Global Scaling of Rainfall With Dewpoint Temperature Reveals Considerable Ocean‐Land Difference

Abstract

Short-duration extreme rainfall events can trigger flash floods in rural and urban environments (Fadhel et al., 2018;Fowler, Lenderink, et al., 2021). The hydrological response to these rainfall bursts is very fast, giving no or very little warning to respond (Archer & Fowler, 2018;ʺFowler, Ali, et al., 2021). Therefore, understanding the mechanisms of extreme rainfall generation can be useful for the planning and mitigation of hazards and fatalities associated with these events (Wasko, Parinussa, et al., 2016). With anthropogenic warming, extreme rainfall events have intensified at the global scale and are projected to further increase

Towards Quantifying the Uncertainty in Estimating Observed Scaling Rates

“…Using two different data measurement precisions (0.25 and 2.54 mm) but for comparatively shorter records, we found substantially higher scaling rates for the higher measurement precision (0.25 mm: median 7.8%/K; 2.54 mm: median 6.6%/K), with the number of gauges showing super‐CC scaling also higher. This is an important result since all previous scaling studies over CONUS, for example, (Ali, Fowler, et al., 2021; Ali, Peleg, et al., 2021) have used the lower measurement precision, and thus underestimated the scaling rate in other global regions where a measurement precision of 0.1 mm is the norm. This may be a reason for the lower scaling rate in CONUS than in other parts of the world in some previous studies.…”

“…The second (GSDR‐QC) is the same set of gauge observations from the Global Sub‐Daily Rainfall (GSDR) data set (Lewis et al., 2019 , 2021 ) and their quality control is discussed in the supplemental information. This data set was generated under the Global Water and Energy Exchanges (GEWEX) Hydroclimateology Panel INTENSE project (Blenkinsop et al., 2018 ) and has been used in many studies (Ali, Fowler, et al., 2021 ; Ali, Peleg, et al., 2021 ; Barbero et al., 2017 , 2019 ; Li et al., 2020 ). We compare these (GSDR‐QC) to the same hourly precipitation observations (RAW‐DATA) over CONUS.…”

“…This “scaling” relationship links air temperature and atmospheric humidity and states that under the limitation of constant relative humidity, atmospheric moisture will increase at a rate similar to the dependency of vapor pressure on temperature (the CC rate: 6%–7%/K) (Trenberth et al., 2003). This theory is supported by scaling studies, which have estimated relationships between daily/sub‐daily precipitation intensities and day‐to‐day temperature variability – the apparent scaling – and reported scaling rates at around CC for many regions and globally (Ali et al., 2018; Ali, Fowler, et al., 2021; Ali, Peleg, et al., 2021; Bao et al., 2017; Gao et al., 2018; Martinkova & Kysely, 2020; Wasko et al., 2016).…”

“…Recently, Ali, Peleg, et al. ( 2021 ) checked the performance of reanalyses (ERA5 and MERRA2) against observations for different macro‐regions, finding an underestimation of hourly scaling rates for the reanalyses compared to gauge observations. Their results question the reliability of using reanalysis products.…”

“…Some previous global scaling studies (e.g., Moustakis et al, 2020;Wasko et al, 2016) have used reanalyses, satellite or climate model outputs to estimate precipitation, due to limitations in the availability of sub-daily observations. Recently, Ali, Peleg, et al (2021) checked the performance of reanalyses (ERA5 and MERRA2) against observations for different macro-regions, finding an underestimation of hourly scaling rates for the reanalyses compared to gauge observations. Their results question the reliability of using reanalysis products.…”