Refractory Black Carbon Results and a Method Comparison between Solid-state Cutting and Continuous Melting Sampling of a West Antarctic Snow and Firn Core

This work presents the refractory black carbon(rBC)results of a snow and firn core drilled in West Antarctica(79°55'34.6"S,94°21'13.3"W)during the 2014?15 austral summer,collected by Brazilian researchers as part of the First Brazilian West Antarctic Ice Sheet Traverse.The core was drilled to a depth of 20 m,and we present the results of the first 8 m by comparing two subsampling methods—solid-state cutting and continuous melting—both with discrete sampling.The core was analyzed at the Department of Geological Sciences,Central Washington University(CWU),WA,USA,using a single particle soot photometer(SP2)coupled to a CETAC Marin-5 nebulizer.The continuous melting system was recently assembled at CWU and these are its first results.We also present experimental results regarding SP2 reproducibility,indicating that sample concentration has a greater influence than the analysis time on the reproducibility for low rBC concentrations,like those found in the Antarctic core.Dating was carried out using mainly the rBC variation and sulfur,sodium and strontium as secondary parameters,giving the core 17 years(1998?2014).The data show a well-defined seasonality of rBC concentrations for these first meters,with geometric mean summer/fall concentrations of 0.016μg L^?1 and geometric mean winter/spring concentrations of 0.063μg L^?1.The annual rBC concentration geometric mean was 0.029μg L^?1(the lowest of all rBC cores in Antarctica referenced in this work),while the annual rBC flux was 6.1μg m^?2 yr^?1(the lowest flux in West Antarctica records so far).     

Influence of mid-latitude circulation on upper Indus basin precipitation: the explicit role of irrigation

Since much of the flow of the Indus River originates in the Himalayas, Karakoram and Hindu Kush Mountains, an understanding of weather characteristics leading to precipitation over the region is essential for water resources management. This study examines the influence of upper level mid-latitude circulation on the summer precipitation over upper Indus basin (UIB). Using reanalysis data, a geopotential height index (GH) is defined at 200 hPa over central Asia, which has a significant correlation with the precipitation over UIB. GH has also shown significant correlation with the heat low (over Iran and Afghanistan and adjoining Pakistan), easterly shear of zonal winds (associated with central Asian high) and evapotranspiration (over UIB). It is argued that the geopotential height index has the potential to serve as a precursor for the precipitation over UIB. In order to assess the influence of irrigation on precipitation over UIB, a simplified irrigation scheme has been developed and applied to the regional climate model REMO. It has been shown that both versions of REMO (with and without irrigation) show significant correlations of GH with easterly wind shear and heat low. However contrary to reanalysis and the REMO version with irrigation, the REMO version without irrigation does not show any correlation between GH index and evapotranspiration as well as between geopotential height and precipitation over UIB, which is further confirmed by the quantitative analysis of extreme precipitation events over UIB. It is concluded that although atmospheric moisture over coastal Arabian sea region, triggered by wind shear and advected northward due to heat low, also contribute to the UIB precipitation. However for the availability of necessary moisture for precipitation over UIB, the major role is played by the evapotranspiration of water from irrigation. From the results it may also be inferred that the representation of irrigated water in climate models is unavoidable for studying the impact of global warming over the region.     

How accurately are climatological characteristics and surface water and energy balances represented for the Colombian Caribbean Catchment Basin?

In Colombia, the access to climate related observational data is restricted and their quantity is limited. But information about the current climate is fundamental for studies on present and future climate changes and their impacts. In this respect, this information is especially important over the Colombian Caribbean Catchment Basin (CCCB) that comprises over 80 % of the population of Colombia and produces about 85 % of its GDP. Consequently, an ensemble of several datasets has been evaluated and compared with respect to their capability to represent the climate over the CCCB. The comparison includes observations, reconstructed data (CPC, Delaware), reanalyses (ERA-40, NCEP/NCAR), and simulated data produced with the regional climate model REMO. The capabilities to represent the average annual state, the seasonal cycle, and the interannual variability are investigated. The analyses focus on surface air temperature and precipitation as well as on surface water and energy balances. On one hand the CCCB characteristics poses some difficulties to the datasets as the CCCB includes a mountainous region with three mountain ranges, where the dynamical core of models and model parameterizations can fail. On the other hand, it has the most dense network of stations, with the longest records, in the country. The results can be summarised as follows: all of the datasets demonstrate a cold bias in the average temperature of CCCB. However, the variability of the average temperature of CCCB is most poorly represented by the NCEP/NCAR dataset. The average precipitation in CCCB is overestimated by all datasets. For the ERA-40, NCEP/NCAR, and REMO datasets, the amplitude of the annual cycle is extremely high. The variability of the average precipitation in CCCB is better represented by the reconstructed data of CPC and Delaware, as well as by NCEP/NCAR. Regarding the capability to represent the spatial behaviour of CCCB, temperature is better represented by Delaware and REMO, while precipitation is better represented by Delaware. Among the three datasets that permit an analysis of surface water and energy balances (REMO, ERA-40, and NCEP/NCAR), REMO best demonstrates the closure property of the surface water balance within the basin, while NCEP/NCAR does not demonstrate this property well. The three datasets represent the energy balance fairly well, although some inconsistencies were found in the individual balance components for NCEP/NCAR.     

Global increase in record-breaking monthly-mean temperatures

The last decade has produced record-breaking heat waves in many parts of the world. At the same time, it was globally the warmest since sufficient measurements started in the 19th century. Here we show that, worldwide, the number of local record-breaking monthly temperature extremes is now on average five times larger than expected in a climate with no long-term warming. This implies that on average there is an 80 % chance that a new monthly heat record is due to climatic change. Large regional differences exist in the number of observed records. Summertime records, which are associated with prolonged heat waves, increased by more than a factor of ten in some continental regions including parts of Europe, Africa, southern Asia and Amazonia. Overall, these high record numbers are quantitatively consistent with those expected for the observed climatic warming trend with added stationary white noise. In addition, we find that the observed records cluster both in space and in time. Strong El Niño years see additional records superimposed on the expected long-term rise. Under a medium global warming scenario, by the 2040s we predict the number of monthly heat records globally to be more than 12 times as high as in a climate with no long-term warming.     

A Comment on “How Well Can We Measure the Vertical Wind Speed? Implications for Fluxes of Energy and Mass” by Kochendorfer et al.

Kochendorfer et al. (Boundary-Layer Meterol, 145:383–398, 2012) conducted an experiment to evaluate azimuth and angle-of-attack dependent errors of sonic anemometer measurements. Several questions are raised regarding the experimental design and the presented results. The finding that instruments with non-orthogonal sonic paths underestimate fluctuations of vertical wind speed and consequently also scalar fluxes by about 10 % is compared with the results of a hitherto unpublished side-by-side field comparison and other past intercomparison experiments. Scale considerations are presented that raise considerable doubts on the validity of the implicit assumption of Kochendorfer et al. (2012) that the turbulent wind vector is highly correlated across a distance of 1.2 m at a height of 2.5 m over flat grassland, which corresponds to the separation between the sonic anemometers tested in their experiment. Nevertheless, new developments in sonic anemometer design to minimize transducer-shadow effects are desirable.     

A note on climate change adaptation for seaports: a challenge for global ports, a challenge for global society

With 80 % of world trade carried by sea, seaports provide crucial linkages in global supply-chains and are essential for the ability of all countries to access global markets. Seaports are likely to be affected directly and indirectly by climatic changes, with broader implications for international trade and development. Due to their coastal location, seaports are particularly vulnerable to extreme weather events associated with increasing sea levels and tropical storm activity, as illustrated by hurricane “Sandy”. In view of their strategic role as part of the globalized trading system, adapting ports in different parts of the world to the impacts of climate change is of considerable importance. Reflecting the views of a diverse group of stakeholders with expertise in climate science, engineering, economics, policy, and port management, this essay highlights the climate change challenge for ports and suggests a way forward through the adoption of some initial measures. These include both “soft” and “hard” adaptations that may be spearheaded by individual port entities, but will require collaboration and support from a broad range of public and private sector stakeholders and from society at large. In particular, the essay highlights a need to shift to more holistic planning, investment and operation.     

Orbital linkages of Comet 6P/d'Arrest based on its asymmetric light curve

We present an investigation of different models of the nongravitational acceleration on Comet 6P/d'Arrest, as used in orbital linkages spanning 150 years from the discovery of the comet in 1851 until the recent observations made in 2001. Some of our models use the time-shifted g-like function to represent the variation of outgassing rate, but the main thrust is on models using instead a production curve that is fitted to recent light curve observations—mainly those in 1976. We pay special attention to the proper scaling of such a production curve, when applied to other apparitions with a different perihelion distance q, and we find a best fit with a q^−1.6 power-law. Generally, the best fit is found with models, in which the acceleration components are expressed in terms of the angular parameters of the rotating nucleus. We thus find the orientation of the spin axis, and using the orbital evolution we are able to predict a variable time shift of the outgassing curve. The very best results are found when applying this time shift to the light-curve based, angular models. The totality of the 1851-2001 observations can then be linked with a mean residual of less than 4″. This may be brought down to ∼^2″ by solving for individual ‘activity parameters’ of all apparitions, which are multiplicative factors applied to the acceleration amplitudes. These turn out to be within 10% of unity for the best fit. We have also performed a linkage to the observations of Comet 1678 (La Hire) using our models. We find an indication of a secular increase of the amount of asymmetry of the outgassing with respect to perihelion, part of which is due to the variable time shift caused by the orbital evolution.     

Structure of the Keck Telescope — An overview

The structure of the Keck Telescope is briefly described. The design required an innovative approach made necessary by the revolutionary nature of the segmented primary mirror, by the very stringent weight and cost limitations, and by observational and operational needs. Analysis of a progressively more detailed computer model predicts that all design objectives will be met, as shown in a summary of performance characteristics. The paper is illustrated with a number of drawings.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2 1988.