Dauphin Island Research Articles

Validation of annual periodicity in otoliths of red snapper, Lutjanus campechanus

The periodicity of otolith growth increments (opaque and translucent zones) from adult red snapper (Lutjanus campechanus) was examined through a mark and recapture study (2005–2010), and laboratory holding of hatchery reared red snapper over a 2 year period (2002–2004). Wild red snapper (n = 295) were caught hook-and-line, marked with anchor tags, injected with oxytetracycline dihydrate (OTC), and released in the Gulf of Mexico 15–40 km south of Dauphin Island, Alabama. Marked fish were recaptured up to 2.8 years after release (n = 35) and sagittal otoliths were dissected, sectioned and examined under white and blue-violet light. The number of opaque growth zones past the OTC mark was compared to time at liberty for each fish and supported an annual periodicity of growth increment formation. Also, most (87%) of the hatchery reared fish showed two opaque zones that supported an annual increment formation rate. However, an unusual timing of opaque zone formation was shown for mark-recaptured fish. Based on known timing of OTC marking, otoliths from mark-recapture fish showed opaque zone formation from late summer (August) to early winter (December). This fall formation of opaque zones is in contrast to previous studies and its timing may relate to the end of spawning for this species.

Gulf of Mexico Origin, Waters, and Biota. Volume 2: Ocean and Coastal Economy. Harte Research Institute for Gulf of Mexico Studies Series. Edited by James C. Cato. College Station (Texas): Texas A&M University Press. $40.00. xix + 110 p.; ill.; index. ISBN: 978-1-60344-086-8. 2009.

Previous articleNext article No AccessNew Biological BooksGulf of Mexico Origin, Waters, and Biota. Volume 2: Ocean and Coastal Economy. Harte Research Institute for Gulf of Mexico Studies Series. Edited by James C. Cato. College Station (Texas): Texas A&M University Press. $40.00. xix + 110 p.; ill.; index. ISBN: 978-1-60344-086-8. 2009.John F. ValentineJohn F. ValentineDauphin Island Sea Lab and Marine Sciences, University of South Alabama, Dauphin Island, Alabama Search for more articles by this author Dauphin Island Sea Lab and Marine Sciences, University of South Alabama, Dauphin Island, AlabamaPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 86, Number 1March 2011 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/658427 Views: 11Total views on this site Copyright © 2011 by The University of Chicago Press. All rights reserved.PDF download Crossref reports no articles citing this article.

Recruitment of Age‐0 Gray Triggerfish to Benthic Structured Habitat in the Northern Gulf of Mexico

AbstractRecruitment of age‐0 gray triggerfish Balistes capriscus to benthic artificial reefs was documented by diver surveys from 2003 to 2007. Divers counted and estimated the sizes of all gray triggerfish that recruited to three types of artificial reefs (all in 20‐m depths) ranging from 1.2 to 4.0 m2 in area. Reefs were located in the Gulf of Mexico 28 km south of Dauphin Island, Alabama. Forty artificial reefs built in June 2003 were surveyed in October–December 2003 and May 2004; 20 artificial reefs built in October 2005 were surveyed in October and December 2005 and May, August, and December 2006; 40 artificial reefs built in July 2006 were surveyed in June 2007; and 30 artificial reefs built in August 2007 were surveyed in September, October, and December 2007. Recruitment patterns were similar in the fall and winter of 2003 and 2007. In 2005 significantly lower numbers of recruits were detected than in other years, which may have been caused by a major hurricane. Peak recruitment of age‐0 gray triggerfish occurred from September to December. Based on known spawning seasonality and the first appearance of recruits in September in this study, gray triggerfish spend 4–7 months in the pelagic environment before recruiting to benthic habitat.

Development and validation of a three-dimensional, wave-current coupled model on unstructured meshes

Using unstructured meshes provides great flexibility for modeling the flow in complex geomorphology of tidal creeks, barriers and islands, with refined grid resolution in regions of interest and not elsewhere. In this paper, an unstructured three-dimensional fully coupled wave-current model is developed. Firstly, a parallel, unstructured wave module is developed. Variations in wave properties are governed by a wave energy equation that includes wave-current interactions and dissipation representative of wave breaking. Then, the existing Finite-Volume Coastal Ocean Model (FVCOM) is modified to couple with the wave module. The couple procedure includes depth dependent wave radiation stress terms, Stokes drift, vertical transfer of wave-generated pressure transfer to the mean momentum equation, wave dissipation as a source term in the turbulence kinetic energy equation, and mean current advection and refraction of wave energy. Several applications are presented to evaluate the developed model. In particular the wind and wave-induced storm surge generated by Hurricane Katrina is investigated. The obtained results have been compared to the in situ measurements with respect to the wave heights and water level elevations revealing good accuracy of the model in reproduction of the investigated events. In a comparison to water level measurements at Dauphin Island, inclusion of the wave induced water level setup reduced the normalized root mean square error from 0.301 to 0.257 m and increased the correlation coefficient from 0.860 to 0.929. Several runs were carried out to analyze the effects of waves. The experiments show that among the processes that represent wave effects, radiation stress and wave-induced surface stress are more important than wave-induced bottom stress in affecting the water level. The Hurricane Katrina simulations showed the importance of the inclusion of the wave effects for the hindcast of the water levels during the storm surge.

Impacts of Oyster Reef Restoration on Primary Productivity and Nutrient Dynamics in Tidal Creeks of the North Central Gulf of Mexico

The ability of oysters to remove large quantities of particulates from the water column, thereby potentially improving water quality, has been cited as one of the reasons for oyster reef restoration. However, this ability has not yet been effectively demonstrated in the field. As part of the Alabama Oyster Reef Restoration Project, this study was designed to assess impacts of restored eastern oyster (Crassostrea virginica) reefs on primary production, nutrient dynamics, and water quality in shallow tidal creeks. Using a Before–After-Control–Impact (BACI) design, we monitored tidal creeks around Dauphin Island, AL, for changes induced by the introduction of oyster reefs. Reef placement resulted in increased ammonium (NH 4 + ) in two of the three experimental creeks. Interestingly, oyster reefs did not seem to reduce water column particulates or have an impact on phytoplankton or microphytobenthic biomass or productivity. We do not believe that our data discount the importance and/or usefulness of oysters in modifying the water column. Rather, we acknowledge that it is difficult to detect these impacts/environmental services in this type of system (i.e., a tidal creek system), because they seem to be very localized and short-lived (i.e., not ecologically relevant on a creek-wide scale). This study highlights the need to consider location and habitat in planning oyster restoration projects. Also, it demonstrates that the types, magnitudes, and spatial extent of changes in ecosystem services that should be expected after reef restoration might need to be re-evaluated.

Constructed Sand Dunes on the Developed Barrier-Spit Portion of Dauphin Island, Alabama (U.S.A)

In August 2005, Hurricane Katrina segmented Dauphin Island into Dauphin Island East and Dauphin Island West. Prior to this event, the island was a 23-km-long microtidal composite barrier island located in the northern Gulf of Mexico approximately 8.0 km offshore from southwestern Alabama (U.S.A.). The eastern portion of Dauphin Island was morphologically a barrier island, and it experienced gulf-facing beach erosion at several isolated hot spots. The western portion of Dauphin Island was an elongated barrier spit with little topographic relief, and it experienced gulf-facing beach erosion and occasional washover due to elevated tides and storm waves. The protection and preservation of the residential property on the barrier-spit portion of the island has been a priority for the incorporated Town of Dauphin Island since the late 1970s. On two separate occasions the Town of Dauphin Island combined funds with those provided by the U.S. Federal Emergency Management Agency and contracted the U.S. Army Corps of Engineers to construct a shore-parallel sand dune. The first dune was built following Hurricane Georges and the second after Hurricane Katrina. Both of these structures were completely eroded away within a short span of time, the post–Hurricane Georges dune in 27 months and the post–Hurricane Katrina dune in 15 months. Despite the high cost, limited effectiveness, and short service life of constructed sand dunes, the remaining options are either unacceptable (e.g., beach armoring, land use reclassification, or abandonment) or too costly (e.g., engineered beach). Constructed shore-parallel sand dunes will likely remain integral to the protection and preservation of the residentially developed, barrier-spit portion of Dauphin Island East due to its low relief and the high probability of washover events from elevated tides and storm waves.

Crassostrea virginica shells record local variation in wastewater inputs to a coastal estuary

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 9:77-84 (2010) - DOI: https://doi.org/10.3354/ab00228 Crassostrea virginica shells record local variation in wastewater inputs to a coastal estuary Carolyn J. Kovacs1, Joshua H. Daskin2,3, Heather Patterson1, Ruth H. Carmichael1,* 1Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin Island, Alabama 36528, USA 2MB 0193 Brandeis University, Waltham, Massachusetts 02454, USA 3Present address: School of Marine and Tropical Biology, James Cook University, Townsville, 4811 Queensland, Australia *Corresponding author. Email: rcarmichael@disl.org ABSTRACT: We measured δ15N values in the acid-insoluble organic portion of shells from Crassostrea virginica transplanted at increasing distance from a major wastewater treatment plant in Mobile Bay, Alabama. To determine whether δ15N in shell material recorded local spatial variation in wastewater influence, we compared δ15N in newly deposited oyster shell to δ15N values in wastewater effluent and in suspended particulate matter in receiving waters. We compared δ15N values in shell to δ15N in adductor muscle and whole tissues to determine the isotopic relationships between shell and soft tissues for this previously untested species. δ15N values in oyster shell reflected differences in wastewater influence relative to distance from the wastewater treatment plant within 38 d of transplanting. δ15N values in shell were enriched by 2.4‰ compared to available foods, consistent with a trophic shift from food source to consumer. δ15N values in shell also were significantly correlated with δ15N values in soft tissues, but were enriched by 1.9‰ compared to whole tissues and 0.8‰ compared to adductor muscle. Overall, δ15N values in oyster shell were a better proxy for adductor muscle than whole tissues. If applied with care, oyster shells provide an ecologically and commercially meaningful wastewater detection tool that may be effective over relatively short spatial and temporal scales. δ15N values in shell material may be particularly useful to enable anthropogenic source tracing and refine food web reconstructions in areas with remnant shells where oysters or other bivalves have been severely depleted or already lost. KEY WORDS: Nitrogen · Stable isotopes · Bivalve · Anthropogenic · Oyster Full text in pdf format PreviousNextCite this article as: Kovacs CJ, Daskin JH, Patterson H, Carmichael RH (2010) Crassostrea virginica shells record local variation in wastewater inputs to a coastal estuary. Aquat Biol 9:77-84. https://doi.org/10.3354/ab00228 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 9, No. 1. Online publication date: March 25, 2010 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2010 Inter-Research.

The Flower Beds of War

The Flower Beds of War Wilmer Mills (bio) —Fort Gaines, Dauphin Island, Alabama Today, as in that war we christened civil,Spring arrives around these magazines.Examine the cannon mounts that used to swivel;The tidal flushing of its brick latrines; And look where violets and grass have spreadBeside the ramparts facing west and east.Was it not so when soldiers there fell dead,When only flax and thistles kept the peace? Can we distinguish flower from weedWhen each is uniformed in blue or dun,On battlefields, or in the human seed,Where life and death are waging to be won? We rage and kill and also love and bless.One grows around the other, truce and bruise,And can't be separated, unlessWe silence one and lose them both, and lose This relic of antique belligerenceThat nature calls a garden, we a fort,Where spring, with its sublime indifference,Has flanked the guns with clumps of spiderwort. [End Page 191] Wilmer Mills Wilmer Mills, who is the Kenan visiting writer at the University of North Carolina at Chapel Hill, is included in the Swallow Anthology of New American Poets. Copyright © 2010 University of the South, Sewanee, Tennessee, 37383

Simulation of storm surge, wave, and coastal inundation in the Northeastern Gulf of Mexico region during Hurricane Ivan in 2004

Hurricane-induced storm surge, waves, and coastal inundation in the northeastern Gulf of Mexico region during Hurricane Ivan in 2004 are simulated using a fine grid coastal surge model CH3D (Curvilinear-grid Hydrodynamics in 3D) coupled to a coastal wave model SWAN, with open boundary conditions provided by a basin-scale surge model ADCIRC (Advanced CIRCulation) and a basin-scale wave model WW3 (WaveWatch-III). The H∗wind, a reanalysis 10-m wind produced by the NOAA/AOML Hurricane Research Division (HRD), and a relatively simple analytical wind model are used, incorporating the effect of land dissipation on hurricane wind. Detailed comparison shows good agreement between the simulated and measured wind, waves, surge, and high water marks. Coastal storm surge along the coast is around 2–3 m, while peak surge on the order of 3.5 m is found near Pensacola, which is slightly to the east of the landfall location on Dauphin Island. Wind waves reach 20 m at the Mobile South station (National Data Buoy Center buoy 42040) on the shelf and 2 m inside the Pensacola/Escambia Bay. Model results show that wave-induced surge (total surge subtracted by the meteorologically-induced surge due to wind and pressure) accounts for 20–30% of the peak surge, while errors of the simulated surge and waves are generally within 10% of measured data. The extent of the simulated inundation region is increased when the effects of waves are included. Surge elevations simulated by the 3D model are generally up to 15% higher than that by the 2D model, and the effects of waves are more pronounced in the 3D results. The 3D model results inside the Pensacola/Escambia Bay show significant vertical variation in the horizontal currents. While the estuary has little impact on the surge elevation along the open coastal water, surge at the head of Escambia Bay is more than 50% higher than that at the open coast with 1.5 h delay.

The Return of 1717 Isle Dauphine (U.S.A.)

Abstract Dauphin Island is a segmented, microtidal barrier island, located in the northern Gulf of Mexico, approximately 8.0 km offshore from southwestern Alabama (United States). It was first mapped by Spanish explorers in 1519 but was not settled until 1699 after being claimed as a French possession. In 1707, the French officially named it Isle Dauphine. Maps of the island from this French colonial period reveal a different morphology than subsequent maps. The first American maps of Dauphin Island and Mobile Bay show two small islands (i.e., Pelican and Sand islands) offshore from the southeastern end of Dauphin Island. Passing storms have moved and reshaped both of these delta margin islands around the south-southwestern periphery of the submerged Mobile Bay ebb-tidal delta. Only in the past 25 years have the two islands combined to slowly move in a northwesterly arc toward Dauphin Island. In early 2008, continued longshore drift and strong tides have combined Pelican-Sand Island and Dauphin Island for...

Assessingin SituTolerances of Eastern Oysters (Crassostrea virginica) Under Moderate Hypoxic Regimes: Implications for Restoration

Increases in the frequency and duration of hypoxia and the loss of biogenic reefs are two of the most prominent environmental insults to estuaries. We investigated the interaction between moderate hypoxia and habitat restoration activities on estuarine ecosystems by measuring population growth and somatic growth for newly settled Eastern oysters (Crassostrea virginica). Experiments were conducted at a site that historically experiences moderate hypoxia (2.0 mg l-1 < [O2] < 4.0 mg l-1) (Whitehouse Reef) and at a site that experiences normoxia (Dauphin Island). Panels with known starting densities of oyster spat were deployed at the surface, 1.25 m above the bottom, and 0.5 m above the bottom at both sites. Population growth at the bottom and the 1.25 m panels at Whitehouse Reef was -1% to 0% individuals day-1 caused by periods of moderate hypoxia; however, as oxygen conditions improved in September, population growth increased to approximately 1 to 3% individuals day-1. For these two panels, total population growth averaged 1% over the experiment duration. For the surface panel at Whitehouse Reef and all three depths at Dauphin Island, population growth remained positive with population growth of between 2% to 17% individuals day-1. Somatic growth indicated significant location and depth specific differences with somatic growth being negatively correlated with depth. Marginal water quality caused by moderate hypoxia may limit oyster population growth to a much greater extent than predicted by previous laboratory experiments. Additionally, we demonstrate that low-cost experiments prior to the initiation of restoration activities can help ensure success by providing critical in situ information on design and location.

On the development and verification of a 2-D coupled wave-current model on unstructured meshes

In this paper, the numerical framework for a freely available fully coupled wave-current model, which solves the Shallow Water and the Wave Action Equation (WAE) on unstructured meshes in geographical space and some first applications are presented. It consists of the hydrodynamic model SHYFEM (Shallow Water Hydrodynamic Finite Elements Model), and the 3rd generation spectral wave model WWM (Wind Wave Model). The application of numerical schemes on unstructured meshes renders the coupled model more efficient in resolving the model domain, the bathymetry and the involved gradient fields of currents, water levels and wave action. The source codes of the models have been coupled using FIFO (First In First Out pipes) data files. This technique makes an effective model coupling possible without cumbersome merging of both codes. Furthermore, it gives both source codes a universal interface for coupling with other flow or wave models. The coupled model was applied to simulate extreme events occurring in the Gulf of Mexico and the Adriatic Sea. In particular the wind and wave-induced storm surge generated by Hurricane Ivan was investigated and the results have been compared to the tidal gauge at Dauphin Island with reasonable results. For the case of the Adriatic Sea, the model, validated for the year 2004, has been applied to simulate waves and water levels induced by the century storm in November 1966 that lead to catastrophic and widespread damages in the regions of the Venice Lagoon. The obtained results have been compared to in situ measurements with respect to the wave heights and water level elevations revealing good accuracy of the model in reproduction of the investigated events. Especially, the Hurricane Ivan simulations showed the importance of inclusion of the wave–current interactions for the hindcast of the water levels during the storm surge. In a comparison to water level measurements at Dauphin Island, inclusion of the wave induced water level setup reduced the root mean square error from 0.13 to 0.11 m and increased the correlation coefficient from 0.75 to 0.79. For the case of the Venice Lagoon, the comparison with the measurements showed that the model without wave–current interactions led to a good hindcast of water levels for the location Punta Salute, which is located in the inner part of the Lagoon. Nevertheless, the comparison of subsequent simulations with and without the influence of the waves clearly showed a simulated effect of intense wave setup-up in the coastal area in front of the lagoon, which is plausible given the intensity of flooding that occurred there.

Characteristics of Extreme Meteorological Forcing and Water Levels in Mobile Bay, Alabama

The paper presents comprehensive statistical analyses of winds and water levels in Mobile Bay, Alabama, based on long-term meteorological and tidal observations at several locations. A procedure has been developed to select the most probable parent distribution function from a list of candidate distributions. The theoretical functions that fit the data best enable us to predict the extreme values of winds and water levels at different return periods. We have demonstrated the importance of dividing the winds into hurricane and nonhurricane seasons and separating astronomical tides from weather-driven water level changes. The statistical analysis suggests that the wind speed averaged over 8 min at Dauphin Island, Alabama, at the 100-year return period would be 48.9 m/s, which is equivalent to a sustained 1-min wind of 205 km/h, a very strong category 3 hurricane on the Saffir-Simpson scale. The probability distribution models predict that the 100-year maximum water level would be 3.23 m above the mean lower low water (MLLW) level at the bay entrance and 3.41 m above the MLLW level near the head of the bay, respectively. Extremely low water levels important to navigation are also found. Application of the predicted extreme winds and surges is illustrated through the development of a storm wave atlas in the estuary. It is expected that the methodology and results presented in this paper will benefit the management and preservation of the ecosystems and habitats in Mobile Bay.

Changes to Dauphin Island, Alabama, Brought about by Hurricane Katrina (August 29, 2005)

Abstract On the morning of August 29, 2005, Hurricane Katrina (a Category 3 hurricane on the Saffir-Simpson scale) made landfall in southeastern Louisiana. Although Dauphin Island, Alabama, is located approximately 180 km to the northeast of where Katrina made landfall, it experienced greater coastal damage than from recent Category 3 hurricanes that were closer to the island (e.g., Frederic in 1979 and Ivan in 2004). This is because the island was within the most intense area of the hurricane as it approached land (i.e., the top-right quadrant). The gulf side of Dauphin Island was impacted by a storm surge of 1.94 m coupled with even higher storm waves. Pelican-Sand Island, to the south of the eastern portion of the island, absorbed much of the storm wave energy, resulting in a lessening of storm water damage to this segment of Dauphin Island. The elevated storm surge and diminished storm waves carried plant debris and sand tens of meters landward across this portion of Dauphin Island. Conversely, with n...

Sediment Spatial Patterns in a Hurricane Katrina Overwash Fan on Dauphin Island, Alabama, U.S.A.

Abstract Hurricane Katrina scoured the seaward side of Dauphin Island, Alabama, and then deposited the sediment on the back side of the island into a repeating pattern of arc-shaped overwash fans. We set out to determine if sediment sorting operated at the scale of the individual overwash fan during the storm. Variograms and kriging were used to create maps of the topography and sediment patterning in terms of the mean grain size, standard deviation, skewness, and mineral composition. Mantel tests were used to correlate hypothesized directional processes with the patterns. We found that sands near the surface were spatially sorted in a direction consistent with the north-northwesterly forces of Katrina. The spatial distribution was not correlated with the topography. Our results support the concept that horizontal spatial pattern formation primarily begins as the extreme forces of a hurricane subside.

Historical Changes in the Mississippi-Alabama Barrier-Island Chain and the Roles of Extreme Storms, Sea Level, and Human Activities

Abstract Barrier-island chains worldwide are undergoing substantial changes, and their futures remain uncertain. An historical analysis of a barrier-island chain in the north-central Gulf of Mexico shows that the Mississippi barriers are undergoing rapid systematic land loss and translocation associated with: (1) unequal lateral transfer of sand related to greater updrift erosion compared to downdrift deposition; (2) barrier narrowing resulting from simultaneous erosion of shores along the Gulf and Mississippi Sound; and (3) barrier segmentation related to storm breaching. Dauphin Island, Alabama, is also losing land for some of the same reasons as it gradually migrates landward. The principal causes of land loss are frequent intense storms, a relative rise in sea level, and a sediment-budget deficit. Considering the predicted trends for storms and sea level related to global warming, it is certain that the Mississippi-Alabama (MS-AL) barrier islands will continue to lose land area at a rapid rate unless ...

Rearing Cactoblastis cactorum (Lepidoptera: Pyralidae) on Artificial Diet and Opuntia Cladodes

The cactus moth, Cactoblastis cactorum Berg, is an invasive species that threatens economically and ecologically important native cacti in Mexico and the U.S. Southwest. The insect presently occurs along the coastal U.S. from Charleston, SC, to Dauphin Island, south of Mobile, AL, and in the interior of Florida. Current control and eradication tactics include manual destruction of infested cactus and the Sterile Insect Technique (SIT), which involves the release of irradiated cactus moths to mate with wild moths and produce sterile offspring. The ability to rear the cactus moths in the laboratory has been crucial in research and development of survey and control techniques. Procedures for rearing the cactus moth in the laboratory on cactus cladodes and artificial diet are described and provide a foundation for the further development of mass-rearing protocols.

Elevated Waves Erode the Western End of the Recently Completed Sand Berm on Dauphin Island, Alabama (U.S.A)

Abstract Dauphin island is a microtidal barrier island located approximately 8.0 km offshore from southwestern Alabama (U.S.A.). Morphological changes to the island, brought about by passing tropical storms and hurricanes, have been noted since it was first settled in 1699. On August 29, 2005, Hurricane Katrina (a Category 3 hurricane) made landfall approximately 117 km west of Dauphin Island. Despite the extended distance, the storm impacted the island with waves that completely overwashed and flattened most of the western low-lying areas. The hurricane also segmented Dauphin Island into two distinct barrier islands, the undeveloped Dauphin Island West, and the residentially developed Dauphin Island East. Immediately following the storm, the Town of Dauphin Island recognized the need to take action to protect low-lying residential property on the western segment of Dauphin Island East. Sand berm construction began on January 29, 2007. The 6.4-km-long berm is to provide sufficient time to allow the Town o...

Radar and Rain Gauge Analysis of the Extreme Rainfall during Hurricane Danny’s (1997) Landfall

Abstract As a minimal hurricane, Danny moved over Mobile Bay around 0900 UTC 19 July 1997 and became stationary by midmorning, while situated within a synoptic col. Danny then evolved into an asymmetric storm with an intensely convective rainband that produced torrential rainfall through 1200 UTC 20 July 1997. Danny’s center remained &amp;lt;100 km from the National Weather Service (NWS) Weather Surveillance Radar-1988 Doppler (WSR-88D) in Mobile, Alabama, for over 48 h, allowing long-term surveillance of the storm’s inner core. This event marked the first time the tropical Z–R relationship was employed on an operational WSR-88D system during tropical cyclone landfall. A radar-estimated maximum rainfall accumulation of 1097 mm (43.2 in.) was analyzed over southwestern Mobile Bay. A NWS cooperative rain gauge located on Dauphin Island, Alabama, measured 896 mm (35.28 in.). An adjacent standard rain gauge measured the highest rainfall amount of 932 mm (36.71 in.). This paper investigates the spatial and temporal distribution and potential magnitude of Danny’s torrential rainfall episode over coastal Alabama. It is shown that both gauges and radar seriously underestimated event rainfall. An estimate is given for what could have been the true event rainfall amount. In the case of the radar, the WSR-88D Algorithm Testing and Display System is used to obtain a better estimate of rainfall using higher dBZ caps than the operational 50 dBZ. In the case of the tipping-bucket rain gauge, wind and mechanical error estimates were applied in order to quantify rainfall underestimation.

Using global positioning system‐derived crustal velocities to estimate rates of absolute sea level change from North American tide gauge records

We identified 37 tide gauges; each located within 40 km of a geodetic station whose International Terrestrial Reference Frame of 2000 (ITRF2000) crustal velocity had been rigorously derived from continuous global positioning system (GPS) observations, spanning from 3 to 11 years. The tide gauges are located along the coasts of North America, Bermuda, Hawaii, and Kwajalein (in the Marshall Islands). We obtained the ITRF2000 crustal velocities by averaging values from six solutions; each produced by a team of investigators acting, essentially, independently of the other teams. We then applied crustal velocities to convert rates of relative sea level change to rates of absolute sea level change. In a sample containing 30 sites, we found that the mean rate of absolute sea level change equals 1.80 ± 0.18 mm/yr in the 1900–1999 period. The scatter about the mean for individual sites in this sample is characterized by a (weighted) RMS value of 0.85 mm/yr. This scatter primarily reflects the uncertainty associated with derived crustal velocities. The remaining seven sites, i.e., five sites on the Pacific coast of Alaska, one on Dauphin Island (Alabama), and one on Kwajalein (an atoll in the Pacific Ocean), experienced relatively low rates of absolute sea level change. We hypothesize the low rates in Alaska are caused by ongoing melting of mountain glaciers and ice masses near the stations, while the low rates found for Dauphin Island and Kwajalein remain unexplained.