Multiple trend tests on air temperature and precipitation anomalies in Vietnam

Abstract

An informed decision on building climate resilience and adaptation requires a deep understanding of long-term changes in temperature and precipitation, especially for most vulnerable countries to climate extremes like Vietnam. Hence, this study aimed to comprehend spatiotemporal trend possibilities of temperature and precipitation in Vietnam by employing multiple non-parametric statistical trend tests. This study also suggested a modified procedure, represented as a Hovmöller-like diagram, for enhancing the characterization of long-term spatiotemporal trends by applying multiple monotonic trend tests to all latitude coordinates through all possible 30-year periods. The superiority of multiple trend tests over a single one is that this methodology can assess the sensitivity of trend test results to the beginning years, ending years, and record lengths, thus emphasizing the necessity of performing monotonic trend tests repeatedly. The results show consistent warming trends in all climate sub-regions over the last 4–5 decades, with the estimated trend slopes varying from approximately 0.010–0.042 °C/year. Precipitation anomalies in most climate sub-regions, especially in the southern part, experienced significant increasing trends at the rate of around 0.29–2.76%/year during the last 3–5 decades. These findings are expected to contribute more insights into the spatiotemporal trend patterns of temperature and precipitation in Vietnam. HIGHLIGHTS A single trend test is sensitive to the analyzed period in terms of trend direction, magnitude, and statistical significance.; Multiple trend tests offer temporal trend patterns concerning different beginning years, ending years, and record lengths.; A modified procedure, visualized as a Hovmöller-like diagram, was proposed to explore spatiotemporal trend possibilities.;

Keywords

• long-term trends
• multiple trend tests
• spatiotemporal trend patterns
• vietnam