著者

Bjorn STEVENS Masaki SATOH

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.99, no.6, pp.1393-1394, 2021 (Released:2021-12-24)

参考文献数

10

著者

Falko JUDT Daniel KLOCKE Rosimar RIOS-BERRIOS Benoit VANNIERE Florian ZIEMEN Ludovic AUGER Joachim BIERCAMP Christopher BRETHERTON Xi CHEN Peter DÜBEN Cathy HOHENEGGER Marat KHAIROUTDINOV 小玉 知央 Luis KORNBLUEH Shian-Jiann LIN 中野 満寿男 Philipp NEUMANN William PUTMAN Niklas RÖBER Malcolm ROBERTS 佐藤 正樹 澁谷 亮輔 Bjorn STEVENS Pier Luigi VIDALE Nils WEDI Linjiong ZHOU

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.99, no.3, pp.579-602, 2021 (Released:2021-06-10)

参考文献数

68

被引用文献数

26

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近年のコンピューターとモデル開発の進歩により、全球ストーム解像モデルの時代が始まり、それに伴って気象や気候予測が一変する可能性を秘めている。本研究では、この新しいクラスのモデルを検証するという一般的なテーマの中で、9つの全球ストーム解像モデルについて、熱帯低気圧(TC)をシミュレートする能力を評価した。その結果、大まかにいえば、これらのモデルは現実的な熱帯低気圧を再現し、熱帯低気圧の強度の正確なシミュレーションを可能とするなど、全球モデルの長年の課題が解消されていることが示された。一方、TCはモデルの設計に強く影響され、全てのモデルはTCの数、強度、大きさ、構造に関して独自のバイアスを持っている。いくつかのモデルは他のモデルよりも優れたTCをシミュレートするが、全ての点で優れたモデルが存在するわけではなかった。全体的な結果は、全球ストーム解像モデルがTC予測の新時代を切り拓くことが可能であることを示しているが、その可能性を最大限に引き出すためには改良が必要である。

著者

Jiawei BAO Bjorn STEVENS

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.99, no.6, pp.1483-1499, 2021 (Released:2021-12-24)

参考文献数

34

被引用文献数

2 5

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Understanding of the tropical atmosphere is elaborated around two elementary ideas, one being that density is homogenized on isobars, which is referred to as the weak temperature gradient (WTG), and the other being that the vertical thermal structure follows a moist-adiabatic lapse rate. This study uses simulations from global storm-resolving models to investigate the accuracy of these ideas. Our results show that horizontally, the density temperature appears to be homogeneous, but only in the mid- and lower troposphere (between 400 hPa and 800 hPa). To achieve a homogeneous density temperature, the horizontal absolute temperature structure adjusts to balance the horizontal moisture difference. Thus, water vapor plays an important role in the horizontal temperature distribution. Density temperature patterns in the mid- and lower troposphere vary by about 0.3 K on the scale of individual ocean basins but differ by 1 K among basins. We use equivalent potential temperature to explore the vertical structure of the tropical atmosphere, and we compare the results assuming the temperature following pseudo-adiabat and reversible-adiabat (isentropic) with the effect of condensate loading. Our results suggest that the tropical atmosphere in saturated convective regions tends to adopt a thermal structure that is isentropic below the zero-degree isotherm and pseudo-adiabatic above it. However, the tropical mean temperature is substantially colder and is set by the bulk of convection, which is affected by entrainment in the lower troposphere.

著者

Bjorn STEVENS Claudia ACQUISTAPACE Akio HANSEN Rieke HEINZE Carolin KLINGER Daniel KLOCKE Harald RYBKA Wiebke SCHUBOTZ Julia WINDMILLER Panagiotis ADAMIDIS Ioanna ARKA Vasileios BARLAKAS Joachim BIERCAMP Matthias BRUECK Sebastian BRUNE Stefan A. BUEHLER Ulrike BURKHARDT Guido CIONI Montserrat COSTA-SURÓS Susanne CREWELL Traute CRÜGER Hartwig DENEKE Petra FRIEDERICHS Cintia Carbajal HENKEN CATHY Hohenegger Marek JACOB Fabian JAKUB Norbert KALTHOFF Martin KÖHLER Thirza W. van LAAR Puxi LI Ulrich LÖHNERT Andreas MACKE Nils MADENACH Bernhard MAYER Christine NAM Ann Kristin NAUMANN Karsten PETERS Stefan POLL Johannes QUAAS Niklas RÖBER Nicolas ROCHETIN Leonhard SCHECK Vera SCHEMANN Sabrina SCHNITT Axel SEIFERT Fabian SENF Metodija SHAPKALIJEVSKI Clemens SIMMER Shweta SINGH Odran SOURDEVAL Dela SPICKERMANN Johan STRANDGREN Octave TESSIOT Nikki VERCAUTEREN Jessica VIAL Aiko VOIGT Günter ZÄNGL

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.98, no.2, pp.395-435, 2020 (Released:2020-05-08)

参考文献数

131

被引用文献数

12 85

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More than one hundred days were simulated over very large domains with fine (0.156 km to 2.5 km) grid spacing for realistic conditions to test the hypothesis that storm (kilometer) and large-eddy (hectometer) resolving simulations would provide an improved representation of clouds and precipitation in atmospheric simulations. At scales that resolve convective storms (storm-resolving for short), the vertical velocity variance becomes resolved and a better physical basis is achieved for representing clouds and precipitation. Similarly to past studies we found an improved representation of precipitation at kilometer scales, as compared to models with parameterized convection. The main precipitation features (location, diurnal cycle and spatial propagation) are well captured already at kilometer scales, and refining resolution to hectometer scales does not substantially change the simulations in these respects. It does, however, lead to a reduction in the precipitation on the time-scales considered – most notably over the ocean in the tropics. Changes in the distribution of precipitation, with less frequent extremes are also found in simulations incorporating hectometer scales. Hectometer scales appear to be more important for the representation of clouds, and make it possible to capture many important aspects of the cloud field, from the vertical distribution of cloud cover, to the distribution of cloud sizes, and to the diel (daily) cycle. Qualitative improvements, particularly in the ability to differentiate cumulus from stratiform clouds, are seen when one reduces the grid spacing from kilometer to hectometer scales. At the hectometer scale new challenges arise, but the similarity of observed and simulated scales, and the more direct connection between the circulation and the unconstrained degrees of freedom make these challenges less daunting. This quality, combined with already improved simulation as compared to more parameterized models, underpins our conviction that the use and further development of storm-resolving models offers exciting opportunities for advancing understanding of climate and climate change.