Simona Bordoni

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In a simulation of seasonal cycles with an idealized general circulation model without a hydrologic cycle and with zonally symmetric boundary conditions, the Hadley cells undergo transitions between two regimes distinguishable according to whether large-scale eddy momentum fluxes strongly or weakly influence the strength of a cell. The center of the summer(More)
[1] Five years (1999–2003) of near-surface QuikSCAT ocean winds over the Gulf of California and northeast Pacific Ocean are used to characterize the changes in the low-level circulation associated with the North American Monsoon. Our analysis shows that the onset of the summer season is accompanied by a seasonal reversal of the flow along the Gulf of(More)
Steady-state and time-dependent Hadley circulations are investigated with an idealized dry GCM, in which thermal forcing is represented as relaxation of temperatures toward a radiative-equilibrium state. The latitude f0 of maximum radiative-equilibrium temperature is progressively displaced off the equator or varied in time to study how the Hadley(More)
The response of the monsoonal and annual-meanHadley circulation to orbital precession is examined in an idealized atmospheric general circulation model with a simplified representation of land surface processes in subtropical latitudes. When perihelion occurs in the summer of a hemisphere with a subtropical continent, changes in the top-of-atmosphere energy(More)
A principal component analysis of the summertime near-surface Quick Scatterometer (QuikSCAT) winds is used to identify the leading mode of synoptic-scale variability of the low-level flow along the Gulf of California during the North American monsoon season. A gulf surge mode emerges from this analysis as the leading EOF, with the corresponding principal(More)
The response of the monsoonal and annual-meanHadley circulation to orbital precession is examined in an idealized atmospheric general circulation model with an aquaplanet slab-ocean lower boundary. Contrary to expectations, the simulated monsoonal Hadley circulation is weaker when perihelion occurs at the summer solstice than when aphelion occurs at the(More)
This paper investigates the dynamical processes throughwhich the Tibetan Plateau (TP) influences theEast Asian summer monsoon (EASM) within the framework of the moist static energy (MSE) budget, using both observations and atmospheric general circulation model (AGCM) simulations. The focus is on the most prominent feature of the EASM, the so-called(More)
Orbital precession changes the seasonal distribution of insolation at a given latitude but not the annual mean. Hence, the correlation of paleoclimate proxies of annual-mean precipitation with orbital precession implies a nonlinear rectification in the precipitation response to seasonal solar forcing. It has previously been suggested that the relevant(More)
3 ied in aquaplanet experiments using the global Weather Research and Fore-4 casting (WRF) model. We show how the scaling of precipitation extremes 5 is highly sensitive to spatial and temporal averaging: while instantaneous grid-6 point extreme precipitation scales more strongly than the percentage increase 7 (7% K −1) predicted by the Clausius-Clapeyron(More)