Experimental High-Resolution Winter Seasonal Climate Reforecasts for Florida

Abstract

We present here the analysis of 20 years of high-resolution experimental winter seasonal CLImate reForecasts for Florida (CLIFF). These winter seasonal reforecasts were dynamically downscaled by a regional atmospheric model at 10km grid spacing from a global model run at T62 spectral resolution (~210km grid spacing at the equator) forced with sea surface temperatures (SST) obtained from one of the global models in the North American Multimodel Ensemble (NMME). CLIFF was designed in consultation with water managers (in utilities and public water supply) in Florida targeting its five water management districts, including two smaller watersheds of two specific stakeholders in central Florida that manage public water supply. This enterprise was undertaken in an attempt to meet the climate forecast needs of water management in Florida.CLIFF has 30 ensemble members per season generated by changes to the physics and the lateral boundary conditions of the regional atmospheric model. Both deterministic and probabilistic skill measures of the seasonal precipitation at the zero-month lead for November-December-January (NDJ) and one-month lead for December-January-February (DJF) show that CLIFF has higher seasonal prediction skill than persistence. The results of the seasonal prediction skill of land surface temperature are more sobering than precipitation, although, in many instances, it is still better than the persistence skill.

Application of High-Resolution Winter Seasonal Climate Forecasts for Streamflow Prediction in Central Florida

“…Thus, these climate models are not useful for streamflow prediction. For this project, we used customized seasonal forecasts for Florida that were produced by dynamically downscaling a global climate model to a resolution of 10 km (Bhardwaj et al 2021).…”

“…As previously mentioned, the precipitation, evaporation, soil moisture, and temperature datasets used in this project are high-resolution experimental winter seasonal climate reforecasts for Florida (CLIFF). CLIFF was developed by using a regional atmospheric model to dynamically downscale a global model to 10 km grid spacing, a resolution that has been shown to work well for the operational needs of water managers in Florida (Bhardwaj et al, 2021). The Atmospheric General Circulation Model (AGCM) was run with 5 ensemble members at 210 km grid spacing.…”

“…For each run of the AGCM, 6 ensemble members from a regional atmosphere model were run (at 10 km grid spacing) to give a total of 30 ensemble members, each predicting daily values for precipitation, evaporation, soil moisture, and surface temperature, from November 1 st through February 28 th of the following year, over a 20-year period. The purpose of the ensembles is to thoroughly sample the uncertainties arising from the initial and boundary conditions, as well as the uncertainties present in the model itself (Bhardwaj et al, 2021).…”

“…Seasonal climate forecasts have proven useful in making water supply decisions on a 3-12-month timescale (Misra et al, 2021). However, water managers do not often make use of these forecasts for a number of reasons, including lack of awareness of the forecasts, institutional inertia, and risk aversion to new methods (Bhardwaj et al 2021;Misra et al 2021). To combat these phenomena, the Florida Water and Climate Alliance (FloridaWCA) was formed in 2010.…”

“…Decisions concerning water supply in the spring are based heavily on winter water demand (Bhardwaj et al, 2021). Occasionally, an anomalously dry winter season creates an acute shortage of water in the spring, and water managers are forced to take costly remediation measures.…”