GGDML: icosahedral models language extensions

The optimization opportunities of a code base are not completely exploited by compilers. In fact, there are optimizations that must be done within the source code. Hence, if the code developers skip some details, some performance is lost. Thus, the use of a general-purpose language to develop a performance-demanding software -e.g. climate models- needs more care from the developers. They should take into account hardware details of the target machine. Besides, writing a high-performance code for one machine will have a lower performance on another one. The developers usually write multiple optimized sections or even code versions for the different target machines. Such codes are complex and hard to maintain. In this article we introduce a higher-level code development approach, where we develop a set of extensions to the language that is used to write a model’s code. Our extensions form a domain-specific language (DSL) that abstracts domain concepts and leaves the lower level details to a configurable source-to-source translation process. The purpose of the developed extensions is to support the icosahedral climate/atmospheric model development. We have started with the three icosahedral models: DYNAMICO, ICON, and NICAM. The collaboration with the scientists from the weather/climate sciences enabled agreed-upon extensions. When we have suggested an extension we kept in mind that it represents a higher-level domain-based concept, and that it carries no lower-level details. The introduced DSL (GGDML- General Grid Definition and Manipulation Language) hides optimization details like memory layout. It reduces code size of a model to less than one third its original size in terms of lines of code. The development costs of a model with GGDML are therefore reduced significantly

Retrievals of ethane from groundbased highresolution FTIR solar observations with updated line parameters: determination of the optimum strategy for the Jungfraujoch station.

Ethane (C2H6) is the most abundant Non-Methane HydroCarbon (NMHC) in the Earth’s atmosphere, with a lifetime of approximately 2 months. Its main sources are biomass burning, natural gas loss and biofuel consumption. Oxidation by the hydroxyl radical is the major C2H6 sink as it controls its strong modulation throug the year. C2H6 is involved in the formation of tropospheric O3 and in the destruction of atmospheric methane through changes in OH. C2H6 is an indirect greenhouse gas with a net-global warming potential of 5.5 (100-yr horizon). Updates of retrieval parameters such as the spectroscopic linelists have been recently published. We will therefore characterize three µ-windows encompassing the strongest C2H6 features after careful selection of these new parameters, accounting at best for all interfering species. The aim is to lessen the fitting residuals while maximizing the information content, the precision and the reliability of the retrieved product. We will present updated C2H6 total and tropospheric column time series, using the SFIT-2 algorithm (v3.91) and high-resolution Fourier Transform Infrared (FTIR) solar absorption spectra recorded with a Bruker 120HR instrument, at the high altitude research station of the Jungfraujoch (46.5°N, 8.0°E, 3580 m asl), within the framework of the Network for the Detection of Atmospheric Composition Change (NDACC, http://www.ndacc.org). Comparisons with synthetic data produced by chemical transport models will also be presented

ナンボク リョウキョクイキ ニオケル タイキチュウ ノ オンシツ コウカ キタイ ト カンレン キタイ ノ ヘンドウ

南北両極域における温室効果気体の変動を明らかにし,それらの放出源・吸収消滅源の変動に関する知見を得るために,南極・昭和基地および北極・スバールバル諸島ニーオルスンにおいて系統的な温室効果気体及び関連気体観測を開始し,現在も継続している.大気中のCO_2 濃度は,両極域共に明瞭な季節変化を伴いながら,化石燃料消費と森林破壊によるCO_2 の放出を反映して約1.9 ppmv yr^ の割合で増加している.CH_4 濃度にも明瞭な季節変化と不規則な経年変化が見られ,両極域において1999年までの濃度増加と2000年以降の濃度停滞,そして2007年には再び濃度増加が観測された.CH_4 の同位体比観測から,CH_4 濃度の季節変化,経年変化の原因に関する情報が得られた.大気中のO_2 濃度(δ(O_2 N_2))は両極域において,季節変化と化石燃料消費に起因する経年的減少を示した.Atmospheric Potential Oxygen(APO)とCO_2 濃度の増加率から見積もられた,陸上生物圏と海洋によるCO_2 吸収量(2001-2009年の平均)はそれぞれ1.1,2.7 GtC yr^ であった.ニーオルスンで観測されたN_2O濃度の季節変化を3次元化学輸送モデルによる計算結果と比較することにより,N_2O濃度の季節変化振幅は,夏季に成層圏起源のN_2O濃度が低い気塊が地表付近まで流入することによって,拡大している可能性が示唆された.昭和基地におけるCO濃度の連続観測と3次元化学輸送モデルを用いた解析により,2003年2-3月と2007年2月に,オーストラリアでの大規模な林野火災によって発生したCOが昭和基地に達していることが示された.昭和基地における地上オゾン濃度連続観測によって,1988-2008年までの間に計40例以上の地上オゾン破壊現象を観測した.To elucidate temporal variations of greenhouse gases and their related gases in the Arctic and Antarctic regions and to investigate their sources and sinks, systematic measurements of atmospheric CO_2, CH_4CO, N_2O, O_2 and tropospheric O_3 concentrations have been carried out at Syowa Station, Antarctica and Ny-Alesund, Svalbard. The CO_2 concentrations at both polar sites have increased at a rate of about 1.9 ppmv yr^, reflecting fossil fuel combustion and land use change. The CH_4 concentrations also showed clear seasonal cycles superimposed on complex secular trends. The increase rate of the CH_4 concentration varied with time. CH_4 increases were observed until 1999, the concentrations remained steady from 2000 to 2006 and then rapid increases were observed in 2007. Stable isotope data of CH_4 revealed causes of the seasonal cycles and the secular variations of the CH_4 concentrations. The O_2 concentrations (δ(O_2 N_2)) at both polar sites showed prominent seasonal cycles and secular decreasing trends. From analyses of the Atmospheric Potential Oxygen (APO) and CO_2 concentrations, the CO_2 uptake rates by the terrestrial biosphere and the ocean were estimated to be 1.1 and 2.7 GtC yr^, respectively. By comparing the N_2O concentrations observed at Ny-Alesund and numerical model results, it was suggested that the observed seasonal N_2O cycle could be enlarged by intrusion of a stratospheric air mass with low N_2O concentration into the troposphere in summer. With an analysis using a three dimensional chemical-transport model and the CO concentration at Syowa Station, sporadic increases of CO concentration observed in February-March, 2003 and February, 2007 were ascribed to CO release by large-scale forest fires in Australia. Surface ozone depletion events were observed more than 40 times at Syowa Station from 1988 to 2007

Extension of the long-term total column time series of atmospheric methane above the Jungfraujoch station: analysis of grating infrared spectra between 1976 and 1989

Methane (CH4) is one of the most abundant greenhouse gases in the Earth’s atmosphere, with current mean volume mixing ratio close to 1800 ppb. Since methane has a global warming potential of 25 (100-yr horizon) and an atmospheric lifetime of 12 years, the Kyoto Protocol has included it among the species to be regulated to limit global warming. Anthropogenic sources of methane are mainly energy production (coal and leaks) and agriculture while main natural sources are swamps and biomass waste. The main sink of methane is oxidation in the troposphere, primarily by reaction with the hydroxyl radical. Methane trends have exhibited significant changes during the last twenty-five years. For instance, long-term monitoring of its vertical total column above the high-altitude station of the Jungfraujoch (46.5°N, 8°E, 3580 m asl) has indeed allowed to derive column changes ranging from +0.72% in 1987-1988 to +0.14% in 1999-2000 (Zander et al., 2002), relative to 1988 and 2000, respectively. More recently and for the same site, Duchatelet et al. (2010) have even reported a significant slowdown of -0.02%/yr between years 2000 and 2005. This study also showed that since then, CH4 is on the rise again, at a rate close to +0.30%/yr. While the numbers reported here above have been derived from the Fourier Transform Infrared (FTIR) data set starting in 1984, earlier pioneering observations have been collected at the Jungfraujoch since 1950, using grating spectrometers. During the 1958-1975 period, the main objectives has been the study of the solar photosphere in the visible and the near infrared and the publication of high-resolution solar atlases. From 1976 to 1989, narrow-band IR solar absorption observations achieving a spectral resolution of about 0.02 cm-1 have been recorded with the high-performance double-pass grating spectrometer. Analysis of these historical spectra provides a unique opportunity to extend the Jungfraujoch’s total column time series of important atmospheric gases, including methane, by nearly 10 years. The aim of this contribution is to present the inversion strategy adopted to derive CH4 from the grating spectra, using the SFIT-2 algorithm (v3.91) We will evaluate the impact of resolution, spectroscopic parameters (from the EU HYMN project -see www.knmi.nl/samen/hymn-, and from HITRAN 2004), atmospheric pressure and temperature profiles on the error budget. The 1976-1989 total column time series produced will be presented and critically discussed. In particular, we will identify and correct for possible biases between double-pass grating spectrometer measurements and more recent FTIR total columns. The harmonized and consolidated time series will be investigated to characterize the long-term trend of methane for the 1976-2010 time period. Comparisons with synthetic data produced by the CHASER 3-dimensional chemical transport model will also be presented and analyzed

Unrealistically pristine air in the Arctic produced by current global scale models

Black carbon aerosol (BCA) in the Arctic has profound impacts on the global climate system through radiation processes. Despite its enormous impacts, current global scale models, powerful tools for estimating overall impact, tend to underestimate the levels of BCA in the Arctic over several seasons. Using a global aerosol transport simulation with a horizontal grid resolution of 3.5 km, we determined that a higher resolution significantly reduced the underestimation of BCA levels in the Arctic, mainly due to an enhancement of the representation of low-pressure and frontal systems. The BCA mass loading in the Arctic simulated with 3.5-km grid resolution was 4.2-times larger than that simulated with coarse (56-km) grid resolution. Our results also indicated that grid convergence had not occurred on both the contrast between the cloud/cloud free areas and the poleward BCA mass flux, despite the use of the 3.5-km grid resolution. These results suggest that a global aerosol transport simulation using kilometre-order or finer grid resolution is required for more accurate estimation of the distribution of pollutants in the Arctic