Ocean submesoscale fronts induce diabatic heating and convective precipitation within storms

Nature Portfolio (Springer Nature) | January 30th, 2025

The intensity of atmospheric storms is influenced by ocean temperature contrasts. While mesoscale sea surface temperature anomalies ( ~ 200 km-size) are known to inte

The intensity of atmospheric storms is influenced by ocean temperature contrasts. While mesoscale sea surface temperature anomalies ( ~ 200 km-size) are known to intensify storms via latent heat release, the role of finer oceanic scales remains unknown. Using a global coupled ocean-atmosphere simulation at a km-scale resolution, we show that half of latent heat flux variability is driven by oceanic motions at the meso- ( ~ 40%) and submesoscale ( ~ 10-20 km-size,  < 10%) in the Kuroshio Extension during winter. Additionally, ocean submesoscale fronts, with temperature gradients of 5 °C per 10 km, induce a secondary circulation reaching 4 km within the troposphere, which enhances diabatic processes and convective precipitations within storms. In the warm sector of storms, ocean submesoscale fronts locally account for half the total precipitations, averaging 14 mm day−1 over five days. As such, ocean submesoscale fronts pump moisture from the ocean to the atmosphere and have the potential to affect storm intensification.

On the Connection Between Global Hydrologic Sensitivity and Regional Wet Extremes

American Geophysical Union (AGU) | October 23rd, 2018

The global water cycle is expected to intensify under climate change and can be generally characterized by greater rainfall and surface evaporation in the future. However

The global water cycle is expected to intensify under climate change and can be generally characterized by greater rainfall and surface evaporation in the future. However, the rate at which the globally averaged precipitation increases is highly variable among different climate models. In this paper, we relate the intermodel variability in global water cycle intensification to differences in model projections of heavy precipitation in tropical and some extratropical regions. We also find that models consistently experience a trade‐off between increasing heavy and decreasing light‐moderate precipitation: Models with larger future increases in heavy precipitation exhibit greater compensating declines in light‐moderate rainfall. Differences in heavy precipitation changes are also tied to model resolution. Our study helps to provide new insight on the factors shaping projections of future precipitation extremes, which have strong implications for water resources, natural hazard risks associated with flooding, and ecosystem stability.

On the dynamics of the Hadley circulation and subtropical drying

Climate Dynamics (Springer) | April 10th, 2014

Changes in subtropical precipitation and the Hadley circulation (HC) are inextricably linked. The original Halley–Hadley model cannot explain certain aspects of the Ear

Changes in subtropical precipitation and the Hadley circulation (HC) are inextricably linked. The original Halley–Hadley model cannot explain certain aspects of the Earth’s meridional circulation in the tropics and is of limited use in understanding regional changes in precipitation. Here, we expand on previous work on the regional and seasonal aspects of the HC, in particular how land–sea temperature contrasts contribute to the strength and width of the HC. We show that the Earth’s HC is well described by three regionally distinct cells along the eastern edges of the major ocean basins with opposite circulations elsewhere. Moreover, comparable summertime hemisphere cells emerge in each region. While it has been recognized that continents modify the meridional pressure gradient, we demonstrate that a substantial part of the Earth’s HC is driven by zonal pressure gradients (ZPGs) that only exist due to continental heating and air–sea interaction. Projected changes in land–sea temperature contrasts in a warming climate due to the relatively low thermal capacity of land will also affect ZPGs and thus HC strength and width, with implications for extremes in hydroclimate and freshwater resources across the increasingly vulnerable subtropics.

On-farm flood capture could reduce groundwater overdraft in Kings River Basin

California Agriculture (UCANR) | November 16th, 2016

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater rechar

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater recharge offers an opportunity to help address this challenge. We studied the infiltration rate of floodwater diverted from the Kings River at a turnout upstream of the James Weir onto adjoining cropland; and calculated how much land would be necessary to capture the available floodwater, how much recharge of groundwater might be achieved, and the costs. The 1,000-acre pilot study included fields growing tomatoes, wine grapes, alfalfa and pistachios. Flood flows diverted onto vineyards infiltrated at an average rate of 2.5 inches per day under sustained flooding. At that relatively high infiltration rate, 10 acres are needed to capture one CFS of diverted flood flow. We considered these findings in the context of regional expansion. Based upon a 30-year record of Kings Basin surplus flood flows, we estimate 30,000 acres operated for on-farm flood recharge would have had the capacity to capture 80% of available flood flows and potentially offset overdraft rates in the Kings Basin. Costs of on-farm flood capture for this study were estimated at $36 per acre-foot, less than the cost for surface water storage and dedicated recharge basins.

One Water LA 2040 Plan

City of Los Angeles | April 30th, 2018

The purpose of the One Water LA 2040 Plan (Plan) is to increase sustainable water management for the City of Los Angeles (City). The City launched One Water LA with two p

The purpose of the One Water LA 2040 Plan (Plan) is to increase sustainable water management for the City of Los Angeles (City). The City launched One Water LA with two primary goals: 1. Develop a vision and implementation strategy to more sustainably and cost-effectively manage water. 2. Identify ways for City departments and regional agencies to integrate their water management strategies. Los Angeles Sanitation (LASAN) and the Los Angeles Department of Water and Power (LADWP) led the Plan's development, partnering with other City departments, regional agencies, academia, the business community, and other stakeholders. The Plan provides a comprehensive strategy for managing water in a more integrated, collaborative, and sustainable way through new project, program, and policy opportunities. The Implementation Strategy provides a roadmap to make the One Water LA Vision a reality. Additional water projects, programs, or policies that are the sole responsibility of one agency, including LADWP's aqueduct or groundwater remediation project, are contained in each agency's appropriate plans. This plan is divided into an Executive Summary and ten sections. Executive Summary Volume One: Summary Report Volume Two: Wastewater Facilities Plan Volume Three: Stormwater and Urban Runoff Facilities Plan Volume Four: Los Angeles River Flow Study Volume Five: Integration Opportunities Analysis Volume Six: Climate Risk and Resilience Assessment for Wastewater and Stormwater Infrastructure Volume Seven: Implementation Strategy Supporting Documents Volume Eight: Technical Support Materials Volume Nine: Stakeholder Engagement Materials, Part 1, Part 2, Part 3 Volume Ten: Programmatic Environmental Impact Report (in progress)

Opportunities to Accelerate Nature-Based Solutions: A Roadmap for Climate Progress, Thriving Nature, Equity, and Prosperity

White House Domestic Climate Policy Office | November 30th, 2022

Origins of Extreme Climate States during the 1982–83 ENSO Winter

American Meteorological Society (AMS) | November 1st, 1997

Overview of the ARkStorm Scenario

U.S. Geological Survey (USGS) | January 13th, 2011

The U.S. Geological Survey, Multi Hazards Demonstration Project (MHDP) uses hazards science to improve resiliency of communities to natural disasters including ea

The U.S. Geological Survey, Multi Hazards Demonstration Project (MHDP) uses hazards science to improve resiliency of communities to natural disasters including earthquakes, tsunamis, wildfires, landslides, floods and coastal erosion. The project engages emergency planners, businesses, universities, government agencies, and others in preparing for major natural disasters. The project also helps to set research goals and provides decision-making information for loss reduction and improved resiliency. The first public product of the MHDP was the ShakeOut Earthquake Scenario published in May 2008. This detailed depiction of a hypothetical magnitude 7.8 earthquake on the San Andreas Fault in southern California served as the centerpiece of the largest earthquake drill in United States history, involving over 5,000 emergency responders and the participation of over 5.5 million citizens. This document summarizes the next major public project for MHDP, a winter storm scenario called ARkStorm (for Atmospheric River 1,000). Experts have designed a large, scientifically realistic meteorological event followed by an examination of the secondary hazards (for example, landslides and flooding), physical damages to the built environment, and social and economic consequences. The hypothetical storm depicted here would strike the U.S. West Coast and be similar to the intense California winter storms of 1861 and 1862 that left the central valley of California impassible. The storm is estimated to produce precipitation that in many places exceeds levels only experienced on average once every 500 to 1,000 years. Extensive flooding results. In many cases flooding overwhelms the state’s flood-protection system, which is typically designed to resist 100- to 200-year runoffs. The Central Valley experiences hypothetical flooding 300 miles long and 20 or more miles wide. Serious flooding also occurs in Orange County, Los Angeles County, San Diego, the San Francisco Bay area, and other coastal communities. Windspeeds in some places reach 125 miles per hour, hurricane- force winds. Across wider areas of the state, winds reach 60 miles per hour. Hundreds of landslides damage roads, highways, and homes. Property damage exceeds $300 billion, most from flooding. Demand surge (an increase in labor rates and other repair costs after major natural disasters) could increase property losses by 20 percent. Agricultural losses and other costs to repair lifelines, dewater (drain) flooded islands, and repair damage from landslides, brings the total direct property loss to nearly $400 billion, of which $20 to $30 billion would be recoverable through public and commercial insurance. Power, water, sewer, and other lifelines experience damage that takes weeks or months to restore. Flooding evacuation could involve 1.5 million residents in the inland region and delta counties. Business interruption costs reach $325 billion in addition to the $400 billion property repair costs, meaning that an ARkStorm could cost on the order of $725 billion, which is nearly 3 times the loss deemed to be realistic by the ShakeOut authors for a severe southern California earthquake, an event with roughly the same annual occurrence probability. The ARkStorm has several public policy implications: (1) An ARkStorm raises serious questions about the ability of existing federal, state, and local disaster planning to handle a disaster of this magnitude. (2) A core policy issue raised is whether to pay now to mitigate, or pay a lot more later for recovery. (3) Innovative financing solutions are likely to be needed to avoid fiscal crisis and adequately fund response and recovery costs from a similar, real, disaster. (4) Responders and government managers at all levels could be encouraged to conduct risk assessments, and devise the full spectrum of exercises, to exercise ability of their plans to address a similar event. (5) ARkStorm can be a reference point for application of Federal Emergency Management Agency (FEMA) and California Emergency Management Agency guidance connecting federal, state and local natural hazards mapping and mitigation planning under the National Flood Insurance Plan and Disaster Mitigation Act of 2000. (6) Common messages to educate the public about the risk of such an extreme disaster as the ARkStorm scenario could be developed and consistently communicated to facilitate policy formulation and transformation. These impacts were estimated by a team of 117 scientists, engineers, public-policy experts, insurance experts, and employees of the affected lifelines. In many aspects the ARkStorm produced new science, such as the model of coastal inundation. The products of the ARkStorm are intended for use by emergency planners, utility operators, policymakers, and others to inform preparedness plans and to enhance resiliency.

Patterns and projections of high tide flooding along the U.S. coastline using a common impact threshold

National Oceanic and Atmospheric Administration (NOAA) | February 1st, 2018

For forecasting purposes to ensure public safety, NOAA has established three coastal flood severity thresholds. The thresholds are based upon water level heights

For forecasting purposes to ensure public safety, NOAA has established three coastal flood severity thresholds. The thresholds are based upon water level heights empirically calibrated to NOAA tide gauge measurements from years of impact monitoring by its Weather Forecast Offices (WFO) and emergency managers. When minor (more disruptive than damaging), moderate (damaging) or major (destructive) coastal flooding is anticipated (not associated with tropical storms), NOAA issues either a flood advisory(for minor) or warning (for moderate or major). Less than half of NOAA tide gauges located along the U.S. coastline have such ‘official’ NOAA flood thresholds, and where they exist, the heights can vary substantially (e.g., 0.3–0.6 meter within minor category). They differ due to the extent of infrastructure vulnerabilities, which vary by topography and relief, land-cover types or existing flood defenses.

Patterns in the use of a restored California floodplain by native and alien fishes

University of California, Davis (UC Davis) | July 7th, 2007

Fishes were sampled on the restored floodplain of the Cosumnes River in Central California in order to determine patterns of floodplain use. The floodplain was sampled fo

Fishes were sampled on the restored floodplain of the Cosumnes River in Central California in order to determine patterns of floodplain use. The floodplain was sampled for seven years (1998-2002, 2004-2005) during the winter-spring flooding season. The fishes fell into five groups: (1) floodplain spawners, (2) river spawners, (3) floodplain foragers, (4) floodplain pond fishes, and (5) inadvertent users. Eight of the 18 abundant species were natives, while the rest were aliens. There was a consistent pattern of floodplain use, modified by timing and extent of flooding. The first fishes to appear were floodplain foragers, inadvertent users, and juvenile Chinook salmon (river spawners). Next were floodplain spawners, principally Sacramento splittail and common carp. At the end of the season, in ponds of residual water, non-native annual fishes, mainly inland silverside and western mosquitofish, became abundant. Adult spawners left when inflow decreased; their juveniles persisted as long as flood pulses kept water levels up and temperatures low. Juvenile splittail and carp quickly grew large enough to dominate floodplain fish samples, along with smaller numbers of juvenile Sacramento sucker and pikeminnow (river spawners). Such juveniles left the Relatively few fishes that used the floodplain for spawning or rearing became stranded, except late season alien fishes. Most alien fishes had resident populations in adjacent river, sloughs, and ditches and were not dependent on the floodplain for persistence. This indicates that Central Valley floodplains managed to favor native fishes should have the following characteristics: (1) extensive early season flooding, (2) complete drainage by the end of the flooding season, (3) few areas with permanent water, (4) a mosaic of physical habitats, (5) regular annual flooding but with high variability in flood regime.