecasts within the first 24 h in coincidence with satellite overpasses are used. Two years of data, from 1 October 2000 to 31 October 2002, have been considered, allowing for an adequate statistical assessment under different wind conditions. This has been carried out by analyzing the fields of the mean wind vectors, wind speed bias, correlation, difference standard deviation, steadiness, gustiness, and mean wind direction difference, in order to investigate spatial variability. Statistics have been computed on a seasonal basis. A comparison of satellite and forecast winds with measurements from three buoys was also performed. Some critical areas of the Mediterranean Sea where wind forecast quality is lower than average have been identified. Such areas correspond to semienclosed basins surrounded by important orography and to small regions at the lee side of the main islands. In open-sea regions the model underestimates wind strength from about 0.5 m s 1 in spring and summer to 1.0 m s 1 in winter, as evidenced by the existing biases against scatterometer data. Also, a wind direction bias (scatterometer minus model) generally between 5° and 15° exists. A survey of the identified and likely sources of forecast error is performed, indicating that orography representation plays an important role. Numerical damping is identified as a likely factor reducing forecast wind strength. The need for a correction scheme is envisaged to provide more accurate forcing for numerical sea state forecasting models, wind energy evaluation, and latent and/or sensible heat exchanges.

Comparison of 10-m Wind Forecasts from a Regional Area Model and QuikSCAT Scatterometer Wind Observations over the Mediterranean Sea

This paper describes a series of wave measurements, taken from an oceanographic tower, concerning water particle kinematics. Attention is focused on the phase relationship between surface elevation and the velocity components. Large phase shifts with respect to the expected values are found under active wave conditions, while swell behavior closely follows the linear theory. The reliability of the measurements is analyzed in detail. Possible physical reasons for the findings are indicated in the final discussion.

Reynolds stresses under wind waves

We present the follow-up of our previously published work, where we described a wavelet-based method to characterize the sea surface backscatter structures in Synthetic Aperture Radar (SAR) images. The method relies on the ability of the 2-D continuous wavelet technique to detect the spatial structure of the Marine Atmospheric Boundary Layer (MABL) and to isolate wind-related cells and features. The analysis of the cells' geometry, molded by the radiometric characteristics of the sea surface, permits the identification of the wind direction inside the cells, due to the along-wind asymmetry of backscatter structures, and thus the computation of the wind speed through standard algorithms. Twenty-one SAR images (ERS-2 and Envisat ASAR Wide Swath) over the Mediterranean Sea have been analyzed, and the results are compared with satellite wind fields. The images cover a range of meteorological conditions from low to moderate winds. Comparison of the SAR-derived wind fields with those provided by satellite scatterometers indicates a good score of success (roughly 70%-80%). The developed methodology, once tested over an adequate number of images to derive statistically reliable results, could be routinely used to enrich SAR images with the wind field as well as to characterize the MABL in terms of size, distribution, and shape of the backscatter cells.

A Wavelet-Based Technique for Sea Wind Extraction from SAR Images

-We present the follow-up of our previously published work, where we described a wavelet-based method to characterize the sea surface backscatter structures in Synthetic Aperture Radar (SAR) images. The method relies on the ability of the 2-D continuous wavelet technique to detect the spatial structure of the Marine Atmospheric Boundary Layer (MABL) and to isolate wind-related cells and features. The analysis of the cells' geometry, molded by the radiometric characteristics of the sea surface, permits the identification of the wind direction inside the cells, due to the along-wind asymmetry of backscatter structures, and thus the computation of the wind speed through standard algorithms. Twenty-one SAR images (ERS-2 and Envisat ASAR Wide Swath) over the Mediterranean Sea have been analyzed, and the results are compared with satellite wind fields. The images cover a range of meteorological conditions from low to moderate winds. Comparison of the SAR-derived wind fields with those provided by satellite scatterometers indicates a good score of success (roughly 70%-80%). The developed methodology, once tested over an adequate number of images to derive statistically reliable results, could be routinely used to enrich SAR images with the wind field as well as to characterize the MABL in terms of size, distribution, and shape of the backscatter cells.

Stefano Zecchetto

Papers

Sea Surface Winds over the Mediterranean Basin from Satellite Data (2000–04): Meso- and Local-Scale Features on Annual and Seasonal Time Scales

Comparison of 10-m Wind Forecasts from a Regional Area Model and QuikSCAT Scatterometer Wind Observations over the Mediterranean Sea

Reynolds stresses under wind waves

A Wavelet-Based Technique for Sea Wind Extraction from SAR Images

A Wavelet-Based Technique for Sea Wind Extraction from SAR Images