Rainy Season Features for the Alcântara Launch Center

Abstract

The rainy season features for the Alcântara Launch Center region (2°S-3°S; 44°W-45°W), located at the northern coast of Brazil, were obtained by using the Climate Prediction Center/National Oceanic and Atmospheric Administration daily precipitation data from 1979 to 2012 accumulated to pentads. The rainy season onset (demise) was defined as the first pentad when precipitation is greater (lower) than the climatological annual average, and this behavior lasts for three out of the four following pentads. The average rainy season features were: 28 January as onset day; 16 June as demise day; 140 days as length; 1527 mm as total precipitation (about 80% of the annual value); and 10.9 mm day -1 as intensity (rain rate). The uncertainty on these climatological values due to the use of different precipitation datasets was estimated as few days for the onset/demise days and length, 100 mm for the total precipitation and about 1 mm day -1 for the intensity. Except for intensity, the rainy season features showed large interannual variability: standard variation of about one month for onset/demise days, and coefficient of variation of 33 and 40% for length and total precipitation, respectively. The three-week period between 24 March and 13 April belonged to the rainy season of all years. In general, longer (shorter) duration was related to early (late) onset, late (early) demise, and higher (lower) total precipitation. Within the rainy season, on an average, precipitation was lower than 0.1 mm day -1 in only four to five days; therefore, the occurrence of "no-rain" days was rather uncommon.

Interannual Variability of Precipitation for the Centro de Lançamento de Alcântara in ENSO-Neutral Years

“…Precipitation values are computed as the area average over the four grid points that surround the CLA (Pinheiro and Oyama 2013), whereas wind values refer to the (45°W; 2.5°S) grid-point values. The computing procedures are not the same because the precipitation and wind data are given on different grids (Table 1), and the idea is to locate the CLA approximately at the center of the area for which the data is representative.…”

“…The precipitation data from the Global Precipitation Climatology Centre (GPCC) have been used in climate studies (Schneider et al 2014) and also in studies focusing on the South America precipitation variability (Kayano et al 2011). For the CLA, GPCC data are compared to the Climate Prediction Center (CPC)/NOAA data, which were used by Pinheiro and Oyama (2013) to obtain the rainy season features for the CLA. For the total precipitation in the rainy quarter (March, April and May), there is close agreement between the time series in the 1979-2010 period, which is the common period for both datasets (Fig.…”

“…Previous studies suggest that this variability would be related to oceanic factors, such as the ENSO phases and the GRAD direction, and to dynamical factors, such as the meridional position of the Atlantic ITCZ and the low-level circulation over the CLA. For instance, Pinheiro and Oyama (2013) showed that anomalies in the rainy season onset, for specific years, would be related to the ENSO phase, GRAD direction and meridional position of the Atlantic ITCZ. Marques and Fortes (2012) showed that the relation between ENSO-warm (cold) phase and below-(above-) average precipitation in the CLA would hold only in intense El Niño or La Niña events occurring in the rainiest months.…”

Wet Days in the Dry Quarter of the Alcântara Launch Center Region: Observational Features

“…These data are based on rain gauge measurements gridded on a regular 0.5° × 0.5° mesh using an optimal interpolation technique (Xie et al 2007;Silva et al 2007b). The daily total for the CLA region is calculated as the area-mean over the 4 grid points that surround CLA (Pinheiro and Oyama 2013); therefore, the CLA region is defined in this work as the 1° × 1° area centered at 2.5° S and 44.5° W. The SON quarter in 2006 is excluded because its quarterly total is clearly unrealistic (> 10 times the mean). In this work, as mentioned previously, only wet (daily total ≥ 1 mm/day) and heavy precipitation days (daily total ≥ 10 mm/day) are considered.…”

“…xx/xx 06/12 (Silva et al 2007b;Pinheiro and Oyama 2013). Regarding the magnitude of the anomalies, higher positive anomalies are found before 1990 (in 1984 and 1989 for PWET and NWET, and in 1986 for NWET).…”