Long Term Temperature Trends at Major, Medium, Small Cities and Hill Stations in India during the Period 1901-2013

Industrialization and urbanization are the most dominant causal factors for long-term changes in surface air temperatures. To examine this fact, the long term changes in the surface-air temperatures have been evaluated by the linear trend for the different periods, i.e. 1901-2013, 1901-1970 and recent period 1971-2013 as rapid industrialization was observed during the recent four decades. In the present study, seasonal and annual mean, maximum and minimum temperature data of 36 stations for the period 1901-2013 have been used. These stations are classified into 4 groups, namely major, medium, small cities and hill stations. During the period 1901-1970, less than 50% stations from each group showed a significant increasing trend in annual mean temperature, whereas in the recent period 1971-2013, more than 80% stations from all the groups except small city group showed a significant increasing trend. The minimum temperature increased faster than that of the maximum temperature over major and medium cities, while maximum temperature increased faster than the minimum temperature over the small cities and hill stations. The annual mean temperature of all the coastal stations showed a significant increasing trend and positive correlation with Precipitable Water Vapour (PWV). The effect of PWV is more pronounced on minimum temperature than that of the maximum.

Systematic improvement in Tong's B-type water drive method

Tong's B-type water drive method was proposed as early as the 1970s and has been widely applied in the dynamic prediction and effective evaluation of oilfield development.Through extensive applications and studies,many researchers found that the statistical constants in the formula of the Tong's B-type water drive method(also referred to as the Tong's B-type formula)are not applicable to multiple types of reservoirs,especially low-permeability ones,due to the limited range of reservoir types when the formula was conceived.Moreover,they put forward suggestions to improve the Tong's B-type formula,most of which focused on the research and calculation of the first constant in the formula.For oilfields in the development stages of high or ultra-high water cuts,it is widely accepted that different types of reservoirs have different limit water cuts.This understanding naturally makes it necessary to further modify the Tong's B-type formula.It is practically significant to establish the water drive formula and cross plot considering that the two constants in the formula vary with reservoir type.By analyzing the derivation process and conditions of the Tong's B-type formula,this study points out two key problems,i.e.,the two constants 7.5 and 1.69 in the formula are not applicable to all types of reservoir.Given this,this study establishes a function between key reservoir parameters and the first constant and another function between key reservoir parameters and recovery efficiency.Based on the established two functions and considering that different types of oil reservoir have different limit water cuts,this study develops an improved Tong's B-type formula and prepares the corresponding improved cross plot.The results of this study will improve the applicability and accuracy of Tong's B-type water drive method in predicting the trend of water cut increasing for different types of oil reservoirs.

Variation Characteristics of Ultraviolet Radiation over the North China Plain

In situ measured data of broadband solar radiation （Rs） and ultraviolet （Uv） radiation were used to investigate the spa- tiotemporal variation properties of Uv radiation and the ratio of Uv radiation to Rs over the North China Plain （NCP）. Based on the analysis, an empirical model for estimating Uv radiation under all weather conditions in this region was developed. The results showed that the annual Uv radiation over the NCP ranges from 0.38-0.52 MJ m^-2 d^-1. The highest value during the study period was recorded at the Changwu site, which is located near the margin of the Loess Plateau, while the lowest value appeared at the station in Beijing. The seasonal variation pattern of the ratio of Uv radiation to Rs is similar to that of Uv radiation; namely, the highest value appears in August and then decreases gradually until the lowest value appears in November. A small increasing trend in the Uv radiation levels and the ratio of Uv radiation to Rs was observed over the NCP. The evaluation results showed that the empirical estimation model can be widely used to estimate Uv radiation under all atmospheric conditions. The relative error between the modeled and measured daily values were within ± 15%.

Numerical study on laminar flame speed of natural gas-carbon monoxide-air mixtures

Laminar flame speeds of natural gas-carbon monoxide-air mixtures are calculated by CHEMKIN II with GRI Mech-3.0 over a large range of fuel compositions,equivalence ratios,and initial temperatures.The calculated results of natural gas are compared with previous experimental results that show a good agreement.The calculated laminar flame speeds of natural gas-carbon monoxide-air mixtures show a nonmonotonic increasing trend with volumetric fraction of carbon monoxide and an increasing trend with the increase of initial temperature of mixtures.The maximum laminar flame speed of certain fuel blend reaches its biggest value when there is 92%volumetric fraction of carbon monoxide in fuel at different initial temperatures.Five stoichiometric natural gas-carbon monoxide-air mixtures are selected to study the detailed chemical structure of natural gas-carbon monoxide-air mixtures.The results show that at stoichiometric condition,the fuel blend with 80%volumetric fraction of carbon monoxide has the biggest laminar flame speed,and the C normalized total production rate of methane with 80%volumetric fraction of carbon monoxide is the largest of the five stoichiometric mixtures.

A 14-year measurement of toxic elements in atmospheric particulates in Hong Kong from 1995 to 2008

Toxic elements in the atmosphere can enter and accumulate in the human body, seriously impacting human health. In this study, we analyzed a 14-year （1995-2008） measurement of three toxic elements （As, Cd and Cr） in PMlo in Hong Kong, China. The pollution of these toxic elements in Hong Kong was not serious. The trend analysis showed that As and Cr in PM10 increased at a statistically significant level （p〈0.05） during the 14-year period, while the Cd in PM10 did not change significantly. Typical seasonal variations were observed for all three toxic elements, largely in relation to the Asian monsoon. Hourly 10-day backward trajectories were computed and cate- gorised into four groups. The continental air masses showed much higher concentrations of the three toxic elements than the marine air masses. The abundances of As and Cd in the PM10 were much higher in the continental air masses than those in the marine air masses, while the abundances of Cr showed an opposite pattern. The trends of the three toxic elements in East China＇s air mass were consistent with those in the overall data set ofHong Kong. Examination of the toxic element data recorded at urban sites and a roadside site also indicated a large contribution of external air masses to particulate As and Cd in Hong Kong. These results suggest that the long-range transport from the mainland of China is the dominant contributor to particulate As and Cd, while both local and long-distance sources determine the particulate Cr in Hong Kong.

加拿大北极地区航运对气候变暖的影响

This paper presents a detailed account of the effect of shipping activity on the increasing trends of air temperatures in the Canadian Arctic region for the period of 1980–2018.Increasing trend of temperature has gained significant attention with respect to shipping activities and sea ice area in the Canadian Arctic.Temperature,sea ice area and shipping traffic datasets were investigated,and simple linear regression analyses were conducted to predict the rate of change(per decade)of the average temperature,considering winter(January)and summer(July)seasons.The results indicate that temperature generally increased over the studied region.Significant warming trend was observed during July,with an increase of up to 1℃,for the Canadian Arctic region.Such increasing trend of temperature was observed during July from the lower to higher latitudes.The increase in temperature during July is speculated to increase the melting of ice.Results also show a decline in sea ice area has a significant positive effect on the shipping traffic,and the numbers of marine vessel continue to increase in the region.The increase in temperature causes the breaking of sea ice due to shipping activities over northern Arctic Canada.