Similarity in Fog and Rainfall Intermittency

Abstract

Intermittent fog occurrences supply significant amounts of moisture to plants in the form of fog drip onto the soil surface thereby prompting interest in their statistical behavior at multiple timescales. A comparison of rainfall and fog measurements collected at an inland tropical cloud forest in Kenya and a coastal rangeland in Northern California is presented to explore whether fog occurrences have similar intermittency characteristics as rainfall. The results confirm that both rainfall and fog show approximate power law relations for distributions of dry period and event size consistent with predictions from self-organized criticality. Moreover, the spectral exponents of the on-off time series of the fog and rainfall exhibited an approximate f −0.8 over a broad range of frequencies f , which is remarkably close to scaling exponents across sites experiencing different rainfall generation mechanisms. These results suggest that fog intermittency shares some properties of critical behavior documented in numerous rainfall studies.Plain Language Summary Beyond rainfall, intermittent fog occurrence provides water subsidy that is needed for sustaining transpiration and photosynthesis in forests. To study the connections between fog formation and rainfall, a comparison of rainfall and fog occurrence statistics is carried out at two sites: a Kenyan inland cloud forest and a coastal forest in Northern California. For durations exceeding 1 day, rainfall and fog event sizes and dry periods appear similar. Due to these similarities, intermittency in fog occurrences may abide by general laws describing critical phenomenon.

Comment on bg-2021-261

“…Our LST estimation using the satellite image was only a snapshot for July 4, 2019, from a sunny almost cloud-free day, and does not represent the year-round situation experiencing two rainy seasons, which are cloudy. In the hills, cloudy and misty conditions are experienced throughout the year (Helle, 2016;Räsänen et al, 2018). A time series comparing the cooling effect of CC over seasons and several years is an interesting future research topic, as the TOMST sensors remained in the 19 field plots.…”

Persistence in complex systems

“…As previously discussed, in [100] a DFA analysis for rainfall was carried out, which showed that this two-range pattern for rainfall series is associated with the binary structure of the time series (the pattern of alternating dry and wet spells independently of the actual values of rainfall intensity. Recently, in [401] it has been shown that rainfall and fog events have a similar structure in terms of on-off intermittency properties. This two ranges pattern with characteristic time has been also shown in other persistence-based studies dealing with DFA such as, orographic fog events [162], SSTA data [132], rainfall time series [22], soil moisture [146] or water level in reservoirs [167], among others.…”

Seasonal precipitation variability in mainland China based on entropy theory

“…Generally, most of the total precipitation recorded at a station is delivered over only a few days with heavy rain, while the many days with light drizzle contribute much less to the total (Pendergrass and Knutti, 2018; Rasanen et al ., 2018). The asymmetric nature of precipitation temporal distribution has been widely examined by many researchers, which is aggravated due to climate change (Chang et al ., 2016; Zhou and Wang, 2017; Cindric et al ., 2019; Li et al ., 2020b).…”