Observation Sensitivity Calculations Using the Adjoint of the Gridpoint Statistical Interpolation (GSI) Analysis System

2008 ◽  
Vol 136 (1) ◽  
pp. 335-351 ◽  
Author(s):  
Yanqiu Zhu ◽  
Ronald Gelaro

Abstract The adjoint of a data assimilation system provides an efficient way of estimating sensitivities of analysis or forecast measures with respect to observations. The NASA Global Modeling and Assimilation Office (GMAO) has developed an exact adjoint of the Gridpoint Statistical Interpolation (GSI) analysis scheme developed at the National Centers for Environmental Prediction (NCEP). The development approach is unique in that the adjoint is derived from a line-by-line tangent linear version of the GSI. Availability of the tangent linear scheme provides an explicit means of assessing not only the fidelity of the adjoint, but also the effects of nonlinear processes in the GSI itself. In this paper, the development of the tangent linear and adjoint versions of the GSI are discussed and observation sensitivity results for a near-operational version of the system are shown. Results indicate that the GSI adjoint provides accurate assessments of the sensitivities with respect to observations of wind, temperature, satellite radiances, and, to a lesser extent, moisture. Sensitivities with respect to ozone observations are quite linear for the ozone fields themselves, but highly nonlinear for other variables. The sensitivity information provided by the adjoint is used to estimate the contribution, or impact, of various observing systems on locally defined response functions based on the analyzed increments of temperature and zonal wind. It is shown, for example, that satellite radiances have the largest impact of all observing systems on the temperature increments over the eastern North Pacific, while conventional observations from rawinsondes and aircraft dominate the impact on the zonal wind increments over the continental United States. The observation impact calculations also provide an additional means of validating the observation sensitivities produced by the GSI adjoint.

2009 ◽  
Vol 24 (6) ◽  
pp. 1691-1705 ◽  
Author(s):  
Daryl T. Kleist ◽  
David F. Parrish ◽  
John C. Derber ◽  
Russ Treadon ◽  
Wan-Shu Wu ◽  
...  

Abstract At the National Centers for Environmental Prediction (NCEP), a new three-dimensional variational data assimilation (3DVAR) analysis system was implemented into the operational Global Data Assimilation System (GDAS) on 1 May 2007. The new analysis system, the Gridpoint Statistical Interpolation (GSI), replaced the Spectral Statistical Interpolation (SSI) 3DVAR system, which had been operational since 1991. The GSI was developed at the Environmental Modeling Center at NCEP as part of an effort to create a more unified, robust, and efficient analysis scheme. The key aspect of the GSI is that it formulates the analysis in model grid space, which allows for more flexibility in the application of the background error covariances and makes it straightforward for a single analysis system to be used across a broad range of applications, including both global and regional modeling systems and domains. Due to the constraints of working with an operational system, the final GDAS package included many changes other than just a simple replacing of the SSI with the new GSI. The new GDAS package contained an upgrade to the Global Forecast System model, including a new vertical coordinate, as well as new features in the GSI that were never developed for the SSI. Some of these new features included changes to the observation selection, quality control, minimization algorithm, dynamic balance constraint, and assimilation of new observation types. The evaluation of the new system relative to the SSI-based system was performed for nearly an entire year of analyses and forecasts. The objective and subjective evaluations showed that the new package exhibited superior forecast performance relative to the old SSI-based system. The new system has been shown to improve forecast skill in the tropics and substantially reduce the short-term forecast error in the extratropics. This implementation has laid the groundwork for future scientific advancements in data assimilation at NCEP.


2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Hongli Fu ◽  
Xinrong Wu ◽  
Wei Li ◽  
Yuanfu Xie ◽  
Guijun Han ◽  
...  

Extracting multiple-scale observational information is critical for accurately reconstructing the structure of mesoscale circulation systems such as typhoon. The Space and Time Mesoscale Analysis System (STMAS) with multigrid data assimilation developed in Earth System Research Laboratory (ESRL) in National Oceanic and Atmospheric Administration (NOAA) has addressed this issue. Previous studies have shown the capability of STMAS to retrieve multiscale information in 2-dimensional Doppler radar radial velocity observations. This study explores the application of 3-dimensional (3D) Doppler radar radial velocities with STMAS for reconstructing a 3D typhoon structure. As for the first step, here, we use an idealized simulation framework. A two-scale simulated “typhoon” field is constructed and referred to as “truth,” from which randomly distributed conventional wind data and 3D Doppler radar radial wind data are generated. These data are used to reconstruct the synthetic 3D “typhoon” structure by the STMAS and the traditional 3D variational (3D-Var) analysis. The degree by which the “truth” 3D typhoon structure is recovered is an assessment of the impact of the data type or analysis scheme being evaluated. We also examine the effects of weak constraint and strong constraint on STMAS analyses. Results show that while the STMAS is superior to the traditional 3D-Var for reconstructing the 3D typhoon structure, the strong constraint STMAS can produce better analyses on both horizontal and vertical velocities.


2009 ◽  
Vol 137 (3) ◽  
pp. 1046-1060 ◽  
Author(s):  
Daryl T. Kleist ◽  
David F. Parrish ◽  
John C. Derber ◽  
Russ Treadon ◽  
Ronald M. Errico ◽  
...  

Abstract The gridpoint statistical interpolation (GSI) analysis system is a unified global/regional three-dimensional variational data assimilation (3DVAR) analysis code that has been under development for several years at the National Centers for Environmental Prediction (NCEP)/Environmental Modeling Center. It has recently been implemented into operations at NCEP in both the global and North American data assimilation systems (GDAS and NDAS, respectively). An important aspect of this development has been improving the balance of the analysis produced by GSI. The improved balance between variables has been achieved through the inclusion of a tangent-linear normal-mode constraint (TLNMC). The TLNMC method has proven to be very robust and effective. The TLNMC as part of the global GSI system has resulted in substantial improvement in data assimilation at NCEP.


2017 ◽  
Vol 34 (4) ◽  
pp. 797-815 ◽  
Author(s):  
Zaizhong Ma ◽  
Eric S. Maddy ◽  
Banglin Zhang ◽  
Tong Zhu ◽  
Sid Ahmed Boukabara

AbstractAs the first of the next-generation geostationary meteorological satellites, Himawari-8 was successfully launched in October 2014 by the Japan Meteorological Agency (JMA) and placed over the western Pacific Ocean domain at 140.7°E. It carries the Advanced Himawari Imager (AHI), which provides full-disk images of Earth at 16 bands in the visible and infrared domains every 10 min. Efforts are currently ongoing at the National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite, Data, and Information Service (NESDIS)/Center for Satellite Applications and Research (STAR) to assimilate Himawari-8 AHI radiance measurements into the National Centers for Environmental Prediction (NCEP) Gridpoint Statistical Interpolation analysis system (GSI). All software development within the GSI to allow for assimilation of Himawari-8 AHI radiance has been completed.This study reports on the assessment of AHI preassimilation data quality by comparing observed clear-sky ocean-only radiances to those simulated using collocated ECMWF analysis, as well as describing procedures implemented for quality control. The impact of the AHI data assimilation on the resulting analyses and forecasts is then assessed using the NCEP Global Forecast System (GFS). A preliminary assessment of the assimilation of AHI data from infrared water vapor channels and atmospheric motion vectors (AMVs) on top of the current global observing system shows neutral to marginal positive impact on analysis and forecast skill relative to an assimilation without AHI data. The main positive impact occurs for short- to medium-range forecasts of global upper-tropospheric water vapor. The results demonstrate the feasibility of direct assimilation of AHI radiances and highlight how humidity information can be extracted within the assimilation system.


Author(s):  
W G S Mahalekamge ◽  
Nilakshi W K Galahitiyawe

The main contribution of this paper is the development of the job-family incivility scale. This paper seeks to explore the complex inter-relationships between workplace incivility and family incivility dimensions of job-family incivility by examining the dynamic processes by which job-family incivility is initiated and sustained using a scale development approach. In doing so, the paper highlights the absence of valid and reliable measures that estimate the compound effect of workplace incivility and family incivility – referred to as job-family incivility. A scale development process introduced by Quazi et al. (2016) is presented and stages in the construction of the scale are discussed including measures of validity and reliability. The findings of the study demonstrate the validity and reliability of the job-family incivility scale developed by the current researchers. The main aims of this research are to emphasize the impact of workplace incivility and family incivility on the employees in the work environment, and to discuss the techniques that can be used to mitigate such detrimental activities.


2010 ◽  
Vol 278 (1712) ◽  
pp. 1661-1669 ◽  
Author(s):  
David Alonso ◽  
Menno J. Bouma ◽  
Mercedes Pascual

Climate change impacts on malaria are typically assessed with scenarios for the long-term future. Here we focus instead on the recent past (1970–2003) to address whether warmer temperatures have already increased the incidence of malaria in a highland region of East Africa. Our analyses rely on a new coupled mosquito–human model of malaria, which we use to compare projected disease levels with and without the observed temperature trend. Predicted malaria cases exhibit a highly nonlinear response to warming, with a significant increase from the 1970s to the 1990s, although typical epidemic sizes are below those observed. These findings suggest that climate change has already played an important role in the exacerbation of malaria in this region. As the observed changes in malaria are even larger than those predicted by our model, other factors previously suggested to explain all of the increase in malaria may be enhancing the impact of climate change.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fatemeh Narenji Thani ◽  
Ebrahim Mazari ◽  
Somaye Asadi ◽  
Maryam Mashayekhikhi

PurposeConsidering innovation and its improvement as an essential strategy to enable organizations to continue their lives in the new competitive environment leads to a focus on employees' self-development as a factor that affects human resource agility (HRA) and the tendency toward organizational innovation. Consequently, the purpose of the study was to explain the impact of self-development on the tendency toward organizational innovation with the role of the mediator, HRA in higher education institutions as one of the most important and vital organizations in any society.Design/methodology/approachThe study was an applicable one with the quantitative approach using the descriptive–correlative method. The population consisted of 477 nonacademic employees of Kharazmi University among whom 214 ones were selected as the sample group, using a simple random sampling technique. Data were collected through the self-development, HRA and the tendency toward organizational innovation questionnaires and then analyzed using the structural equation modeling approach.FindingsThe study findings revealed a positive impact of self-development on the HRA (γ = 0/79) and HRA on the tendency toward organizational innovation (β = 0/6). Also, self-development with mediating HRA impacts the tendency toward organizational innovation (β = 0/58). Finally, self-development had no direct impact on the tendency toward organizational innovation.Research limitations/implicationsTaking the circumstances of doing this research into consideration, if there were the opportunity to do the research on the staffs of more than one university simultaneously and categorize the university staff into executives, managers and experts, more favorable results could be achieved. Also, considering group and organizational factors with the attention to the self-development approach and its factors would provide more awareness-training information on the higher education system in Iran. For future researches, both the individual and group factors are suggested to be surveyed and compared, to assess the weight and impact of these factors all together and to provide an adequate clarification of the role of the group and the organization. Finally, in future studies, it is also recommended that a qualitative approach be used to reach deeper clarifications on the aspects of these variables in the context of higher education.Practical implicationsThese findings have major practical implications concerning the higher educational settings. The findings of this study must give significant and practical insights for policymakers of universities and other higher education stakeholders, as well as recommendations to the academic community for further research in this area. First, they should recognize that nonacademic staff members are professional employees who contribute to improving organizational innovation. Higher education must focus on designing and implementing successful mechanisms and a well-planned self-development program that can help and promote the self-development approach among all staff. If the above-mentioned programs are designed based on the employees' needs analysis, they will get trained in a way to enhance mental and behavioral flexibility. The programs with such an approach can result in the proactive, adaptive, resilient behavior and agility of HR.Originality/valueThe model for this study has integrated and prioritized the key innovation drivers that would help universities design, adopt and implement policies and practices that facilitate and encourage improvements and adaptation to a fast-paced environment. Furthermore, the convincing reason for the significance of the current research is that although several types of research have been carried out on each of these three variables in different contexts separately, very few studies, like this, have directly examined the correlation between these three variables among the non-academic staff in higher education institutes. So, given the importance of the issue and rare availability of evidence in this regard, the authors were intrigued to discover whether the self-development through the mediation of HRA could reinforce and strengthen the tendency toward organizational innovation and whether HRA could be an appropriate mediator of the relationship between self-development and the tendency toward organizational innovation among the nonacademic staff of Kharazmi University as one of the most prestigious and celebrated universities in Iran.


2019 ◽  
Author(s):  
Yuke Wang ◽  
Valery Shulga ◽  
Gennadi Milinevsky ◽  
Aleksey Patoka ◽  
Oleksandr Evtushevsky ◽  
...  

Abstract. The impact of a major sudden stratospheric warming (SSW) in the Arctic in February 2018 on the mid-latitude mesosphere was investigated by performing microwave radiometer measurements of carbon monoxide (CO) and zonal wind above Kharkiv, Ukraine (50.0° N, 36.3° E). The mesospheric peculiarities of this SSW event were observed using recently designed and installed microwave radiometer in East Europe for the first time. The data from the ERA-Interim and NCEP–NCAR reanalyses, as well as the Aura Microwave Limb Sounder measurements, have been also used. Microwave observations of the daily CO profiles in January–March 2018 allowed retrieving mesospheric zonal wind at 70–85 km (below the winter mesopause) over the Kharkiv site. The reverse of the mesospheric westerly from about 10 m s−1 to the easterly wind of about −10 m s−1 around 10 February has been registered. Local microwave observations in the NH midlatitudes combined with reanalysis data show wide ranges of daily variability in CO, zonal wind, temperature and geopotential height in the mesosphere and stratosphere during the SSW 2018. Oscillations in the vertical CO profile, zonal wind, and geopotential height during the SSW, stratopause disappearance after the SSW onset and strong CO and westerly wind peaks at the start of the SSW recovery phase have been observed. The observed CO variability can be explained by vertical and horizontal air mass redistribution due to planetary wave activity with the replacement of the CO-rich air by CO-poor air and vice versa, in agreement with other studies. The results of microwave measurements of CO and zonal wind in the midlatitude mesosphere at 70–85 km altitudes, which still is not adequately covered by ground-based observations, are useful for improving our understanding of the SSW impacts in this region.


2021 ◽  
Vol 11 (22) ◽  
pp. 10518
Author(s):  
Gil-Eon Jeong

There has been an increasing demand for the design of an optimum topological layout in several engineering fields for a simple part, along with a system that considers the relative behaviors between adjacent parts. This paper presents a method of designing an optimum topological layout to achieve a linear dynamic impact and frictionless contact conditions in which relative behaviors can be observed between adjacent deformable parts. The solid isotropic method with penalization (SIMP) method is used with an appropriate filtering scheme to obtain an optimum topological layout. The condensed mortar method is used to handle the non-matching interface, which inevitably occurs in the impact and contact regions, since it can easily apply the existing well-known topology optimization approach even in the presence of a non-matching interface. The validity of the proposed method is verified through a numerical example. In the future, the proposed optimization approach will be applied to more general and highly nonlinear non-matching interface problems, such as friction contact and multi-physics problems.


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