Spatial and temporal distribution of Sandy precipitation samples.

<p>(<b>A</b>) Histogram of the temporal distribution of collected precipitation isotope samples with NOAA classification of Sandy development: TS, Tropical Storm; HU, Hurricane; EX, Extra Tropical. (<b>B</b>) Spatial distribution of collected precipitation isotope samples by region (New England, Mid-Atlantic, Midwest, and South) with the Sandy storm track. Average regional precipitation (<b>C</b>) O and (<b>D</b>) -excess throughout the course of the storm color-coded by region.</p

Snapshot of rainfall and O isotope values during landfall of Superstorm Sandy.

<p>Storm track has landfall6hrs as solid line.</p

Sandy precipitation isotopic composition relative to storm center.

<p>Precipitation (<b>A</b>) O and (<b>C</b>) deuterium-excess with data points positioned relative to the storm center at time of sample collection. (<b>B</b>) Samples are grouped by region as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091117#pone-0091117-g001" target="_blank">Figure 1</a>.</p

Estimates of vapor source regions.

<p>(<b>A–F</b>) Back trajectory estimates from the STILT model of regions contributing moisture to the atmosphere above six locations where precipitation samples were collected on October 31st 2013, 00 hrs EDT.</p

Stable Isotope Analysis of Precipitation Samples Obtained via Crowdsourcing Reveals the Spatiotemporal Evolution of Superstorm Sandy

<div><p>Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-associated precipitation and water vapor, and isotopic analysis provides constraints on difficult-to-observe cyclone dynamics. During Superstorm Sandy, a unique crowdsourced approach enabled 685 precipitation samples to be obtained for oxygen and hydrogen isotopic analysis, constituting the largest isotopic sampling of a synoptic-scale system to date. Isotopically, these waters span an enormous range of values (21‰ for O, 160‰ for H) and exhibit strong spatiotemporal structure. Low isotope ratios occurred predominantly in the west and south quadrants of the storm, indicating robust isotopic distillation that tracked the intensity of the storm's warm core. Elevated values of deuterium-excess (25‰) were found primarily in the New England region after Sandy made landfall. Isotope mass balance calculations and Lagrangian back-trajectory analysis suggest that these samples reflect the moistening of dry continental air entrained from a mid-latitude trough. These results demonstrate the power of rapid-response isotope monitoring to elucidate the structure and dynamics of water cycling within synoptic-scale systems and improve our understanding of storm evolution, hydroclimatological impacts, and paleo-storm proxies.</p></div

Isotopic signatures of Sandy intensity and interaction with dry continental air.

<p>(<b>A</b>) Rayleigh rainout fraction at STILT sites based on change in isotopic composition from estimated source moisture to collected precipitation sample. (<b>B</b>) Deuterium-excess at STILT trajectory locations and times (symbols) as a function of surface normalized source vapor relative humidity, . The linear trend fit to collected samples (gray line) falls between values expected from vapor with sea surface temperatures (SST) of 0°C and 25°C (dotted lines). Symbols are the same in <b>A</b> and <b>B</b> and colors match the regions of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091117#pone-0091117-g002" target="_blank">Figure 2</a>.</p