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This study presents a climatology of water vapor fluxes for the eastern United States and adjacent Atlantic with particular focus on the Northeast. Pathways of moisture transport comprising this climatology were discerned using a self-organizing map methodology ingesting daily integrated vapor transport data from ECMWF ERA-Interim Reanalysis from 1979 to 2017 at a 2.5° × 2.5° spatial resolution. Sixteen spatially distinct moisture transport patterns capture the variety of water vapor transport in the region. The climatology of water vapor transport is precisely and comprehensively defined via synthesis of spatial and temporal characteristics of the fluxes. Each flux has a distinct seasonality and frequency. The fluxes containing the highest amounts of moisture transport occur less frequently than those with less moisture transport. Because the patterns showing less moisture transport are prevalent, they are major contributors to the manner in which water vapor is moved through the eastern United States. The spatial confinement of fluxes is inversely related to persistence, with strong, narrow bands of enhanced moisture transport most often moving through the region on daily time scales. Many moisture fluxes meet a threshold-based definition of atmospheric rivers, with the diversity in trajectories and moisture sources indicating that a variety of mechanisms develop these enhanced moisture transport conditions. Temporal variability in the monthly frequencies of several of the fluxes in this study aligns with changes in the regional precipitation regime, demonstrating that this water vapor flux climatology provides a precise moisture-delivery framework from which changes in precipitation can be investigated.

Precipitation throughfall (TF) plays an important role in the water balance of tropical forests. This study used 164 gauges to quantify precipitation and TF variability in a tropical pre-montane transitional cloud forest on the Caribbean slope of the Cordillera Tilaran, Costa Rica, to identify the ecological and meteorological drivers of this variability. Daily TF measurements were taken from 28 June to 17 July 2012 and 12 June to 16 July 2013, for a total of 39 precipitation events. The total mean TF was 87.9 percent and TF at individual gauges ranged from 22.7 percent to 245.7 percent. Leaf area index (LAI) was calculated above each gauge using hemispheric photography for a mean study-site LAI of 7.7. There was no statistically significant relationship between LAI and TF. However, the amount of TF was positively correlated with precipitation intensity, while the variability of TF was negatively correlated with precipitation intensity. Our calculations indicate that at least 61 gauges are required to obtain mean TF estimates with less than 5 percent error. This study demonstrates that TF is highly spatially heterogeneous due to multiple compounding effects. RESUMEN Precipitacion interna a traves del dosel del bosque (TF) es una parte importante del equilibrio de agua en bosques tropicales. Este estudio tuvo como objetivo cuantificar la variabilidad de precipitacion y TF en un bosque nuboso transicional y premontano en el lado Caribe de la Cordillera Tilaran, especificamente en el Centro Soltis, Costa Rica, e identificar los factores ecologicos y meteorologicos en esta variabilidad. Mediante 164 pluviometros, se obtuvieron lecturas diarias de precipitacion interna, desde 28 Junio –17 Julio 2012 y 12 Junio–16 Julio 2013, abarcando 39 eventos pluviales. El promedio total de la precipitacion interna fue 87.9% y la precipitacion interna de los pluviometros fluctuaron entre 22.7% y 245.7%. Mediante fotografia hemisferica se calcularon los indices de area foliar (LAI) sobre cada pluviometro. El promedio del LAI fue 7.7. No hubo una relacion estadisticamente significativa entre LAI y TF; sin embargo, hubo una correlacion positiva entre la precipitacion interna y la intensidad de la precipitacion, y la variabilidad de la precipitacion interna correlaciono negativamente con la intensidad de la precipitacion. Nuestros resultados indican que al menos 61 pluviometros son necesarios para determinar los promedios de precipitacion interna con menos de 5% de error. Este estudio demuestra que la precipitacion interna es espacialmente heterogenea debido a muchos efectos amontonados.

High-volume hydraulic fracturing (HVHF) gas-drilling operations in the Marcellus Play have raised environmental concerns, including the risk of groundwater contamination. Fingerprinting water impacted by gas-drilling operations is not trivial given other potential sources of contamination. We present a multivariate statistical modeling framework for developing a quantitative, geochemical fingerprinting tool to distinguish sources of high salinity in shallow groundwater. The model was developed using new geochemical data for 204 wells in New York State (NYS), which has a HVHF moratorium and published data for additional wells in NYS and several salinity sources (Appalachian Basin brines, road salt, septic effluent, and animal waste). The model incorporates a stochastic simulation to predict the geochemistry of high salinity (20 mg/L Cl) groundwater impacted by different salinity sources and then employs linear discriminant analysis to classify samples from different populations. Model results indicate Appalachian Basin brines are the primary source of salinity in 35% of sampled NYS groundwater wells with20 mg/L Cl. The model provides an effective means for differentiating groundwater impacted by basin brines versus other contaminants. Using this framework, similar discriminatory tools can be derived for other regions from background water quality data.