El Niño impacts in the Limpopo River Basin

Higher-than-average temperatures are predicted for the Limpopo Basin from June to November 2023. A delay in the onset of the rainy season in November is predicted. A reduction in rainfall and higher temperatures induced by the 2023 strong El Niño event are expected for the Limpopo Basin from January to March 2024. Historic data suggests a negative impact of El Niño on maize yields of the following season in South Africa, Mozambique and Zimbabwe

Developing timely and actionable drought forecasts for the Limpopo River Basin

Southern Africa is highly drought-prone, and its agricultural and hydrological systems are vulnerable. Climate forecasts provide tools for decision-making and adaptation to climate extreme events. This report presents the preliminary results regarding the development of seasonal drought forecasts for the Limpopo River basin. Using multiple climate-relevant datasets, a diagnosis of the climate of the Limpopo basin was carried out, and the relevance of using the SPEI drought index for characterizing droughts was also assessed. The results showed strong climatic seasonality, in addition to the strong relationship between the seasonal drought conditions captured by SPEI. Outputs from four climate models, gridded rainfall observations, and a machine-learning method were used to generate a real-time experimental probabilistic forecast of rainfall in the Limpopo basin. Finally, the next steps are presented to meet the objectives of the Initiative, strengthening the capacities of the Limpopo Watercourse Commission

El Niño impacts in the Inkomati-Usuthu catchment

Near normal but increasing temperature anomalies are predicted for the Inkomati-Usuthu catchment from August 2023 to January 2024. Predicted near-normal rainfall anomalies turn negative as summer 2023/34 approaches in the catchment. A reduction in rainfall, higher than normal temperatures and evaporative demand, along with drought conditions induced by the 2023 El Niño event can be expected for the Inkomati-Usuthu catchment from January to March 2024 and likely until the next wet season

Lagrangian descriptors for the Bunimovich stadium billiard

We apply the concept of Lagrangian descriptors to the dynamics on the Bunimovich stadium billiard, a two-dimensional ergodic system with singular families of trajectories, namely, the bouncing ball and the whispering gallery orbits. They play a central role in structuring the phase space, which is unveiled here by means of the Lagrangian descriptors applied to the associated map on the boundary. More interestingly, we also consider the open stadium, which in the optical case (Fresnel's laws) can be directly related to recent microlaser experiments. We find that the structure of the emission profile of these systems can be easily described thanks to the open version of the Lagrangian descriptor

Lagrangian descriptors for the Bunimovich stadium billiard

We apply the concept of Lagrangian descriptors to the dynamics on the Bunimovich stadium billiard, a two-dimensional ergodic system with singular families of trajectories, namely, the bouncing ball and the whispering gallery orbits. They play a central role in structuring the phase space, which is unveiled here by means of the Lagrangian descriptors applied to the associated map on the boundary. More interestingly, we also consider the open stadium, which in the optical case (Fresnel's laws) can be directly related to recent microlaser experiments. We find that the structure of the emission profile of these systems can be easily described thanks to the open version of the Lagrangian descriptor

Surface atmospheric circulation patterns and associated minimum temperatures in the Maipo and Casablanca valleys, central Chile

Abstract This paper analyzes the influence of circulation anomalies on the magnitude of minimum air temperature (T min ) at a daily scale in two important agricultural valleys of Chile (Maipo and Casablanca) during the period [2001][2002][2003][2004][2005][2006][2007]. A statistical classification of synoptic fields was performed, resulting in eight circulation patterns (CPs, 84 % of explained variance). The corresponding anomalies of T min (AT min ) of each CP were analyzed in order to understand their synoptic-scale forcing mechanisms. Results showed a direct association between AT min and the synoptic structure. The average weakening in sea level pressure (SLP) yields positive AT min , while negative AT min is associated with a strengthening in SLP. In the latter case, it was also found that a synoptic structure (10.2 % of frequency) corresponding to a migratory high-pressure system passing eastward across the Andes led to the lowest AT min and a higher probability of frost in both valleys (22 % on average) in winter and springtime

On the Utility of Agronomic Monsoon Onset Definitions for Rainfed Aman Rice in Bangladesh

The monsoon-season ‘aman' rice crop contributes approximately 40% of total rice production in Bangladesh, where per-capita rice consumption rates are among the highest in the world. Aman rice is primarily rainfed and relies largely on monsoon rainfall, more specifically monsoon onset and withdrawal. Aman rice farmers’ perception on the monsoon onset for the preparation of seedling does not necessarily coincide with typical meteorological onset definitions and varies with different locations. Therefore, agronomic definitions of monsoon onset, rather than meteorological definitions are needed in order to produce climate forecast information that can better support smallholder farmers’ decision making, and the definitions should be tailored for different regions. In this study, we analyzed historical daily rainfall from three regional weather stations across a north-south gradient in Bangladesh where rainfed transplanted rice is the dominant summer crop. We defined threshold numbers including the duration of the initial wet spell, amount of rainfall received during the initial wet spell, length of dry spell during the monsoon, and the maximum amount of rainfall received during the dry spell to develop a set of actionable and region-specific agronomic onset definitions. Because transplanting dates can affect crop productivity, a region-specific onset definition was evaluated in terms of crop model simulated attainable yields in comparison with the results of (a) conventional meteorological onset defined by the quantity of rainfall received and (b) static onset date definitions. When year-to-year varying agronomic onset definition was used predicted attainable yields were higher than those derived from traditional fixed onset date in the case of fully rainfed condition. If irrigation is available at the time of transplanting, however, simulated yields did not show distinctive differences between the different onset methods, underscoring how irrigation can be used as a climate-smart adaptive strategy to cope with monsoon variability. Our tailored agronomic definitions of monsoon onset can be used to assist rainfed rice farmers in choosing more favourable dates for the establishment of seedbeds and transplanting, especially when more advanced seasonal or sub- seasonal forecasts are available in addition to real-time and high-resolution rainfall monitoring

SN 2006gy: was it really extra-ordinary?

We present an optical photometric and spectroscopic study of the very luminous type IIn SN 2006gy for a time period spanning more than one year. In photometry, a broad, bright (M_R~-21.7) peak characterizes all BVRI light curves. Afterwards, a rapid luminosity fading is followed by a phase of slow luminosity decline between day ~170 and ~237. At late phases (>237 days), because of the large luminosity drop (>3 mag), only upper visibility limits are obtained in the B, R and I bands. In the near-infrared, two K-band detections on days 411 and 510 open new issues about dust formation or IR echoes scenarios. At all epochs the spectra are characterized by the absence of broad P-Cygni profiles and a multicomponent Halpha profile, which are the typical signatures of type IIn SNe. After maximum, spectroscopic and photometric similarities are found between SN 2006gy and bright, interaction-dominated SNe (e.g. SN 1997cy, SN 1999E and SN 2002ic). This suggests that ejecta-CSM interaction plays a key role in SN 2006gy about 6 to 8 months after maximum, sustaining the late-time-light curve. Alternatively, the late luminosity may be related to the radioactive decay of ~3M_sun of 56Ni. Models of the light curve in the first 170 days suggest that the progenitor was a compact star (R~6-8 10^(12)cm, M_ej~5-14M_sun), and that the SN ejecta collided with massive (6-10M_sun), opaque clumps of previously ejected material. These clumps do not completely obscure the SN photosphere, so that at its peak the luminosity is due both to the decay of 56Ni and to interaction with CSM. A supermassive star is not required to explain the observational data, nor is an extra-ordinarily large explosion energy.Comment: 33 pages, 8 figures. Accepted by ApJ. Paper with high-resolution figures available at http://web.oapd.inaf.it/supern/sn2006gy_astroph/agnoletto_2006gy.pd

Localization and size of colon adenomas as factors related to high grade dysplasia

Objective: To determine whether localization and size are related to the presence of high-grade dysplasia of colon adenomas in patients of a Peruvian hospital. Materials and methods: This is a descriptive transversal study. We checked colonoscopy reports of 2014-2015 years of Hospital Daniel Alcides Carrion, we included the polyps found in patients older than 18 years old, and excluded reports from patients with colorectal cancer, an antecedent of oncological surgery, inflammatory bowel disease and polyposis (6 or more). We used data based on localization (proximal and distal colon, based on the splenic angle), size (less than 10 mm and 10 mm or more), shape (pediculate and sessile) and grade of dysplasia (low and high-grade). We calculated the strength of association by OR, and we determined whether there was association by Chi-square test with a significance value less than 0.05. Results: We reviewed a total of 1710 of colonoscopy reports, 378 patients had polyps, so the adenoma detection rate was 22.1%. There were 458 polyps, from which 254 were adenomas. From these adenomas, we found an association between distal colon localization and high-grade dysplasia (OR 2.68 IC 1.12-6.42, p<0.05); likewise, there was an association between the size of the adenomas and high-grade dysplasia (OR 7.75 IC 3.05-19.69, p<0.05). We did not find any association between the shape and grade of dysplasia. Conclusion: This study concludes that there is an association between the size of 10 mm or more and localization in the distal colon with high-grade dysplasia of adenomas.Revisión por pare

Developing a framework for an early warning system of seasonal temperature and rainfall tailored to aquaculture in Bangladesh

The occurrence of high temperature and heavy rain events during the monsoon season are a major climate risk affecting aquaculture production in Bangladesh. Despite the advances in the seasonal forecasting, the development of operational tools remains a challenge. This work presents the development of a seasonal forecasting approach to predict the number of warm days (NWD) and number of heavy rain days (NHRD) tailored to aquaculture in two locations of Bangladesh (Sylhet and Khulna). The approach is based on the use of meteorological and pond temperature data to generate linear models of the relationship between three-monthly temperature and rainfall statistics and NWD and NHRD, and on the evaluation of the skill of three operational dynamical models from the North American Multi-Model Ensemble (NMME) project. The linear models were used to evaluate the forecasts for two seasons and 1-month lead time: May to July (MJJ), forecast generated in April, and August to October (ASO), forecast generated in July. Differences were observed in the skill of the models predicting maximum temperature and rainfall (Spearman correlation, Root Mean Square Error, Bias statistics, and Willmott’s Index of Agreement,), in addition to NWD and NHRD from linear models, which also vary for the target seasons and location. In general, the models show higher predictive skill for NWD than NHRD, and for Sylhet than in Khulna. Among the three evaluated NMME models, CanSIPSv2 and GFDL-SPEAR exhibit the best performance, they show similar features in terms of error metrics, but CanSIPSv2 presents a lower interannual standard deviation