PPP Correction of the IPCC Emission Scenarios – Does it Matter?

Ian Castles and David Henderson have criticized IPCC’s Special Report on Emissions Scenarios (SRES) (IPCC: 2000, Special Report on Emissions Scenarios, Intergovernmental Panel on Climate Change (IPCC), Cambridge University Press, Cambridge, 595 pp. http://www.grida.no/climate/ipcc/emission/index.htm) for using market exchange rates (MER) instead of purchasing power parities (PPP), when converting regional GDP into a common denominator. The consequence is that poor countries generally appear to be poorer than they actually are. An overstated income gap between the rich and poor countries in the base year gives rise to projections of too high economic growth in the poor countries, because the scenarios are constructed with the aim of reducing the income gap. Castles and Henderson claim that overstated economic growth means that greenhouse gas emissions are overstated as well. However, because closure of the emission-intensity gap between the rich and the poor parts of the world is another important driving force in the scenarios, we argue that the use of MER in the SRES scenarios has not caused an overestimation of the global emission growth because, as far as global emissions are concerned, the overstated income gap is effectively neutralized by the overstated emission-intensity gap.     

A reliable and efficient two-stream algorithm for spherical radiative transfer: Documentation of accuracy in realistic layered media

We present a fast and well documented two-stream algorithm for radiative transfer and particle transport in vertically inhomogeneous, layered media. The physical processes considered are internal production (emission), scattering, absorption, and Lambertian reflection at the lower boundary. The medium may be forced by internal sources as well as by parallel or uniform incidence at the top boundary. This two-stream algorithm is based on a general purpose multi-stream discrete ordinate algorithm released previously. It incorporates all the advanced features of this well-tested and unconditionally stable algorithm, and includes two new features: (i) corrections for spherical geometry, and (ii) an efficient treatment of internal sources that vary rapidly with depth. It may be used to compute fluxes, flux divergences and mean intensities (actinic fluxes) at any depth in the medium. We have used the numerical code to investigate the accuracy of the two-stream approximation in vertically inhomogeneous media. In particular, computations of photodissociation and warming/cooling rates and surface fluxes of ultraviolet and visible radiation for clear, cloudy and aerosol-loaded atmospheres are presented and compared with results from multi-stream computations. The O₃ +hv O(¹D) + O₂ and O₃ +hv O(³P) + O₂ photodissociation rates were considered for solar zenith angles between 0.0–70.0° and surface albedos in the range 0.0–1.0. For small and moderate values of the solar zenith angle and the surface albedo the error made by the two-stream approximation is generally smaller, <10%, than the combined uncertainty in cross sections and quantum yields. Surface ultraviolet and visible fluxes were calculated for the same range of solar zenith angles and surface albedos as the photodissociation rates. It was found that surface ultraviolet and visible fluxes may be calculated by the two-stream approximation with 10% error or less for solar zenith angles less than 60.0° and surface albedos less than 0.5. For large solar zenith angles and/or large surface albedos, conditions typical at high latitudes, the error made by the two-stream approximation may become appreciable, i.e. 20% or more for the photodissociation rates in the lower stratosphere and for ultraviolet and visible surface fluxes for large surface albedos. The two-stream approximation agrees well with multi-stream results for computation of warming/cooling rates except for layers containing cloud and aerosol particles where errors up to 10% may occur. The numerical code provides a fast, well-tested and robust two-stream radiative transfer program that can be used as a software tool by aeronomers, atmospheric physicists and chemists, climate modellers, meteorologists, photobiologists and others concerned with radiation or particle transport problems. Copies of the FORTRAN77 program are available to interested users.     

Analytic approach to auroral electron transport and energy degradation

The interaction of a beam of auroral electrons with the atmosphere is described by the linear transport equation, encompassing discrete energy loss, multiple scattering and secondary electrons. A solution to the transport equation provides the electron intensity as a function of altitude, pitch angle (with respect to the geomagnetic field) and energy. A multi-stream (discrete ordinate) approximation to the transport equation is developed. An analytic solution is obtained in this approximation. The computational scheme obtained by combining the present transport code with the energy degradation method of Swartz (1979) conserves energy identically. The theory provides a framework within which angular distributions can be easily calculated and interpreted. Thus, a detailed study of the angular distributions of “non-absorbed” electrons (i.e., electrons that have lost just a small fraction of their incident energy) reveals a systematic variation with incident angle and energy, and with penetration depth. The present approach also gives simple yet accurate solutions in low order multi-stream approximations. The accuracy of the four-stream approximation is generally within a few per cent, whereas two-stream results for backscattered mean intensities and fluxes are accurate to within 10–15%.     

Late Pleistocene genesis of the middle Yarlung Zhangbo Valley,southern Tibet (China), as deduced by sedimentological and luminescence data

Knowledge on valley formation and palaeohydrology of the Yarlung Zhangbo (named Brahmaputra south of the Himalayas) is still in an early stage. Research was conducted in the middle valley reach around Gonggar in order to investigate the sediment properties, age and palaeoenvironmental implication of a widespread aggradational valley terrace. This heavily dissected terrace, lying c. 25 m above the present floodplain, consists of topping aeolian and colluvial deposits, intermediate lacustrine fines and basal fluvial sands. Sedimentological properties of the lacustrine layers suggest a cold-climate depositional environment. Geochemical data refer to a common provenance of all sediments investigated from a regional catchment area, implying a local provenance of topping loesses and sands by aeolian sorting of nearby fluvial deposits. OSL dates, representing the first luminescence dating effort partly applied to non-aeolian sediments in this valley, cluster closely in the interval 11.7 ± 0.8–17.4 ± 1.4 ka. During the Late Pleistocene (until c. 16 ka) the investigated middle valley reach around Gonggar was occupied by a lake attaining an extension of at least 100 km.     

Dynamics of carbohydrates in the Norwegian Sea inferred from monthly profiles collected during 3 years at 66°N, 2°E

Water samples were collected monthly for 3 years at 66°N, 2°E in the Norwegian Sea, 250 nautical miles off the Norwegian coast. Concentrations of mono- and polysaccharides were measured with the 2,4,6-tripyridyl-s-triazine (TPTZ) spectroscopic method. Total dissolved carbohydrates varied from 3.4 to 28.2 μM C of all samples and the ratio of carbohydrate to dissolved organic C (DOC) varied from an average of 14% at 0–25 m depth to 11% at 800–2000 m depth. This indicates that dissolved carbohydrates were a significant constituent of DOC in the Norwegian Sea. Polysaccharides varied from 0.4 to 21.5 μM C and monosaccharides from 0.7 to 11.7 μM C at all depths. The level of monosaccharides was relatively constant at 2.8–3.2 μM C below the euphotic zone, whereas polysaccharides showed more varying concentrations. Dissolved carbohydrates accumulated during the productive season, reaching maximum concentrations during summer although interannual differences were observed. A significant positive correlation between Chl a and soluble carbohydrate was found in one growing season with nutrient analyses. Average values for total carbohydrates were highest in the surface – 0 to 25 m – with 13.3 μM C and decreased to 8.4 μM C at 800–2000 m depth. The ratio of monosaccharides to polysaccharides exhibited a marked seasonal variation, increased from January to a maximum in June of 1.1, and declined to 0.5 in July.     

Saalian to Weichselian stratigraphy and sedimentation along the Lågjæren – Høgjæren escarpment,southwest Norway

Quaternary sediments along a profile crossing the southern part of the Jæren escarpment, southwestern Norway, have been investigated with regard to their glacial history and sea-level variations. Deposits from at least three glaciations and two ice-free periods between Oxygen Isotope Stage 6 and the Late Weichselian have been identified. Subglacial till directly overlain by a glaciomarine regressional succession indicates a deglaciation, and amino acid ratios in Elphidium excavatum between 0.083 and 0.118 date this event to Oxygen Isotope Stage 6. Sea-level dropped from 130 to below 110 m a.s.l. Subsequently, a short-lived ice advance deposited a marginal moraine and a sandur locally on the escarpment. Stratigraphical position and luminescence dates around 148 ka BP suggest deposition during the final stage 6 deglaciation. A Late Weichselian till covers most of the surface of Jæren. In addition to a well documented westerly ice flow, glaciotectonic indications of ice flow towards the north have been found. Ice flow directions and a hiatus between Oxygen Isotope Stage 6 and the Weichselian indicate enhanced erosion along the escarpment and the influence of a Norwegian Channel ice-stream. Copyright © 1999 John Wiley & Sons, Ltd.     

Scour effects in piled structures—A sensitivity analysis

A sensitivity analysis is presented in this paper to judge the importance of several parameters influencing scour effects on piles of offshore foundations. The decrease of the pile reliability due to scour is also studied by applying the first-order reliability method. Suggestions for lateral pile resistance in design are included.     

Fishing vessel profitability and local economic link obligations—the case of Norwegian trawlers

This paper investigates to what extent limited entry licence local-link obligations hamper economic performance of Norwegian wet fish trawlers. For 1999 average landing prices, gross revenue, net profit and some other economic indicators are compared for three groups of trawlers: (A) vessels that had local-link licence obligations and complied with them; (B) vessels that had such obligations but did not comply; and (C) vessels without local-link obligations. Average operating profit was highest for Group C. Group B vessels’ operating profit was just above that of Group A, despite significantly higher revenues. For all fish species, except redfish, Group C trawlers received higher prices than the other vessels.     

Transferability of hydrological model parameter spaces in the estimation of runoff in ungauged catchments

Abstract

In this study, transferability options of the Hydrologiska Byråns Vattenbalansavdelning (HBV) hydrological model parameter (MP) spaces were investigated to estimate ungauged catchment runoff. Three approaches were applied in the study: MP space transfer from single, neighbouring and all potential donor catchments. The model performance was evaluated by a jackknife procedure, where one catchment at a time was treated as if ungauged, and behavioural MP sets from candidate donor catchments were used to estimate the “ungauged” runoff. The results showed that ungauged catchment runoff estimation could not be guaranteed by transferring MP sets from a single physiographically nearest donor catchment. Integrating MP sets typically from one to six donor catchments supplemented the lack of effective MP sets and improved the model performance at the ungauged catchments. In addition, the analysis results revealed that the model performance converged to an average performance when the MP sets of all potential donor catchments were integrated.     

Geomorphic evolution of small river–lake‐systems in northeast Germany during the Late Quaternary

This study investigates the post‐glacial development of four small river–lake systems in the Weichselian belt of northern central Europe. The valleys investigated are part of an immature drainage system characterized by frequent and abrupt changes in flow direction and the presence of numerous stagnant‐ice depressions in the valley course. The depressions contain thick sedimentary sequences which provide excellent archives for the reconstruction of the post‐glacial valley development. Study results indicate that the valleys reuse segments of former subglacial meltwater channels. During the Late Pleniglacial these channels carried meltwater streams. Stagnant‐ice melting occurred in stages from the Oldest Dryas to the early Holocene and was often followed by the formation of lakes in the valley course. Flow reversals occurred during the Late‐glacial–Holocene transition and were in response to general base‐level lowering caused by stagnant‐ice melting, headwater erosion and lake overspills. Lacustrine deposition typically started during the early Late‐glacial comprising mainly silicate gyttjas, whereas organic gyttjas and peats accumulated during the Allerød. The Younger Dryas is associated with a marked increase in fluvial and aeolian sedimentation, and lake‐level high stands. This was followed by early Holocene lake‐level low stands and a subsequent stabilization phase with decreasing silicate input and increasing organic lacustrine deposition. In general, dramatic changes in Late Pleniglacial to early Holocene sedimentation suggest that small‐scale catastrophic events played a more important role in triggering geomorphic changes then previously recognized. Infilling continued until peat accumulation and terrestrialization of lake basins became widespread during the mid‐ to late Holocene. Beginning in the late Holocene anthropogenic influences become important mainly involving an increase in sediment supply due to forest clearing and land use, followed by mill stowage, river course correction and anthropogenic lake‐level manipulations. Copyright © 2007 John Wiley & Sons, Ltd.