Long-range transport of ozone, carbon monoxide, and acidic trace gases at Oki Island, Japan, during PEM-WEST B / PEACAMPOT B campaign

Ground based measurements of ozone, CO, HNO3, SO2, HCl, and formic acid were carried out at Oki, a remote island site in the Sea of Japan, during Feburuary 26 to March 16, 1994, as the Pacific Exploratory Mission in the Western Pacific / Perturbation by East Asian Continental Air Mass to the Pacific Oceanic Troposphere (PEM-West B / PEACAMPOT B) campaign. According to trajectory analysis, the air mass reaching Oki was classified into four groups: northerly, northwesterly, west-northwesterly, and westerly flows. Clear dependence of gas concentrations on flow direction of air mass was found for all species studied. Lowest concentrations were observed in the northerly airflow originating from the Bering Sea. The mean concentrations of ozone and CO in northerly flow were 37.6±1.9 and 157±7 ppbv, respectively. The mean values of HNO3, SO2, HCl, and formic acid in the northerly flow were 34±10, 41±5, 107±23, and 54±81 pptv, respectively. The highest concentrations of all species were observed in the westerly flow passing through a lower boundary layer over the Yellow Sea and South Korean Peninsula. The mean concentrations of ozone and CO in the westerly flow were 45.9±4.0 and 292±44 ppbv, respectively. The mean values of HNO3, SO2, HCl, and formic acid in the westerly flow were 137±37, 2075±1307, 515±214, and 264±183 pptv, respectively. Clear seasonal variation of the background concentrations of ozone and CO were identified by comparison with the data from the PEM-West A /PEACAMPOT A campaign conducted in the fall. In contrast to other species, strong diurnal variation of formic acid with a daytime maximum was observed. The possibility of photochemical formation of formic acid from HCHO and the HO2 radical is discussed

Measurements of NO, NO \u3c inf\u3e y , CO and O \u3c inf\u3e 3 and estimation of the ozone production rate at Oki Island, Japan, during PEM-West

Copyright 1996 by the American Geophysical Union. Measurements of NO, NOy, CO, and O3 were conducted at Oki Island, 65 km west of the Japanese mainland during September-October 1991. The results show that the Oki Island site is relatively clean with mean (and median) CO and NOy concentrations of 137 (130) ppbv and 713(505) pptv, respectively. These relatively low concentrations reflect the frequent occurrence of winds from the less populated regions to the north during this campaign. During several periods, elevated CO, NOy, and O3 concentrations were associated with transport of pollutants from Japan and Korea. CO and NOy are significantly correlated in the entire data set, reflecting the overall influence of anthropogenic emissions. Mean CO and NOy concentrations show small diurnal cycles with a maximum in the morning and early evening hours. Hourly mean O3 concentrations exhibit a diurnal cycle of amplitude 3.5 parts per billion by volume, with a maximum in the early afternoon attributed to photochemical O3 production. The source of this afternoon O3 enhancement is analyzed using regression analysis of O3 and NOy and of O3 and CO. Bom NOy and CO are significantly correlated with O3 during the daytime but are poorly or insignificantly correlated with O3 at night, indicating mat upwind photochemistry operating within me previous ∼1 day was responsible for the observed afternoon O3 enhancement. The NOy-O3 regression analysis indicates formation of ∼9 O3 molecules per NOy molecule reaching Oki Island. The mean and median midday NO concentrations of 55 and 23 parts per trillion by volume, respectively, were sufficient to support net production of O3. Using the results of these measurements and prior modeling studies (Lin et al., 1988), we estimate a lifetime-averaged O3 production efficiency of 10 molecules O3 per NOx molecule. Combined with estimated East Asian NOx emissions for 1987, tins indicates an annual O3 production of 1.0 × 1014 g O3 from photochemistry which is approximately 2 times me annual stratospheric flux in this region. This value must be considered as a rough estimate but is probably accurate to within a factor of 2

Growth Trajectories during the First 6 Years in Survivors Born at Less Than 25 Weeks of Gestation Compared with Those between 25 and 29 Weeks

We aimed to determine the differences in the growth trajectories of the youngest gestational survivors (<25 weeks’ gestation) up to 6 years of age compared to those of older gestational ages. Preterm infants were divided into two groups: 22–24 weeks’ gestation (male (M) 16, female (F) 28) and 25–29 weeks’ gestation (M 84, F 59). Z-scores of body weight (BW), body length (BL), and body mass index (BMI) were derived from Japanese standards at 1, 1.5, 3, and 6 years of corrected age. Comparisons between the two groups by sex were made using the Wilcoxon test and linear regression analysis to examine the longitudinal and time-point associations of anthropometric z-scores, the presence of small for gestational age (SGA), and the two gestational groups. BW, BL, BMI, and z-scores were significantly lower in the 22–24 weeks group at almost all assessment points. However, there were no significant differences in BW, BL, BMI, and z-scores between the two female groups after 3 years. BMI z-scores were significantly associated with the youngest gestational age and the presence of SGA at all ages in males, but not in females. The youngest gestational age had a greater influence in males on the z-score of anthropometric parameters up to 6 years of age

Long-range transport of ozone in the East Asian Pacific rim region

Copyright 1996 by the American Geophysical Union. Measurements of surface ozone were conducted at three remote island sites in the East Asian Pacific rim region during the Pacific Exploratory Mission-West (A) campaign period in September-October, 1991. The ozone concentrations observed at the three measurement stations at Oki and Okinawa, Japan, and Renting, Taiwan, had similar ranges varying between 6-63, 8-58, and 4-65 ppb, respectively, except for one event of short-range transport of polluted air at Kenting. Day-to-day variations have been analyzed by using backward air parcel trajectories on isentropic surfaces. The results showed that continental air masses which originated from northwestern Asia and passed through the high anthropogenic emission region of East Asia contained the highest concentration of ozone, 30-60 ppb with an average of 43-45 ppb at the three stations. In contrast, the lowest concentrations were observed for air parcels originating from the mid-Pacific and transported without mixing with the continental outflow. These parcels contained 5-20 ppb of ozone with the average of 11, 15, and 9 ppb at Oki, Okinawa, and Kenting, respectively. The air parcels from the South China Sea contained 22 and 18 ppb of ozone at Okinawa and Kenting, respectively, which were higher than those from mid-Pacific. Continental air mass from the north-northeast to Oki containing 35-40 ppb ozone with the average of 37 ppb was recognized as continental background. The high ozone concentrations in the northwesterly continental outflow exceeding the background was ascribed to photochemical buildup in the planetary boundary layer