Implications of a decrease in the precipitation area for the past and the future

Abstract

The total area with 24 hrs precipitation has shrunk by 7% between 50 • S-50 • N over the period 1998-2016, according to the satellite-based Tropical Rain Measurement Mission data. A decrease in the daily precipitation area is an indication of profound changes in the hydrological cycle, where the global rate of precipitation is balanced by the global rate of evaporation. This decrease was accompanied by increases in total precipitation, evaporation, and wet-day mean precipitation. If these trends are real, then they suggest increased drought frequencies and more intense rainfall. Satellite records, however, may be inhomogeneous because they are synthesised from a number of individual missions with improved technology over time. A linear dependency was also found between the global mean temperature and the 50 • S-50 • N daily precipitation area with a slope value of −17 × 10 6 km 2 / • C. This dependency was used with climate model simulations to make future projections which suggested a continued decrease that will strengthen in the future. The precipitation area evolves differently when the precipitation is accumulated over short and long time scales, however, and there has been a slight increase in the monthly precipitation area while the daily precipitation area decreased. An increase on monthly scale may indicate more pronounced variations in the rainfall patterns due to migrating rain-producing phenomena.

Shift Toward Intense and Widespread Precipitation Events Over the United States by Mid‐21st Century

“…For example, Chang et al's (2016) conclusions are based on subdaily precipitation events with magnitudes ≥0.1 mm in contrast to the use of daily precipitation events of ≥12.5 mm in this study. Likewise, Benestad's (2018) findings are based on spatial aggreagtaion of daily precipitation events in contrast to gird‐scale changes in our analyses. More importantly, our findings are consistent with recent trends in the PRISM observations over the United States and therefore provide a well‐grounded perspective.…”

“…The projected changes in the frequency and intensity of heavy precipitation events evident in our analyses is consistent with previous studies in terms of increases in the number of destructive storms and their precipitation intensities (Balling & Goodrich, 2011; Donat, Alexander, et al, 2016; Fischer & Knutti, 2016; NOAA, 2020). On the other hand, while the projected increase in the spatial extent of precipitation events is supported by a number of earlier findings (Lochbihler et al, 2019; Prein et al, 2017), numerous studies also show a potential shrinking of precipitation storms in response to enhanced radiative forcing (Benestad, 2018; Chang et al, 2016). As previously noted, the disagreement regarding the spatial extent of future extremes can potentially stem from the differences in methodologies, model simulations, and storm selection criteria.…”

“…Such an increase in atmospheric moisture with warming can also impact the spatial extent of precipitation events. However, research efforts that focus on this aspect of precipitation storm characteristics are relatively limited as only a few studies thus far have investigated the spatial characteristics of mean and extreme precipitation in observations (Hamada et al, 2014; Kunkel et al, 2012; Lochbihler et al, 2017; Touma et al, 2018, 2019; Wasko et al, 2016) and model simulations (Benestad, 2018; Chang et al, 2016; Guinard et al, 2015; Li et al, 2018; Lochbihler et al, 2019; Prein et al, 2017). Moreover, modeling studies that investigate changes in the spatial characteristics of precipitation in future climates vary in their conclusions, which partly stems from their methodological (e.g., type size and scale of events, detection algorithm) and modeling differences.…”

Frequency of extreme precipitation increases extensively with event rareness under global warming

“…Global warming increases both the intensity and frequency of extreme precipitation, so to characterize the full response of extreme precipitation to global warming, either their total or both of their individual contributions must be communicated. The duration 34 and area 35–37 of the extreme precipitation events may also be affected by climate change. We have shown here that extreme precipitation events occurring on average twice per decade will increase in frequency by 1–2 events per decade per degree of warming.…”

A simple equation to study changes in rainfall statistics

“…A change in the hydrological cycle is expected to affect the vertical energy flow and the atmospheric overturning [37], and more intense rainfall is also often associated with higher cloud tops [38]. In addition, a decrease in the global area with daily rainfall implies a general decrease in f w and increase in μ [39]. Here figure 2 presented a heat map for a set of different thresholds to show that equation (1) works for a range of different thresholds.…”