Precipitation varies spatio‐temporally in amount, intensity, and frequency. Although, much research has been conducted on analyzing precipitation patterns and variation at the global scale, trend types have still not received much attention. This study developed a new polynomial‐based model for detecting nonlinear and linear trends in a satellite precipitation product (TRMM 3B43) for the 1998–2017 period at a near‐global scale. We used an automated trend classification method that detects significant trends and classifies them into linear and nonlinear (cubic, quadratic, and concealed) trend types in satellite‐based precipitation at near‐global, continental, and climate zone scales. We found that 12.3% of pixel‐based precipitation time series across the globe have significant trend at 0.05 significance level (50% positive and 50% negative trends). In all continents except Asia, decreasing trends were found to cover larger areas than corresponding increasing trends. Regarding climate zone and precipitation trend change, our results indicate that a linear trend is dominant in the warm temperate (77.7%) and equatorial climates (80.4%) while the least linear change was detected in the polar climate (68.9%). The combined results of continental and climate zone scales indicate significant increasing trends in Asia and arid climate over the last 20 yr. Furthermore, positive trends were found to be more significant at the continental scale, particularly, in Asia relative to the climate zone scale. Linear change in precipitation (80%) was the most dominant trend observed as opposed to nonlinear (quadratic [11%] and cubic [9%]) trend types at the global scale.

中文翻译：

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1998-2017年全球卫星降水的线性和非线性趋势分析

降水量，强度和频率随时间而变化。尽管在分析全球范围内的降水模式和变化方面已经进行了很多研究，但是趋势类型仍然没有引起足够的重视。这项研究开发了一种新的基于多项式的模型，用于在1998-2017年期间以近全球范围检测卫星降水产物（TRMM 3B43）的非线性和线性趋势。我们使用了一种自动趋势分类方法，该方法可以检测到近乎全球，大陆和气候带尺度的卫星降水中的重大趋势，并将其分为线性和非线性（三次，二次和隐式）趋势类型。我们发现，在全球范围内，以像素为基础的降水时间序列的12.3％在显着性水平为0.05时具有显着趋势（正向趋势为50％，负向趋势为50％）。在除亚洲以外的所有大洲，发现下降的趋势所占的面积比相应的上升趋势要大。关于气候区和降水趋势变化，我们的结果表明，在暖温带（77.7％）和赤道气候（80.4％）中线性趋势占主导地位，而在极地气候（68.9％）中线性变化最小。大陆和气候带尺度的综合结果表明，过去20年中亚洲和干旱气候的增长趋势显着。此外，发现在大陆范围内，尤其是在亚洲，相对于气候带范围而言，积极趋势更为显着。在全球范围内，降水的线性变化（80％）是最主要的趋势，与非线性（二次[11％]和三次[9％]）趋势类型相反。发现下降趋势比相应的上升趋势覆盖更大的区域。关于气候区和降水趋势变化，我们的结果表明，在暖温带（77.7％）和赤道气候（80.4％）中线性趋势占主导地位，而在极地气候（68.9％）中线性变化最小。大陆和气候带尺度的综合结果表明，过去20年中亚洲和干旱气候的增长趋势显着。此外，发现在大陆范围内，尤其是在亚洲，相对于气候带范围而言，积极趋势更为显着。在全球范围内，降水的线性变化（80％）是最主要的趋势，与非线性（二次[11％]和三次[9％]）趋势类型相反。发现下降趋势比相应的上升趋势覆盖更大的区域。关于气候区和降水趋势变化，我们的结果表明，在暖温带（77.7％）和赤道气候（80.4％）中线性趋势占主导地位，而在极地气候（68.9％）中线性变化最小。大陆和气候带尺度的综合结果表明，过去20年中亚洲和干旱气候的增长趋势显着。此外，发现在大陆范围内，尤其是在亚洲，相对于气候带范围而言，积极趋势更为显着。在全球范围内，降水的线性变化（80％）是最主要的趋势，与非线性（二次[11％]和三次[9％]）趋势类型相反。