Recent patterns of water use and supply in California are presented based on a new data set compiled from the California Department of Water Resources water balance data for 2002 through 2016. The water use and supply include surface water and groundwater, although groundwater reporting has been incomplete. These data are used to support the Water Plan released every 3 to 5 years and are the most comprehensive and finest spatial- and temporal-scale data set for California water resources. First, using the Bay–Delta watershed as a case example, we show that recent fluctuations in water use are highly correlated with variations in precipitation. Developed water supplies and use show these fluctuations, but they are modified by reservoir inflows and releases, groundwater supplies, and Delta outflows. Second, although the annually precipitated water supply in the Bay–Delta varies by about 30%, the developed water supply damps this considerably. The water management system maintained nearly constant agricultural water use even in periods of intense drought, with year-to-year variation of about 7%. Variability in urban water use is higher (∼20%), largely from conservation during periods of drought. Finally, this information can help improve water resource management because it connects regional-scale data to meaningful policy decision-making at county and sub-county levels. At a time when water policy and management are being re-evaluated across the American West in the light of changing climate, decision-making informed by science and data is urgently needed. The statewide water balance data provide the means to establish a consistent, quantitative framework for water resource analysis throughout the state.

Accurate forecasts of precipitation during landfalling atmospheric rivers (ARs) are critical because ARs play a large role in water supply and flooding for many regions. In this study, we have used hundreds of observations to verify global and regional model forecasts of atmospheric rivers making landfall in Northern California and offshore in the midlatitude northeast Pacific Ocean. We have characterized forecast error and the predictability limit in AR water vapor transport, static stability, onshore precipitation, and standard atmospheric fields. Analysis is also presented that apportions the role of orographic forcing and precipitation response in driving errors in forecast precipitation after AR landfall. It is found that the global model and the higher-resolution regional model reach their predictability limit in forecasting the atmospheric state during ARs at similar lead times, and both present similar and important errors in low-level water vapor flux, moist-static stability, and precipitation. However, the relative contribution of forcing and response to the incurred precipitation error is very different in the two models. It can be demonstrated using the analysis presented herein that improving water vapor transport accuracy can significantly reduce regional model precipitation errors during ARs, while the same cannot be demonstrated for the global model.

Abstract The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region’s economy and environment, as evidenced by the recent California drought. This variability is strongly influenced by atmospheric rivers (ARs), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, and by aerosols (from local sources and transported from remote continents and oceans) that modulate clouds and precipitation. A better understanding of these processes is needed to reduce uncertainties in weather predictions and climate projections of droughts and floods, both now and under changing climate conditions. To address these gaps, a group of meteorologists, hydrologists, climate scientists, atmospheric chemists, and oceanographers have created an interdisciplinary research effort, with support from multiple agencies. From 2009 to 2011 a series of field campaigns [California Water Service (CalWater) 1] collected atmospheric chemistry, cloud microphysics, and meteorological measurements in California and associated modeling and diagnostic studies were carried out. Based on the remaining gaps, a vision was developed to extend these studies offshore over the eastern North Pacific and to enhance land-based measurements from 2014 to 2018 (CalWater-2). The dataset and selected results from CalWater-1 are summarized here. The goals of CalWater-2, and measurements to date, are then described. CalWater is producing new findings and exploring new technologies to evaluate and improve global climate models and their regional performance and to develop tools supporting water and hydropower management. These advances also have potential to enhance hazard mitigation by improving near-term weather prediction and subseasonal and seasonal outlooks.

Large tabular icebergs represent a disruptive influence on a stable water column when drifting in the open ocean. This is a study of one iceberg, C18A, encountered in the Powell Basin in the Weddell Sea in March 2009, formed from iceberg C18 ( 76x7km) originating from the Ross Ice Shelf in May 2002. C18A was lunate in shape with longest dimensions of 31kmx7kmx184m. The meltwater field from C18A was characterized using 18O from water samples collected near C18A (Near-field, 0.4-2 km) and contrasted with a Far-field comprised of samples from an Away site (19 km from C18A), a Control site (70 km away), and a region populated with small icebergs (Iceberg Alley, 175 km away). The in-sample fractions of meteoric water were calculated relative 18O in iceberg ice and Weddell Deep Water and converted to meteoric water height (m) and a percentage within 100 m depth bins. The Near-field and Far-field difference from surface to 200 m was 0.510.28%. The concentration of meteoric water dropped to approximately half that value below 200 m, approximate keel depth of the iceberg, although detectable to 600 m. From surface to 600 m, the overall difference was statistically significant ( P<0.0001). From this, we estimate the Near-field volume astern of the iceberg ( 0.16km3d-1) as a continuous source of meteoric water.

A sand balance coastal profile model for estimating cliff and shoreline retreats considering sea level rise is discussed. The model, specifically designed for cliffed coasts fronted by sandy beaches, conditionally permits beach and cliff retreat to occur independently, and includes subaerial cliff erosion and external beach sand sources. The model accommodates complex nearshore and inland topography, high volume beaches, and variable cliff composition, and is suitable where local sand balance is thought to be a primary controller of coastal evolution over decade–century time scales. Designating an upper active beach boundary and beach–cliff intersection divides the coastal profile into active beach and cliff sections separated by a back beach buffer. The buffer acts as a sand reservoir and delays marine driven cliff erosion, resulting in lower estimated cliff retreat compared to previous models neglecting protective beaches. The model was applied on 21km of cliffs in Marine Corps Base Camp Pendleton, California considering sea level rise ranging from 0.5 to 2m over 100yrs using 207 profiles, sand budget deficits estimated from historical data, and sand inputs from terrestrial erosion estimated from a time series of lidar data. Modeled mean and maximum scenario cliff retreats ranged from 4–87m and 21–179m, respectively, and provide order of magnitude estimates, but are reliant on model assumptions and do not include potential coastal changes unrelated to local sand balance. The results underscore the influence of protective beaches on cliff retreat.

Multiyear climate variations influence North Pacific storm intensity and resultant variations in wave energy levels. The timing of these decadal fluctuations and strong El Niño's have had a strong influence on long‐term trends. Here we investigate variations in the North Pacific wave power, PW, determined from WAVEWATCH III (WW3) wave model significant wave height, Hs, and peak period data forced by NRA‐1 winds spanning the 1948–2008 epoch. Over the entire hindcast, upward trends in Hs and PW, especially in winter, are observed over much of the North Pacific, strongly influenced by an apparent storm intensification after the mid‐1970s regime shift. Heightened PW is concentrated in particular regions of the basin, and is associated with increased wave activity during the warm phase of the Pacific Decadal Oscillation (PDO). Wave power events, PE, defined as episodes when Hs exceeded the 90th percentile threshold for at least 12 h, exhibit significant upward trends along much of the U.S. Pacific coast during winter months. Importantly, the hindcast exhibits a recent decrease in PW across much of the North Pacific, in contrast to the long‐term increase of PW and Hs. This recent decrease is associated with the prevalent PDO cool phase that developed after the late 1990s. Variability and intensification of coastal PW and PE have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm‐surge flooding, and coastal planning. These considerations will become increasingly important as sea level rises.

Regional warming around West Antarctica, including the Antarctic Peninsula, is related to the retreat of glaciers that has resulted in significant ice mass loss in recent decades (De Angelis and Skvarca, 2003). Large icebergs (> 18.5 km long) originating from ice shelves in the Ross and Weddell Seas (Scambos et al., 2000) are attributed primarily to major loss events in these regions. Once free, icebergs become entrained in the counterclockwise Antarctic Coastal Current (Figure 1), eventually entering a strong northward flow in the Northwest Weddell Sea. We examined free-drifting icebergs in the Atlantic sector of the Southern Ocean in December 2005, aboard ARSV Laurence M. Gould, and in June 2008 and March/April 2009, aboard RVIB Nathaniel B. Palmer. Prior to these studies, little information was available about the effects of icebergs on the pelagic realm. On these cruises, we investigated the "iceberg ecosystem" (Smith et al., 2007; Smith, 2011) to assess the degree to which icebergs are (1) hotspots of biological activity across multiple trophic levels, and (2) focal points for enhanced export of organic carbon to the deep sea. An important focus of this work was to examine the fundamental mechanisms by which icebergs affect the pelagic ecosystem, including physical disruption and effects on the availability of critical nutrients (e.g., iron, nitrate).

Observations near a large tabular iceberg in the Weddell Sea in March and April 2009 show evidence that water from ice melting below the surface is dispersed in two distinct ways. Warm, salty anomalies in T–S diagrams suggest that water from the permanent thermocline is transported vertically as a result of turbulent entrainment of meltwater at the iceberg's base. Stepped profiles of temperature, salinity, and density in the seasonal thermocline are more characteristic of double-diffusive processes that transfer meltwater horizontally away from the vertical ice face. These processes contribute comparable amounts of meltwater–O(0.1m3) to the upper 200m of a 1m2 water column–but only basal melting results in significant upwelling of water from below the Winter Water layer into the seasonal thermocline, suggesting that these two processes may have different effects on vertical nutrient transport near an iceberg.

Iceberg C-18a (35×7×0.184 km) was studied repeatedly by five circumnavigational surveys in March-April 2009. During the period of the surveys, C-18a travelled 109 nautical miles in 23 days covering an area of 8.1×103 km2. This iceberg was formed from iceberg C-18 (76×7 km) that originated from the Ross Ice Shelf in May, 2002. Ship-based measurements show that this iceberg produced fresh meltwater above the seasonal pycnocline that diluted and chilled the water it passed through from the surface to a depth of approximately 50 m (summer mixed layer). The surface meltwater effects were detectable as far away as 19 km and persisted for at least 10 days. We also found evidence that this iceberg was disrupting the Weddell Deep Water to depths up to 1500 m. If we include these deep effects through the water column, the estimate of ocean water altered by this single iceberg reaches 3×1012 m3 over 23 days. Chemical and biological effects were detected at the same space and time scales as the physical properties, with decreasing partial pressure of carbon dioxide (pCO2) close to the iceberg and lower particle and chlorophyll concentration. Ten days after the passage of C-18a, chlorophyll-a had increased by 15%. These results are consistent with alternative hypotheses regarding the role of icebergs as mediators of a localized geophysical disturbance (H1) as well as promoters of chlorophyll-a production (H2).

Author(s): Chadwick, D B; Flick, R E; Helly, J; Nishikawa, T; Wang, P F; O'Reilly, W C; Guza, R T; Bromirski, P D; Young, A P; Crampton, W; Wild, B; Canner, I

We describe an analysis framework to determine military installation vulnerabilities under increases in local mean sea level as projected over the next century. The effort is in response to an increasing recognition of potential climate change ramifications for national security and recommendations that DoD conduct assessments of the impact on U.S. military installations of climate change. Results of the effort described here focus on development of a conceptual framework for sea level rise vulnerability assessment at coastal military installations in the southwest U.S. We introduce the vulnerability assessment in the context of a risk assessment paradigm that incorporates sources in the form of future sea level conditions, pathways of impact including inundation, flooding, erosion and intrusion, and a range of military installation specific receptors such as critical infrastructure and training areas. A unique aspect of the methodology is the capability to develop wave climate projections from GCM outputs and transform these to future wave conditions at specific coastal sites. Future sea level scenarios are considered in the context of installation sensitivity curves which reveal response thresholds specific to each installation, pathway and receptor. In the end, our goal is to provide a military-relevant framework for assessment of accelerated SLR vulnerability, and develop the best scientifically-based scenarios of waves, tides and storms and their implications for DoD installations in the southwestern U.S.

Seabird abundances and distributions can be influenced by seasonal variations in surface productivity, winds, and other environmental factors. Recently evidence emerged that free-drifting icebergs were hotspots of biogeochemical and ecological activity. They also represent physical habitat structure both above and below the sea surface. Here we found seabird abundances that were 2 to 6 times greater within about one-half km of free drifting icebergs than the area between about one-half and one km from the iceberg edge. Aggregation was measured by surveys with an experimental design for determining potential local impacts of free-drifting icebergs on seabird density. Seabird surveys were conducted during three cruises in the Weddell Sea from 4 to 20 December 2005, 11 to 25 June 2008, and 21 March to 2 April 2009. Visual surveys were done on the vessel bridge typically for periods of five minutes facing the port or starboard side. Differences in species composition were also linked to distance from the iceberg edge for the most sampled icebergs with Daption capense exhibiting change in relative abundance. On a local scale, environmental factors such as surface productivity, air temperature, and winds were not consistently related to seabird distributions and community dynamics. The results suggest that climatically-driven variations in iceberg abundance would influence local seabird distributions with unknown impacts on regional abundances and species composition.

We describe the results from a spatial cyberinfrastructure developed to characterize the meltwater field around individual icebergs and integrate the results with regional- and global-scale data. During the course of the cyberinfrastructure development, it became clear that we were also building an integrated sampling planning capability across multidisciplinary teams that provided greater agility in allocating expedition resources resulting in new scientific insights. The cyberinfrastructure-enabled method is a complement to the conventional methods of hydrographic sampling in which the ship provides a static platform on a station-by-station basis. We adapted a sea-floor mapping method to more rapidly characterize the sea surface geophysically and biologically. By jointly analyzing the multisource, continuously sampled biological, chemical, and physical parameters, using Global Positioning System time as the data fusion key, thissurface-mappingmethod enables us to examine the relationship between the meltwater field of the iceberg to the larger-scale marine ecosystem of the Southern Ocean. Through geospatial data fusion, we are able to combine very fine-scale maps of dynamic processes with more synoptic but lower-resolution data from satellite systems. Our results illustrate the importance of spatial cyberinfrastructure in the overall scientific enterprise and identify key interfaces and sources of error that require improved controls for the development of future Earth observing systems as we move into an era of peta- and exascale, data-intensive computing.

Poster session IN13B-1211 presented 10 December 2007 at the AGU Fall Meeting, 10–14 December 2007, San Francisco, CA, USA

A second-generation automated archiving system has recently processed more than 1000 cruises at SIO, and a prototype established at WHOI for cruises and submergence operations. Scalability is achieved by sorting similar data from diverse sources into appropriate locations in a “Canonical Cruise Data Structure (CCDS).” Metadata are auto-generated by rules and vocabulary templates based on the CCDS. http://gdc.ucsd.edu:8080/digarch Data Diversity is a Challenge

The objective of this research is to identify, develop, adapt, prototype, integrate and demonstrate open access force protection and security technologies and processes. The goal is to provide more open public access to recreational and other non-restricted facilities on military bases and to improve the overall base safety and security utilizing advanced video and signal based surveillance. A testbed was created at the Pacific Missile Range Facility (PMRF), Kauai, Hawaii to demonstrate novel and innovative security solutions that serve these objectives. The testbed consists of (1) novel sensors (video cameras, radio frequency identification tags, and seismic, lidar, microwave, and infrared sensors), (2) a computer, data storage, and network infrastructure, and (3) behavior analysis software. The behavior analysis software identifies patterns of behavior and discriminates "normal" and "anomalous" behavior in order to anticipate and predict threats so that they can be interdicted before they impact mission critical operations or cause harm to people and infrastructure.

The proliferation of icebergs from Antarctica over the past decade has raised questions about their potential impact on the surrounding pelagic ecosystem. Two free-drifting icebergs, 0.1 and 30.8 square kilometers in aerial surface area, and the surrounding waters were sampled in the northwest Weddell Sea during austral spring 2005. There was substantial enrichment of terrigenous material, and there were high concentrations of chlorophyll, krill, and seabirds surrounding each iceberg, extending out to a radial distance of ∼3.7 kilometers. Extrapolating these results to all icebergs in the same size range, with the use of iceberg population estimates from satellite surveys, indicates that they similarly affect 39% of the surface ocean in this region. These results suggest that free-drifting icebergs can substantially affect the pelagic ecosystem of the Southern Ocean and can serve as areas of enhanced production and sequestration of organic carbon to the deep sea.