Simulation of modern climate with the new version of the INM RAS climate model

The INMCM5.0 numerical model of the Earth’s climate system is presented, which is an evolution from the previous version, INMCM4.0. A higher vertical resolution for the stratosphere is applied in the atmospheric block. Also, we raised the upper boundary of the calculating area, added the aerosol block, modified parameterization of clouds and condensation, and increased the horizontal resolution in the ocean block. The program implementation of the model was also updated. We consider the simulation of the current climate using the new version of the model. Attention is focused on reducing systematic errors as compared to the previous version, reproducing phenomena that could not be simulated correctly in the previous version, and modeling the problems that remain unresolved.     

Probability distributions for cyclones and anticyclones from the NCEP/NCAR reanalysis data and the INM RAS climate model

Analysis of statistical characteristics of cyclones and anticyclones in the latitudinal belt between 20° and 80°N has been performed with the NCEP/NCAR reanalysis data and simulations with the general circulation climate model of the Institute of Numerical Mathematics of the Russian Academy of Sciences (INM RAS GCCM). The model results have been analyzed for the second half of the 20th century against the NCEP/NCAR reanalysis data and for the 21st century with the SRES-A2 anthropogenic scenario. Overall for the 20th century, no statistically significant changes in the number of cyclones and anticyclones are obtained from either the NCEP/NCAR reanalysis data [1] or from simulations with the INM RAS GCCM [2]. It is found that the total number of cyclones and anticyclones decreased in the 20th century as compared to the 21st century. It is shown that cumulative distributions of the number of cyclones and anticyclones by their intensities and areas have an exponential form from both the reanalysis data and the model simulations, although the corresponding exponents are different.     

On the Mechanism of Arctic Climate Oscillation with a Period of About 15 Years According to Data of the INM RAS Climate Model

Izvestiya, Atmospheric and Oceanic Physics - According to data from a preindustrial experiment, a mechanism of Arctic climate oscillation with a period of about 15 years in the INM-CM5 climate...     

Simulation of the spatiotemporal variability of the World Ocean sea surface hight by the INM climate models

The results of simulations of the World Ocean sea surface hight (SSH) in by various versions of the Climate Model of the Institute of Numerical Mathematics, Russian Academy of Sciences, are compared with the CNES-CLS09 fields of the mean dynamic topography (deviation of the ocean level from the geoid). Three models with different ocean blocks are considered which slightly differ in numerical schemes and have various horizontal spatial resolution, i.e., the INMCM4 model, which participated in the Climate Model Intercomparison Project (CMIP Phase 5, resolution of 1° × 1/2°); the INMCM5 model, which participates in the next project, CMIP6 (resolution of 1/2° × 1/4°); and the advanced INMCM-ER eddy-resolving model (resolution of 1/6° × 1/8°). It is shown that an increase in the spatial resolution improves the reproduction of ocean currents (with Agulhas and Kuroshio currents as examples) and their variability. A probable cause of relatively high errors in the reproduction of the SSH of Southern and Indian oceans is discussed.     

Changes in climatic characteristics of Northern Hemisphere extratropical land in the 21st century: Assessments with the IAP RAS climate model

Assessments of future changes in the climate of Northern Hemisphere extratropical land regions have been made with the IAP RAS climate model (CM) of intermediate complexity (which includes a detailed scheme of thermo- and hydrophysical soil processes) under prescribed greenhouse and sulfate anthropogenic forcing from observational data for the 19th and 20th centuries and from the SRES B1, A1B, and A2 scenarios for the 21st century. The annual mean warming of the extratropical land surface has been found to reach 2–5 K (3–10 K) by the middle (end) of the 21st century relative to 1961–1990, depending on the anthropogenic forcing scenario, with larger values in North America than in Europe. Winter warming is greater than summer warming. This is expressed in a decrease of 1–4 K (or more) in the amplitude of the annual harmonic of soil-surface temperature in the middle and high latitudes of Eurasia and North America. The total area extent of perennially frozen ground S _p in the IAP RAS CM changes only slightly until the late 20th century, reaching about 21 million km², and then decreases to 11–12 million km² in 2036–2065 and 4–8 million km² in 2071–2100. In the late 21st century, near-surface permafrost is expected to remain only in Tibet and in central and eastern Siberia. In these regions, depths of seasonal thaw exceed 1 m (2 m) under the SRES B1 (A1B or A2) scenario. The total land area with seasonal thaw or cooling is expected to decrease from the current value of 54–55 million km² to 38–42 in the late 21st century. The area of Northern Hemisphere snow cover in February is also reduced from the current value of 45–49 million km² to 31–37 million km². For the basins of major rivers in the extratropical latitudes of the Northern Hemisphere, runoff is expected to increase in central and eastern Siberia. In European Russia and in southern Europe, runoff is projected to decrease. In western Siberia (the Ob watershed), runoff would increase under the SRES A1B and A2 scenarios until the 2050s–2070s, then it would decrease to values close to present-day ones; under the anthropogenic forcing scenario SRES B1, the increase in runoff will continue up to the late 21st century. Total runoff from Eurasian rivers into the Arctic Ocean in the IAP RAS CM in the 21st century will increase by 8–9% depending on the scenario. Runoff from the North American rivers into the Arctic Ocean has not changed much throughout numerical experiments with the IAP RAS CM.     

Interaction of the methane cycle and processes in wetland ecosystems in a climate model of intermediate complexity

The climate model of the Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) has been supplemented with a module of soil thermal physics and the methane cycle, which takes into account the response of methane emissions from wetland ecosystems to climate changes. Methane emissions are allowed only from unfrozen top layers of the soil, with an additional constraint in the depth of the simulated layer. All wetland ecosystems are assumed to be water-saturated. The molar amount of the methane oxidized in the atmosphere is added to the simulated atmospheric concentration of CO₂. A control preindustrial experiment and a series of numerical experiments for the 17th–21st centuries were conducted with the model forced by greenhouse gases and tropospheric sulfate aerosols. It is shown that the IAP RAS CM generally reproduces preindustrial and current characteristics of both seasonal thawing/freezing of the soil and the methane cycle. During global warming in the 21st century, the permafrost area is reduced by four million square kilometers. By the end of the 21st century, methane emissions from wetland ecosystems amount to 130–140 Mt CH₄/year for the preindustrial and current period increase to 170–200 MtCH₄/year. In the aggressive anthropogenic forcing scenario A2, the atmospheric methane concentration grows steadily to ≈3900 ppb. In more moderate scenarios A1B and B1, the methane concentration increases until the mid-21st century, reaching ≈2100–2400 ppb, and then decreases. Methane oxidation in air results in a slight additional growth of the atmospheric concentration of carbon dioxide. Allowance for the interaction between processes in wetland ecosystems and the methane cycle in the IAP RAS CM leads to an additional atmospheric methane increase of 10–20% depending on the anthropogenic forcing scenario and the time. The causes of this additional increase are the temperature dependence of integral methane production and the longer duration of a warm period in the soil. However, the resulting enhancement of the instantaneous greenhouse radiative forcing of atmospheric methane and an increase in the mean surface air temperature are small (globally < 0.1 W/m² and 0.05 K, respectively).     

Mathematical Modeling of Climate,Dynamics Atmosphere and Ocean: to the 95th Anniversary of G. I. Marchuk and the 40th Anniversary of the INM RAS

Izvestiya, Atmospheric and Oceanic Physics - Introductory article on the issue of the journal Izvestiya RAN, Atmospheric and Oceanic Physics, 2020, vol. 56, no. 3 dedicated to the 40th anniversary...     

中国科学院气候系统模式模拟的ENSO循环

On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences(CAS-ESM-C) in simulating the El Ni?o-Southern Oscillation(ENSO) cycle is evaluated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature(SST) in the tropical Pacific, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the El Ni?o onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster development of an El Ni?o. During the decay stage, owing to a stronger El Ni?o in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an El Ni?o decays into a La Ni?a through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attributed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean.     

Atmosphere-ocean general circulation model with the carbon cycle

Results from numerical experiments with an atmosphere-ocean general circulation model coupled to the carbon evolution cycle are analyzed. The model is used to carry out an experiment on the simulation of the climate and carbon cycle change in 1861–2100 under a specified scenario of the carbon dioxide emission from fossil fuel and land use. The spatial distribution of vegetation, soil, and oceanic carbon in the 20th century is generally close to available estimates from observational data. The model adequately reproduces the observed growth of atmospheric CO₂ in the 20th century and the uptake of excess carbon by land ecosystems and by the ocean in the 1980s and 1990s. By 2100, the atmospheric CO₂ concentration is calculated to reach 742 ppmv under emission and land-use scenario A1B. The feedback between climate change and the carbon cycle in the model is positive, with a coefficient close to the mean of all the current models. The ocean and land uptakes of the CO₂ emission by 2100 in the model are 25 and 19%, which are also close to the mean over all models.     

An ocean model for climate variability studies

Models of the time dependent ocean circulation can be simplified considerably by filtering out all short term, small scale motions which are unimportant for climatic processes. For time scales large compared with a day and space scales large compared with the internal Rossby radius of deformation (～50 km), the currents in most of the interior ocean can be determined diagnostically as quasi-equilibrium fields, so that only the salinity and temperature fields need be treated prognostically.Regions of closed f/h contours, however, represent exceptions. Here trapped vorticity gyres exist as free flow solutions without external forcing, and in the presence of forcing the barotropic velocity field must therefore be determined prognostically through a potential vorticity equation for the gyres.Lateral boundary layers and the equatorial regions also require separate treatment. These were not considered specifically, but it is suggested that integrated (parametrical) models analogous in structure to mixed-layer models or the integrated boundary layer models of aerodynamics may be the most appropriate technique for coupling these regions to the interior ocean in a comprehensive ocean model suitable for climate studies.A coupled multi-region model of the global ocean circulation based on these scale considerations could be sufficiently cost-effective to permit systematic investigation of the role of the oceanic heat storage and transport in climate variability studies over a wide spectrum of space and time scales.The analysis of the seasonal variations of the interior ocean circulation represents a simple example in which the filtered model yields considerably simpler and more readily interpretable results than a fully three-dimensional, unfiltered model.     

Downscaling of greenhouse gas induced climate change in two GCMs with the Rossby Centre regional climate model for northern Europe

Two 2×10‐year climate change experiments made with the Rossby Centre regional Atmospheric climate model (RCA) are reported. These two experiments are driven by boundary data from two global climate change simulations, one made with HadCM2 and the other with ECHAM4/OPYC3, in which the global mean warming is virtually the same, 2.6°C. The changes in mean temperature and precipitation show similarities (including broadly the same increase in temperature and in northern Europe a general increase in annual precipitation) as well as differences between the two RCA experiments. These changes are strongly governed by the driving GCM simulations. Even on the RCA grid box scale, the differences in change between RCA and the driving GCM are generally smaller than the differences between the two GCMs. Typically about a half of the local differences between the two RCA simulations are attributed to noise generated by internal variability, which also seems to explain a substantial part of the RCA‐GCM differences particularly for precipitation change. RCA includes interactive model components for the Baltic Sea and inland lakes of northern Europe. The simulated changes in these water bodies are discussed with emphasis on the wintertime ice conditions. Comparison with an earlier RCA experiment indicates that a physically consistent treatment of these water bodies is also of importance for the simulated atmospheric climate change.     

Deep North Atlantic freshening simulated in a coupled climate model

The observed recent freshening trend in the deep North Atlantic and the Labrador Sea is investigated in three forced ensembles and a long control simulations using the HadCM3 coupled ocean–atmosphere–sea-ice climate model. The 40 yr freshening trend during the late half of the 20th century is captured in the all forcings ensemble that applies all major external (natural and anthropogenic) forcing factors. Each ensemble has four members with different initial conditions taking from the control run at a 100 yr interval. No similar freshening trend is found in each of the four corresponding periods of the control simulation. However, there are five large freshening events in a 1640 yr period of the control run, each following a sudden salinity increase. A process analysis revealed that the increase in salinity in the Labrador Sea is closely linked to deep convections while the following freshening trend is accompanied by a period of very weak convective activities.The fact that none of the five large freshening events appears in the four corresponding periods following the initial conditions of the four members of the all forcings ensemble suggest that external forcings may have contributed to triggering the events. Further analyses of two other ensemble simulations (natural forcings only and anthropogenic forcings only) have shown that natural rather than anthropogenic factors are responsible. Based on our model results, we can not attribute the simulated freshening to anthropogenic climate change.     

Improved sea-ice radiative processes in a global coupled climate model

1Introduction Seaiceplaysanimportantroleinmoderating heatandmoistureexchangesbetweentheatmosphere andtheoceanathighlatitudes.Seaicealsointeracts withthebroaderclimatesystembythepositiveice albedofeedback(Curryetal.,1995),whichamplifies projectedclimatewarmingatthehighlatitudes,andby theoceanicfeedbackinvolvingicegrowthandmelt, whichinfluencesglobalthermohalinecirculation(i.e., theNorthAtlanticDeepWaterandtheAntarcticBot- tomWater)(Walsh,1983;Barryetal.,1993). Recently,theimplementationofas…     

渤海温盐场季节循环时空参数模型

根据1978年1月-1981年11月渤海温盐场逐月调查资料,采用旋转经验正交函数（REOF）、最大熵谱分析、调和分析等方法,构建渤海表底层温盐场季节循环时空参数模型。表底层温度场主要有两种季节循环时空模态,第一模态是对潮流混合局地水体热容量扩散作用和太阳辐射季节变化的响应;第二模态是对东南-西北季风风向转变产生风海流-补偿流形态变化引起水体水平-垂直热量输送差异和东南-西北季风风向转变的响应。表底层盐度场存在3种变化形式：线性趋势、季节循环和年度跃变。黄河口月径流量逐年减少是盐度线性趋势和跃变升高的主要原因。表底层盐度场主要有2种季节循环时空模态,第一模态是对黄河、辽河月径流量季节变化的响应;第二模态是对月降水量和河流月径流量季节变化的响应。     

Methane in the western North Pacific

The concentration of methane in about 400 seawater samples collected in the western North Pacific, mostly from 40°N to 5°S along 165°E was determined. While the concentration of methane in the surface water was slightly greater in the high-latitudes, it did not widely vary with a standard deviation of 0.29 n mol/l for a mean value of 2.49 n mol/l. The 90% confidence limit of the mean was 0.08 n mol/l. The degree of oversaturation in 1991 (31±4%) was not different from that in circa 1970. If we assume that this degree of oversaturation occurs in the entire oceans, the annual flux of methane becomes 6×10¹²g CH₄. Both the concentrations of methane and chlorophylla were higher in the surface 100 m layer. However, the correlation between them was not well in the entire surface waters. This may indicate that the production of methane is not directly related to the photosynthetic process. The concentration of methane decreased gradually with increasing depth down to 1000 m. Its horizontally and vertically uniform concentration in the abyssal water suggests that the turnover time of methane in the oxic pelagic water is in the range between a few years and a few hundred years.     

Influence of volcanic activity on climate change in the past several centuries: Assessments with a climate model of intermediate complexity

The climate model of intermediate complexity developed at the A.M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) is supplemented by a scheme which takes into account the volcanic forcing of climate. With this model, ensemble experiments have been conducted for the 1600s–1900s, in which, along with the volcanic forcing, the anthropogenic forcing due to greenhouse gases and sulfate aerosols and the natural forcing due to variations in solar irradiance were taken into account. The model realistically reproduces the annual mean response of surface air temperature and precipitation to major eruptions both globally and regionally. In particular, the decreases in the annual mean global temperature T _g in the IAP RAS CM after the largest eruptions in the latter half of the 20th century, the Mt. Agung (1963), El Chichon (1982), and Mt. Pinatubo (1991) volcanic eruptions, are 0.28, 0.27, and 0.46 K, respectively, in agreement with estimates from observational data. Moreover, in the IAP RAS CM, the volcanic eruptions result in a general precipitation decrease, especially over land in the middle and high latitudes of the Northern Hemisphere. The seasonal distribution of the response shows good agreement with observations for high-latitude eruptions and worse agreement for tropical and subtropical volcanoes. On interdecadal scales, volcanism leads to variations in T _g on the order of 0.1 K. In numerical experiments with anthropogenic and natural forcings, the model reproduces a general change in surface air temperature over the past several centuries. Taking into account the volcanic forcing, along with that due to variations in solar irradiance, the model has partly reproduced the nonmonotonic global warming for the 20th century.