Methane Emission Reduction: An Application of FUND

Methane is, after carbon dioxide, the most important anthropogenic greenhouse gas. Governments plan to abate methane emissions. A crude set of estimates of reduction costs is included in FUND, an integratedassessment model of climate change. In a cost-benefit analysis, methane emission reduction is found to be instrumental in controlling the optimal rate of climate change. In a cost-effectiveness analysis, methane emission reduction largely replaces carbon dioxide emission reduction. Methane emission reduction reinforces the case for international cooperation in climate policy, but complicates the efficient allocation of emission reduction efforts. Methane emission reduction at the short run does not help to achieve the ultimate objective of the Framework Convention on Climate Change.     

The High Concentration Tails Of The Probability Density Function Of A Dispersing Scalar In The Atmosphere

The distribution function for concentrations of a scalar pollutant dispersing in the turbulent atmosphere has a finite domain that is bounded above and below. Three methods, based on extreme value statistics, are used to obtainestimates for the upper bound and to describe the high concentration tailbehaviour of the distribution; all three methods are applied to concentrationdata obtained from experimental atmospheric releases. Quantile quantile (QQ)plots are used to assess the goodness of fit of the resulting estimates of thedistribution, and also to compare the performance of the three methods. Thepredicted values for the upper bound are orders of magnitude less than thesource concentration, illustrating that molecular diffusion has a large effecton the high concentrations.     

Evaluation of turbulent fluxes over Maitri,Antarctica

Turbulent fluxes have been evaluated for clear sunny days over the Indian Antarctic station, Maitri, using the basic meteorological data recorded at four levels of a 28 m tower. The data are supplemented with radiation data. The surface layer over Maitri remains thermally stratified during the hours of minimum solar insolation, the so-called nighttime period. The surface winds during this period are generally very strong resulting in high momentum fluxes. In particular, for high winds (>12 m s^–1), the temperature gradient is found to be less positive than for moderate winds (4 to 7 m s^–1). Solar insolation provided the daytime heating necessary for the diurnal variation of atmospheric stability, and hence, for the turbulent fluxes. Thus, on clear days daytime conditions are marked by upward transport of heat with reduced momentum flux, while stable nighttime conditions are marked by a downward heat flux with increased momentum fluxes.     

IMPACT OF LATENT HEAT FLUX ON INDIAN SUMMER MONSOON DURING EL NI(N)O/LA NI(N)A YEARS

El Ni(n)o or La Ni(n)a manifest in December over the Pacific and will serve as an index for the forecasting of subsequent Indian summer monsoon,which occurs from June to mid-September.In the present article,an attempt is made to study the variation of latent heat flux (LHF) over the north Indian Ocean during strong El Ni(n)o and strong La Ni(n)a and relate it with Indian monsoon rainfall.During strong El Ni(n)o the LHF intensity is higher and associated with higher wind speed and lower cloud amount.During E1 Ni(n)o all India rainfall is having an inverse relation with LHF.Seasonal rainfall is higher in YY+1 (subsequent year) than YY (year of occurrence).However there is a lag in rainfall during El Ni(n)o YY+1 from June to July when compared with the monthly rainfall.     

Vertical behaviour and meteorological properties of air masses in the southwest of the Iberian Peninsula (1997–2007)

Air masses are characterized by physical (temperature, humidity) and chemical (transported gases and aerosols) properties, being associated their arrival to different meteorological scenarios. The knowledge of the air masses over a region is fundamental as complementary information in several atmospheric studies, being the calculation of back-trajectory the most widely used tool whenever air masses are analyzed. A study of air masses has been carried out in southwestern Iberian Peninsula using 5-day kinematic back trajectories computed by the HYSPLIT model at three heights (500, 1,500 and 3,000 m) from 1997 to 2007. The main aims have been to characterize their vertical behaviour and their thermal and humidity properties. Thirteen trajectory clusters have been defined, showing the northerly and westerly clusters a high coupling degree. Seasonal daily variation of potential temperature and specific humidity has been analyzed, obtaining higher differences among clusters in the cold season.     

Stratosphere-troposphere Dynamical Coupling over Boreal Extratropics during the Sudden Stratospheric Warming in the Arctic in January–February 2017

The dynamic coupling between the stratospheric and tropospheric processes is studied for the sudden stratospheric warming registered in January-February 2017. Also, the effects of these processes on the tropospheric circulation and weather conditions in the middle and high latitudes via the reflection of wave activity from the stratosphere are investigated.     

Boundary-layer depth and entrainment zone characterization with a boundary-layer profiler

A technique for determining the height of the convective atmospheric boundary layer (CBL) with a 915 MHz boundary-layer profiler is discussed. The results are compared with CBL heights determined from radiosonde measurements. The profiler provides continuous CBL height measurements with very good time resolution (30 minutes or less), allowing for detailed understanding of the growth and fluctuations of the CBL. In addition, the profiler provides information about the degree of definition of the CBL top and the thickness of the entrainment zone. The measurements discussed were taken during the Rural Oxidants in the Southern Environment II (ROSE II) experiment.     

Multi-Source Emission Determination Using an Inverse-Dispersion Technique

Inverse-dispersion calculations can be used to infer atmospheric emission rates through a combination of downwind gas concentrations and dispersion model predictions. With multiple concentration sensors downwind of a compound source (whose component positions are known) it is possible to calculate the component emissions. With this in mind, a field experiment was conducted to examine the feasibility of such multi-source inferences, using four synthetic area sources and eight concentration sensors arranged in different configurations. Multi-source problems tend to be mathematically ill-conditioned, as expressed by the condition number κ. In our most successful configuration (average κ = 4.2) the total emissions from all sources were deduced to within 10% on average, while component emissions were deduced to within 50%. In our least successful configuration (average κ = 91) the total emissions were calculated to within only 50%, and component calculations were highly inaccurate. Our study indicates that the most accurate multi-source inferences will occur if each sensor is influenced by only a single source. A “progressive” layout is the next best: one sensor is positioned to “see” only one source, the next sensor is placed to see the first source and another, a third sensor is placed to see the previous two plus a third, and so on. When it is not possible to isolate any sources κ is large and the accuracy of a multi-source inference is doubtful.     

The role of the subtropical jet stream during heat wave events over north-central Greece

Summary The role of the subtropical jet stream (SJ) in the occurrence of heat waves in South Balkans and Greece is sought here. For this purpose ECMWF grid-point data is examined, concerning the Balkan heat wave of 5–9 July 1988, that cost human lifes, at least in Greece. For the city of Thessaloniki, Greece, a temperature budget is presented, as a function of time. It turns out that the most important heating mechanism is the adiabatic heating. Horizontal mass convergence at the maximum wind level (200 hPa) causes descent and adiabatic heating. The convergence occurs in association with the Hadley Cell, as well as with the right exit quadrant of an anticyclonically curved subtropical jet streak. As air parcels that exit the above jet streak slow down and turn anticyclonically, a strong ageostrophic wind current is established towards and to the right of the flow direction. This ageostrophic current converges above the northeastern Balkans. Downward ageostrophic motion emerges from the above area of horizontal convergence and heads towards the SSW, affecting the Balkans. From the above case study, it is concluded that intense heat waves are favoured in the South Balkans and Greece when the SJ is anticyclonically curved to the north of the Balkans and a jet streak is situated to the north west of the Balkans.     

Comparison of manual and automatic methods for measurement of methane emission from rice paddy fields

The methane emission flux from rice paddies was simultaneously measured with automatic and manual methods in the suburban of Suzhou. Both methods were based on the static chamber/ GC-FID techniques. Detail analysis of the experimental results indicates: a) The data of methane emission measured with the automatic method is reliable. b) About 11 or 19 o’clock of local time is recommended as the optimum sampling time for the manual spot measurement of methane emission from rice paddies. The methane emission fluxes measured by manual sampling at local time other than the optimum time have to be corrected. The correction coefficient may be determined by automatic and continuous measurement. c) In order to get a more accurate result, an empirical correction factor, such as 18%, is recommended to correct the seasonally total amount of measured methane emission by enlarging the au-tomatically measured data or reducing the manually measured ones.