Sea breeze

About: Sea breeze is a research topic. Over the lifetime, 2544 publications have been published within this topic receiving 55651 citations.

Vertical Heat Fluxes Generated by Mesoscale Atmospheric Flow Induced by Thermal Inhomogeneities in the PBL

Abstract: An analytical evaluation of the vertical heat fluxes associated with the mesoscale flow generated by thermal inhomogeneities in the PBL in the absence of a synoptic wind is presented. Results show that the mesoscale fluxes are of the same order as the diabatic heat fluxes. In the sea-breeze case results show that in the lower layer of the atmosphere the heat flux is positive over the land and negative over the sea with an overall positive horizontal average. In the free atmosphere above the PBL the mesoscale vertical heat flux is negative over the land and over the sea; that is, the lower atmosphere becomes warmer while the free atmosphere above becomes cooler. As a result the mesoscale flow contributes to the weakening of the atmospheric stability within a region that extends a Rossby radius distance from the coastline, and up to an altitude larger than twice the depth of the convective PBL. The average momentum flux equals zero because the momentum removed over the sea is fed back into the atmo...

The Diurnal Cycle of Winds, Rain, and Clouds over Taiwan during the Mei-Yu, Summer, and Autumn Rainfall Regimes

Abstract: The diurnal variations in surface winds, rain, and clouds over Taiwan are presented for three rainfall regimes: the mei-yu (16 May‐15 June), summer (16 July‐31 August), and autumn (16 September‐15 October). Though the magnitude of diurnal island divergence and convergence is similar under each regime, the diurnal variations of rain and clouds vary considerably between the regimes. These differences are related to the seasonal changes in environment winds, stability, moisture, and weather systems. In addition to orographic lifting on the windward side, rainfall occurrences for all three rainfall regimes are strongly modulated by the diurnal heating cycle with an afternoon maximum. The largest day‐night differences in rainfall occur in summer and the smallest differences occur in autumn. The upper-level high cloud (,235 K) frequencies have a pronounced afternoon maximum over the mountainous areas in the afternoon because of combined effects of orographic lifting and solar heating. These clouds are advected downstream by the upper-level winds in late afternoon and early evening. The highest afternoon high cloud frequencies occur in summer (.30%) with the lowest upper-level cloud cover in autumn (;10%). In autumn, most of the orographic showers on the eastern and northeastern windward side in the late afternoon and early evening are not from deep clouds. The weak early-morning rainfall maxima for all three seasons are related to the localized boundary layer convergence due to the orographic blocking of the prevailing winds and their interactions with the offshore/land breeze. During disturbed, prefrontal periods in the mei-yu, bands of high clouds and rain tend to develop in the early morning in the convergence zone off the northwest coast. These rainbands are responsible for the early-morning rainfall maximum on the northwest coast. They do not occur in summer or autumn.

The Temporal Behavior of the Atmospheric Boundary Layer in Israel

Abstract: Upper-air measurements collected for three consecutive years (1987‐89) from the Israel Meteorological Service permanent sounding site, in Beit-Dagan, Israel, enabled the temporal behavior of the atmospheric boundary layer over Israel to be characterized. Data analyzed consisted of the layer depth, the thermal gradient within the layer, and occurrence frequency of radiative and elevated inversions. To adequately represent the multiyear seasonal and diurnal behavior, the 3-yr databases were merged based on the tested hypothesis that the month sample in each individual year comes from the same population. The analysis shows that the depth of the radiative ground-based inversion, its frequency, as well as its thermal profile are maximal during spring and early summer. The upper-inversion layer is well defined during the summer, its lowest base (0.5‐1 km MSL) indicating a sharp interface layer formed between the marine turbulent boundary layer at the shallow layer of the atmosphere and the subsiding downward motion caused by the subtropical high pressure system. During the other three seasons a significant temporal variation of the upper-inversion base is observed as a result of the frequent larger-scale synoptic weather systems. The diurnal variation of the mixed-layer depth is most evident during the summer because it is mainly governed by heat fluxes and the daily sea-breeze cycle that are most intensive then. Henceforth, the layer minimal depth, along the coast, usually occurs during late afternoon hours when the wind speed of the cool sea breeze reaches its minimal rate and heat fluxes dissipate rapidly, leading to a decrease of the marine turbulent boundary layer.

The impact of land cover change on storms in the Sydney Basin, Australia

Abstract: This study has used a numerical model (RAMS) at 1 km horizontal grid intervals over the Sydney Basin to assess the impact of land cover change on storms. Multiple storms using the National Center for Environmental Prediction (NCEP) reanalysis data were simulated with pre-European settlement land cover then re-simulated with land cover representing Sydney's current land use pattern. While all simulated storms did not respond to the change in land cover consistently, storms of similar types responded in comparable ways. All simulated synoptically forced storms (e.g. those triggered by cold fronts) were unresponsive to a changed land surface, while local convective storms were highly sensitive to the triggering mechanism associated with land surface influences. Storms travelling over the smoother agricultural land in the south-west of the Sydney Basin experienced an increase in velocity, and in a special case, the dense urban surface of Sydney's city core appears to trigger an intense convective storm. It is shown that the dynamical setting predominantly triggers storm outbreaks. This is seen most clearly in the isolated convective storm category where the sea breeze front often dictates the location of storm cell initiation.

Diurnal Cycle of Water Vapor as Documented by a Dense GPS Network in a Coastal Area during ESCOMPTE IOP2

Abstract: Global positioning system (GPS) data from a dense network have been used for the analysis of the diurnal cycle of water vapor over Marseille, France, during the second intensive observation period (IOP2; 21–26 June 2001) of the Experience sur Sites pour Contraindre les Modeles de Pollution Atmospherique et de Transport d'Emission (ESCOMPTE) field experiment. Both tomographic analyses and integrated water vapor (IWV) contents from GPS have been used, in addition to wind profiler data and surface observations. Tomographic analysis of data from the dense GPS network and radiosondes provided the continuous temporal evolution of the vertical distribution of water vapor over the city of Marseille. The city is located on the shore of the Mediterranean Sea in southeastern France and is often under the influence of sea-breeze effects. Two different layers of breeze circulation are identified: a shallow sea breeze, blowing perpendicular to the local coastline, and a deep sea breeze, induced by the regional temperature gradient between sea and land. The origin of water vapor is shown to be mainly due to the advection of marine moist air by these sea-breeze circulations. However, the diurnal cycle of water vapor over Marseille is strongly influenced by the synoptic situation, which changes during the IOP2 (between a northerly mistral in the early stage of the IOP and an easterly wind at the end). It is shown that vertical profiles from tomographic analyses (combined with wind profiler data) allow for a proper interpretation of the diurnal cycle observed in IWV. Two-dimensional maps of IWV are also shown to complement the description of the horizontal advection of moisture by the different circulation regimes.