Japanese progress in climatology 

About: Japanese progress in climatology is an academic journal. The journal publishes majorly in the area(s): Urban heat island & Monsoon. Over the lifetime, 185 publications have been published receiving 1233 citations.

Seasonal variation of carbon dioxide exchange in rice paddy field in Japan

Abstract: Based on the results of continuous flux measurements at the Mase paddy flux site in central Japan, carbon dioxide (CO 2 ) exchange between a customarily cultivated single rice-cropping paddy field and the atmosphere during the 2002 growing season was analyzed. The daily Net Ecosystem CO 2 Exchange (NEE) showed a seasonal variation with a maximum uptake rate of 39 g CO 2 m -2 day -1 in late July when the leaf area index of the rice reached its peak. Daily NEE turned positive, indicating emission from the paddy. about 2 weeks before harvest, because of the declining photosynthesis rate of rice in its mature stage and enhanced ecosystem respiration from the drained paddy. Quantum yield of the primary crop showed a declining seasonal trend from 0.11 mol CO 2 (mol quantum) -1 in the early growth stage to below 0.05 mol CO 2 (mol quantum) -1 after heading. The ratoon crop had little effect on the seasonal CO 2 budget of 2002. because its growing period was restricted to I month. The paddy field acted as a CO 2 sink for about 100 days from late May until the end of August, indicating that the paddy Held functioned as asource of CO 2 for more than 70% of the year. The ratio of gross primary production (GPP) to ecosystem respiration (R c ) was 1.53 for the primary crop period and 0.43 for the ratoon crop period. Drained days accounted for as many as a half of the primary crop period days and the ratoon crop period was restricted in length, thus we obtained small ratios of GPP to R c in the two periods. During the post-heading period, the half-hourly CO 2 storage below the flux measurement height was occasionally comparable in magnitude to the eddy CO 2 flux over the canopy. When the friction velocity was less than 0.1 m s -1 , the storage term accounted for 6% of NEE on average even after influence of temperature on nighttime NEE was removed. Estimating the storage term from a single height measurement underestimated it by 22%.

A comparison of summer sea level pressure over east eurasia between NCEP-NCAR reanalysis and ERA-40 for the period 1960-99

Abstract: A comparison between two reanalysis datasets (the NCEP-NCAR and ERA-40 reanalyses) is conducted over East Eurasia. The summer sea level pressure (SLP) from these datasets are specifically compared in the two periods from 1960 to 1979, and 1980 to 1999 in order to examine the long-term homogeneity and reliability of these datasets. The SLP of the NCEP-NCAR over Mongolia and its vicinity exhibits an obvious increase between the two periods, but it is not recognized in the ERA-40. This discrepancy is mainly due to sudden increases in the SLP around Mongolia in the mid-1960s and mid-1970s in the NCEP-NCAR, which are not recognized in the ERA-40. Other observational datasets used in this study show similar variations to those appeared in the ERA-40. It is likely that the sudden increases in SLP observed in the NCEP-NCAR before the 1970s are spurious, and this result implies that the NCEP-NCAR reanalysis over Mongolia and its vicinity before the 1970s does not reproduce the actual surface conditions. The ERA-40 may also have some problems such as the lower SLP than that of the observational data before the 1980s, but the difference is, in general, less than 3 hPa and this value is smaller than that recognized between the NCEP-NCAR and the observational data before the mid1970s. Therefore, it seems that the ERA-40 is more accurate, and is more appropriate to use than the NCEP-NCAR, for the moment, in investigations of the interdecadal climate change in the late 1970s over East Eurasia. However, care must also be taken into the above-mentioned problems.

A numerical study of the effect of urban geometry upon the surface energy budget

Abstract: This numerical study investigates the effect of urban canyon geometry upon the thermal environment using a parking lot model and an urban canyon model in identical meteorological conditions. The urban canyon model assumes two buildings on opposite sides of a street, no windows or interior anthropogenic heat source, an infinitely long east-west oriented canyon, and waterproof surfaces. The simulated surface temperatures agree well with those obtained by field measurement. The energy balance of the urban canyon is represented by that of the canyon top, which is an imaginary surface. The urban canyon, whose top surface is a plane above the canyon at the same level as the roof surface of the building, absorbs more heat in the daytime and releases more at night than the parking lot. The urban thermal environment depends on an urban geometry which particular to the urban canyon model produces reduced small sky view factors and complicated daytime shadow patterns. The results show that this urban geometry contributes to urban heat island formation.

The Impact of Trans-equatorial Monsoon Flow on the Formation of Repeated Torrential Rains over Java Island

Abstract: Torrential rains that repeatedly occurred over Java Island causing widespread floods in late January and early February 2007 coincided with a strong and persistent trans-equatorial monsoon flow from the Northern Hemisphere. While convections develop frequently over the island's mountainous areas in the afternoon, convections over the northern plains are active during the night and morning hours. The strong trans-equatorial monsoon flow with an upper southeasterly wind produces a strong low-level vertical shear of wind and dry mid-level environment over the island. These conditions allow the severe convections to occur repeatedly for days and to sustain for an extended period of time. The results suggest that the trans-equatorial monsoon flow plays a principal role in the formation of the repeated torrential rains. The probability of occurrence of a strong and persistent trans-equatorial monsoon flow that causes torrential rains and widespread floods over Java Island is estimated to be once every 5-10 years.

Urban-rural temperature differences in coastal cities : Influence of rural sites

Abstract: This paper considers problems in calculating the heat island magnitude of coastal cities. We examined the influence on heat island magnitude (1) when a rural observatory located in an inland area is compared with an urban observatory and (2) when an observatory in an atypical countryside setting is chosen as the rural site. The results showed that the urban-rural temperature difference was bigger in winter than in summer when the rural observatory was located in a relatively inland area in comparison with the corresponding urban observatory. This tendency was more marked at night than in the daytime. When an observatory in an atypical rural setting was used, the urban-rural temperature difference was greater from 11 :00 p.m. to midnight in summer. Therefore, only observatories located in typical rural areas and located roughly the same distance from the sea as the corresponding urban observatories should be selected for investigation of urban heat island magnitude.