Modeling the air‐sea feedback system of Madeira Island

Abstract

A realistic nested data‐assimilating two‐way coupled ocean/atmosphere modeling study (highest resolution 2 km) of Madeira Island was conducted for June 2011, when conditions were favorable for atmospheric vortex shedding. The simulation's island lee region exhibited relatively cloud‐free conditions, promoting warmer ocean temperatures (∼2°C higher than adjacent waters). The model reasonably reproduced measured fields at 14 meteorological stations, and matched the dimensions and magnitude of the warm sea surface temperature (SST) wake imaged by satellite. The warm SSTs in the wake are shown to imprint onto the atmospheric boundary layer (ABL) over several diurnal cycles by modulating the ABL depth up to ∼200–500 m. The erosion and dissipation of the warm ocean wake overnight was aided by atmospheric drainage flow and offshore advection of cold air (ΔT = 2°C) that produced strong upward heat fluxes (∼50 W/m2 sensible and ∼250 W/m2 latent) on an episodic basis. Nevertheless, the warm wake was never entirely eroded at night due to the cumulative effect of the diurnal cycle. The spatial pattern of the diurnal warming varied day‐to‐day in location and extent. Significant mutual interaction of the oceanic and atmospheric boundary layers was diagnosed via fluxes and temperature cross sections and reinforced by sensitivity runs. The simulation produces for the first time the interactive nature of the ocean and atmosphere boundary layers in the warm wake region of an island with complex terrain.

Persistence of observed air temperatures in Iceland

“…In general, the spatial variability of warming due to less snow and sea ice in the Arctic in future climate, is believed to have a complex impact on the flow pattern and may lead to amplification of mid‐tropospheric waves (Vavrus et al, ). On a smaller scale, there exist extensive studies on the feedback between the air and the sea (e.g., Pullen et al, )…”

“…In general, the spatial variability of warming due to less snow and sea ice in the Arctic in future climate, is believed to have a complex impact on the flow pattern and may lead to amplification of mid-tropospheric waves (Vavrus et al, 2017). On a smaller scale, there exist extensive studies on the feedback between the air and the sea (e.g., Pullen et al, 2017) A connection between the soil moisture and snow cover on the one hand and monthly mean temperatures on the other hand is quite well established (Walsh et al, 1985;Kolstad et al, 2017 and ref. therein).…”

The UKC3 regional coupled environmental prediction system

“…Recent research focussed on other locations includes the work of Pullen et al (2017b), who successfully applied a regional coupled model to assess the role of air-sea feedbacks on vortex shedding in the lee of Maderia Island. This modelling system 25 incorporated nested implementations of the NOGAPS atmosphere and NCOM ocean models, run at up to 2 km horizontal resolution and with coupled fields exchanged every 6 minutes using the Earth System Modeling Framework (ESMF) coupler through the 20 day simulation period.…”

Hydraulic studies and their influence for regional urban planning: a pratical approach to Fynchal’s rivers

“…To the East, the land is dry, windswept and deserted. The climate changes from subtropical to alpine forest along the mountains sides (França & Almeida, 2003;Ribeiro & Ramalho, 2009;Brum da Silveira, et al, 2010;Ramalho, et al, 2015;Pullen, et al, 2017).…”

“…To analyse the selected portionsit's important to characterize the watershed where they are inserted, obtaining important parameters for the calculation of peak flow rates, in an expedited and relatively simple manner, using the software ArcMap 10.3, main component of ArcGIS system (geographic information system) from the company ESRI (Environmental Systems Research Institute), mainly used to view, edit, create and analyse geospatial data, complemented with the support of a spreadsheet and CAD software, obtaining the parameters required for the 3 watersheds: Sao João, Santa Luzia and João Gomes (Figure 4). From a geological perspective, Funchal consists essentially of superior complex layers, intermediate (highest percentage) and sedimentary cover (at the river mouth): local lava spills with tephra, between a million and six thousand years, extrusive igneous rocks; intermediate complex -lava sequences with tephra, separated by erosion levels, age between 1 and 2.5 million years, extrusive igneous rocks; sedimentary cover -riverine and marine sedimentarygravels, mudslides, beach sands, and sedimentary rocks (França & Almeida, 2003;Ribeiro & Ramalho, 2009;Brum da Silveira, et al, 2010;Ramalho, et al, 2015;Pullen, et al, 2017).…”