User’s Guide to ADMB2R: A Set of AD Model Builder Output Routines Compatible with the R Statistics Language

ADMB2R is a collection of AD Model Builder routines for saving complex data structures into a file that can be read in the R statistics environment with a single command.1 ADMB2R provides both the means to transfer data structures significantly more complex than simple tables, and an archive mechanism to store data for future reference. We developed this software because we write and run computationally intensive numerical models in Fortran, C++, and AD Model Builder. We then analyse results with R. We desired to automate data transfer to speed diagnostics during working-group meetings. We thus developed the ADMB2R interface to write an R data object (of type list) to a plain-text file. The master list can contain any number of matrices, values, dataframes, vectors or lists, all of which can be read into R with a single call to the dget function. This allows easy transfer of structured data from compiled models to R. Having the capacity to transfer model data, metadata, and results has sharply reduced the time spent on diagnostics, and at the same time, our diagnostic capabilities have improved tremendously. The simplicity of this interface and the capabilities of R have enabled us to automate graph and table creation for formal reports. Finally, the persistent storage in files makes it easier to treat model results in analyses or meta-analyses devised months—or even years—later. We offer ADMB2R to others in the hope that they will find it useful. (PDF contains 30 pages)

Southern California's megaflood event of ca. 1605 AD linked to large-scale atmospheric forcing

A distinct, 1- to 2-cm-thick flood deposit found in Santa Barbara Basin with a varve-date of 1605 AD ± 5 years testifies to an intensity of precipitation that remains unmatched for later periods when historical or instrumental records can be compared against the varve record. The 1605 AD ± 5 event correlates well with Enzel's (1992) finding of a Silver Lake playa perennial lake at the terminus of the Mojave River (carbon-14-dated 1560 AD ± 90 years), in relative proximity to the rainfall catchment area draining into Santa Barbara Basin. According to Enzel, such a persistent flooding of the Silver Lake playa occurred only once during the last 3,500 years and required a sequence of floods, each comparable in magnitude to the largest floods in the modern record. To gain confidence in dating of the 1605 AD ± 5 event, we compare Southern California's sedimentary evidence against historical reports and multi-proxy time-series that indicate unusual climatic events or are sensitive to changes in large-scale atmospheric circulation patterns. The emerging pattern supports previous suggestions that the first decade of the 17th century was marked by a rapid cooling of the Northern Hemisphere, with some indications for global coverage. A burst of volcanism and the occurrence of El Nino seem to have contributed to the severity of the events. The synopsis of the 1605 AD ± 5 years flood deposit in Santa Barbara Basin, the substantial freshwater body at Silver Lake playa, and much additional paleoclimatic, global evidence testifies for an equatorward shift of global wind patterns as the world experienced an interval of rapid, intense, and widespread cooling.

Sea surface temperature and paleo-El Niño events in Santa Barbara Basin, AD 1841-1941

Like pages of a "natural coastal diary", successive layers of anoxic varved sediment in the central Santa Barbara Basin have been used by paleoceanographers to reconstruct aspects of past coastal climate. This report focuses on the end of the "Little Ice Age" (15th to 19th century) and on the beginning of this century, a period known to encompass extreme climate excursions and weather events in the Santa Barbara Basin and other parts of Southern California. El Niño events are known to disrupt Southern California's coastal ecosystems and to cause anomalous weather conditions, but El Niño events in Southern California before 1990 have been largely undocumented.

The Little Ice Age: glacier variations and climate since AD 1250 [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): During the past hundred years, mountain glaciers throughout the world have retreated significantly from moraines built during the previous several centuries. In the 1930s, Francois Matthes of the U.S. Geological Survey concluded that the moraines represent the greatest advances of glaciers since the end of the last glacial age, some 10,000 years earlier, and informally referred to this late Holocene interval of expanded ice cover as the Little Ice Age.

The near-AD 1600 multi-proxy puzzle

EXTRACT (SEE PDF FOR FULL ABSTRACT): A varve chronology with annual resolution (AD 1117-1992) has been developed recently for Santa Barbara Basin. Varve thickness and water content show an exponential trend consistent with expected patterns in the presence of sediment compaction over time. Annual varve thickness was decomposed into orthogonal components using singular spectrum analysis (SSA) to identify and retrieve inter-decadal oscillations. ... This suggests a connection with global-scale decadal cycles identified in the subtropical Pacific gyre circulation and, possibly, with solar-driven phenomena. The near-1600 AD event coincides with (a) a similarly sudden change of state in nearby Santa Monica Basin that triggered the onset of anoxic conditions and the preservation of laminated sediments, (b) an extreme drought over the American Southwest, (c) a transformation of the age structure in a number of forest populations throughout Arizona and New Mexico. Total organic carbon burial flux in Santa Barbara Basin varves also shows a marked change after AD 1600. A possible climatic link is proposed that involves pathways for moisture transport in the Southwest at decadal and longer time scales.

Marine fisheries development in India, 2000 AD: a perspective

The status of marine fisheries research and development in India is discussed and the need for a high power national body to coordinate these activities is stressed. Priority areas for research and development have been outlined. It has been stressed that the strategy should be to achieve a production target of 3 million tonnes on the capture fisheries front (2.5 million tonnes from the inner shelf and 0.5 million tonnes from the outer shelf and slope areas) and 1 million tonne through aquaculture by 2000 AD.

Prospects of fisheries development in India by 2000 AD

The fishery resources of India are extensive. The demand for fish for domestic consumption will be at least 10 million by 2000 AD. With proper planning and management, fish production from inland, brackishwater and marine sources can be increased to 5 million tonnes, 1 million tonne and 4 million tonnes respectively. But the increase in the last 37 years is approximately equals 2.1 million tonnes over the base level of 1950. If the present trend is continued, the expected fish production will be approximately equals 6 million tonnes by 2000 AD, and hence, only approximately equals 60% of the domestic demand can be met.