Regional Climate Model–Simulated Timing and Character of Seasonal Rains in South America

Rauscher, Sara A.; Seth, Anji; Liebmann, Brant; Qian, Jian-Hua; Camargo, Suzana J.
July 2007
Monthly Weather Review;Jul2007, Vol. 135 Issue 7, p2642
Academic Journal
The potential of an experimental nested prediction system to improve the simulation of subseasonal rainfall statistics including daily precipitation intensity, rainy season onset and withdrawal, and the frequency and duration of dry spells is evaluated by examining a four-member ensemble of regional climate model simulations performed for the period 1982–2002 over South America. The study employs the International Centre for Theoretical Physics (ICTP) regional climate model, version 3 (RegCM3), driven with the NCEP–NCAR reanalysis and the European Centre–Hamburg GCM, version 4.5. Statistics were examined for five regions: the northern Amazon, southern Amazon, the monsoon region, Northeast Brazil, and southeastern South America. RegCM3 and the GCM are able to replicate the distribution of daily rainfall intensity in most regions. The analysis of the rainy season timing shows the observed onset occurring first over the monsoon region and then spreading northward into the southern Amazon, in contrast to some previous studies. Correlations between the onset and withdrawal date and SSTs reveal a strong relationship between the withdrawal date in the monsoon region and SSTs in the equatorial Pacific, with above-average SSTs associated with late withdrawal. Over Northeast Brazil, the regional model errors are smaller than those shown by the GCM, and the strong interannual variability in the timing of the rainy season is better simulated by RegCM3. However, the regional model displays an early bias in onset and withdrawal over the southern Amazon and the monsoon regions. Both RegCM3 and the GCM tend to underestimate (overestimate) the frequency of shorter (longer) dry spells, although the differences in dry spell frequency during warm and cold ENSO events are well simulated. The results presented here show that there is potential for added value from the regional model in simulating subseasonal statistics; however, improvements in the physical parameterizations are needed for this tropical region.


Related Articles

  • Summer monsoon rainfall patterns over South Korea and associated circulation features. B.-J. Kim; R. H. Kripalani; J.-H. Oh; S.-E. Moon // Theoretical & Applied Climatology;2002, Vol. 72 Issue 1/2, p65 

    Summary Seasonal summer monsoon (June through August) rainfall patterns over South Korea are classified by an objective method using data for a 40-year period (1961?2000). The rainfall patterns are represented by the percentage departures from the normal rainfall of 12 stations spread uniformly...

  • Weather Types and Rainfall over Senegal. Part I: Observational Analysis. Moron, Vincent; Robertson, Andrew W.; Ward, M. Neil; Ndiaye, Ousmane // Journal of Climate;Jan2008, Vol. 21 Issue 2, p266 

    A k-means cluster analysis is used to summarize unfiltered daily atmospheric variability at regional scale over the western Sahel and eastern tropical North Atlantic during the boreal summer season [July–September (JAS)] 1961–98. The analysis employs zonal and meridional regional...

  • Linkages between Orographic Forcing and the Scaling Properties of Convective Rainfall in Mountainous Regions. Nykanen, Deborah K. // Journal of Hydrometeorology;Jun2008, Vol. 9 Issue 3, p327 

    Heavy rainfall over mountainous terrain often results in catastrophic flooding and presents a great challenge for forecasters. Statistical downscaling methods provide a way to bridge across the scale gap between rainfall forecasts from numerical weather prediction models and the high-resolution...

  • Semi-parametric and Parametric Inference of Extreme Value Models for Rainfall Data. AghaKouchak, Amir; Nasrollahi, Nasrin // Water Resources Management;Apr2010, Vol. 24 Issue 6, p1229 

    Extreme rainfall events and the clustering of extreme values provide fundamental information which can be used for the risk assessment of extreme floods. Event probability can be estimated using the extreme value index (γ) which describes the behavior of the upper tail and measures the degree...

  • South and East Asian Summer Monsoon Climate and Variation in the MRI Coupled Model (MRI-CGCM2). Rajendran, K.; Kitoh, A.; Yukimoto, S. // Journal of Climate;Feb2004, Vol. 17 Issue 4, p763 

    Simulations of the major characteristics of the summer monsoon climate over South Asia, East Asia, and the western North Pacific by the new version of the Meteorological Research Institute coupled GCM (MRI-CGCM2) are analyzed. In addition to assessing the simulation of mean summer monsoon...

  • Projected Midlatitude Continental Summer Drying: North America versus Europe. Rowell, David P. // Journal of Climate;Jun2009, Vol. 22 Issue 11, p2813 

    A common signal in climate model projections is a decline in average summer rainfall over midlatitude continents due to anthropogenic warming. Most models suggest this rainfall decline will be less severe over North America than over Europe. This study aims to understand this difference in...

  • Analyse de la Variabilit� du R�gime Pluviom�trique dans la R�gion Agricole d'Ina au B�nin. Emmanuel, Lawin Agnid�; Abel, Afouda; Thierry, Lebel // European Journal of Scientific Research;3/ 1/2011, Vol. 50 Issue 3, p425 

    No abstract available.

  • Modelling of monsoon rainfall for a mesoscale catchment in North-West India I: assessment of objective circulation patterns. Zehe, E.; Singh, A. K.; Bárdossy, A. // Hydrology & Earth System Sciences;2006, Vol. 10 Issue 6, p797 

    Within the present study we shed light on the question whether objective circulation patterns (CP) classified from either the 500 HPa or the 700H Pa level may serve as predictors to explain the spatio-temporal variability of monsoon rainfall in the Anas catchment in North West India. To this end...

  • An investigation into the conditions leading to monsoon onset over Kerala. Ramesh Kumar, M. R.; Sankar, S.; Reason, C. // Theoretical & Applied Climatology;2009, Vol. 95 Issue 1/2, p69 

    Monsoon onset over the Kerala (MOK) coast has been studied using the recently released high resolution Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite data (HOAPS 3). Columnar water vapour content, sea surface temperature and evaporation have been utilised to examine the conditions...


Read the Article

Courtesy of

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics