Warm Index Research Articles

ＴＭの熱赤外データとＡＭｅＤＡＳの気温データを利用した東京圏のヒートアイランドの広域化の解析

The relationship between temperature changes and the expansion of Tokyo Metropolitan Area was studied using multi-temporal Landsat Thematic Mapper (TM) satellite images. The correlation between the ratio of green covering and brightness temperature was assumed to be an index of urbanization, thus, the relation between the ratio of green covering and air temperature in different seasons was verified around the Automated Meteorological Data Acquisition System (AMeDAS) observation point in Tokyo Metropolitan Area. The area located in NDVI >0.1 was assumed to be a vegetation region, on the other hand, the vegetation in the concentric circle of 0.6 km from the point where AMeDAS was observed, had been extracted from multitemporal TM data.The interrelationships between vegetated area and air temperature in Tokyo metropolis were established by comparing the daily average maximum temperature (Tmax), the daily average minimum temperature (Tmin) the average temperature at 9 p.m. (T21), during winter, summer and autumn using TM images and AMeDAS data. As a result, the strong correlation between a green covering and the daily minimum temperature was revealed at each season. In contrast, such a relation was not observed between the ratio of green covering and the maximum temperature.The variation of brightness temperature of the Tokyo area was estimated using thermal infrared data of TM band 6. Because the DN value changes with the state of performance degradation of the sensor or the atmosphere interface, the absolute value of derived temperature can not be compared to the heat island phenomena. Therefore, the relative change of DN value of thermal infrared data was ideal for studying the heat island phenomena. DN values were extracted from 2 Landsat TM night images acquired on August 1984 and August 1994, which had been used to estimate the expansion of the heat island phenomena.Relative Warming Index (RWI) of the AMeDAS observation point was also evaluated from the rate of change (19841994) of the daily minimum temperature of Tokyo (Otemachi). The rate of change of RWI corresponded to the distribution of differences in brightness temperature around Tokyo. The spatial analysis of relative warming index (RWI) for the 10 years of observations suggests that the warming rate of suburban area was much more pronounced than that of central Tokyo, and the rural side of the suburban area recorded a relatively low RWI than that of the same facing towards central Tokyo. The results from satellite images show of consistency with meteorological records.

Climate indexes of phytoliths fromHomo erectus’ cave deposits in Nanjing

A study on phytoliths and their climate indexes is carried out fromHomo erectus’ cave deposits in Hulu Cave, Nanjing. Evidence shows that phytolith assemblages of the cave deposits are dominated by the cold resistant types with a lower warm index, reflecting an overall cold inclined climate. This possibly connects the cave deposits with glacial climate to a great extent, which is in accordance with the northern fauna revealed by fossil mammals and temperate climate indicated by pollen assemblages. According to the distributional state of the phytoliths and their climate indexes on 4 profiles in the cave, it is revealed that profiles I and II display certain cold/warm, and dry/wet fluctuations; profile HI shows a humid and cold condition with the highest humility in the cave deposits; while profile IV indicates a possible quick accumulating process because of its stable climate indexes except for its bottom and top.

Late Eocene foraminifers and palaeoenvironment, Cascade Seamount, southwest Pacific Ocean: implications for seamount subsidence and Australia Antarctica Eocene correlation

A Late Eocene foraminiferal fauna of free specimens is recorded from Cascade Seamount, a feature of volcanic origin, whose age and fauna were previously studied only in thin section. The fauna is of Late Eocene (P15) age because of the presence of Globigerapsis index, Globigerapsis rubriformis, Subbotina linaperta, Subbotina angiporoides and Chiloguembelina cubensis. Many typical Eocene indicators, such as Hantkenina, Pseudohastigerina and key globorotaliids, are absent. The age is a little older than that estimated for previous samples from the seamount. The fauna is dominated (78%) by benthic species, especially species of Cibicides that have greater affinities with New Zealand faunas than with coeval southern Australian faunas. The sediment and its fauna accumulated near the lower limits of wave activity, off the coast of a volcano that probably stood at least 400 m above sea level. The location has subsided nearly 1000 m over the past 40 million years to its present water depth of 1000 m, suggesting that the entire East Tasman Plateau was approximately 1000 m above its current depth at the time. Conditions were cool temperate and the fauna lacks any warm water indices, consistent with a palaeolatitude of 55–60°S, but also with cool waters at a time of oscillating conditions in southern Australia and also in Antarctica. There is essentially no infauna and the waters were highly oxygenated in the turbulent zone.

Global warming from chlorofluorocarbons and their alternatives: Time scales of chemistry and climate

The halocarbons (chloroflurocarbons, CFCs, and their replacement chemicals: the hydrochloroflurocarbons, HCFCs, and the hydrofluorocarbons, HFCs) are greenhouse gases. The atmospheric accumulation of these gases is expected to add to the global warming predicted for expected increases of CO 2, CH 4, N 2O, tropospheric ozone and H 2O. Over the next decades, production of CFCs is scheduled to be phased out, while emissions of their alternatives are expected to increase. A simple model is used to illustrate the methodology for determining the time variations of the radiative forcing and temperature changes attributable to the direct greenhouse effect from potential emissions of the halocarbons. Although there are uncertainties associated with the lifetimes of the greenhouse gases, CFCs and their substitutes, the future growth rates of these gases, and the parameters used to simulate the response of the Earth-climate system, the method serves to illustrate an important aspect of the greenhouse warming issue beyond what is provided by the various greenhouse warming indices. Our results show that for likely substitution scenarios, the warming due to halocarbons will correspond to 4–10% of the total expected greenhouse warming at the year 2100. However, uncontrolled growth of the substitutes could result in an eight-fold increase in halocarbon production and a doubling of the halocarbon contribution by 2100.

Oligocene planktonic foraminiferal biostratigraphy and paleoclimatic interpretation from Hole 538A, DSDP Leg 77, Gulf of Mexico

A relatively extended Oligocene pelagic sequence with good to medium recovery, drilled during DSDP Leg 77 in the Gulf of Mexico, yielded rich and well diversified planktonic foraminiferal faunas. Planktonic foraminifera recorded in Hole 538A span the interval from Zone P19 through P22. Evolutionary lineages were observed among the globoquadrinids, the globigernitids, and the “ Globigerina” ciperoensis and Globigerinoides primordius groups. Quantitative analysis of planktonic foraminiferal assemblages shows that faunas fluctuate in abundance and species diversity throughout the sequence. A few of these fluctuations that could be related to selective dissolution are mainly confined to the early-mid Oligocene. A climatic curve was constructed using a warmer indicators, Turborotalia pseudoampliapertura, Globoquadrina tripartita, Dentoglobigerina globularis, Dentoglobigerina baroemoenensis, “Globigerina” ciperoensis and Globigerinoides groups, and Cassigerinella chipolensis; and as cooler indicators, Catapsydrax spp., Globorotaloides spp., Subbotina angiporoides group, Globigerina s. str., and the tenuitellids. Three major intervals are identifiable in the climatic curve: Interval 1 (lower) up to Zone P20 predominantly cooler; Interval 2 (intermediate) up to the upper part of Zone P21a with warm and cool fluctuations; and Interval 3 (upper), warmer, with large positive peak, due to abundant “ G” angulisuturalis, at the beginning of Zone P21b with recooling midway in Zone P22. In intervals 1 and 2 planktonic foraminiferal faunas are dominated by temperate forms. Interpretation of planktonic foraminiferal data suggests that cooler water conditions characterize the early-mid Oligocene; during the mid Oligocene (most of Zone P21a) water masses exhibit peculiar characteristics transitional to the warmer waters prevailing during the late Oligocene. Warmer conditions were not definitely settled in Zone P22, however, as indicated by the cooler episode following the warmest peak. These climatic trends are inconsistent with those inferred from oxygen isotopes except at small scale. In fact, oxygen isotope values for Oligocene Atlantic Ocean are too heavy (thus too cool) in comparison with the high abundance and diversity of warm taxa, especially in Zone P22. When values are lighter (warmer), as in Zone P19, abundance and diversity of warm indices are too low. To explain such a cool isotope values in presence of highly diversified and abundant warm planktonic foraminifera, we suggest (1) that the oxygen isotope ratio used for estimating Oligocene paleotemperatures might be 1/%. heavier than Eocene values and further increased for the late Oligocene. This hypothesis implies the presence of a relatively extended ice cap in Antarctica in the early and mid Oligocene, and probably an increase in ice volume during the late Oligocene; (2) heavier isotope values might be related to an increase in salinity, or (3) by a combination of both ice cap and increase in salinity.