No abstract

No abstract

Climate modeling is a significant tool to reproduce the observed features of present climate changes and can provide reliable estimations for future climate changes at global and regional levels. In the present study we use latest version of International Center for Theoretical Physics (ICTP) regional climate model (RegCM4.3) to examine its ability by analyzing the European Community-Hamburg atmospheric model (ECHAM5) and the European Centre for Medium-Range Weather Forecast (ECMWF) 40 years reanalysis data (ERA-40) over South Asia. Seasonal mean climatology and annual cycle are compared with different observation based data sets and also with the reanalysis and driving GCM. Two experiments are conducted for present day simulation by using ERA-40 reanalysis and ECHAM5 GCM to provide the initial and lateral boundary conditions. In spite of complex topography of the domain RegCM4.3 shows an improved performance in various aspects as compared to the earlier applications of this model over South Asia. Near surface air temperature are reproduced well over the most part of the domain. Indian monsoon precipitation patterns are better captured by RegCM4.3 as compared to the driving data set of ECHAM5 and ERA40. Simulation results show that RegCM4.3 has cold bias in winter and summer over the foothills of the Hindu-Kush-Himalaya (HKH) region. Simulation with ERA40 and ECHAM5 overestimated the seasonal mean precipitation over some part of the domain which requires further improvement in the physical parameterization scheme of RegCM4.3.

This study tests the Pecking Order Theory for the capital structure of listed firms in Pakistan. As per Pecking Order Theory in capital structure formulation, internally generated resources would have first priority, followed by debt issuance where equity is used as a last resort. In its strong form, the Pecking Order Theory sustains that equity issues would never occur, whereas in its weak form, limited amounts of issues are acceptable. The methodology adopted in this empirical study involves cross-section regressions and the testing of hypotheses stemming from the underlying theory in its strong and weak forms. A sample of capital structure of non-financial firms listed at KSE is considered from 2001 to 2008. A statistical tool of panel data regression analysis is used to test different firms' data. The value of R2, t-test and F-Stat indicate firms in KSE supporting the weak form of pecking order theory, i.e., the option of using internal equity and debt is more preferred and a limited amount of external equity is used for reinvestment and fund raising purposes.

Nonlinearity in the Northern Hemisphere’s wintertime atmospheric flow is investigated from both an intermediate-complexity model of the extratropics and reanalyses. A long simulation is obtained using a three-level quasigeostrophic model on the sphere. Kernel empirical orthogonal functions (EOFs), which help delineate complex structures, are used along with the local flow tendencies. Two fixed points are obtained, which are associated with strong bimodality in two-dimensional kernel principal component (PC) space, consistent with conceptual low-order dynamics. The regimes reflect zonal and blocked flows. The analysis is then extended to ERA-40 and JRA-55 using daily sea level pressure (SLP) and geopotential heights in the stratosphere (20 hPa) and troposphere (500 hPa). In the stratosphere, trimodality is obtained, representing disturbed, displaced, and undisturbed states of the winter polar vortex. In the troposphere, the probability density functions (PDFs), for both fields, within the two-dimensional (2D) kernel EOF space are strongly bimodal. The modes correspond broadly to opposite phases of the Arctic Oscillation with a signature of the negative North Atlantic Oscillation (NAO). Over the North Atlantic–European sector, a trimodal PDF is also obtained with two strong and one weak modes. The strong modes are associated, respectively, with the north (or +NAO) and south (or −NAO) positions of the eddy-driven jet stream. The third weak mode is interpreted as a transition path between the two positions. A climate change signal is also observed in the troposphere of the winter hemisphere, resulting in an increase (a decrease) in the frequency of the polar high (low), consistent with an increase of zonal flow frequency.