Precipitation events in distant locations can occur as statistically independent phenomena
the verdict
CONTESTED PARTIAL
refutedsupported
the weight of evidence
1 source for · 3 against
The retrieved literature indicates that while multi-site precipitation models sometimes incorporate dependency structures, studies on climate teleconnections and synchronized weather patterns show that distant precipitation and drought events frequently exhibit significant spatial interdependencies rather than pure statistical independence.
Spatial and temporal dependence framework in multi-site precipitation modelling | Stochastic Environmental Research and Risk Assessment | Springer Nature Link
# Spatial and temporal dependence framework in multi-site precipitation modelling
- Original Paper
- Open access
- Published: 03 July 2025
- Volume 39, pages 3781–3811, (2025)
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## Abstract
Multi-site stochastic models consist of a rich class of models that can be utilised to analyse environmental data and provide a range of possible inputs to hydrological models to quantify uncertainty and assess risk in environmental systems. We develop a class of multi-site hidden Markov models that incorporate a copula to capture the characteristics of the daily precipitation process across a network of stations. The construction of the likelihood function of the proposed multi-site precipitation models is described. A copula with appropriate dependence structure is selected from the family of Archimedean copulas. The maximum likelihood method is used to estimate the parameters of
Australia is an agricultural nation characterised by one of the most naturally diverse climates in the world, which translates into significant sources of risk for agricultural production and subsequent farm revenues. Extreme climatic events have been significantly affecting large parts of Australia in recent decades, contributing to an increase in the vulnerability of crops, and leading to subsequent higher risk to a large number of agricultural producers. However, attempts at better managing climate related risks in the agricultural sector have confronted many challenges.
First, crop insurance products, including classical claim-based and index-based insurance, are among the financial implements that allow exposed individuals to pool resources to spread their risk. The classical claim-based insurance indemnifies according to a claim of crop loss from the insured customer, and so can easily manage idiosyncratic risk, which is the case where the loss occurs independently.Nevertheless, the existence of systemic weather risk (covariate risk), which is the spread of extreme events over locations and times (e.g., droughts and floods), has been identified as the main reason for the failure of private insurance markets, such as the classical multi-peril crop insurance, for agricultural crops. The index-based insurance is appropriate to handle systemic but not idiosyncratic risk. The indemnity payments of the index-based insurance are triggered by a predefined threshold of an index (e.g., rainfall), which is related to such losses. Since the covariate nature of a climatic event, it sanctions the insurers to predict losses and ascertain indemnifications for a huge number of insured customers across a wide geographical area. However, basis risk, which is related to the strength of the relationship between the predefined indices used to estimate the average loss by the insured community and the actual loss of insured assets by an individual, is a major barrier that hinders uptake of the index-based insurance. Clearly, the high basis risk, which is a weak relationship between the index and loss, destroys the willingness of potential customers to purchase this insurance product.
Second, the impact of multiple synoptic-scale climate mode indices (e.g., Southern Oscillation Index (SOI) and Indian Ocean Index (IOD)) on precipitation and crop yield is not identical in different spatial locations and at different times or seasons across the Australian continent since the influence of large-scale climate heterogeneous over the different regions. The occurrence, role, and amplitude of synoptic-scale climate modes contributing to the variability of seasonal crop production have shifted in recent decades. These variables generally complicate the climate and crop yield relationship that cannot be captured by traditional modelling and analysis approaches commonly found in published agronomic literature such as
linear regression. In addition, the traditional linear analysis is not able to model the nonlinear and asymmetric interdependence between extreme insurance losses, which may occur in the case of systemic risk. Relying on the linear method may lead to the problem that different behaviour may be observed from joint distributions, particularly in the upper and lower regions, with the same correlation coefficient. As a result, the likelihood of extreme insurance losses can be underestimated or overestimated that lead to inaccuracies in the pricing of insurance policies. Another alternative is the use of the multivariate normal distribution, where the joint distribution is uniquely defined using the marginal distributions of variables and their correlation matrix. However, phenomena are not always normally distributed in practice.
It is therefore important to develop new, scientifically verified, strategic measures to solve the challenges as mentioned above in order to support mitigating the influences of the climate-related risk in the a
The intensifying climate crisis has exacerbated the frequency and severity of prolonged droughts, particularly in environmentally and socio-economically vulnerable climate change hot-spot regions. Despite advancements in monitoring, the spatiotemporal propagation and interdependencies of drought events remain poorly understood. This study analyzes drought synchronization within the Po River Basin, a critical hydrological system contributing approximately 40% of Italy's GDP. Using the 12-month Standardized Precipitation Index (SPI-12) and complex network methods, we reveal the spatiotemporal dynamics of drought propagation, identifying key hubs and hot-spot regions. Our analysis identifies spatial hubs where droughts originate and terminal zones where impacts converge. This process follows a diffusive propagation mechanism, whereby local events spread through preferential pathways until they are interrupted by seasonal climatic conditions that restore precipitation regime. These findings enhance understanding of drought dynamics in interconnected systems, advancing the application of complex network theory to hydro-climatology. They also provide a foundation for research on societal resilience to climate change and the development of adaptive strategies for sustainable hydrological systems.
plex networks were again used as a data exploration method to reveal patterns that might be useful for prediction when combined with mechanistic insights. The spatiotemporal structure of those extreme rainfall events (above the 99% percentile), as inferred from high-resolution satellite data, can be mapped onto a directed and weighted network: The link weights between two grid points are a measure for how often two grid points show a time-delayed, significantly similar precipitation event pattern, and the direction is determined by the temporal sequence of the events. The resulting network allows for identifying the source and the sink regions of extreme precipitation across the South American continent. SI Appendix , Fig. S1 shows that the Intertropical Convergence Zone and the northern Amazon are a source of extreme events, while the central parts of South America are sink regions of extremes.
Surprisingly, the network approach reveals that the exit region of the low-level monsoonal wind flow in southeastern South America turns out to be a source area of extreme rainfall events. The directed network structure allows the inference that events occurring there tend to be followed by further events along a narrow band extending northwestward to the Bolivian Central Andes, and thus in the opposite direction of the low-level monsoon circulation. Combining the results of this data exploration with process knowledge reveals the mechanisms underlying these extreme events and opens the door for prediction. A detailed analysis of the atmospheric conditions exhibits that not the rainfall systems themselves, but rather the atmospheric conditions that favor the development of large convective systems and thus lead to extreme rainfall, propagate against the direction of the monsoon circulation ( 41 ). These atmospheric conditions are determined by westward-moving Rossby wave trains that originate from the southern Pacific Ocean and turn northward after crossing the southern tip
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