scholarly journals Skill and independence weighting for multi-model assessments

2017 ◽  
Vol 10 (6) ◽  
pp. 2379-2395 ◽  
Author(s):  
Benjamin M. Sanderson ◽  
Michael Wehner ◽  
Reto Knutti
Keyword(s):  
Weather Extremes ◽  
Climate Assessment ◽  
Temperature And Precipitation ◽  
Weighted Means ◽  
Relevant Variables ◽  
National Climate Assessment ◽  
Two Parameters ◽  
Precipitation Changes ◽  
Model Weighting

Abstract. We present a weighting strategy for use with the CMIP5 multi-model archive in the fourth National Climate Assessment, which considers both skill in the climatological performance of models over North America as well as the inter-dependency of models arising from common parameterizations or tuning practices. The method exploits information relating to the climatological mean state of a number of projection-relevant variables as well as metrics representing long-term statistics of weather extremes. The weights, once computed can be used to simply compute weighted means and significance information from an ensemble containing multiple initial condition members from potentially co-dependent models of varying skill. Two parameters in the algorithm determine the degree to which model climatological skill and model uniqueness are rewarded; these parameters are explored and final values are defended for the assessment. The influence of model weighting on projected temperature and precipitation changes is found to be moderate, partly due to a compensating effect between model skill and uniqueness. However, more aggressive skill weighting and weighting by targeted metrics is found to have a more significant effect on inferred ensemble confidence in future patterns of change for a given projection.

scholarly journals Skill and independence weighting for multi-model assessments

2016 ◽  
Author(s):  
Benjamin Sanderson ◽  
Michael Wehner ◽  
Reto Knutti
Keyword(s):  
Weather Extremes ◽  
Climate Assessment ◽  
Temperature And Precipitation ◽  
Weighted Means ◽  
Relevant Variables ◽  
National Climate Assessment ◽  
Two Parameters ◽  
Precipitation Changes ◽  
Model Weighting

Abstract. We present a weighting strategy for use with the CMIP5 multi-model archive in the 4th National Climate Assessment which considers both skill in the climatological performance of models over North America as well as the inter-dependency of models arising from common parameterizations or tuning practices. The method exploits information relating to the climatological mean state of a number of projection-relevant variables as well as metrics representing long term statistics of weather extremes. The weights, once computed can be used to simply compute weighted means and significance information from an ensemble containing multiple initial condition members from co-dependent models of varying skill. Two parameters in the algorithm determine the degree to which model climatological skill and model uniqueness are rewarded; these parameters are explored and final values are defended with respect to the Assessment. The influence of model weighting on projected temperature and precipitation changes is found to be moderate, partly due to a compensating effect between model skill and uniqueness. However, more aggressive skill weighting and weighting by targeted metrics is found to have a more significant effect on inferred ensemble confidence in future patterns of change for a given projection.

scholarly journals Observations of greenhouse gases as climate indicators

2021 ◽  
Vol 165 (1-2) ◽  
Author(s):  
Lori Bruhwiler ◽  
Sourish Basu ◽  
James H. Butler ◽  
Abhishek Chatterjee ◽  
Ed Dlugokencky ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Radiative Forcing ◽  
Fossil Fuels ◽  
Atmospheric Composition ◽  
Climate Feedback ◽  
Climate Mitigation ◽  
Climate Assessment ◽  
Climate Indicators ◽  
National Climate Assessment

AbstractHumans have significantly altered the energy balance of the Earth’s climate system mainly not only by extracting and burning fossil fuels but also by altering the biosphere and using halocarbons. The 3rd US National Climate Assessment pointed to a need for a system of indicators of climate and global change based on long-term data that could be used to support assessments and this led to the development of the National Climate Indicators System (NCIS). Here we identify a representative set of key atmospheric indicators of changes in atmospheric radiative forcing due to greenhouse gases (GHGs), and we evaluate atmospheric composition measurements, including non-CO2 GHGs for use as climate change indicators in support of the US National Climate Assessment. GHG abundances and their changes over time can provide valuable information on the success of climate mitigation policies, as well as insights into possible carbon-climate feedback processes that may ultimately affect the success of those policies. To ensure that reliable information for assessing GHG emission changes can be provided on policy-relevant scales, expanded observational efforts are needed. Furthermore, the ability to detect trends resulting from changing emissions requires a commitment to supporting long-term observations. Long-term measurements of greenhouse gases, aerosols, and clouds and related climate indicators used with a dimming/brightening index could provide a foundation for quantifying forcing and its attribution and reducing error in existing indicators that do not account for complicated cloud processes.

Variability of Some Meteorological Parameters in the Basin of Azov Sea

2020 ◽  
pp. 62-70
Author(s):  
Olesya V. Nazarenko
Keyword(s):  
Summer Precipitation ◽  
Steppe Zone ◽  
Industrial Area ◽  
Warming Trend ◽  
Precipitation Trend ◽  
Temperature And Precipitation ◽  
Azov Sea ◽  
Precipitation Changes ◽  
Term Data

The results of research of trends in temperature and precipitation variability in the Azov sea basin are presented. The territory is an important agricultural and industrial area, the nature of which has undergone major changes. The paper considers changes in temperature and precipitation at stations located mainly in the steppe zone. The analysis of both long – term data and for the period 2001-2015 is carried out. Over the past 15-20 years there have been sig-nificant changes in climate features. A comparative analysis of annual and season changes is given. A steady warming trend has been established. An increase in annual temperatures by 0.4-2.8 °C, January - by 2.6-3.1 °C and July - by 0.7-2.1 °C. The study of air temperature by season showed that winter become warmer by 1.1 (Krasnodar) - 5.8 °C (Gigant). The temperature changed the least in summer in Uryupinsk and Frolovo (0.8-0.9 °C), the most in Krasnodar (2.2 °C). The precipitation trend is less noticeable. There is an increase in the amount of precipitation in the winter and autumn periods. In the spring the amount of precipitation increases for all the stations under unvestigation, with the exception for Voronezh and Chertkovo. In summer precipitation changes complicatedly. A decrease in precipita-tion prevails (Voronezh, Krasnodar, Matveev Kurgan, Taganrog, Gigant, Frolovo, Tsimlyansk) and a slight increase (Chertkovo, Armavir, Rostov, Uryupinsk, and Remontnoye).

Quantification of temperature and precipitation changes in northern China during the “5000-year” Chinese History

2021 ◽  
Vol 255 ◽  
pp. 106819 ◽  
Author(s):  
Can Zhang ◽  
Cheng Zhao ◽  
Aifeng Zhou ◽  
Haixia Zhang ◽  
Weiguo Liu ◽  
...  
Keyword(s):  
Northern China ◽  
Chinese History ◽  
Temperature And Precipitation ◽  
Precipitation Changes

scholarly journals High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Atanu Bhattacharya ◽  
Tobias Bolch ◽  
Kriti Mukherjee ◽  
Owen King ◽  
Brian Menounos ◽  
...  
Keyword(s):  
Mass Loss ◽  
River Flow ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
Temperature And Precipitation ◽  
Multi Temporal ◽  
The 1960S ◽  
Northern Tien Shan

AbstractKnowledge about the long-term response of High Mountain Asian glaciers to climatic variations is paramount because of their important role in sustaining Asian river flow. Here, a satellite-based time series of glacier mass balance for seven climatically different regions across High Mountain Asia since the 1960s shows that glacier mass loss rates have persistently increased at most sites. Regional glacier mass budgets ranged from −0.40 ± 0.07 m w.e.a−1 in Central and Northern Tien Shan to −0.06 ± 0.07 m w.e.a−1 in Eastern Pamir, with considerable temporal and spatial variability. Highest rates of mass loss occurred in Central Himalaya and Northern Tien Shan after 2015 and even in regions where glaciers were previously in balance with climate, such as Eastern Pamir, mass losses prevailed in recent years. An increase in summer temperature explains the long-term trend in mass loss and now appears to drive mass loss even in regions formerly sensitive to both temperature and precipitation.

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