E. Natasha Stavros

Climate and very large wildland fires in the contiguous western USA

Very large wildfires can cause significant economic and environmental damage, including destruction of homes, adverse air quality, firefighting costs and even loss of life. We examine how climate is associated with very large wildland fires (VLWFs

ISS observations offer insights into plant function

50 000 acres, or ,20 234 ha) in the western contiguous USA. We used composite records of climate and fire to investigate the spatial and temporal variability of VLWF-climatic relationships. Results showed quantifiable fire weather leading up and up to 3 weeks post VLWF discovery, thus providing predictors of the probability that VLWF occurrence ina given week. Models were created for eight National Interagency Fire Center Geographic Area Coordination Centers (GACCs). Accuracy was good (AUC.0.80) for all models, but significant fire weather predictors of VLWFs vary by GACC, suggesting that broad-scale ecological mechanisms associated with wildfires also vary across regions. These mechanisms are very similar to those found by previous analyses of annual area burned, but this analysis provides a means for anticipating VLWFs specifically and thereby the timing of substantial area burned within a given year, thus providing aquantifiable justification forproactive firemanagement practices tomitigatethe risk andassociated damage of VLWFs. Additional keywords: AUC, GACC, logistic regression, niche space, precision, rare events, recall, wildland fire.

THEO Concept Mission: Testing the Habitability of Enceladus's Ocean

In 2018 technologies on the International Space Station will provide ~1 year of synchronous observations of ecosystem composition, structure and function. We discuss these instruments and how they can be used to constrain global models and improve our understanding of the current state of terrestrial ecosystems.

Deconstructing the King megafire

Abstract Saturn’s moon Enceladus offers a unique opportunity in the search for life and habitable environments beyond Earth, a key theme of the National Research Council’s 2013–2022 Decadal Survey. A plume of water vapor and ice spews from Enceladus’s south polar region. Cassini data suggest that this plume, sourced by a liquid reservoir beneath the moon’s icy crust, contain organics, salts, and water–rock interaction derivatives. Thus, the ingredients for life as we know it – liquid water, chemistry, and energy sources – are available in Enceladus’s subsurface ocean. We have only to sample the plumes to investigate this hidden ocean environment. We present a New Frontiers class, solar-powered Enceladus orbiter that would take advantage of this opportunity, Testing the Habitability of Enceladus’s Ocean (THEO). Developed by the 2015 Jet Propulsion Laboratory Planetary Science Summer School student participants under the guidance of TeamX, this mission concept includes remote sensing and in situ analyses with a mass spectrometer, a sub-mm radiometer–spectrometer, a camera, and two magnetometers. These instruments were selected to address four key questions for ascertaining the habitability of Enceladus’s ocean within the context of the moon’s geological activity: (1) how are the plumes and ocean connected? (2) are the abiotic conditions of the ocean suitable for habitability? (3) how stable is the ocean environment? (4) is there evidence of biological processes? By taking advantage of the opportunity Enceladus’s plumes offer, THEO represents a viable, solar-powered option for exploring a potentially habitable ocean world of the outer solar system.

Synthesizing Remote Sensing Data on the Carbon and Water Cycles

Hypotheses that megafires, very large, high-impact fires, are caused by either climate effects such as drought or fuel accumulation due to fire exclusion with accompanying changes to forest structure have long been alleged and guided policy, but their physical basis remains untested. Here, unique airborne observations and microscale simulations using a coupled weather-wildland-fire-behavior model allowed a recent megafire, the King Fire, to be deconstructed and the relative impacts of forest structure, fuel load, weather, and drought on fire size, behavior, and duration to be separated. Simulations reproduced observed details including the arrival at an inclined canyon, a 25-km run, and later slower growth and features. Analysis revealed that fire-induced winds that equaled or exceeded ambient winds and fine-scale airflow undetected by surface weather networks were primarily responsible for the fires rapid growth and size. Sensitivity tests varied fuel moisture and amount across wide ranges and showed that both drought and fuel accumulation effects were secondary, limited to sloped terrain where they compounded each other, and, in this case, unable to significantly impact the final extent. Compared to standard data, fuel models derived solely from remote sensing of vegetation type and forest structure improved simulated fire progression, notably in disturbed areas, and the distribution of burn severity. These results point to self-reinforcing internal dynamics rather than external forces as a means of generating this and possibly other outlier fire events. Hence, extreme fires need not arise from extreme fire environment conditions. Kinematic models used in operations do not capture fire-induced winds and dynamic feedbacks so can underestimate megafire events. The outcomes provided a nuanced view of weather, forest structure, fuel accumulation, and drought impacts on landscape-scale fire behavior-roles that can be misconstrued using correlational analyses between area burned and macroscale climate data or other exogenous factors. A practical outcome is that fuel treatments should be focused on sloped terrain, where factors multiply, for highest impact.

Regional projections of the likelihood of very large wildland fires under a changing climate in the contiguous Western United States

This year two of NASAs Earth missions, Orbiting Carbon Observatory 2 (OCO-2; http://oco.jpl.nasa.gov) and Soil Moisture Active Passive (SMAP; http://smap.jpl.nasa.gov), will collect data relating to water and carbon cycles at unprecedented spatial and temporal resolutions. Synthesizing these data provides unique opportunities for understanding interactions, patterns, underlying processes, and variability among climate, carbon, and hydrologic cycles.