About

Professor Leila Carvalho is an interdisciplinary researcher who investigates coupled systems to advance understanding of the Earth’s climate on multiple scales. Her work involves exploring the interactions within climate systems to better comprehend climate variability and change. As a professor at UC Santa Barbara, she contributes to the department's efforts in atmospheric and climate science, focusing on the complex processes that influence global and regional climate patterns.

Research topics

• Environmental science
• Climatology
• Meteorology
• Geology
• Geography
• Ecology
• Computer Science
• Social Science
• Sociology
• Political Science
• Atmospheric sciences
• Business
• Engineering
• Environmental planning
• Oceanography
• Environmental resource management
• Environmental ethics
• Law

Selected publications

• Impact of Unprotected Area (UPA) Deforestation on Amazonian Climate: Mapping Regional Shifts and Localized Risk

  Climate · 2026-04-16

  articleOpen access

  Deforestation in unprotected areas (UPAs) within the Brazilian Amazon affects environmental sustainability and regional climate. This study quantifies shifts in near-surface air temperature, precipitation, and evapotranspiration (ET) during the dry season resulting from UPA loss. Utilizing a five-year ensemble (2015–2019) to isolate the climatic response from interannual variability, simulations indicate a warmer (+1.0 ± 0.4 °C) and drier climate, characterized by a basin-wide 12 ± 8% reduction in precipitation and a 12 ± 4% reduction in ET following UPA removal. This shifted climate state extends to Rondônia, a southwestern state where detailed risk mapping was developed by integrating changes in climate variables with socio-economic, agricultural, and demographic. UPA deforestation, largely external to Rondônia, is associated with a simulated decrease in precipitation by 20 ± 7% and ET by 11 ± 9% coupled with an increase in air temperature by 1.2 ± 0.4 °C. These shifts indicate increased vulnerability for municipalities, including the capital, potentially affecting agricultural productivity. Findings suggest that to protect remaining forests these biophysical risks must be mitigated. This study establishes a spatial framework for identifying municipalities most suceptible to the climatic shifts triggered by UPA loss.

  PublisherOA PDFDOI

• Impacts of Northerly Low‐Level Jets on Mesoscale Convective Systems East of the Andes

  Journal of Geophysical Research Atmospheres · 2025-10-31

  articleOpen access

  Abstract Low‐level jets (LLJs) play a critical role in moisture transport, vertical motion enhancement, and orographic lifting, frequently leading to deep, organized convection formation in South America. This study examines the impacts of three types of LLJs (Central, Northern, and Andes) on Mesoscale Convective Systems (MCSs), using a 4 km horizontal grid spacing Weather Research and Forecasting (WRF) model simulation and satellite‐based data. The Central and Andes LLJ types facilitate significant moisture flux convergence over the La Plata Basin (LPB), contributing to intense MCS activity and heavy precipitation. In contrast, the Northern LLJ type, operating over the eastern slopes of the northern Andes, exerts a weaker impact on MCS development over the Amazon Basin, leading to more scattered convection. Stronger LLJs support larger, longer‐lived MCSs with higher mean precipitation in jet exit regions. El Niño Southern Oscillation modulates these relationships, with El Niño increasing MCS size and duration in the Central LLJ region, while La Niña enhances MCS frequency in the Andes and Northern LLJ regions. The WRF model captures many of these dynamics but produces higher extreme MCS mean precipitation than IMERG. These findings highlight the importance of LLJ variability in modulating MCSs and suggest that future LLJ changes could alter the hydroclimate and extreme weather patterns in the region. This study underscores the utility of km‐scale models in representing the complex interactions of LLJs and MCSs, making them a promising tool to improve our understanding of these interactions and to assess the potential impacts of climate change on water resources and extreme weather in South America.

  PublisherOA PDFDOI

• Heat-related rest-break recommendations for farmworkers in California based on wet-bulb globe temperature

  Communications Earth & Environment · 2025-05-09 · 2 citations

  articleOpen access

  Extreme heat is a global public health concern that is becoming more frequent and severe in recent periods. Translating Earth science data into policy-relevant metrics, such as rest breaks, is challenging but needed to protect outdoor workers from heat stress. Here, we determine rest-break requirements for the farmworkers of the Imperial and Coachella Valleys in southern California, which have a high poverty rate and the highest heat-illness rates in California. We used high-resolution outputs from a validated Weather Research and Forecasting Model (WRF) at 1-km grid resolution that includes irrigation, a key modulator of heat stress in the study region. We calculated exceedances of heat stress indicators under three existing policy guidelines that use wet-bulb globe temperature (WBGT), heat index (HI), or dry-bulb temperature (DBT), and translated them into rest breaks needed for farmworker safety. WBGT-based rest minutes are most sensitive to the spatiotemporal variation in heat exposure compared to DBT or HI and vary with acclimatization status, season, and work shifts. Recommended rest breaks to protect farmworkers from heat stress range from 2 to 32 min per work-hour between April and August. Although results are specific to California, our method is adaptable for calculating region-specific rest break requirements worldwide. California’s farmworkers require 2–32 min of rest per hour depending on season and work shift to mitigate health risks from extreme heat, according to a study using high-resolution model outputs to translate exceedances of Wet Bulb Globe Temperature thresholds into rest break requirements.

  PublisherOA PDFDOI

• Storm Structure Properties and Reflectivity Patterns in Post-Fire Debris Flow-Triggering Events Using Radar Composites

  2025-12-19

  preprint

  Post-fire debris flows are fast-moving, sediment-rich flows triggered by short-duration, high-intensity rainfall over recently burned slopes. In California, the close succession of wildfire and intense precipitation creates a recurring hazard cascade with significant risk to life and infrastructure. This study uses radar reflectivity composites to implement a modified storm-tracking algorithm that identifies reflectivity regions, enabling the characterization of both large-scale storm structure (area, propagation speed, direction, eccentricity) and localized reflectivity signatures within fire perimeters. Applied to an inventory of documented post-fire debris flow events, the algorithm performed well across storm types and durations, capturing key structural distinctions between seasons. Fall and winter storms tended to be larger, faster-moving, and more elongated, while spring and summer storms were typically smaller, slower, and more circular. Importantly, within burn areas, warmer-season storms more frequently exhibited brief, intense reflectivity bursts (>45 dBZ), whereas colder-season events presented broader zones of moderate reflectivity (25–45 dBZ). Across cases, the timing of peak reflectivity over fire perimeters aligned more closely with peak 15-minute rainfall from nearby gauges than did broader reflectivity metrics, particularly during short-duration storms. These findings highlight the value of radar data for characterizing the atmospheric conditions of storms that trigger post-fire debris flows. In addition, the approach offers a scalable tool for linking atmospheric and geomorphic processes and supports efforts to improve real-time hazard monitoring in recently burned landscapes.

  PublisherDOI

• Investigating the performance of high-resolution subseasonal precipitation forecasts in support of food insecurity early warning

  Environmental Research Climate · 2025-04-09 · 1 citations

  articleOpen access

  Abstract Anticipating precipitation extremes across sub-Saharan Africa can help mobilize interventions, trigger anticipatory actions, and promote beneficial actions like water harvesting. Reliable crop model forecasts can help identify when and where food aid interventions can be most beneficial. To date, however, there has been little research evaluating the utility of rainfall forecasts. This study, therefore, assesses the efficacy of the Subseasonal Consortium database (SubC) for use in a regional crop water balance model—the Water Requirement Satisfaction Index (WRSI)—in east Africa. We find that combining two dekads (20 days) of statistically downscaled and bias-corrected SubC precipitation data with climatological information delivers improved estimates of end-of-season conditions over a 17-year test period.
Our results show that SubC forecasts provide a 35-55% reduction in end-of-season WRSI Root Mean Squared Error in 60% of the east African agropastoral areas during the short rains, with the highest accuracy being in areas most vulnerable to inconsistent precipitation timing and quantities. Across the 17 tested seasons, 1999/00 to 2015/16, use of the SubC either improved or did not degrade the accuracy of WRSI prediction compared to a benchmark model for over 70% of the seasons and for 90% of the study region. In general, the improved accuracy provided by two dekads of SubC forecast is nearly equivalent to what can be attained with one dekad of “perfect” forecast (i.e., observation data). In effect, a 20 day forecast provides a 10-day advance in our early warning capabilities. During extreme events, such the 2005/2006 drought in east Africa, the SubC-driven WRSI could provide advanced warning of poor cropping conditions and potential crop failure up to 3 months before the end of the season. Overall, these improvements provide earlier and more accurate estimates of likely seasonal water balance outcomes, and allow for the identification of where interventions may be needed.

  PublisherDOI

• Increasing dry-season vapor pressure deficit in the Amazon Basin: historical trends, future projections, and links to deforestation

  Environmental Research Communications · 2025-09-26 · 2 citations

  articleOpen access

  Abstract Vapor Pressure Deficit (VPD) strongly influences agricultural productivity, vegetation health, and ecosystem resilience in the Amazon Basin. Rising VPD intensifies plant water stress by increasing atmospheric evaporative demand, exacerbating drought-induced vegetation mortality. We analyze historical (1983–2016) and projected (∼2050) seasonal and extreme VPD trends across the Amazon. Using CMIP6 projections and CHIRTS observational data, we quantify future dry-season VPD shifts and changes in extreme VPD event frequency under moderate (SSP245) and high-emission (SSP585) scenarios. Historical analyses reveal increasing dry-season VPD, driven primarily by warming-induced rises in saturation vapor pressure (∼7% increase per °C, Clausius–Clapeyron) and declining actual vapor pressure associated with deforestation-reduced evapotranspiration. Quantitative attribution analyses further indicate that recent deforestation significantly amplifies local atmospheric drying, with VPD increases strongest near recently deforested regions. SSP585 projections indicate severe atmospheric drying, with widespread and frequent extreme VPD events (>30 days/month) during peak dry months, surpassing historical extremes. Such conditions significantly threaten agricultural productivity and ecosystem stability, highlighting the urgent need for sustainable land management and effective climate mitigation policies in the Amazon.

  PublisherDOI

• Insights on the Spatiotemporal Variability of Downslope Winds in Coastal Santa Barbara: A Case Study from the Sundowner Winds Experiment (SWEX)

  Monthly Weather Review · 2025-09-03 · 1 citations

  article

  Abstract The coastal plain of Santa Barbara County (SBC) is bounded by the cool waters of the Pacific Ocean to the south and the west–east-oriented Santa Ynez Mountains (SYM) to the north. Downslope windstorms with a typical onset after sunset are frequently observed on the lee slopes of the SYM. These northerly winds are known as Sundowner winds or simply Sundowners. The Sundowner Winds Experiment (SWEX), conducted between 1 April and 15 May 2022, aimed to unravel mechanisms responsible for the spatiotemporal variability of these winds. The present study examines data collected from lidar wind profilers, radiosondes, and surface stations during the 12–13 May 2022 intensive observation period (IOP). Gusty winds were observed on both the western and eastern slopes of the SYM. This event was associated with the second-largest observed mean sea level pressure difference between the Santa Barbara and Bakersfield airports during SWEX. However, horizontal wind speeds exceeding 20 m s −1 were recorded on the eastern slopes of the SYM hours before the most pronounced observed pressure differences. Furthermore, lidar measurements in the foothills of the eastern SYM exhibited positive vertical wind speeds of approximately 6 m s −1 . These ascending vertical motions were associated with the lifting of the lee-slope jet and a concurrent weakening of winds near ground level—a clear indication of mountain-wave activity influencing surface winds. While mesoscale numerical simulations with 1-km grid spacing captured the spatial patterns of the winds, their temporal variability was inadequately represented in highly turbulent regions.

  PublisherDOI

• Wildfire and power grid nexus in a changing climate

  Nature Reviews Electrical Engineering · 2025-03-24 · 21 citations

  articleOpen access
  PublisherOA PDFDOI

• Rainfall Conditions of Post-Fire Debris Flows between 2012 – 2023 Across Regions in California

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

• ALPS: A system dynamic simulator towards food security policies in Africa. Application to Morocco

  AIP conference proceedings · 2024-01-01

  articleOpen accessSenior author

  During last decades, African countries have gone through important changes for the sake of their development. Yet, several big challenges need to be addressed to sustain the development in the continent. Sorting out the best policies in this case is not straightforward. Morocco has implemented many programs aiming at tackling agriculture issues. However, one critical factor emerged as a key limitation to pursue such program: climate change. Water scarcity remains a critical constraint. Thus Morocco has to constantly change its policy in order to cope with these limitations. Stakeholders are in need of adaptation tools, that can help them to assess reasonably the different potential policies. In that work, we present a new system dynamics based framework for the Agriculture and Land Policy Simulations to support policy-makers decisions. Fitted to the case of Morocco, we use this tool to examine how elements of the Moroccan Green Plan can contribute to secure food production under different constraints.

  PublisherOA PDFDOI

Recent grants

• The Madden-Julian Oscillation and Predictability of Extreme Precipitation in the United States

  NSF · $466k · 2011–2016

• The Dynamics and Variability of the South American Low-Level Jet (SALLJ)

  NSF · $487k · 2020–2026

Frequent coauthors

• Leila M. V. Carvalho

  University of California, Santa Barbara

  103 shared

• Wayne Sumner

  37 shared

• Tigger Jourard

  Max Planck Institute for the Study of Religious and Ethnic Diversity

  37 shared

• Leslie Green

  37 shared

• Andrew Botterell

  Western University

  37 shared

• David Dyzenhaus

  37 shared

• Margaret Martin

  University of Glasgow

  37 shared

• Barry Hoffmaster

  37 shared

Labs

• Charles Jones's LabPI

  1-2 sentence research focus

Education

• Ph.D., Department of Land, Air and Water Resources

  University of California Davis

  1994

• M.S., Department of Atmospheric Sciences

  University of Utah

  1990

• B.S., Department of Atmospheric Sciences

  University of Sao Paulo

  1986