scholarly journals How do the sea and the land conditions affect the coastal breezes? 20 days analysed from WRF simulations in the Gulf of Cádiz (Iberian Peninsula)

2021 ◽  
Author(s):  
Carlos Román-Cascón ◽  
Roberto Mulero-Martínez ◽  
Miguel Bruno ◽  
Carlos Yagüe ◽  
Marie Lothon ◽  
...  

<p>Sea breezes are common and recurrent thermally-driven winds formed in coastal areas under conditions of weak synoptic forcing, due to the differential heat capacity of the sea and the land. Their accurate forecast is key because of the impacts on maxima near-surface temperatures, humidity (and then thermal comfort), pollutants distribution, convective-systems formation, etc., being crucial for the wind energy sector and because they develop in areas that are normally densely populated.</p><p>Some studies have investigated the impacts of the surface conditions in coastal breezes in different regions around the world. Their findings are diverse, mostly attributed to differences in the marine boundary layer stability, which can favour or inhibit the vertical mixing. This is needed to vertically distribute thermal changes in the land or the sea surfaces to deeper atmospheric layers, and thus to modify the horizontal surface pressure gradients. In this work, we use the Weather Research and Forecasting (WRF) model to investigate how the coastal breezes are affected by changes in the surface representation in the Gulf of Cádiz, in the Atlantic coast of the Southwestern Iberian Peninsula. We focus on artificial and realistic changes in land use, soil moisture and sea surface temperature. The analysis is performed for a case study of 20 days in August 2020, characterised by many coastal-breeze events in the area analysed and by a gradual decrease in the sea surface temperature. The model is evaluated with observational data at different coast locations, inland and on the ocean, as well as using wind speed transects from satellite altimetry.</p>

Author(s):  
Berina Kilicarslan ◽  
ismail yucel ◽  
Heves Pilatin ◽  
Eren Duzenli ◽  
Mustafa Yılmaz

In this study, the impact of spatio-temporal accuracy of four different sea surface temperature (SST) datasets on the accuracy of the Weather Research and Forecasting (WRF)-Hydro system to simulate hydrological response during two catastrophic flood events over Eastern Black Sea (EBS) and Mediterranean (MED) regions of Turkey is investigated. Three time-varying and high spatial resolution external SST products (GHRSST, Medspiration, and NCEP-SST) and one coarse-resolution and invariable SST product (ERA5- and GFS-SST for EBS and MED regions, respectively) already embedded in the initial and boundary condition dataset of WRF model are used in deriving near-surface weather variables through WRF. After the proper event-based calibration performed to the WRF-Hydro using hourly and daily streamflow data of small catchments in both regions, uncoupled model simulations for independent SST events are conducted to assess the impact of SST-triggered precipitation on simulated extreme runoff. Some localized and temporal differences in the occurrence of the flood events with respect to observations depending on the SST representation are noticeable. SST products represented with higher temporal and spatial correlation revealed significant improvement in flood hydrographs for both regions. The higher spatial and temporal correlations of GHRSST dataset show RMSE reduction up to 20% and increase in correlation from 0.3 to 0.8 with respect to the invariable SST (ERA5) in simulated runoffs over the EBS region. The error reduction with GHRSST reached 35% after the calibration of hydrological model parameters compared to not calibrated model. The use of both GHRSST and Medspiration SST data characterized with high spatiotemporal correlation resulted in runoff simulations exactly matching the observed runoff peak of 300 m3/s by reducing the overestimation seen in not calibrated runs over the MED region.


2016 ◽  
Vol 38 ◽  
pp. 11
Author(s):  
Alcimoni Nelci Comin ◽  
Otávio Costa Acevedo

The in situ data of sea surface temperature (SST) were measured onboard the Polar Ship Almirante Maximiano in the southern Shetland Islands between 5 and 23 February 2011. For the simulations, three concentric nested grids have been used at the 9 km, 3 km and 1 km spatial resolution in the simulations of the skin sea surface temperature (SSST) with WRF model. The grids are displaced every day, always centered in the middle position of the ship (latitude/longitude) during transect. The SSST is underestimated in comparison with SST on average 1.5°C. The real average wind speed observed was 8.7 ms-1. Therefore the amount of mixing between SST and SSST is greater, and the temperature difference between the two layers is smaller, on average 0.5°C. The underestimation of the model is mean 1°C. This underestimation directly interfere on the amount of ocean evaporation for the atmosphere, which may cause error in the energy balance. The correlation of the SSST with real SST data was 0.84 and root mean square error 1.87. 


2019 ◽  
Vol 124 (1) ◽  
pp. 171-183 ◽  
Author(s):  
S. Pimentel ◽  
W.‐H. Tse ◽  
H. Xu ◽  
D. Denaxa ◽  
E. Jansen ◽  
...  

2005 ◽  
Vol 44 (11) ◽  
pp. 1723-1744 ◽  
Author(s):  
Volker Wulfmeyer ◽  
Tijana Janjić

Abstract Shipborne observations obtained with the NOAA high-resolution Doppler lidar (HRDL) during the 1999 Nauru (Nauru99) campaign were used to study the structure of the marine boundary layer (MBL) in the tropical Pacific Ocean. During a day with weak mesoscale activity, diurnal variability of the height of the convective MBL was observed using HRDL backscatter data. The observed diurnal variation in the MBL height had an amplitude of about 250 m. Relations between the MBL height and in situ measurements of sea surface temperature as well as latent and sensible heat fluxes were examined. Good correlation was found with the sea surface temperature. The correlation with the latent heat flux was lower, and practically no correlation between the MBL height and the sensible heat and buoyancy fluxes could be detected. Horizontal wind profiles were measured using a velocity–azimuth display scan of HRDL velocity data. Strong wind shear at the top of the MBL was observed in most cases. Comparison of these results with GPS radiosonde data shows discrepancies in the wind intensity and direction, which may be due to different observation times and locations as well as due to multipath effects at the ship’s platform. Vertical wind profiles corrected for ship’s motion were used to derive vertical velocity variance and skewness profiles. Motion compensation had a significant effect on their shape. Normalized by the convective velocity scale and by the top of the mixed layer zi, the variance varied between 0.45 and 0.65 at 0.4z/zi and decreased to 0.2 at 1.0z/zi. The skewness ranged between 0.3 and 0.8 in the MBL and showed in almost all cases a maximum between 1.0z/zi and 1.1z/zi. These profiles revealed the existence of another turbulent layer above the MBL, which was probably driven by wind shear and cloud condensation processes.


2013 ◽  
Vol 26 (21) ◽  
pp. 8616-8627 ◽  
Author(s):  
Jing-Wu Liu ◽  
Su-Ping Zhang ◽  
Shang-Ping Xie

Abstract Effects of the sea surface temperature (SST) front along the East China Sea Kuroshio on sea surface winds at different time scales are investigated. In winter and spring, the climatological vector wind is strongest on the SST front while the scalar wind speed reaches a maximum on the warm flank of the front and is collocated with the maximum difference between sea surface temperature and surface air temperature (SST − SAT). The distinction is due to the change in relative importance of two physical processes of SST–wind interaction at different time scales. The SST front–induced sea surface level pressure (SLP) adjustment (SF–SLP) contributes to a strong vector wind above the front on long time scales, consistent with the collocation of baroclinicity in the marine boundary layer and corroborated by the similarity between the thermal wind and observed wind shear between 1000 and 850 hPa. In contrast, the SST modulation of synoptic winds is more evident on the warm flank of the SST front. Large thermal instability of the near-surface layer strengthens temporal synoptic wind perturbations by intensifying vertical mixing, resulting in a scalar wind maximum. The vertical mixing and SF–SLP mechanisms are both at work but manifest more clearly at the synoptic time scale and in the long-term mean, respectively. The cross-frontal variations are 1.5 m s−1 in both the scalar and vector wind speeds, representing the vertical mixing and SF–SLP effects, respectively. The results illustrate the utility of high-frequency sampling by satellite scatterometers.


2013 ◽  
Vol 77 ◽  
pp. 1-10 ◽  
Author(s):  
Marcos Rubal ◽  
Puri Veiga ◽  
Eva Cacabelos ◽  
Juan Moreira ◽  
Isabel Sousa-Pinto

Sign in / Sign up

Export Citation Format

Share Document