Long-term seasonality of rainfall in the southwest Florida Gulf coastal zone

Abstract

In addition to supporting fisheries and wildlife, coastal water resources provide a variety of ecosystem services including water purification and storm surge protection, and the intangible such as educational, spiritual, and inspirational benefits. The integrity of these resources is, however, threatened by the inherent impacts of climate variability and change. Seasonality of climate is particularly important as it influences ecosystem diversity and other sensitive ecosystem components that are important to water resource integrity. For example, rainfall seasonality affects water availability, timing of inputs, seasonal water balance, ecological responses, and inter-annual responses of water resource systems. This study examines long-term seasonality of rainfall in the coastal zone with particular focus on the southwest Florida Gulf coastal zone. Analyses show marked inter-annual variations in rainfall seasonality, although trends are not significant. Decadal patterns show a primarily seasonal regime (0.6 ≤ Decadal Seasonality Index ≤ 0.79) with one markedly wet season and 2 drier periods. A cyclic pattern in seasonality is discernible on a regional basis, although there seems to have been a shift in cycle spans from 20 yr in the earlier decades to 30 yr in more recent decades, which could render water resource systems more vulnerable to climate change effects. The analyses showed a tendency towards long drier periods along with increases in rainy season (June−September) rainfall and progressive decreases in October−December rainfall. Results provide information useful for management decision-making and a basis for further assessments in the region. Approaches and methodologies are applicable to other coastal areas.

Patterns in Indices of Daily and Seasonal Rainfall Extremes: Southwest Florida Gulf Coastal Zone

“…Rainfall data used in the aforementioned previous work [9] were used in this study. As these data only included values up to 31 December 2014, additional data were downloaded from the NOAA Climate Data Online facility (https://www.ncdc.noaa.gov/cdo-web/) to cover the period 1 January 2015-31 December 2017.…”

“…The resulting datasets were checked for integrity by comparing their statistical properties and distribution with those of the original datasets. For this study, seasons were defined as Dry1 (January-May), Rainy (June-September), and Dry2 (October-December), consistent with previous work [9]. To determine seasonal rainfall amounts, monthly totals for the constituent months were summed up based on the seasons.…”

“…The region is characterized by severe storms, including tropical storms, which typically occur annually and hurricanes which occur about once every 10 years [8]. Results from previous work in the region [9] show a regional tendency towards long drier periods and decreases in rainfall in the period between October through December. Results also show increases in rainy season (June-September) rainfall.…”