過去のセミナー

2016年9月13日 Yvan Orsolini博士セミナー

場 所:東京大学先端科学技術研究センター3号館307号室 (アクセス)
日 時:9月13日(火)16:00~17:30
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講演者:Dr. Yvan Orsolini (University of Bergen)
題 目:Coupling of the troposphere-stratosphere-mesosphere-thermosphere during SSW
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2016年7月22日 Seok-Woo Son教授セミナー

場 所:東京大学先端科学技術研究センター3号館 中2階セミナールーム (アクセス)
日 時:7月22日(金)16:30~17:00
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講演者:Prof. Seok-Woo Son (Seoul National University)
題 目:The role of stratosphere-troposphere dynamic coupling on the subseasonal-to-seasonal prediction

要 旨
It has been widely recognized that stratosphere can affect tropospheric circulation on various time scales. Such influences include downward coupling associated with the Antarctic ozone (O3), equatorial Quasi-Biennial Oscillation (QBO), and stratospheric sudden warming (SSW).
In this presentation, their implications to the subseasonal-to-seasonal (S2S) prediction are discussed with a particular emphasis on the possible impacts of the QBO on the boreal-winter Madden-Julian Oscillation (MJO) and the associated teleconnection pattern in the operational S2S prediction models.
The predictability of SSW and its influence on the extratropical surface weather and climate are also briefly discussed.
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2016年7月8日 Thomas Spengler教授セミナー

場 所:東京大学先端科学技術研究センター3号館 307号室 (アクセス)
日 時:7月8日(金)16:00~17:30
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講演者:Prof. Thomas Spengler (University of Bergen)
題 目:Upper Tropospheric Jet Axis Detection: Winter 2013/2014 and Northern Hemispheric Variability
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2016年6月29日 Shang-Ping Xie教授セミナー

場 所:東京大学先端科学技術研究センター3号館 中2階セミナールーム (アクセス)
日 時:6月29日(金)15:00~16:30
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講演者:Prof. Shang-Ping Xie (Scripps Institution of Oceanography)
題 目:Convective jump, post-El Niño Pacific-Japan pattern, and the conundrum of SST-convection relationship over the Northwest Pacific

要 旨
The abrupt onset of deep convection in late July over the tropical Northwest Pacific is associated with dramatic changes in East Asian climate, including the termination of the Meiyu-Baiu rainy period in southeastern China-Japan and the start of the rainy season for northeastern China (Ueda et al. 1995). What triggers this Ueda Jump has been a mystery as local SSTs exceed 28oC at least a month earlier. We show that the gradual moistening of the mid-troposphere leads to a threshold behavior in the Ueda Jump. Specifically, the entrainment in the stable dry layer above the planetary boundary layer causes convective plumes lose buoyancy until the gradual moistening of the dry layer eventually allows the entraining plume to retain positive buoyancy. Once breaking through the dry layer, the convection can reach all the way to the tropopause, forcing a Pacific-Japan pattern to transform East Asian climate.
This summer is being closely watched because the Pacific-Japan pattern tends to develop following a major El Nino, resulting in an active Meiyu-Baiu season in East Asia. On one hand, atmospheric GCMs forced with observed SST can generally simulate the interannual Pacific-Japan pattern but on the other hand, they distort the local SST-rainfall correlation. We will tackle this conundrum in the seminar.
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2015年11月24日 Yang Zhang博士セミナー

場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
日 時:11月24日(火)17:00~18:30
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講演者:Dr. Yang Zhang (Nanjing University)
題 目:Roles of barotropic and baroclinic eddy feedbacks in the midlatitude eddy-driven jet response to lower-tropospheric thermal forcing

要 旨
Both observations and climate model simulations have shown that the eddy-driven jet exhibits significant meridional shift in response to the lower-boundary thermal forcing, such as the recent Arctic amplified warming induced by the sea ice loss, extra-tropical sea surface temperature anomalies and El Nino-like oceanic warming. Understanding the dynamical mechanisms of the atmospheric response to such lower- boundary thermal forcing is central for the prediction of the mid-latitude climate and evaluation on the climate change sensitivity. In this talk, the mechanism through which lower level thermal forcing affecting the jet shift is investigated by using an idealized dynamical model. Further more, through the Finite Amplitude Wave Activity diagnostics and by overriding the barotropic wind in the potential vorticity advection, the relative roles of barotropic and baroclinic processes in the eddy feedbacks are quantified and explicitly compared. Unlike the conventional baroclinic viewpoint, our study suggests the important role of barotropic feedback process in the total atmospheric response to the lower boundary thermal forcing. The mechanism revealed in this study also provides a dynamical interpretation for the change in Rossby wave breaking frequency during El Nino or under climate warming. ------------

2015年11月26日 Yang Zhang博士・Harry Hendon博士セミナー

場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
日 時:11月26日(木)15:00~18:30
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講演者:Dr. Yang Zhang (Nanjing University)
題 目:The Annular Modes: dynamics, diagnostics and model simulations

要 旨
The annular modes (with its former name Artic Oscillation, Antarctic Oscillation) are the leading modes of Northern/Southern Hemisphere extratropical variability on intraseasonal time scales, which is often described as a nearly zonally symmetric latitudinal displacement of the midlatitude jet. The dominance and persistence of the annular modes are suggested due to the positive eddy-mean flow feedbacks. Understanding the dynamics of the Annular Modes is important for the extratropical intraseasonal and decadal predictability. In this talk, I will first review the barotropic and baroclinic mechanisms that have been proposed for the positive eddy-mean flow feedbacks, and introduce a new mechanism through which low-frequency and synoptic eddies working symbiotically extending the persistence of the jet shift. This talk further introduces a new method to quantify the relative contributions of the barotropic and baroclinic eddy feedbacks to the Annular Modes persistence. Through a “hybrid Eulerian-Lagrangian Finite Amplitude Wave Activity diagnostic” using the ERA-40 and ERA- Interim reanalysis data, the different roles of barotropic and baroclinic eddy feedbacks in the annular modes are identified. The new diagnostics are also applied to assess the Annular Mode simulations in the CMIP5 models. The abilities of the state of the art climate models in simulating the eddy feedbacks in the annular modes are discussed.
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講演者:Dr. Harry Hendon (Bureau of Meteorology in Melbourne Australia)
題 目:Weakened Predictability of El Nino in the Early 21st Century

要 旨
Predictive skill for El Niño in the tropical eastern Pacific across a range of forecast systems and models declined sharply in the early 21st century relative to what was achieved in the last two decades of the 20th century despite ongoing improvements of forecast systems and ocean observations used to initialize the forecasts. This decline coincided with a reduction of El Niño variability together with a shift in Pacific climate to a stronger Walker circulation at the end of the 20th century that has previously been associated with the hiatus in global warming. We show, using seasonal forecast sensitivity experiments with the Australian Bureau of Meteorology coupled model seasonal prediction system POAMA2.4, that the shift to a stronger Walker circulation weakened the ocean-atmosphere feedbacks that amplify El Niño in the eastern Pacific, thus resulting in weaker variability that is less predictable. Anticipating future decadal changes in El Niño predictability is an outstanding challenge because prediction of natural decadal variations of Pacific climate such as occurred at the end of the 20th century has not been demonstrated and no consensus has yet emerged about impacts of anthropogenic climate change on El Niño variability, hence predictability, in a future climate.
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2015年6月22日 Stuecker博士セミナー

場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
日 時:6月22日(水)16:00~
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講演者:Dr. Malte Stuecker (ハワイ大学)
題 目:ENSO/Annual Cycle interactions and their impact on Indo-Pacific climate

要 旨
Nonlinear interactions between the El Niño-Southern Oscillation (ENSO) and the Western Pacific warm pool annual cycle generate an atmospheric combination mode (C-mode) of atmospheric circulation variability. We demonstrate that C-mode dynamics are responsible for the development of an anomalous low-level North-West Pacific anticyclone (NWP-AC) during El Niño events. The NWP-AC is embedded in a large-scale meridionally anti-symmetric Indo-Pacific atmospheric circulation response and has been shown to exhibit large impacts on the Asian Monsoon system.
In contrast to previous studies, we find the role of air-sea coupling in the Indian Ocean and North-West Pacific only of secondary importance for the NWP-AC genesis. Moreover, the NWP-AC is clearly marked in the frequency domain by near-annual combination tones, which have been overlooked in previous Indo-Pacific climate studies.
Furthermore, we hypothesize a positive feedback loop involving the anomalous low-level NWP-AC through El Niño and C-mode interactions: the development of the NWP-AC as a result of the C-mode acts to rapidly terminate El Niño events. The subsequent phase shift from retreating El Niño conditions towards a developing La Niña phase terminates the low-level cyclonic circulation response in the Central Pacific and thus indirectly enhances the NWP-AC and allows it to persist until boreal summer. Anomalous local circulation features in the Indo-Pacific (such as the NWP-AC) can be considered a superposition of the quasi-symmetric linear ENSO response and the meridionally anti-symmetric annual cycle modulated ENSO response (C-mode).
We emphasize that it is not adequate to assess ENSO impacts by considering only interannual timescales. C-mode dynamics are an essential (extended) part of ENSO and result in a wide range of deterministic high-frequency variability. A general framework for this frequency cascade will be discussed.
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2015年4月22日 Orsolini博士ほかセミナー

場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
日 時:4月22日(水)14:00~
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講演者:Dr. Thomas Spengler (ベルゲン大学)
題 目:Climatological analysis of the slope of isentropic surfaces and its tendencies over the North Atlantic

要 旨
The maintenance of baroclinicity along the mid- and high-latitude storm tracks is a matter of ongoing debate. Using an isentropic framework, a novel diagnostic based on the tendency equation for the slope of isentropic surfaces ? a measure of the potential for baroclinic development ? is presented. The tendency comprises contributions from dynamic processes, latent heat release, radiation, and sub-gridscale turbulence, which incorporates the effect of sensible heat fluxes. A climatology of these tendencies over the North Atlantic is compiled for the winters 2009 and 2010.
It is found that adiabatic tilting flattens the isentropic surfaces, reflecting the action of growing baroclinic cyclones. This tendency is climatologically balanced by the generation of slope by diabatic processes. In the lower troposphere, the most intense diabatic increase of slope is found along the oceanic frontal zone associated with the Gulf Stream and at higher latitudes in the Labrador Sea, the Nordic Seas and the Barents Sea. Latent heat release and sensible heat fluxes both contribute substantially in these regions. A quantitative analysis of cold air outbreaks emphasises their important role for restoring the slope in the lower troposphere over the Gulf Stream region and off the sea-ice edge at high latitudes. In the upper troposphere, latent heat release due to cloud microphysical processes is the dominant mechanism maintaining the slope.
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講演者:Dr. Annick Terpstra (ベルゲン大学)
題 目:The influence of surface fluxes on forward shear polar low development in idealized simulations

要 旨
To gain insight into the influence of surface fluxes on the dynamical mechanisms of polar low formation we utilise an idealised numerical baroclinic channel model with boundary layer parameterisations. Growth of the perturbation is initiated by a low level warm-cored cyclone.

Firstly, we explore the role of latent heating during polar low formation. The experimental design resembles a typical forward-shear moist-baroclinic environment at high-latitudes. Cyclogenesis is triggered by a weak, low-level thermal perturbation in hydrostatic and geostrophic balance. Within the experimental setup, significant disturbance growth is possible in absence of upper level forcing, surface fluxes, and radiation. The relative importance of the generation of eddy available potential energy by diabatic versus baroclinic processes is used to differentiate between the dynamical processes contributing to disturbance growth. The experiments indicate that sufficient latent heat release in the north-eastern quadrant of the cyclone is crucial for rapid disturbance intensification, where environmental relative humidity, baroclinicity and static stability all play a role in the potential of latent heat release to occur. The relative shallow perturbation depth at high-latitudes improves the effectiveness of latent heat release on cyclone amplification.

Secondly, we explore the role of surface fluxes during polar low formation. In addition to the previous experimental design we included parameterisations for surface friction and surface turbulence fluxes. Furthermore we imitate a cold air outbreak by introducing a uniform temperature difference between the sea-surface temperature and low-level air temperature. Evaluation of the spatial distribution of the generation of eddy available potential energy indicates that surface sensible heat fluxes are decreasing the eddy available potential energy. Futhermore, simulations including surface turbulence fluxes exhibit the development of a warm-core, which in addition decreases the eddy available potential energy.
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講演者:Dr. Yvan Orsolini (ベルゲン大学)
題 目:Impact of springtime snow over the Himalayan-Tibetan Plateau on the onset of the Indian summer monsoon in coupled forecasts

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2015年3月26日 Hsu博士セミナー

場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
日 時:3月26日(木)16:30~18:30
講演者:Dr. Huang-Hsiung Hsu (中央研究院)
題 目:SSTa, SICa, and Extreme Circulation during the 2013–14 Boreal Winter

要 旨
Unprecedented atmospheric circulations with extreme weather and climate were observed in the extratropical Northern Hemisphere during the winter of 2013-2014. The anomalous circulations were the manifestation of the Pacific pattern or the North Pacific Oscillation/Western Pacific teleconnection pattern but with extremely large amplitude. Simulation results suggest that the anomalous atmospheric circulations were constructively induced by anomalous sea surface temperature (SST) in the tropical Pacific and extratropical North Pacific, as well as the low sea ice concentration (SIC) in the Arctic. Natural variability played a major role in inducing the anomaly pattern, whereas the anomalously warm SST and low sea ice concentration in the Bering Sea contributed to the intensity. If the anthropogenic warming has a significant impact on causing the synchronization of the aforementioned anomalies in SST and SIC and this trend continues, severe winters similar to that in 2013–2014 may occur more frequently in the near future.
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2014年11月21日 Ping Chang教授セミナー

日 時:11月21日(金)16:30~18:00
場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
講演者Prof. Ping Chang (Department of Oceanography, Texas A&M University; 東大先端研フェロー,学振招聘研究者)
題 目:Ocean Mesoscale Eddy-Atmosphere (OMEA) Interaction

要 旨
Like storms and weather in the atmosphere, mesoscale eddies are ubiquitous features in the world oceans, and carry more than half of the kinetic energy of the global ocean circulation. It has been widely recognized that mesoscale ocean eddies play a major role in the mixing and transport of water properties, affecting the generation and maintenance of strong ocean currents and fronts, as well as the physical and biogeochemical properties of water mass. However, the extent to which ocean mesoscale eddies can directly influence the atmosphere, and thereby impact weather and climate, is far from being fully understood. The central theme of this talk is to demonstrate that the ocean and atmosphere interact strongly at frontal- and meso-scales, and this interaction can be critically important for understanding, simulating and predicting weather and climate extremes, such as tropical cyclones and extratropical winter storms. High-resolution modeling and observational evidence will be presented to showcase how ocean mesoscale eddies can exert both local and remote influences on near-surface wind and rainfall patterns and how ocean mesoscale eddy-atmosphere (OMEA) feedback can potentially affect energetics and structures of strong ocean currents and fronts. Current generation global climate models and observing systems are inadequate in fully resolving the complex nature of OMEA interaction. Improving our capability to better observe and model OMEA interaction remains one of the grand challenges for oceanographers and climate scientists.
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2015年1月23日 東大先端研セミナー

場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
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日 時:1月23日(金)10:00~11:30
講演者:Dr. Lin Wang (中国大気科学院大気物理研究所)
題 目:The extreme European cold spell in 2011/12 winter: observed features and possible causes
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日 時:1月23日(金)12:30~14:00
講演者:Prof. Ping Chang (Texas A&M University)
題 目:Towards Understanding of Extratropical Climate Variability: Role of Atmospheric Synoptic Storms and Frontal-and Meso-scale Ocean-Atmosphere Interaction

要 旨
Western boundary current regimes, such as the Kuroshio and Gulf Stream Extension regions, are critical regions for atmospheric synoptic storm development and strong frontal-and meso-scale ocean-atmosphere interaction. In this talk, we will attempt to explore potential contributions from both these processes to large-scale extratropical climate variability.
In the first part of the talk, we will present results of an observationally-based analysis on the relationship between extreme flux events over Kuroshio Extension region (KER) and Gulf Stream region (GSR) associated with North Pacific and Atlantic cold-air outbreaks and patterns of large-scale climate variability in these regions.
In the second part of the talk, we will present results of high-resolution climate model simulations designed to explore and understand how frontal-and meso-scale ocean-atmosphere interaction can affect large-scale atmospheric and oceanic circulations.
Collectively, the findings of these studies point to the importance of frontal-and meso-scale ocean-atmosphere dynamics in extratropical climate variability, and thus the need of improving their representation in climate models.
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2014年11月21日 Ping Chang教授セミナー

日 時:11月21日(金)16:30~18:00
場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
講演者Prof. Ping Chang (Department of Oceanography, Texas A&M University; 東大先端研フェロー,学振招聘研究者)
題 目:Ocean Mesoscale Eddy-Atmosphere (OMEA) Interaction

要 旨
Like storms and weather in the atmosphere, mesoscale eddies are ubiquitous features in the world oceans, and carry more than half of the kinetic energy of the global ocean circulation. It has been widely recognized that mesoscale ocean eddies play a major role in the mixing and transport of water properties, affecting the generation and maintenance of strong ocean currents and fronts, as well as the physical and biogeochemical properties of water mass. However, the extent to which ocean mesoscale eddies can directly influence the atmosphere, and thereby impact weather and climate, is far from being fully understood. The central theme of this talk is to demonstrate that the ocean and atmosphere interact strongly at frontal- and meso-scales, and this interaction can be critically important for understanding, simulating and predicting weather and climate extremes, such as tropical cyclones and extratropical winter storms. High-resolution modeling and observational evidence will be presented to showcase how ocean mesoscale eddies can exert both local and remote influences on near-surface wind and rainfall patterns and how ocean mesoscale eddy-atmosphere (OMEA) feedback can potentially affect energetics and structures of strong ocean currents and fronts. Current generation global climate models and observing systems are inadequate in fully resolving the complex nature of OMEA interaction. Improving our capability to better observe and model OMEA interaction remains one of the grand challenges for oceanographers and climate scientists.
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2014年10月10日 堀田大介博士セミナー

日 時:10月10日(金)16:45~18:15
場 所:東京大学先端科学技術研究センター3号館207号室 (アクセス)
講演者:堀田大介(気象庁数値予報課技術専門官)
題 目:アンサンブル・データ同化に基づく観測の予報感度(EFSO)を用いた「先回り的品質管理」(Proactive QC)

要 旨
 2011年8月より3年間、米国メリーランド大学の応用数学プログラムに留学し、数値天気予報、特にデータ同化に関する研究を行って博士号を取得した。本セミナーでは博士論文の成果のうち、アンサンブル・データ同化を用いた感度解析に関連する話題を2つ紹介する。セミナーでは冒頭で数値予報とデータ同化に関する簡単な解説を行なう予定なので、以下に述べた研究の概要が理解できなくとも心配しないで頂きたい。

 1つ目は観測データの品質管理への応用である。大気はカオス的力学系であり、初期値に誤差があればそれが如何に微小であってもモデルの積分時間が長くなるとともに予報が現実から乖離してしまう。数値予報システムにおいては、短時間の予報を観測により修正し新たな初期値を作成することにより予報の現実からの乖離を防いでいる。この処理をデータ同化という。しかし、実際の観測値には品質の悪いものも含まれており、これらを同化してしまうとかえって予報が極端に悪化することがある。現業システムでは、個々の観測値を他の観測値やモデルの予報と比較し、不整合がある場合にはこれを排除する処理(品質管理(Quality Control; QC)という)を行い「悪い観測」の同化を防いでいるが、完全に防ぐことはできない。一つ一つの観測について、それが実際に予報を改善するかをどうかを基準に品質管理を行なうことができれば理想的であるが、これまでそれを実現可能な計算コストで行う方法がなかった。一方、近年になって、一つ一つの観測が予報に与えるインパクトを、アンサンブル・データ同化を用いることにより低い計算コストで診断できる手法(Ensemble Forecast Sensitivity to Observations; EFSO)が開発され(Kalnayet al. 2012; Tellus A)、NCEPの現業システムにてその有用性が確認された(Ota et al. 2013; Tellus A)。そこで本研究では、EFSOを用いて予報に悪影響を与えうる観測データを事前に同定しこれを同化しないことで予報の改善をはかる新しい品質管理手法「先回り的品質管理」(Proactive QC) を提案し、これを低解像度版のNCEP現業数値予報システムに実装して実験を行った。実験の結果、34日間136事例中20事例において、予報を悪化させたであろう「悪い」観測がEFSOにより検出された。さらに、検出された20事例について「悪い」観測を排除して同化・予報実験を行ったところ、18事例で予報が改善されること、またそのうち7事例については局所的な予報誤差が30%以上も小さくなることが確認された。本手法は、予報をオンライン的に改善できるのみならず、検出された「悪い」観測に関する知見を蓄積することでオフライン品質管理の改善にも資することが期待できる。また、再解析は実時間の現業システムに比べ時間的制約が厳しくないことから、この手法の応用には特に適している。

 2つ目は観測誤差共分散行列の最適化への応用である。データ同化では予報と観測を「最適な」重みにより加重平均することで解析値を得る。この「最適な重み」(カルマンゲイン行列)は予報と観測それぞれの先験的な不確かさを表わす背景誤差共分散行列(B)および観測誤差共分散行列(R)をもとに算出される。これらの共分散行列はデータ同化システムへ外部から与えられるパラメータであり、チューニングの対象となる。Rのチューニング手法の一つとして、Rの各要素に微小な変分を与えた場合の予報誤差の増減をアジョイント法により見積もる方法が提案されている(Daescu 2008; MWR)が、アジョイントモデルが必要となることから開発や計算にかかるコストが大きいという問題がある。本研究では、アンサンブルを用いた、アジョイント不要で計算コストの低いアルゴリズム(Ensemble Forecast Sensitivity to R; EFSRと呼ぶ)を考案し、簡単な低次元モデルを用いた系でその有効性を確認したのち、これをNCEPの現業システムに実装した。実験の結果、EFSRの診断結果に基づきRをチューニングすることで実際に観測による予報へのインパクトを改善できることが示された。
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Title: Proactive QC based on Ensemble Forecast Sensitivity to Observations(EFSO) and Ensemble Forecast Sensitivity to observation covariance matrix R (EFSR)

Abstract:
Despite recent major improvements in numerical weather prediction (NWP) systems, operational NWP forecasts occasionally suffer from an abrupt drop in forecast skill, a phenomenon called “ orecast skill dropout." Recent studies have shown that the "dropouts" occur not because of the model's deficiencies but by the use of flawed observations that the operational quality control (QC) system failed to filter out. Thus, to minimize the occurrences of forecast skill dropouts, we need to detect and remove such flawed observations.A diagnostic technique called Ensemble Forecast Sensitivity to Observations (EFSO) enables us to quantify how much each observation has improved or degraded the forecast. A recent study (Ota et al., 2013, Tellus A) has shown that it is possible to detect flawed observations that caused regional forecast skill dropouts by using EFSO with 24-hour lead time and that the forecast can be improved by not assimilating the detected observations.

Inspired by their success, in the first part of this study, we propose a new QC method, which we call Proactive QC (PQC), in which flawed observations are detected 6 hours after the analysis by EFSO and then the analysis and forecast are repeated without using the detected observations. This new QC technique is implemented and tested on a lower-resolution version of NCEP's operational global NWP system. The results we obtained are extremely promising; we have found that we can detect regional forecast skill dropouts and the flawed observations after only 6 hours from the analysis and that the rejection of the identified flawed observations indeed improves 24-hour forecasts.

In the second part, we show that the same approximation used in the derivation of EFSO can be used to formulate the forecast sensitivity to observation error covariance matrix R, which we call EFSR. We implement the EFSR diagnostics in both an idealized system and the quasi-operational NWP system and show that it can be used to tune the R matrix so that the utility of observations is improved. Proactive QC, if implemented into the operational system, will allow us to build a database of defective observations. We believe that we can help instrument and algorithm developers to identify and fix potential flaws in their algorithms by providing such database along with relevant metadata. Another important application of this study is to use EFSO and EFSR to accelerate the development of optimal assimilation methods for new observing systems. Current approach based on Observing System Experiment (OSE) has difficulties in obtaining statistically significant signals from new observing systems in the presence of the already abundant observations that are available in the "control" system. EFSO should address this issue by finding forecast impact of each observation and allowing the comparison of the impacts of different observation processing algorithms. Another non-trivial issue in designing assimilation methods for new observing systems is how to optimally specify the R matrix for them; our EFSR diagnostics can be used in this respect.
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2013年

2012年