scholarly journals Aircraft observations of the lake‐land breeze circulation over Lake Victoria

2021 ◽  
Author(s):  
Beth J. Woodhams ◽  
Paul A. Barrett ◽  
John H. Marsham ◽  
Cathryn E. Birch ◽  
Caroline L. Bain ◽  
...  
Keyword(s):  
Lake Victoria ◽  
Land Breeze ◽  
Breeze Circulation ◽  
Aircraft Observations

A complete sea-breeze circulation cell derived from aircraft observations

1995 ◽  
Vol 73 (3) ◽  
pp. 299-317 ◽  
Author(s):  
Klara Finkele ◽  
J�rg M. Hacker ◽  
Helmut Kraus ◽  
Roland A. D. Byron-Scott
Keyword(s):  
Sea Breeze ◽  
Breeze Circulation ◽  
Aircraft Observations ◽  
Circulation Cell

scholarly journals Identifying Key Controls on Storm Formation over the Lake Victoria Basin

2019 ◽  
Vol 147 (9) ◽  
pp. 3365-3390 ◽  
Author(s):  
Beth J. Woodhams ◽  
Cathryn E. Birch ◽  
John H. Marsham ◽  
Todd P. Lane ◽  
Caroline L. Bain ◽  
...  
Keyword(s):  
Large Scale ◽  
Lake Victoria ◽  
Hot Spot ◽  
Land Breeze ◽  
Lake Victoria Basin ◽  
Convective Storms ◽  
Moisture Availability ◽  
Lake Victoria Region ◽  
The Mean ◽  
Horizontal Grid

Abstract The Lake Victoria region in East Africa is a hot spot for intense convective storms that are responsible for the deaths of thousands of fishermen each year. The processes responsible for the initiation, development, and propagation of the storms are poorly understood and forecast skill is limited. Key processes for the life cycle of two storms are investigated using Met Office Unified Model convection-permitting simulations with 1.5 km horizontal grid spacing. The two cases are analyzed alongside a simulation of a period with no storms to assess the roles of the lake–land breeze, downslope mountain winds, prevailing large-scale winds, and moisture availability. While seasonal changes in large-scale moisture availability play a key role in storm development, the lake–land-breeze circulation is a major control on the initiation location, timing, and propagation of convection. In the dry season, opposing offshore winds form a bulge of moist air above the lake surface overnight that extends from the surface to ~1.5 km and may trigger storms in high CAPE/low CIN environments. Such a feature has not been explicitly observed or modeled in previous literature. Storms over land on the preceding day are shown to alter the local atmospheric moisture and circulation to promote storm formation over the lake. The variety of initiation processes and differing characteristics of just two storms analyzed here show that the mean diurnal cycle over Lake Victoria alone is inadequate to fully understand storm formation. Knowledge of daily changes in local-scale moisture variability and circulations are keys for skillful forecasts over the lake.

The characteristics and drivers of climatological precipitation over the Serengeti-Mara region

2020 ◽  
Author(s):  
Josephine Mahony ◽  
Ellen Dyer ◽  
Richard Washington
Keyword(s):  
Annual Cycle ◽  
Large Scale ◽  
Lake Victoria ◽  
Basic Structure ◽  
Local Source ◽  
Land Breeze ◽  
Rainfall Gradient ◽  
Annual Cycles ◽  
Precipitation Patterns ◽  
And Cluster Analysis

<p>The Serengeti National Park is famous for the biological phenomenon of the annual wildebeest migration. This migration is reliant on unique local precipitation conditions: a rainfall gradient stretching across the park, the strength and inclination of which alters from month to month. Given the ecological significance and the complexity of the regional precipitation, a detailed study of the region’s climatology is essential for understanding why these precipitation patterns exist, and whether they are likely to change.</p><p>Using multiple observational datasets, we studied the spatial distribution of annual and monthly climatological precipitation. We carried out harmonic analysis and cluster analysis to identify areas with similar annual cycles. We then examined regional wind, moisture and precipitation patterns on seasonal, monthly and diurnal timescales.</p><p>We found that the large-scale wind circulation patterns dictate the basic structure of the annual cycle over the region. However the shape of the annual cycle was distinctly different in 5 parts of the region, with varying peak rainfall months and dry season rainfall totals. Analysis of the diurnal wind patterns showed that the regional seasonality is strongly augmented by the lake and land breeze from Lake Victoria, and the interactions between this local source of moisture and the complex topography of the East African rift. This leads to a low-level convergence zone between the prevailing large-scale easterlies, and westerlies from Lake Victoria over the Serengeti in the afternoon. This in turn results in the rainfall gradient across the region, the orientation of which changes depending on the mid-tropospheric wind direction.</p>

scholarly journals Numerical Study of the Effects of Topography and Urbanization on the Local Atmospheric Circulations over the Beijing-Tianjin-Hebei, China

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Yucong Miao ◽  
Shuhua Liu ◽  
Yijia Zheng ◽  
Shu Wang ◽  
Bicheng Chen
Keyword(s):  
Numerical Study ◽  
Wrf Model ◽  
Sea Breeze ◽  
Land Breeze ◽  
Bohai Bay ◽  
Breeze Circulation ◽  
Thermally Induced ◽  
Atmospheric Circulations ◽  
Mountain Valley ◽  
Bth Region

The effects of the topography and urbanization on the local atmospheric circulations over the Beijing-Tianjin-Hebei (BTH) region were studied by the weather research and forecasting (WRF) model, as well as the interactions among these local atmospheric circulations. It was found that, in the summer day time, the multiscale thermally induced local atmospheric circulations may exist and interact in the same time over the BTH region; the topography played a role in the strengthening of the sea breeze circulations; after sunset, the inland progress of sea breeze was slowed down by the opposite mountain breeze; when the land breeze circulation dominated the Bohai bay, the mountain breeze circulation can couple with the land breeze circulation to form a large circulation ranging from the coastline to the mountains. And the presence of cities cannot change the general state of the sea-land breeze (SLB) circulation and mountain-valley breeze (MVB) circulation but acted to modify these local circulations slightly. Meanwhile, the development of the urban heat island (UHI) circulation was also strongly influenced by the nearby SLB circulation and MVB circulation.

Characterization of sea/land breeze circulation along the west coast of Indian sub-continent during pre-monsoon season

2010 ◽  
Vol 95 (4) ◽  
pp. 367-378 ◽  
Author(s):  
S. Indira Rani ◽  
Radhika Ramachandran ◽  
D. Bala Subrahamanyam ◽  
Denny P. Alappattu ◽  
P.K. Kunhikrishnan
Keyword(s):  
West Coast ◽  
Monsoon Season ◽  
Land Breeze ◽  
Breeze Circulation ◽  
The West

scholarly journals Estimativa da altura da camada limite planetária no Centro de Lançamento de Alcântara

2020 ◽  
Vol 42 ◽  
pp. e23
Author(s):  
Diogo Ramos ◽  
Gilberto Fisch
Keyword(s):  
Boundary Layer ◽  
Rainy Season ◽  
Internal Boundary Layer ◽  
Internal Boundary ◽  
Land Breeze ◽  
Breeze Circulation ◽  
Wet Season ◽  
Atmospheric Humidity ◽  
Estimation Uncertainty ◽  
Remote Measurements

Sea and land breeze circulation and the internal boundary layer are some aspects that make it difficult to determine the coastal Planetary Boundary Layer (PBL) height (h). This paper evaluates the h estimation for the Alcantara Launch Center (CLA) in Maranhão state using 14 months of remote measurements obtained by a ceilometer and by the ERA5 reanalysis. This response depends on the concentration of aerosols and atmospheric humidity present. Mean results indicated that dry months (September to November, with  = 637  488 m) tend to have less hourly and seasonal variability of h compared to wet months (March to May, with  = 770  912 m). A higher mean error in the wet season was obtained with ERA5 PBL h (h = 708  53 m over the land; e h = 648  46 m over the ocean) than in the dry season (h = 18  89 m; e h = 46  77 m). The greater amount of atmospheric humidity during the rainy season increases the estimation uncertainty. This condition was more frequent at night due to typical rainfall in the place.

scholarly journals Implications of Improved Representation of Convection for the East Africa Water Budget Using a Convection-Permitting Model

2019 ◽  
Vol 32 (7) ◽  
pp. 2109-2129 ◽  
Author(s):  
Declan L. Finney ◽  
John H. Marsham ◽  
Lawrence S. Jackson ◽  
Elizabeth J. Kendon ◽  
David P. Rowell ◽  
...  
Keyword(s):  
East Africa ◽  
Water Budget ◽  
Large Scale ◽  
Lake Victoria ◽  
Regional Climate ◽  
Moisture Flux ◽  
Land Breeze ◽  
Moist Convection ◽  
Atmospheric Water ◽  
Lake Victoria Basin

Abstract The precipitation and diabatic heating resulting from moist convection make it a key component of the atmospheric water budget in the tropics. With convective parameterization being a known source of uncertainty in global models, convection-permitting (CP) models are increasingly being used to improve understanding of regional climate. Here, a new 10-yr CP simulation is used to study the characteristics of rainfall and atmospheric water budget for East Africa and the Lake Victoria basin. The explicit representation of convection leads to a widespread improvement in the intensities and diurnal cycle of rainfall when compared with a parameterized simulation. Differences in large-scale moisture fluxes lead to a shift in the mean rainfall pattern from the Congo to Lake Victoria basin in the CP simulation—highlighting the important connection between local changes in the representation of convection and larger-scale dynamics and rainfall. Stronger lake–land contrasts in buoyancy in the CP model lead to a stronger nocturnal land breeze over Lake Victoria, increasing evaporation and moisture flux convergence (MFC), and likely unrealistically high rainfall. However, for the mountains east of the lake, the CP model produces a diurnal rainfall cycle much more similar to satellite estimates, which is related to differences in the timing of MFC. Results here demonstrate that, while care is needed regarding lake forcings, a CP approach offers a more realistic representation of several rainfall characteristics through a more physically based realization of the atmospheric dynamics around the complex topography of East Africa.

scholarly journals The seasonal characteristics of the breeze circulation at a coastal Mediterranean site in South Italy

2010 ◽  
Vol 4 (1) ◽  
pp. 47-56 ◽  
Author(s):  
S. Federico ◽  
L. Pasqualoni ◽  
A. M. Sempreviva ◽  
L. De Leo ◽  
E. Avolio ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Large Scale ◽  
Land Breeze ◽  
Breeze Circulation ◽  
Local Circulation ◽  
Coastal Site ◽  
Local Climate ◽  
Hourly Data

Abstract. We present a study on the characteristics of the sea breeze flow at a coastal site located in the centre of the Mediterranean basin at the southern tip of Italy. This study is finalized to add new data on breeze circulations over a narrow peninsula and present a unique experimental coastal site at about 600 m from the coastline in a flat open area at the foot of a mountain chain located in a region of complex orography. We study the seasonal behaviour of the sea-land breeze circulation by analysing two years of hourly data of wind speed and direction, temperature, radiation and relative humidity from a surface meteorological station, eighteen-months data from a wind profiler, and two-year data from the ECMWF analysis. Results show that breezes dominate the local circulation and play a major role for the local climate. They are modulated by the season, through the sea-land temperature difference and the large-scale flow. The large-scale forcing acts in phase with the diurnal breeze and opposes the nocturnal breeze. In summer, the daytime difference between the land surface temperature and the SST (Sea Surface Temperature) reaches its maximum, while the nigh-time difference has its minimum. This causes a strong, frequent and intense diurnal breeze and a weak nocturnal breeze. In winter and fall the nocturnal difference between the sea and land surface temperature reaches a maximum value, while the diurnal difference is at its minimum value. This causes a strong, frequent and intense nocturnal breeze despite of the large-scale forcing that is usually opposed to local-scale flow.

Sign in / Sign up

Export Citation Format

Share Document