Frost-Free Record Reconstruction for Eastern Massachusetts, 1733-1980

A reconstruction methodology utilizing such varied documents as diaries, agricultural journals, U.S. Weather Bureau killing frost records and instrumental records is discussed. A resultant 248-year frost record for eastern Massachusetts exhibits marked variations in the length of the growing season, that occur on a time scale of approximately 70 years. There is an apparent systematic long-term relationship between the timing of spring and fall killing frosts and the last 100 years of record reveals a decline in year-to-year variability.

Prismatine and Ferrohogbomite-2N2S in Granulite-Facies Fe-Oxide Lenses in the Eastern Ghats Belt at Venugopalapuram, Vizianagaram District, Andhra Pradesh, India: Do Such Lenses Have a Tourmaline-Enriched Lateritic Precursor?

Fluorine-rich prismatine, (square,Fe,Mg)(Mg,Al,Fe)(5)Al-4(Si,B,Al)(5)O-21(OH,F), with F/(OH+F) = 0.36-0.40 and hercynite are major constituents of a Fe-Al-B-rich lens in ultrahigh-temperature granulite-facies quartz-sillimanite-hypersthene-cordierite gneisses of the Eastern Ghats belt, Andhra Pradesh, India. Hemo-ilmenite. sapphirine, magnetite, biotite and sillimanite are subordinate. Lithium, Be and B are concentrated in prismatine (140 ppm Li, 170 ppm Be, and 2.8-3.0 wt.% B2O3). Another Fe-rich lens is dominantly magnetite, which encloses fine-grained zincian ferrohogbomite-2N2S, (Fe2+ Mg,Zn,Al)(6) (Al,Fe3+,Ti)(16)O-30(OH)(2), containing minor Ga2O3 (0.30-0.92 wt.%). Fe-Al-B-rich lenses with prismatine (or kornerupine) constitute a distinctive type of B-enrichment in granulite-facies rocks and have been reported from four other localities worldwide. A scenario involving a tourmaline-enriched lateritic precursor affected by dehydration melting is our preferred explanation for the origin of the Fe-Al-B-rich lenses at the five localities. Whole-rock analyses and field relationships at another of these localities, Bok se Puts, Namaqualand, South Africa, are consistent with this scenario. Under granulite-facies conditions, tourmaline would have broken down to give korner-upine-prismatine ( other borosilicates) plus a sodic melt containing H2O and B. Removal of this melt depleted the rock in Na and B, but the formation of ferromagnesian borosilicate phases in the restite prevented total loss of B.

Observations of the Eastern Maine Coastal Current and Its Offshore Extensions in 1994

Cold surface temperatures, reflecting Scotian Shelf origins and local tidal mixing, serve as a tracer of the Eastern Maine Coastal Current and its offshore extensions, which appear episodically as cold plumes erupting from the eastern Maine shelf. A cold water plume emanating from the Eastern Maine Coastal Current in May 1994 was investigated using advanced very high resolution radiometer (AVHRR) imagery, shipboard surveys of physical and biochemical properties, and satellite-tracked drifters. Evidence is presented that suggests that some of the plume waters were entrained within the cyclonic circulation over Jordan Basin, while the major portion participated in an anticyclonic eddy at the distal end of the plume. Calculations of the nitrate transported offshore by the plume show that this feature can episodically export significant quantities of nutrients from the Eastern Maine Coastal Current to offshore regions that are generally nutrient depleted during spring-summer. A series of AVHRR images is used to document the seasonal along-shelf progression of the coastal plume separation point. We speculate on potential causes and consequences of plume separation from the coastal current and suggest that this feature may be an important factor influencing the patterns and overall biological productivity of the eastern Gulf of Maine.

Physical and Biological Controls on the Latitudinal Asymmetry of Surface Nutrients and pCO(2) in the Central and Eastern Equatorial Pacific

Surface nutrients and dissolved inorganic carbon (DIC) in the central (CEP) and eastern equatorial Pacific (EEP) show much higher concentrations to the south than to the north of the equator. In this study, the physical and biological controls on this asymmetry are investigated using a coupled physical-biogeochemical model. Two numerical experiments are conducted to examine the effects of asymmetrical photosynthetic efficiency (a) due to asymmetrical iron supply about the equator. The experiment with asymmetrical photosynthesis produces improved results as compared with historical observations. A nitrate budget analysis suggests that in the EEP the divergence of upwelling waters controls the surface nitrate asymmetry with additional contribution from the South Equatorial Current (SEC) carrying nutrient-rich Peru upwelling water. The changes of a affect the surface nitrate distribution but not the overall asymmetry. The SEC further carries excess nitrate to the west and thus extends the asymmetry in the east to the CEP. In the CEP, however, stronger northward than southward transport tends to reduce the nitrate asymmetry, while the asymmetrical photosynthesis would help to maintain it. Similar processes also control the distributions of surface silicate and DIC in the equatorial Pacific, which is also affected by the air-sea CO(2) exchange. The asymmetrical photosynthesis influences the distribution of surface DIC, pCO(2), and the air-sea CO(2) flux, by redistributing about 20% CO(2) flux from the north to the south of the equator. Owing to the adjustment of air-sea CO(2) flux, however, the net surface DIC change is smaller than the direct change associated with primary production.