Breaks in monsoon and related precursors

A comprehensive analysis of eleven break monsoon situations that occurred during the period 1987 to 1997 have been attempted in the study. The various features like daily rainfall departures, wind anomalies and the satellite derived Outgoing Long wave Radiation (OLR) associated with the commencement/cessation of the break monsoon condition are studied with a view to identifying the precursors associate the break situation. The results reveal that there is progressive decrease of below normal rainfall departures 5 days prior to the actual break day in the latitude belts south of 20° N. During the period of the revival of the monsoon, the time section of the daily rainfall departures shows that the daily rainfall departure first starts becoming above normal in the southern most latitudinal belt 5° N to 10°N from the second day onwards after the cessation of the break. Similarly, the easterly anomalies in the zonal wind are first noticed in the southern latitude even 5 days prior to the starting of the break in the lower and middle troposphere. The maximum easterly anomalies in the lower and the middle troposphere move northwards upto 20° N. The composite latitudinal time section of OLR anomaly show a large area of negative OLR anomaly extending from 20°S to 10°N. The area is defined as the Southern. Hemispheric Convective Zone ( SHCZ). The negative OLR anomaly (10 Wm-2 is noticed around 5° S to 0° N. It increases to 20 Wm-2 on the second day of the break on the same latitudinal belt. The daily OLR anomaly pattern shows that the area of the negative OLR anomaly around the equatorial region increases with the approach of a break epoch. The forecasting aspects of the commencement / cessation of the break have been also discussed.

Energetics of zonal waves during different phases of monsoon

Energetics of lower tropospheric zonal waves during onset, established and withdrawal phases of monsoon have been studied for 1994, 1995 and 1996. The analysis show that energetics of wave 0 over R1 (10°S-10°N), long waves (waves 1-2) over R2 (10°N - 30°S) and short waves (waves 3-10) over R3 (30° N - 50° N) influence the monsoon activity over India on intra-seasonal scale. The weekly analysis of the energetics of zonal waves indicates that the momentum transport of wave 0 over latitudinal belt L0 (12° S - 3° N), wave 1 over the belt L1(10° N - 15° N) and wave 2 over the belt L2 (33° N - 45° N) is related to all India rainfall on a weekly scale. Larger southward momentum transport of wave 0 over L0 and larger northward momentum transport of wave 1 over L1 and wave 2 over L2 enhance the monsoon activity over India.

Effects of Coriolis force, vorticity and divergence on nonlinear energy conversions during different phases of July 1979 monsoon

ABSTRACT. Kinetic energy (KE) of the rotational and divergent flows and the nonlinear energy conversion between them due to the action of Coriolis force, divergence and vorticity, partition) further into stationary and transient motions are computed in the Fourier spectral domain during different phases of July 1979 monsoon over the latitudinal belt 10° S - 30° at 850 and 200 hPa and studied. It is found that nonlinear divergent to rotational KE exchange due to the action of Coriolis force is the primary contributor for all categories of stationary and transient waves at both the levels over tropics. Our results indicate that in the transient scale dynamics the wave-wave interaction plays a dominant role at 850 hPa. Divergent to rotational KE conversion by zonal-wave interaction due to divergence and wave-wave interaction due to Coriolis force are identified as important mechanisms for maintenance of rotational stationary planetary and transient synoptic scale waves respectively at 200 hPa. It is inferred that nonlinear energy conversions due to Coriolis force and vorticity oppose each other at 200 hPa. The results support that the energy conversion phenomenon may not be entirely barotropic. The importance of ageostrophic effect at different stages of monsoon activities is also shown.

Justification of the calculated values of strength and deformation characteristics of clay soils for pavement design in economically promising areas of Western Siberia

In the first quarter of the 21st century, Russia will face the need to develop the southern latitudinal belt and form a new northern latitudinal belt of Russia’s economic development in Siberia. At the same time, specialists from the Institute of Economics and Industrial Engineering of the Siberian Branch of the Russian Academy of Sciences predict the possibility of strengthening the single economic space of the state, relying not only on raw materials, but also on the transport and logistics opportunities that open up when servicing transport corridors. The development of the road network of the northern latitudinal belt of economic development requires taking into account the features of the geocomplex elements when designing roads in the territory of the second climatic zone of Western Siberia. The article presents the structure of research aimed at studying the relations and patterns that determine the systemic relationship between the components of the «highway – environment» system in economically promising areas of Western Siberia. The research structure is based on the systems approach and includes two main blocks – theoretical and experimental ones, as well as their elements and internal and external relations. The study gives the detailed examination of such issues as organization and performance of experimental part of research on studying composition and properties of clay soils. The main outcomes of field and laboratory studies are shown. The dependences of variations of elastic modulus, angle of internal friction, and specific adhesion of clay soils on their relative humidity are established. Deviations are determined between the values of soil characteristics calculated from these dependences and the values presented in Industry Road Code 218.046-01 (preliminary national standard PNST 265-2018). The article is prepared on the basis of the author’s PhD dissertation research on the topic of «Justification of regional calculated values of clay soil characteristics for the road pavement design in Western Siberia» (STU, Novosibirsk, 2017).

Bioclimate of Jericho in Palestine

Jericho is an ancient Canaanite Palestinian city and one of the oldest cities in history, which dates back to more than 10.000 BC (Stone Age). It is located near to the Jordan River, north of the Dead Sea, and north of Jerusalem. Moreover, it considered the lowest area in the earth and has a unique climatic zone. during the study period (1975-1995), was utilized the Salvador Rivas Martinez scale to classify the bioclimate of the earth to analysis the climate and bioclimate data, which was obtained from one station from Palestinian Meteorology Department (Jericho station). The results revealed that the mean monthly temperature was 22.4 0C, mean maximum temperature was 34.8 0C, mean monthly minimum temperature was 15.3 0C, the value of the annual ombrothermic index was 0.6, the compensated thermicity index is very high around 1209/1209 and the simple continentality index was 16.7. The bioclomate of Jericho is located within the zones of the thermal model under the inframediterranean basin, the dry and arid regions. Jericho is belong to Mediterranean desertic-oceanic, the latitudinal belt as subtropical, while continentality is oceanic-low eu-oceanic.

Bioclimate of Jericho in Palestine

Jericho is an ancient Canaanite Palestinian city and one of the oldest cities in history, which dates back to more than 10.000 BC (Stone Age). It is located near to the Jordan River, north of the Dead Sea, and north of Jerusalem. Moreover, it considered the lowest area in the earth and has a unique climatic zone. during the study period (1975-1995), was utilized the Salvador Rivas Martinez scale to classify the bioclimate of the earth to analysis the climate and bioclimate data, which was obtained from one station from Palestinian Meteorology Department (Jericho station). The results revealed that the mean monthly temperature was 22.4 0C, mean maximum temperature was 34.8 0C, mean monthly minimum temperature was 15.3 0C, the value of the annual ombrothermic index was 0.6, the compensated thermicity index is very high around 1209/1209 and the simple continentality index was 16.7. The bioclomate of Jericho is located within the zones of the thermal model under the inframediterranean basin, the dry and arid regions. Jericho is belong to Mediterranean desertic-oceanic, the latitudinal belt as subtropical, while continentality is oceanic-low eu-oceanic.

Recent trends in the frequency and duration of global floods

Frequency and duration of floods are analyzed using the global flood database of the Dartmouth Flood Observatory (DFO) to explore evidence of trends during 1985–2015 at global and latitudinal scales. Three classes of flood duration (i.e., short: 1–7, moderate: 8–20, and long: 21 days and above) are also considered for this analysis. The nonparametric Mann–Kendall trend analysis is used to evaluate three hypotheses addressing potential monotonic trends in the frequency of flood, moments of duration, and frequency of specific flood duration types. We also evaluated if trends could be related to large-scale atmospheric teleconnections using a generalized linear model framework. Results show that flood frequency and the tails of the flood duration (long duration) have increased at both the global and the latitudinal scales. In the tropics, floods have increased 4-fold since the 2000s. This increase is 2.5-fold in the north midlatitudes. However, much of the trend in frequency and duration of the floods can be placed within the long-term climate variability context since the Atlantic Multidecadal Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation were the main atmospheric teleconnections explaining this trend. There is no monotonic trend in the frequency of short-duration floods across all the global and latitudinal scales. There is a significant increasing trend in the annual median of flood durations globally and each latitudinal belt, and this trend is not related to these teleconnections. While the DFO data come with a certain level of epistemic uncertainty due to imprecision in the estimation of floods, overall, the analysis provides insights for understanding the frequency and persistence in hydrologic extremes and how they relate to changes in the climate, organization of global and local dynamical systems, and country-scale socioeconomic factors.

Coupled oscillations of deformable spherical-cap droplets. Part 1. Inviscid motions

A spherical drop is constrained by a solid support arranged as a latitudinal belt. This belt support splits the drop into two deformable spherical caps. The edges of the support are given by lower and upper latitudes yielding a ‘spherical belt’ of prescribed extent and position: a two-parameter family of constraints. This is a belt-constrained Rayleigh drop. In this paper we study the linear oscillations of the two coupled spherical-cap surfaces in the inviscid case, and the viscous case is studied in Part 2 (Bostwick & Steen, J. Fluid Mech., vol. 714, 2013, pp. 336–360), restricting to deformations symmetric about the axis of constraint symmetry. The integro-differential boundary-value problem governing the interface deformation is formulated as a functional eigenvalue problem on linear operators and reduced to a truncated set of algebraic equations using a Rayleigh–Ritz procedure on a constrained function space. This formalism allows mode shapes with different contact angles at the edges of the solid support, as observed in experiment, and readily generalizes to accommodate viscous motions (Part 2). Eigenvalues are mapped in the plane of constraints to reveal where near-multiplicities occur. The full problem is then approximated as two coupled harmonic oscillators by introducing a volume-exchange constraint. The approximation yields eigenvalue crossings and allows post-identification of mass and spring constants for the oscillators.

Total cloud cover from satellite observations and climate models

Global and zonal monthly means of cloud cover fraction for total cloudiness (CF) from the ISCCP D2 dataset are compared to same quantity produced by the 20th century simulations of 21 climate models from the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset archived by the Program for Climate Model Diagnosis and Intercomparison (PCMDI). The comparison spans the time frame from January 1984 to December 1999 and the global and zonal average of CF are studied. The restriction to total cloudiness depends on the output of some models that does not include the 3D cloud structure. It is shown that the global mean of CF for the PCMDI/CMIP3 models, averaged over the whole period, exhibits a considerable variance and generally underestimates the ISCCP value. Very large discrepancies among models, and between models and observations, are found in the polar areas, where both models and satellite observations are less reliable, and especially near Antarctica. For this reason the zonal analysis is focused over the 60° S–60° N latitudinal belt, which includes the tropical area and mid latitudes. The two hemispheres are analyzed separately to show the variation of the amplitude of the seasonal cycle. Most models overestimate the yearly averaged values of CF over all of the analysed areas, while differences emerge in their ability to capture the amplitude of the seasonal cycle. The models represent, in a qualitatively correct way, the magnitude and the weak sign of the seasonal cycle over the whole geographical domain, but overestimate the strength of the signal in the tropical areas and at mid-latitudes, when taken separately. The interannual variability of the two yearly averages and of the amplitude of the seasonal cycle is greatly underestimated by all models in each area analysed. This work shows that the climate models have an heterogeneous behaviour in simulating the CF over different areas of the Globe, with a very wide span both with observed CF and among themselves. Some models agree quite well with the observations in one or more of the metrics employed in this analysis, but not a single model has a statistically significant agreement with the observational datasets on yearly averaged values of CF and on the amplitude of the seasonal cycle over all analysed areas.