Mean Daily Rainfall Research Articles

Performance of TRMM TMPA 3B42 V7 in Replicating Daily Rainfall and Regional Rainfall Regimes in the Amazon Basin (1998–2013)

Knowledge and studies on precipitation in the Amazon Basin (AB) are determinant for environmental aspects such as hydrology, ecology, as well as for social aspects like agriculture, food security, or health issues. Availability of rainfall data at high spatio-temporal resolution is thus crucial for these purposes. Remote sensing techniques provide extensive spatial coverage compared to ground-based rainfall data but it is imperative to assess the quality of the estimates. Previous studies underline at regional scale in the AB, and for some years, the efficiency of the Tropical Rainfall Measurement Mission (TRMM) 3B42 Version 7 (V7) (hereafter 3B42) daily product data, to provide a good view of the rainfall time variability which is important to understand the impacts of El Nino Southern Oscilation. Then our study aims to enhance the knowledge about the quality of this product on the entire AB and provide a useful understanding about his capacity to reproduce the annual rainfall regimes. For that purpose we compared 3B42 against 205 quality-controlled rain gauge measurements for the period from March 1998 to July 2013, with the aim to know whether 3B42 is reliable for climate studies. Analysis of quantitative (Bias, Relative RMSE) and categorical statistics (POD, FAR) for the whole period show a more accurate spatial distribution of mean daily rainfall estimations in the lowlands than in the Andean regions. In the latter, the location of a rain gauge and its exposure seem to be more relevant to explain mismatches with 3B42 rather than its elevation. In general, a good agreement is observed between rain gauge derived regimes and those from 3B42; however, performance is better in the rainy period. Finally, an original way to validate the estimations is by taking into account the interannual variability of rainfall regimes (i.e., the presence of sub-regimes): four sub-regimes in the northeast AB defined from rain gauges and 3B42 were found to be in good agreement. Furthermore, this work examined whether TRMM 3B42 V7 rainfall estimates for all the grid points in the AB, outgoing longwave radiation (OLR) and water vapor flux patterns are consistent in the northeast of AB.

Correlates of Climate Variability and Dengue Fever in Two Metropolitan Cities in Bangladesh.

Dengue fever is a major public health concern in Bangladesh with increased incidence during monsoon. We aimed to assess the correlation of temperature, humidity, and rainfall on dengue fever in two dengue endemic cities in Bangladesh. It was a time series analysis of climate factors and dengue occurrence data in Dhaka and Chittagong cities from 1 January 2000 to 31 December 2009. Daily mean temperature, rainfall, and humidity data were obtained from the Bangladesh meteorological department and daily dengue cases data were obtained from the directorate general of health services (DGHS) of Bangladesh. The mean dengue incidence was 31.62 (SD 28.7) per 100,000 in Dhaka whereas it was 5.76 (SD 11.7) per 100,000 population in Chittagong. The incidence of dengue cases was found significantly associated with the monthly mean temperature, total rainfall, and mean humidity in Dhaka, though in Chittagong, the significantly associated factors​ ​​​​​​were monthly total rainfall and mean humidity. The autoregressive integrated moving average (ARIMA) model identified monthly mean humidity and total rainfall as the most significant contributing factors for dengue cases in Dhaka and Chittagong, respectively. Our study reinforces the relationship of climate parameters with dengue fever, which will support policy-makers in developing a climate-based early warning system for dengue in Bangladesh.

DOWNSCALING OF DAILY AVERAGE RAINFALL OF KOTA BHARU KELANTAN, MALAYSIA

Downscaling Global Circulation Model (GCM) output is important in order tounderstand the present climate as well as future climate changes at local scale. In this study,Random Forest (RF) was used to downscale the mean daily rainfall at Kota Bahru meteorologicalstation located in Kelantan Malaysia. The RF model was used to downscale daily rainfall fromGCM of Coupled Model Intercomparison Project Phase 5 (CMIP5), BCC-CSM1.1. The potentialpredictors were selected using stepwise regression at grid points located around the study area.Quantile mapping was used to remove the bias in the prediction. The results showed that the RFmodel was able to establish a good relation between observed and downscaled rainfall. TheQuantile mapping was found to perform well to correct errors in prediction. The statisticalmeasures of performance of downscaling and bias correction approaches show that they are ableto replicate daily observed rainfall with Nash-Schutclif efficiency greater than 0.75 for all themonths. It can be concluded that RF and Quantile mapping are reliable and effective methods fordownscaling rainfall.

DOWNSCALING OF DAILY AVERAGE RAINFALL OF KOTA BHARU KELANTAN, MALAYSIA

Downscaling Global Circulation Model (GCM) output is important in order tounderstand the present climate as well as future climate changes at local scale. In this study,Random Forest (RF) was used to downscale the mean daily rainfall at Kota Bahru meteorologicalstation located in Kelantan Malaysia. The RF model was used to downscale daily rainfall fromGCM of Coupled Model Intercomparison Project Phase 5 (CMIP5), BCC-CSM1.1. The potentialpredictors were selected using stepwise regression at grid points located around the study area.Quantile mapping was used to remove the bias in the prediction. The results showed that the RFmodel was able to establish a good relation between observed and downscaled rainfall. TheQuantile mapping was found to perform well to correct errors in prediction. The statisticalmeasures of performance of downscaling and bias correction approaches show that they are ableto replicate daily observed rainfall with Nash-Schutclif efficiency greater than 0.75 for all themonths. It can be concluded that RF and Quantile mapping are reliable and effective methods fordownscaling rainfall.

TREND OF DAILY RAINFALL AND TEMPERATURE IN PENINSULAR MALAYSIA BASED ON GRIDDED DATA SET

A gridded data set with the size of 0.05 degree resolution (approximately 5.5km) which representing ground observations of daily rainfall and temperature of Peninsular Malaysia has been created over 1975-2006. The integration and processing of the variety of data sources and data assessment is also presented. The 32-year period of the daily gridded rainfall and temperature data set were assessed to see how the daily mean rainfall and temperature have changed over time and space. Northeast monsoon (NEM) contributes more rainfall over the country compare to southwest monsoon (SWM). The rainfall trend during NEM is found significantly increased at the 95% confidence level (7mm/season/year), meanwhile SWM rainfall does not pose any significant trends. Both NEM and SWM temperature trends show significant increasing trends at 95% confidence level at 0.32oC/decade and 0.31oC/decade, respectively over the 32-year period. A drastic increased of mean temperature (1.20oC) was found in Klang Valley over the 20-year period. The mean decadal temperature was found consistently decrease as it approached the northern, east coast and southern part of the country.

Non-linear effects of mean temperature and relative humidity on dengue incidence in Guangzhou, China

BackgroundDengue fever is an important infectious disease in Guangzhou, China; previous studies on the effects of weather factors on the incidence of dengue fever did not consider the linearity of the associations. MethodsThis study evaluated the effects of daily mean temperature, relative humidity and rainfall on the incidence of dengue fever. A generalized additive model with splines smoothing function was performed to examine the effects of daily mean, minimum and maximum temperatures, relative humidity and rainfall on incidence of dengue fever during 2006–2014. ResultsOur analysis detected a non-linear effect of mean, minimum and maximum temperatures and relative humidity on dengue fever with the thresholds at 28°C, 23°C and 32°C for daily mean, minimum and maximum temperatures, 76% for relative humidity, respectively. Below the thresholds, there was a significant positive effect, the excess risk in dengue fever for each 1°C in the mean temperature at lag7–14days was 10.21%, (95% CI: 6.62% to 13.92%), 7.10% (95% CI: 4.99%, 9.26%) for 1°C increase in daily minimum temperature in lag 11days, and 2.27% (95% CI: 0.84%, 3.72%) for 1°C increase in daily maximum temperature in lag 10days; and each 1% increase in relative humidity of lag7–14days was associated with 1.95% (95% CI: 1.21% to 2.69%) in risk of dengue fever. ConclusionsFuture prevention and control measures and epidemiology studies on dengue fever should consider these weather factors based on their exposure-response relationship.

Quantitative Research on the Relationship between Yield of Winter Wheat and Agroclimatological Resources—the Case Study from Yanzhou District, Shandong Province, China

Agroclimatological resources provide material and energy for agricultural production. This study is aimed to analyze the impact of selected climate factors change on wheat yield over the different growth period applied quantitatively method, by comparing two different time division modules of wheat growth cycle- monthly empirical-statistical multiple regression models ( From October to June of next year ) and growth stage empirical-statistical multiple regression models (Including sowing stage, seedling stage, tillering stage, overwintering period, regreening period, jointing stage, heading stage, maturity stage) analysis of relationship between agrometeorological data and growth stage records and winter wheat production in Yanzhou, Shandong Province of China. Correlation analysis(CA)was done for 35 years (from 1981 to 2015) between crop yield and corresponding weather parameters including daily mean temperature, sunshine duration, and average daily precipitation selected from 18 different meteorological factors. The results shows that the greatest impact on the winter wheat yield is the precipitation overwintering period in this area, each 1mm increase in daily mean rainfall was associated with 201.64 kg/hm2 lowered output. Moreover, the temperature and sunshine duration in heading period and maturity stage also exert significant influence on the output, every 1°C increase in daily mean temperature was associated with 199.85kg/hm2 adding output, every 1h increase in mean sunshine duration was associated with 130.68kg/hm2 reduced output. Comparing with the results of experiment which using months as step sizes and using farming as step sizes was in better agreement with the fluctuation in meteorological yield, offered a better explanation on the growth mechanism of wheat. Eventually the results indicated that 3 factors affects the yield during different growing periods of wheat in different extent and provided more specific reference to guide the agricultural production management in this area.

Association of dengue fever with Aedes spp. abundance and climatological effects.

To analyze the association of dengue fever incidence with Aedes mosquito's abundance, and the effect of climatological and geographical variables, in a region in Morelos State, Mexico. Weekly data during the period 2010 to 2014 was used. Mosquito abundance was determined using ovitraps. Confirmed dengue cases were obtained from the Epidemiological Surveillance System. Climatic variables were obtained from weather monitoringstations. The correlation between climate variables and ovitraps data was estimated using a multivariate regression model. A correlation of mosquito abundance with dengue fever incidence, and a yearly pattern with seasonal variations were observed. The daily mean temperature, relative humidity and rainfall parameters were associated with mosquito egg abundance. Time lags of three and four weeks between egg counts and dengue fever incidence were observed. Time lags between egg counts and dengue incidence could be useful for prevention and control interventions.

The Relationship Between Weather and Objectively Measured Physical Activity Among Individuals With COPD.

Although daily variation in weather impacts physical activity (PA) levels among relatively healthy individuals, it is largely unknown whether this relationship occurs for those living with chronic obstructive pulmonary disease (COPD). The purpose of this study was to examine how daily variation in temperature, rain, and snow is related to objectively measured PA among patients with COPD, and whether demographic or clinical characteristics moderate these relationships. Patients with COPD completed a questionnaire and wore a pedometer for 7 days at baseline, end of pulmonary rehabilitation (PR), and 3 and 9 months after completing PR (28 days in total). Hierarchal linear modeling showed that daily mean temperature and total daily rainfall, but not snowfall, independently predicted steps/day, controlling for demographic and clinical covariates in 189 patients in PR. Specifically, an increase of 10°C translates into 316 more steps (6.6% of mean steps/day) whereas a rainfall of 10 mm translates to 175 less steps (3.6% of mean steps/day). Furthermore, those with higher income had more steps/day on warmer days. These results add to converging evidence that weather plays an important role in determining PA among individuals with COPD.

English

This study investigates the possible effects of solar and geomagnetic activity on climatic parameters in Nigeria. Data of sunspot number and geomagnetic aa index from 1950 – 2012 and 1950 – 2010 were used as solar indices respectively. Monthly mean daily rainfall, minimum and maximum temperature data from 1950 – 2012 for 15 stations were used as climatic parameters. Descriptive and bivariate analyses as well as Mann-Kendall trend test were employed in analyzing the data, while power spectral density (PSD) analysis was performed using XLSTAT. The results reveal significant upward trends in the variability of minimum and maximum temperature, whereas no significant trends were observed in the variation trend of rainfall for the period under study. This was ascertained from the Mann-Kendall trend test. The variability in rainfall and temperature could be evidence of climate change. The correlation between solar indices and climatic parameters were statistically insignificant at 0.05 level of significant. Similar periodicities were observed in the spectrum of solar and geomagnetic activity indices, as well as the climatic parameters. There were indications of Schwabe, Hale and Gleissberg cycles on rainfall and temperature spectral. These depict signatures of solar and geomagnetic activities. Hence, we infer that, apart from human activities, solar and geomagnetic activities could play important roles in climate change observed in Nigeria. Key words: Solar activity, periodicities, climate change, Nigeria.

Sensitivity of the ACCESS forecast model statistical rainfall properties to resolution

The representation of the statistical properties of rainfall over Darwin is assessed in four versions of the Australian Community Climate and Earth‐System Simulator (ACCESS) forecast model against the dual‐polarization C‐band polarimetric (CPOL) radar observation for one rainy season (November 2014 to April 2015). This is an extended analysis of a companion study assessing the earlier version of the regional ACCESS‐12 km rainfall properties with the same CPOL observations. By comparing four different horizontal resolutions (40, 12, 4 and 1.5 km) of ACCESS, it is shown that increasing resolution results in improved total domain rainfall but does not change the compensation effect of underestimated intensity and overestimated frequency of occurrence. In all versions where the convective parametrization is still turned on, a strong and spurious land–sea contrast with too much rain over ocean not exporting to land is found. This problem is only solved by switching off the convective parametrization in the model (1.5 km resolution). However, in this explicit version, high rain rates are this time largely overestimated, resulting in a similar order of magnitude of the mean daily rainfall bias as when convection is parametrized, albeit with a different spatial distribution. The diurnal peak of hourly rain rates is also found to occur too early (around noon at the maximum insolation) when convection is parametrized, but is correct (around 1500 local time) when convection is explicit. More work needs to be done to assess if these errors are common to most cloud‐resolving models, and to solve these two main issues of excessive rainfall in the explicit version of the model and artificial land–sea contrast in the parametrized version of the model.

Connecting spatial and temporal scales of tropical precipitation in observations and the MetUM-GA6

Abstract. This study analyses tropical rainfall variability (on a range of temporal and spatial scales) in a set of parallel Met Office Unified Model (MetUM) simulations at a range of horizontal resolutions, which are compared with two satellite-derived rainfall datasets. We focus on the shorter scales, i.e. from the native grid and time step of the model through sub-daily to seasonal, since previous studies have paid relatively little attention to sub-daily rainfall variability and how this feeds through to longer scales. We find that the behaviour of the deep convection parametrization in this model on the native grid and time step is largely independent of the grid-box size and time step length over which it operates. There is also little difference in the rainfall variability on larger/longer spatial/temporal scales. Tropical convection in the model on the native grid/time step is spatially and temporally intermittent, producing very large rainfall amounts interspersed with grid boxes/time steps of little or no rain. In contrast, switching off the deep convection parametrization, albeit at an unrealistic resolution for resolving tropical convection, results in very persistent (for limited periods), but very sporadic, rainfall. In both cases, spatial and temporal averaging smoothes out this intermittency. On the ∼ 100 km scale, for oceanic regions, the spectra of 3-hourly and daily mean rainfall in the configurations with parametrized convection agree fairly well with those from satellite-derived rainfall estimates, while at ∼ 10-day timescales the averages are overestimated, indicating a lack of intra-seasonal variability. Over tropical land the results are more varied, but the model often underestimates the daily mean rainfall (partly as a result of a poor diurnal cycle) but still lacks variability on intra-seasonal timescales. Ultimately, such work will shed light on how uncertainties in modelling small-/short-scale processes relate to uncertainty in climate change projections of rainfall distribution and variability, with a view to reducing such uncertainty through improved modelling of small-/short-scale processes.

Modelling the relationship between zooplankton biomass and environmental variations in the distribution of 210Po during a one year cycle in northwestern Mediterranean coastal waters

To clarify the relationship between zooplankton biomass and the environmental kinetics of the natural radionuclide 210Po during a one-year period (October 1995 to November 1996) in northwestern Mediterranean coastal waters, a modelling analysis was applied. Using 210Po concentrations in seawater and zooplankton, the 210Po uptake rate constant from food for zooplankton was evaluated using a biokinetics calculation involving the uptake and the excretion rate constants between seawater and zooplankton. Using the transfer constants obtained, the 210Po concentrations in zooplankton were reconstructed and validated by observed concentrations. The simulation results were in good agreement with the measured 210Po concentrations in zooplankton. Assuming that 210Po fecal excretion represents the majority of the excretion of 210Po from zooplankton, the fecal matter associated 210Po vertical flux was calculated, and compared with the observed vertical fluxes of 210Po measured in sediment traps. The modelling evaluation showed that fecal pellet vertical transport could not fully explain the observed sinking fluxes of particulate organic matter at 150 m depth, suggesting that other sinking biodetrital aggregates are also important components of the plankton-derived vertical flux of 210Po.The relationship between 210Po concentration in seawater and that in rain and dry fallout and their potential effect on 210Po concentrations in zooplankton at this location were also examined. A similar, but diphased trend between 210Po in zooplankton and 210Po in rain and dry fallout deposition rate was demonstrated. 210Po concentrations in the dissolved phase of seawater tended to diminish as mean daily rainfall increased suggesting that rain inputs serve as a 210Po dilution mechanism in seawater at this location.

Spatial variation of deterministic chaos in mean daily temperature and rainfall over Nigeria

Daily rainfall and temperature data from 47 locations across Nigeria for the 36-year period 1979–2014 were treated to time series analysis technique to investigate some nonlinear trends in rainfall and temperature data. Some quantifiers such as Lyapunov exponents, correlation dimension, and entropy were obtained for the various locations. Positive Lyapunov exponents were obtained for the time series of mean daily rainfall for all locations in the southern part of Nigeria while negative Lyapunov exponents were obtained for all locations in the Northern part of Nigeria. The mean daily temperature had positive Lyapunov exponent values (0.35–1.6) for all the locations. Attempts were made in reconstructing the phase space of time series of rainfall and temperature.

Orographic Precipitation in Coastal Southern Chile: Mean Distribution, Temporal Variability, and Linear Contribution

AbstractThe Nahuelbuta Mountains (NM) are a semielliptical massif 1300 m high in coastal southern Chile (37°–38°S) facing frontal storms that move from the Pacific. Mean precipitation between 900 and 1200 mm yr−1 is observed in the surrounding lowland, but river flow measurements suggest values ≥3000 mm yr−1 atop the mountains. To verify and characterize such marked orographic enhancement, 15 rain gauges were deployed around and over the NM. The observations were supplemented by a high-resolution WRF simulation and linear theory (LT) modeling during the winter of 2011. The estimated mean precipitation increases gradually from offshore (~1000 mm yr−1) to the north-facing foothills (2000 mm yr−1). The precipitation rapidly increases in the upslope sector to reach ~4000 mm yr−1 over the northern half of the NM elevated plateau, and decreases farther south to reach background values 20–30 km downstream of the mountains. The upstream (downstream) orographic enhancement (suppression) was relatively uniform among storms when considering event accumulations but varied substantially within each storm, with larger modifications during pre- and postfrontal stages and minor modifications during the brief but intense frontal passage. WRF results are in good agreement with observations in terms of seasonal and daily mean rainfall distributions, as well as temporal variability. Given its linear, steady-state formulation, the LT model cannot resolve rainfall variability at short (hourly) time scales, which in WRF is at least characterized by transient, mesoscale rainbands. Nonetheless, the rainbands are mobile so the accumulation field at monthly or longer time scales produced by the linear model is remarkably similar to its WRF counterpart.

Spatial and temporal characteristics of rainfall across Ganjiang River Basin in China

The hydrological variations of Ganjiang River Basin have significant influence on the ecological environment of Poyang Lake, which is one of the largest freshwater lake and wetland in the world. This study analyzed the spatial and temporal characteristics of rainfall across Ganjiang River Basin. The analyses include annual total rainfall amount (ATRA), annual total rainy day (ATRD) and annual mean daily rainfall intensity (AMDRI). To detect changes in the hydrological trends, data from 19 rainfall stations from 1953 to 2013 were used in the analyses. First, quality control and homogeneity detection was carried out to examine the annual rainfall series. Second, the spatial correlation analysis was used to identify the spatial relationship among the measurements from different stations. Finally, the statistics of coefficient of variation (CV) and average were used to analyze the interannual variation trend. The modified Mann–Kendall (MMK) trend test method was used to detect the temporal characteristics of rainfall. The results include: (1) Some outliers were detected and corrected. (2) The correlation of ATRA and ATRD series of all the stations had lower spatial variability while the AMDRI series of all the stations had higher spatial variability. On the other hand, the ATRA, ATRD and AMDRI series of single stations show similar spatial variability and the influencing radius of the rainfall events was less than 50 km. (3) the rainfall at the northern and southern parts of the basin had smaller CV. Further, by applying the MMK test method to the ATRA, ATRD, and AMDRI series, the ATRA series has an increasing trend which is opposite to that of the ATRD series. The increasing trend in the ATRA series also led to the increasing trend in the AMDRI series. These stations are mainly in central and northern parts of the basin which are more likely to experience droughts and floods. Thus, for the central and northern parts of the basin, they should receive particular attention on the prevention and treatment of droughts and floods.

Anomalously wet and dry rainy seasons in Equatorial East Africa and associated differences in intra-seasonal characteristics

Differences between anomalously wet and dry rainy seasons over the period 1961–2001 in Equatorial East Africa (Kenya, northern Tanzania) are studied at local scale using a 53 rain-gauge network and analysing six intra-seasonal characteristics (ISCs): the onset and end dates, the wet spells number and length, daily mean rainfall amount and the dry spells length. As compared to anomalously dry Long Rains, anomalously wet ones record earlier onsets, more wet spells with higher daily mean rainfall amounts (above 14 mm/day). For the Short Rains, the end date is also widely modulated across the rain gauge network, and daily mean rainfall amounts above (below) 10 mm/day are more (less) frequent during anomalously wet (dry) seasons. The differences in the number, length and daily mean rainfall amount of wet spells between anomalously wet and anomalously dry rainy seasons is also analysed in an ensemble of 24 sea surface temperature-forced runs of the ECHAM4.5 Atmospheric General Circulation Model. For the Long Rains, results are inconsistent between runs which suggests a lack of reproducibility of the ISCs in the model. For the Short Rains, the ISCs distributions between anomalously wet and anomalously dry years are significantly different in most of the runs/locations. In particular, daily mean rainfall amounts above 8 mm/day are more (less) frequent in the model during anomalously wet (dry) years.

A Field Experiment on the Small-Scale Variability of Rainfall Based on a Network of Micro Rain Radars and Rain Gauges

AbstractSmall-scale summer rainfall variability in a semiarid zone was studied by deploying five vertically pointing Micro Rain Radars (MRRs) along a nearly straight line and by using 12 rain gauges in the study area of the Xilin River catchment in China. The spatial scales of 4 and 9 km correspond to the resolution of precipitation radar and rainfall products from satellites. The dataset of the MRRs and rain gauges covers two months in the summer of 2009. Three parameters, that is, spatial correlation, intermittency, and the coefficient of variation (CV), were used to describe the rainfall variability as based on the data from the MRRs and rain gauges. The probability of partial beamfilling in a 4-km (9 km) pixel over a 30-min temporal scale was 17%–20% (28%–37%). More accurate equipment can measure lower rainfall intermittency. For scales of 4 and 9 km, the median CV of the accumulation times that were longer than 3 h with rainfall > 1 mm was 0.17–0.42. The accuracy of areal rainfall measured by different quantities of equipment was also evaluated. One MRR was sufficient for measuring the daily areal rainfall at a 4-km scale, with a fraction of prediction within a factor of 2 of observations of 1.0 and a correlation coefficient of ≥0.58 when daily mean rainfall was >1 mm.

MJO Modulation of Station Rainfall in the Semiarid Seridó, Northeast Brazil

The influence of the Madden Julian Oscillation (MJO) on station rainfall over the Seridó region of Rio Grande do Norte state, Northeast Brazil is examined based on 17 raingauge daily data over 30-year period (1 January-31 December, 1981-2010). The Seridó is one of the driest regions in Northeast Brazil and is recognized as particularly vulnerable to desertification by the United Nations Convention to Combat Desertification. Firstly, daily anomalies were calculated by removing the 30-year daily climatology. Then, to distinguish the MJO signal from other patterns of climate variability, the daily anomalies were band pass filtered in the frequency domain (20 - 90 days) by applying Fast Fourier Transform (FFT). Composites of rainfall anomalies were computed for each of the eight phases of the MJO during February-May (FMAM) rainy season, based on the Jones-Carvalho MJO index. Only days classified as MJO events were considered in the composites. For each phase composite, statistical significance tests were computed independently at each individual station by applying a two-tailed Student’s t-test at 5% significance level. Preliminary results showed that the rainfall anomalies have a spatial coherence throughout the MJO cycle. Extreme positive (negative) anomalies occurred in phase 2 (phase 5), where 13 (12) out of the 17 stations showed statistically significant anomalies in the range of 0.9 - 1.9 mm/day (0.8 - 1.7 mm/day). The typical difference between the wet MJO phase 2 and dry phase 5 represented at least 50% modulation of the daily mean rainfall.

Spatiotemporal population dynamics of the banana rind thrips, Elixothrips brevisetis (Bagnall) (Thysanoptera: Thripidae)

AbstractThe understanding of how environmental factors and agricultural practices affect population dynamics of insect pests is necessary for pest management. Here, we provide insight into the ecology of the banana rind thrips Elixothrips brevisetis (Bagnall) (Thysanoptera: Thripidae) by collecting and analysing a spatiotemporal database of population estimates in Martinique (West French Indies). We assessed the influence of climatic variables (which were rainfall and temperature) and biotic variables (which were banana and three weed species) on the adult thrips abundance for different components of the banana plant (sucker, mother plant and bunch) and evaluated the effect of thrips abundance and standard bunch covers on damages. The abundance of thrips on the sucker, the mother plant, and the bunch was significantly related to the abundance on neighbouring banana plants, and spatial autocorrelation indicated that E. brevisetis dispersed for only short distances. The number of thrips on the mother plant and on the bunch was positively related to the number of thrips on the sucker, suggesting that the thrips may disperse from the sucker to the mother plant and then to the bunch. The abundance of thrips on the sucker increased with sucker height and was positively correlated with the mean daily rainfall during the 17 days before sampling; the length of that period might correspond with the time required for an individual to complete its life cycle. Covered bunches had 98% fewer thrips than non‐covered bunches, and the damage caused by thrips was linearly related to the number of thrips present between the 2nd and 4th week after flowering. Finally, we found that the presence of Alocasia cucullata, Dieffenbachia seguine and Peperomia pellucida is significantly related with a decrease in thrips abundance on banana plants, suggesting the use of these weeds as potential trap plants.