Nonparametric tests against trend
About: This article is published in Econometrica.The article was published on 1945-07-01. It has received 10523 citations till now. The article focuses on the topics: Nonparametric statistics.
Citations
More filters
TL;DR: In this article , both the water demand mechanisms of natural vegetation and farmland were discovered by creatively constructing the vegetation water demand route model in the TRB (Tarim River Basin), a typical arid inland basin system that RFA is separated from RCA.
2 citations
TL;DR: In this article , the authors quantified the contribution of CC and HA to the global NEP under six different scenarios based on a boosted regression tree model and sensitivity analysis over the last 40 years.
Abstract: Introduction Accurate assessment of the net ecosystem productivity (NEP) is very important for understanding the global carbon balance. However, it remains unknown whether climate change (CC) promoted or weakened the impact of human activities (HA) on the NEP from 1983 to 2018. Methods Here, we quantified the contribution of CC and HA to the global NEP under six different scenarios based on a boosted regression tree model and sensitivity analysis over the last 40 years. Results and discussion The results show that (1) a total of 69% of the areas showed an upward trend in the NEP, with HA and CC controlled 36.33 and 32.79% of the NEP growth, respectively. The contribution of HA (HA_con) far exceeded that of CC by 6.4 times. (2) The CO2 concentration had the largest positive contribution (37%) to NEP and the largest influence area (32.5%). It made the most significant contribution to the NEP trend in the range of 435–440 ppm. In more than 50% of the areas, the main loss factor was solar radiation (SR) in any control area of the climate factors. (3) Interestingly, CC enhanced the positive HA_con to the NEP in 44% of the world, and in 25% of the area, the effect was greater than 50%. Our results shed light on the optimal range of each climatic factor for enhancing the NEP and emphasize the important role of CC in enhancing the positive HA_con to the NEP found in previous studies.
2 citations
TL;DR: In 2018, in the extreme south of Algeria, the In-Guezzam City suffered a devastating flood that caused significant damage and loss of human and material resources as discussed by the authors .
Abstract: Natural risks, particularly flood risk, are a topical subject in Algeria and throughout the world, particularly given the last major catastrophic floods in Sudan (2020) and North Africa. With the development of the climate change phenomenon in the world, risk management is becoming increasingly necessary for all the actors concerned (decision-makers, technicians, and the population) to identify protection issues. In 2018, in the extreme south of Algeria, In-Guezzam City suffered a devastating flood that caused significant damage and loss of human and material resources. More than 100 homes collapsed, and approximately 345 families were displaced. Currently, there is no research work to assess the hydrological situation and the risk of flooding in this region. Therefore, the main purpose of this study is to shed light on the risk of flash floods in the extreme south of Algeria with more specific attention to the August 2018 floods as well as the climate trends over the past 30 years using Mann–Kendall test and Sen’s Slope Estimator. The chosen approach involves a hydrological study and hydrodynamic modeling using HEC-RAS software. This latter allows for simulating floods using statistical methods and creating several regional flood hazard maps.
2 citations
TL;DR: Cai et al. as discussed by the authors used Scanning Multi-channel Microwave Radiometer (SMMR), SVM/I and SSMIS data from the CETB dataset to extract the ice phenology for 56 lakes across the Northern Hemisphere from 1979 to 2019.
Abstract: Abstract. Seasonal ice cover is one of the important attributes of lakes at middle and high latitude regions. The annual freeze-up and break-up dates and the durations of ice cover (i.e., lake ice phenology) are sensitive to the weather and climate, and hence can be used as an indicator of climate variability and change. The Calibrated Enhanced Resolution Brightness Temperature (CETB) dataset available from the National Snow and Ice Data Center (NSIDC) provides an alternate source of passive microwave brightness temperature (TB) measurements for the determination of lake ice phenology on a 3.125 km grid. This study used Scanning Multi-channel Microwave Radiometer (SMMR), Special Sensor Microwave Image (SSM/I) and Special Sensor Microwave Imager/Sounder (SSMIS) data from the CETB dataset to extract the ice phenology for 56 lakes across the Northern Hemisphere from 1979 to 2019. According to the differences in TB between lake ice and open water, a threshold algorithm based on the moving t test method was applied to determine the lake ice status for grids located at least 6.25 km away from the lake shore, and the ice phenology dates for each lake were then extracted. When ice phenology could be extracted from more than one satellite over overlapping periods, results from the satellite offering the largest number of observations were prioritized. The lake ice phenology results showed strong agreement with an existing product derived from Advanced Microwave Scanning Radiometer for EOS (AMSR-E) and Advanced Microwave Scanning Radiometer 2 (AMSR-2) data (2002 to 2015), with mean absolute errors of ice dates ranging from 2 to 4 days. Compared to near-shore in-situ observations, the lake ice results, while different in terms of spatial coverage, still showed overall consistencies. The produced lake ice record also displayed significant consistencies when compared to a historical record of annual maximum ice cover of the Laurentian Great Lakes of North America. From 1979 to 2019, the average complete freezing duration and ice cover duration for lakes forming a complete ice cover on an annual basis were 153 and 161 days, respectively. The lake ice phenology dataset – a new climate data record (CDR) – will provide valuable information to the user community about the changing ice cover of lakes in the last four decades. The dataset is available at https://www.pangaea.de/tok/c8fc0eab3d30777fc38979ad514217b6b7e86a65 (Cai et al., 2021).
2 citations
TL;DR: In this article , the authors investigated the long-term variations and the associated mechanisms of total cloud amount (TC), low cloud amount, the number of precipitation days (PN) and precipitation amount (PA), as well as SN and SD have significant interannual decreasing trends.
Abstract: The changes in clouds and precipitation are essential to understand the variation of water cycle under a changing climate and have not been well investigated on the Tibetan Plateau (TP). In this study, the long‐term variations and the associated mechanisms of total cloud amount (TC), low cloud amount (LC), the number of precipitation days (PN) and precipitation amount (PA), as well as the number of snow cover days (SN) and mean snow depth (SD) on the TP and its subregions of northeast (NE), central south (SC) and southeast (SE) are investigated with observational data in 1979–2016. The results indicate that TC has an overall decreasing trend, while LC has a significant increasing trend on the whole TP. PA in the NE has a significant increasing trend, and that in the SE has an insignificant decreasing trend. Light precipitation events tend to decrease and heavy precipitation events tend to increase. SN and SD have significant interannual decreasing trends. It is found that the atmospheric thermodynamic condition on the TP tends to become stable under a warming climate. The northward shifting of the westerly winds in association with the Hadley cell expanding in cold seasons and the strengthening South Asian high and the South Asian monsoon in warm seasons should be directly responsible for the generally decreasing trends in TC and related precipitation events on the south TP, and the increasing trends in LC and associated warm precipitation on the whole TP.
2 citations