Cold air intrusions over southeastern South America — GFDL model behavior regarding climate simulations in the 20th century and future projections

Cavalcanti, Iracema Fonseca de Albuquerque; Müller, Gabriela V.; Andrade, Kelen Martins; Long, María Elena Fernández

doi:10.1016/j.gloplacha.2013.08.006

Cited by 6 publications

(2 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, Yin et al (2013) showed that GCM's handicaps in predicting fully CAI space-time features result in significant simulated rainfall bias, especially in the transition seasons, and more so in the spring (SON). In the austral winter, that is the dry season (May-September), GCM CAI climatology also points to decreases in frequency albeit accompanied by increases in intensity under global warming (Cavalcanti et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Extreme Orographic Rainfall in the Eastern Andes Tied to Cold Air Intrusions

Eghdami

Barros

2019

Front. Environ. Sci.

View full text Add to dashboard Cite

Long-duration localized heavy rainfall (> 6 h, < 10 km 2) was recorded by raingauges on October 4, 2013 at mid-elevations (∼ 1, 500 m) in the Peruvian Andes, which was not apparent in infrared or microwave measurements from either geostationary or polar orbiting satellites. This spring event is investigated here through a numerical modeling study using the Weather and Research Forecasting (WRF) model, and examined in the context of the climatology of Cold Air Intrusions (CAIs) along the eastern flanks of the tropical Andes. The model results suggest significant precipitation enhancement from intense shallow convection at the CAI frontal boundary amplified by orographic lifting as it propagates northward latched to the slopes of Andes. Analysis of CAI mesoscale dynamics was conducted using four decades of European Center Medium-Range Weather Forecasts (ECMWF) reanalysis, Tropical Rainfall Measurement Mission (TRMM) data products, and rain-gauge observations with emphasis on characterizing year-round CAI frequency, CAI interactions with Andes topography, and their impact on orographic precipitation climatology. The data show a robust enhancement of the diurnal cycle of precipitation during CAI events in all seasons, and in particular increases in surface rainfall rate during early morning at intermediate elevations (∼ 1,500 m), that is the eastern Andes orographic maximum. This link between CAI frequency and rainfall suggests that they play an important role in maintaining the Andes to Amazon year-round terrestrial connectivity through runoff production and transport by the river networks.

show abstract

Section: Introductionmentioning

confidence: 99%

Extreme Orographic Rainfall in the Eastern Andes Tied to Cold Air Intrusions

Eghdami

Barros

2019

Front. Environ. Sci.

View full text Add to dashboard Cite

show abstract

“…There are few studies on climatology of frontal systems over South America in modelling simulations. Global models, such as GFDL‐CM2.0 (Geophysical Fluid Dynamics Laboratory), represented the cold air intrusions from May to September from 1961 to 1990 over different regions of Southeast South America, where the frontal systems impact, but overestimated the frequency of cases (Cavalcanti et al, ). For the same regions and historical period, Andrade et al .…”

Section: Introductionmentioning

confidence: 99%

Atmospheric characteristics that induce extreme precipitation in frontal systems over Southeastern Brazil during summer: Observations and atmospheric model simulation

Andrade

Cavalcanti

2018

Intl Journal of Climatology

View full text Add to dashboard Cite

Cold fronts are the most frequent synoptic systems that affect Southeast Brazil during the whole year. The highest frequency of these systems at these latitudes occurs in the months of spring (SON) and winter (JJA), but the highest associated precipitation occurs in the spring (SON) and summer (DJF). Some of these fronts present light rains but others cause heavy precipitation, giving rise to flooding and landslides, mainly in the summer. Composites of the two cases (light and heavy rainfall) are analysed for the summer season. Large‐scale and regional features are shown to discuss the differences in precipitation. Regional differences are seen in the position and intensity of low pressure and postfrontal high. The differences are also associated with the humidity flux and convergence over the region. The main difference at high levels is the position of the frontal trough, which is close to the region in the wet cases and displaced to the ocean in the dry cases. Features of the Southern Annular Mode and Madden–Julian Oscillation show opposite patterns in the two cases. These modes of variability can modulate extra‐tropical wave trains over the Pacific, which have different behaviour downstream, over South America and South Atlantic Ocean. The eddy kinetic energy is stronger over Southeastern Pacific and Southern South America, and wave activity shows energy propagation towards the continent in the wet cases. Similar analyses with results of a global atmospheric model show that the general atmospheric characteristics of a frontal system are reproduced, as the temperature gradient, the wind confluence and the ridge‐trough pair associated with the frontal system. The model represents the differences with respect to moisture flux and the frontal trough position, but underestimates the moisture convergence, eddy kinetic energy and wave activity, in the wet cases.

show abstract