Janet Campbell

The lognormal distribution as a model for bio‐optical variability in the sea

The lognormal distribution is presented as a useful model for bio-optical variability at a variety of spatial and temporal scales. A parametric statistical framework is presented for using the lognormal model to assess the effects of heterogeneity and scale on closure. Variability at small scales affects but is unresolved by large-scale measurements. An assumed lognormal distribution allows one to integrate over small-scale variability to predict large-scale measurements. Examples are presented to demonstrate how knowledge of the variance can be incorporated into models to relate measurements made at different scales.

Coastal Acidification by Rivers:A Threat to Shellfish?

Increasing atmospheric CO2 is likely to cause a corresponding increase in oceanic acidity by lowering pH by 0.20.5 pH units by the end of the 21st century [Royal Society, 2005]. In light of increasing acidity, there are growing concerns about the future health of a variety of marine organisms, particularly shellfish, which in the United States is a

Dynamics of the Coastal Zone

1.6 billion industry. Shellfish predominantly inhabit coastal regions, and in addition to the projected stress caused by the global trend in ocean acidification, some coastal ecosystems receive persistent or episodic acid inputs as a result of interactions with river water, bottom sediments, or atmospheric deposition of terrigenous materials. Most river plumes are acidic relative to the receiving ocean, and river water is mixed extensively over the continental shelf. Moreover, the chemical nature and magnitude of discharge are changing rapidly due to climate change and land-use practices.

Ocean color and river data reveal fluvial influence in coastal waters

Earth’s coastline has evolved for many thousands ofyears, experiencing changes to habitat, coastal dynam-ics and the supply of sediment from the continentalinterior. Relative sea level has risen in some areas, butfallen elsewhere. There is an acknowledged range innatural variability within a given region of the globalcoastal zone, within a context of longer-term geologicalprocesses.Many of the regional controls on sea level involvelong-term geological processes (e.g., subsidence, iso-stasy), and have a profound influence on controllingshort-term dynamics. As sea levels fluctuate, the mor-phology of a coastal zone will further evolve, changingthe boundary conditions of other coastal processes: cir-culation, waves, tides and the storage of sediment onflood plains.Human development of coastal regions has modifiedpristine coastlines around the globe, by deforestation,cultivation, changes in habitat, urbanisation, agriculturalimpoundment and upstream changes to river flow.Humans can also influence changes in relative sea levelat the local scale. For example, removal of groundwaterand hydrocarbons from subterranean reservoirs maycause subsidence in nearby areas, with a concomitantrise in relative sea level. Our concern in LOICZ is notjust in the magnitude of change, but also in the recentand accelerated rate of change. Our interests extendto whether alterations on the local level can cumula-tively give rise to coastal zone changes of global signifi-cance.Climate warming may also contribute significantlyto sea level fluctuations. Predictions by the InternationalPanel on Climate Change (IPCC) suggest that sea levelis rising globally (15 to 95 cm by 2100) as a result of therecent warming of the ocean and the melting of ice caps(Houghton et al. 2001). As sea levels rise, coastal desta-bilisation may occur due to accelerated beach erosion,trapping of river sediment on flood plains and increas-ing water residence during floods. The predicted IPCCclimate-warming scenario will undoubtedly impactsome regions more than others. The Siberian coast isexperiencing a reduction in offshore sea-ice cover, witha associated increase in ocean fetch, leading to highersea levels during the open-water summer and accelera-tion of coastal erosion. Recent studies also suggest thattropical and temperate coastal environments are expe-riencing stormier conditions (i.e., increased numbersand severity of hurricanes). Will local storm surges mag-nify the impact of a global sea-level rise, increasing risksto humans and their infrastructure? Are there negativefeedbacks to engineering options for the protection ofcoastal settlements?Perhaps the largest impact on coastal stability is dueto modification to the global flux of sediment to thecoastal zone. Changes in global hydrology have modi-fied the timing and intensity of floods, and thereforethe effective discharge available for sediment transport.Climate shifts have varied the contributions from melt-water (snow, ice), altered the intensity of rainfall,changed drainage basin water-storage capacity, and al-tered precipitation and evaporation rates. Human influ-ences have also greatly modified downstream flow. Overhalf of the world’s rivers have seen stream-flow modi-fication through the construction of large reservoirs.These and other rivers have also been impacted by wa-ter withdrawal for agriculture, industry and settlements.Our understanding of the importance of submarinegroundwater discharge in the coastal zone and of itsprocesses has improved markedly in recent years; asignificant impetus has been given to this understand-ing by the LOICZ-associated SCOR Working Group 112.The outcomes of its work are summarised in this chap-ter.Human migration to the coastal zone and consequentland-use changes have also greatly impacted the stabil-ity of our coastal areas. Human impacts on the coastalzone ranges from massive (e.g., reduction in wetlands,urbanisation) to non-existent (e.g., many polar coast-lines). This chapter synthesises how climate shifts andhumans can affect and have affected our coasts on a glo-bal scale.

Impact of high‐frequency waves on the ocean altimeter range bias

A critical yet poorly quantified aspect of the Earth system is the influence of river-borne constituents on coastal biogeochemical dynamics. Coastal waters contain some of the most productive ecosystems on Earth and are sites of intense downward particle fluxes and organic accumulation. Also, in many parts of the world, coastal ecosystems are experiencing unfavorable changes in water quality some of which can be linked directly to the transport of waterborne constituents from land. These include the well-publicized, increasing frequency of hypoxia events in the Gulf of Mexico [Goolsby, 2000], harmful algal blooms [Smayda, 1992], diminished water quality and changes in marine biodiversity [Radach et al., 1990].

Evaluation of MODIS ocean colour products at a northeast United States coast site near the Martha's Vineyard Coastal Observatory

New aircraft observations are presented on the range determination error in satellite altimetry associated with ocean waves. Laser-based measurements of the cross correlation between the gravity wave slope and elevation are reported for the first time. These observations provide direct access to a long, O(10 m), gravity wave statistic central to nonlinear wave theory prediction of the altimeter sea state bias. Coincident Ka-band radar scattering data are used to estimate an electromagnetic (EM) range bias analogous to that in satellite altimetry. These data, along with ancillary wind and wave slope variance estimates, are used alongside existing theory to evaluate the extent of long- versus short-wave, O(cm), control of the bias. The longer wave bias contribution to the total EM bias is shown to range from 25 to as much as 100%. Moreover, on average the term is linearly related to wind speed and to the gravity wave slope variance, consistent with WNL theory. The EM bias associated with interactions between long and short waves is obtained assuming the effect is additive to the independently observed long-wave factor. This second component is also a substantial contributor, is observed to be quadratic in wind speed or wave slope, and dominates at moderate wind speeds. The behavior is shown to be consistent with EM bias prediction based in hydrodynamic modulation theory. Study implications for improved correction of the on-orbit satellite sea state bias are discussed.

Oceanic Chlorophyll-a Content

Moderate Resolution Imaging Spectroradiometer (MODIS) marine and atmospheric products were evaluated using match‐ups of MODIS and in situ measurements collected by an above‐water radiometric system, the SeaWiFS Photometer Revision for Incident Surface Measurements (SeaPRISM), deployed near the Marthas Vineyard Coastal Observatory from 2004 to 2005. The products evaluated include the normalized water‐leaving radiance L wn in the visible and near‐infrared bands, and the aerosol optical thickness at 870 nm τa(870), and the Ångström exponent α(531). With a restricted match‐up criterion, the result shows that the MODIS‐retrieved L wn at 488, 531 and 551 nm agree very well with SeaPRISM measurements, giving mean per cent differences δ(%) of 3–7%, absolute mean per cent differences |δ|(%) of ∼16%, and coefficient of determination R 2 of 0.84–0.88. However, the MODIS‐retrieved L wn at 412 nm are underestimated significantly with δ(%), |δ|(%) and R 2 of −35%, 57% and 0.32, respectively, corresponding to a consistent overestimation and underestimation for the MODIS‐retrieved τa(870) and α(531), respectively. Temporal patterns of match‐ups revealing two distinct cases of the discrepancy of MODIS retrievals from in situ SeaPRISM measurements are discussed.

Committee of Visitors Advises NSF Division of Ocean Sciences

Ever since the first Earth-observing satellite was launched, it became the dream of oceanographers to measure ocean chlorophyll a from space. Through more than a decade of dedicated theoretical, laboratory, and field research, the Coastal Zone Color Scanner was launched onboard NASA’s Nimbus-7 satellite in 1978. Originally intended as a proof-of-concept mission, the CZCS endured well beyond its two-year design life (1978–1986), and provided oceanographers with clear evidence that ocean chlorophyll a could be observed from space. Continued community effort led to the successor missions of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, 1997–2010), Moderate Resolution Imaging Spectroradiometer (MODIS, 1999—present for Terra and 2002—present for Aqua), Medium Resolution Imaging Spectrometer (MERIS, 2002–2012), and other modern satellite instruments. This chapter provides a brief review of how oceanic chlorophyll a is “measured”, validated, and used in various research studies and applications including the ocean’s response to climate variability and the assessment of coastal ocean changes to help resource management. Particular emphasis is given to atmospheric correction, bio-optical inversion, and algorithm validation. Finally, future satellite ocean color missions and research directions to support these missions are briefly discussed.

A comparison of global estimates of marine primary production from ocean color

The U.S. National Science Foundation (NSF) relies on external Committees of Visitors (COV) convened every 3 years to assess the quality and integrity of program operations and program-level technical and managerial matters pertaining to proposal decisions. Members of COVs are chosen by program officers and division directors to represent scientific diversity, in terms of disciplines, institutions, and potential principal investigators (PIs). One such COV recently assessed NSFs Ocean Sciences (OCE) division. The COV for OCE found that the science receiving funding is highly relevant to the overarching objectives of NSF and that the OCE peer-review process is robust. Further, the COV found that program officers—NSF staff who manage programs in ocean sciences and administer proposals and grants—are conscientious and are funding projects of top quality that are well balanced across a broad spectrum.