The response of stratospheric climate and circulation to increasing amounts of greenhouse gases (GHGs) and ozone recovery in the twenty-first century is analyzed in simulations of 11 ...chemistry–climate models using near-identical forcings and experimental setup. In addition to an overall global cooling of the stratosphere in the simulations (0.59 ± 0.07 K decade−1at 10 hPa), ozone recovery causes a warming of the Southern Hemisphere polar lower stratosphere in summer with enhanced cooling above. The rate of warming correlates with the rate of ozone recovery projected by the models and, on average, changes from 0.8 to 0.48 K decade−1at 100 hPa as the rate of recovery declines from the first to the second half of the century. In the winter northern polar lower stratosphere the increased radiative cooling from the growing abundance of GHGs is, in most models, balanced by adiabatic warming from stronger polar downwelling. In the Antarctic lower stratosphere the models simulate an increase in low temperature extremes required for polar stratospheric cloud (PSC) formation, but the positive trend is decreasing over the twenty-first century in all models. In the Arctic, none of the models simulates a statistically significant increase in Arctic PSCs throughout the twenty-first century. The subtropical jets accelerate in response to climate change and the ozone recovery produces a westward acceleration of the lower-stratospheric wind over the Antarctic during summer, though this response is sensitive to the rate of recovery projected by the models. There is a strengthening of the Brewer–Dobson circulation throughout the depth of the stratosphere, which reduces the mean age of air nearly everywhere at a rate of about 0.05 yr decade−1in those models with this diagnostic. On average, the annual mean tropical upwelling in the lower stratosphere (∼70 hPa) increases by almost 2% decade−1, with 59% of this trend forced by the parameterized orographic gravity wave drag in the models. This is a consequence of the eastward acceleration of the subtropical jets, which increases the upward flux of (parameterized) momentum reaching the lower stratosphere in these latitudes.
The present study compares simulations of the 2009 sudden stratospheric warming (SSW) from four different whole atmosphere models. The models included in the comparison are the Ground‐to‐topside ...model of Atmosphere and Ionosphere for Aeronomy, Hamburg Model of the Neutral and Ionized Atmosphere, Whole Atmosphere Model, and Whole Atmosphere Community Climate Model Extended version (WACCM‐X). The comparison focuses on the zonal mean, planetary wave, and tidal variability in the middle and upper atmosphere during the 2009 SSW. The model simulations are constrained in the lower atmosphere, and the simulated zonal mean and planetary wave variability is thus similar up to ∼1 hPa (50 km). With the exception of WACCM‐X, which is constrained up to 0.002 hPa (92 km), the models are unconstrained at higher altitudes leading to considerable divergence among the model simulations in the mesosphere and thermosphere. We attribute the differences at higher altitudes to be primarily due to different gravity wave drag parameterizations. In the mesosphere and lower thermosphere, we find both similarities and differences among the model simulated migrating and nonmigrating tides. The migrating diurnal tide (DW1) is similar in all of the model simulations. The model simulations reveal similar temporal evolution of the amplitude and phase of the migrating semidiurnal tide (SW2); however, the absolute SW2 amplitudes are significantly different. Through comparison of the zonal mean, planetary wave, and tidal variability during the 2009 SSW, the results of the present study provide insight into aspects of the middle and upper atmosphere variability that are considered to be robust features, as well as aspects that should be considered with significant uncertainty.
Key Points
Compare simulations of 2009 SSW in four whole atmosphere models
The simulations reveal different dynamics at MLT altitudes
Differences are attributed primarily to gravity wave drag parametrizations
The distinctive spatial patterns of the ionosphere's total electron content (TEC) response to solar, seasonal, diurnal, and geomagnetic influences are determined across the globe using a new ...statistical model constructed from 2‐hourly TEC observations from 1998 to 2015. The model combines representations of the physical solar EUV photon and geomagnetic activity drivers with solar‐modulated sinusoidal parameterizations of four seasonal cycles and solar‐modulated and seasonally modulated parameterizations of three diurnal cycles. The average absolute residual of the data‐model differences is 2.1 total electron content unit, 1 TECU = 1016 el m−2 (TECU) (9%) and the root‐mean‐square error is 3.5 TECU (15%). Solar and geomagnetic variability, the semiannual oscillation and the diurnal and semidiurnal oscillations all impact TEC most at low magnetic latitudes where TEC itself maximizes, with differing degrees of longitudinal inhomogeneity. In contrast, the annual oscillation manifests primarily in the Southern Hemisphere with maximum amplitude over midlatitude South America, extending to higher southern latitudes in the vicinity of the Weddell Sea. Nighttime TEC levels in the vicinity of the Weddell Sea exceed daytime levels every year in Southern Hemisphere summer as a consequence of the modulation of the diurnal oscillations by the seasonal oscillations. The anomaly, which is present at all phases of the solar cycle, commences sooner and ends later under solar minimum conditions. The model minus data residuals maximize at tropical magnetic latitudes in four geographical regions similar to the ionosphere pattern generated by lower atmospheric meteorology. Enhanced residuals at northern midlatitudes during winter are consistent with an influence of atmospheric gravity waves.
Key Points
Maximum TEC response to solar, SAO, diurnal, and geomagnetic influences is at low magnetic latitudes and to AO in SH
Solar‐modulated seasonal oscillations cause Weddell Sea diurnal anomaly in SH summer, lasting longer at solar minima
Evidence for lower atmosphere meteorologic influence on TEC in the EIA and at NH midlatitudes in winter
A comparison of different model simulations of the ionosphere variability during the 2009 sudden stratosphere warming (SSW) is presented. The focus is on the equatorial and low‐latitude ionosphere ...simulated by the Ground‐to‐topside model of the Atmosphere and Ionosphere for Aeronomy (GAIA), Whole Atmosphere Model plus Global Ionosphere Plasmasphere (WAM+GIP), and Whole Atmosphere Community Climate Model eXtended version plus Thermosphere‐Ionosphere‐Mesosphere‐Electrodynamics General Circulation Model (WACCMX+TIMEGCM). The simulations are compared with observations of the equatorial vertical plasma drift in the American and Indian longitude sectors, zonal mean F region peak density (NmF2) from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites, and ground‐based Global Positioning System (GPS) total electron content (TEC) at 75°W. The model simulations all reproduce the observed morning enhancement and afternoon decrease in the vertical plasma drift, as well as the progression of the anomalies toward later local times over the course of several days. However, notable discrepancies among the simulations are seen in terms of the magnitude of the drift perturbations, and rate of the local time shift. Comparison of the electron densities further reveals that although many of the broad features of the ionosphere variability are captured by the simulations, there are significant differences among the different model simulations, as well as between the simulations and observations. Additional simulations are performed where the neutral atmospheres from four different whole atmosphere models (GAIA, HAMMONIA (Hamburg Model of the Neutral and Ionized Atmosphere), WAM, and WACCMX) provide the lower atmospheric forcing in the TIME‐GCM. These simulations demonstrate that different neutral atmospheres, in particular, differences in the solar migrating semidiurnal tide, are partly responsible for the differences in the simulated ionosphere variability in GAIA, WAM+GIP, and WACCMX+TIMEGCM.
Key Points
Compare different ionosphere model simulations with observations for the 2009 SSW
Simulations capture broad features of SSW, but model‐model and model‐data discrepancies are apparent
Differences can partly be attributed to differences in the simulated middle atmospheres
The Model for Ozone and Related Chemical Tracers, version 3 (MOZART‐3), which represents the chemical and physical processes from the troposphere through the lower mesosphere, was used to evaluate ...the representation of long‐lived tracers and ozone using three different meteorological fields. The meteorological fields are based on (1) the Whole Atmosphere Community Climate Model, version 1b (WACCM1b), (2) the European Centre for Medium‐Range Weather Forecasts (ECMWF) operational analysis, and (3) a new reanalysis for year 2000 from ECMWF called EXP471. Model‐derived tracers (methane, water vapor, and total inorganic nitrogen) and ozone are compared to data climatologies from satellites. Model mean age of air was also derived and compared to in situ CO2 and SF6 data. A detailed analysis of the chemical fields simulated by MOZART‐3 shows that even though the general features characterizing the three dynamical sets are rather similar, slight differences in winds and temperature can produce substantial differences in the calculated distributions of chemical tracers. The MOZART‐3 simulations that use meteorological fields from WACCM1b and ECMWF EXP471 represented best the distribution of long‐lived tracers and mean age of air in the stratosphere. There was a significant improvement using the ECMWF EXP471 reanalysis data product over the ECMWF operational data product. The effect of the quasi‐biennial oscillation circulation on long‐lived tracers and ozone is examined.
Limited data exist about cancer prognosis and the development of second cancers in renal transplant recipients. In a retrospective cohort study on 3537 patients incidence rates of the first and, if ...any, of a second cancer, and standardized incidence ratios SIR (95% CI) were computed. Two hundred and sixty‐three (7.5%) patients developed a NMSC, and 253 (7.2%) another type of cancer after a median follow‐up of 6.5 and 9.0 years, respectively. A statistically significant excess risk, if compared to an age‐ and sex‐matched reference general population, was observed for Kaposi sarcoma and NMSC, followed by non‐Hodgkin lymphoma and carcinoma of cervix uteri; a small number of unusual cancers such as tumors of the salivary glands, small intestine and thyroid also were detected at a level worthy of additional scrutiny. Ten‐year survival rate of all noncutaneous cancers was 71.3%, with lower rates for lung carcinoma and non‐Hodgkin lymphoma (0% and 41.7%, respectively). Patients with NMSC had an increased risk of developing a second NMSC SIR 8.3 (7.0–10.0), and patients with a primary noncutaneous cancer had increased risk of developing a second noncutaneous cancer SIR 1.8 (1.2–2.8), if compared to the whole cohort. Our study underscore that the high risk of primary and second cancer in renal transplant recipients, including unusual cancers.
Renal transplant recipients are at high risk of primary and second cancers, including unusual cancers, but cancer‐related mortality is not substantially increased if compared to an age‐ and sex‐matched reference population.
The NCAR Whole Atmosphere Community Climate Model, version 3 (WACCM3), is used to study the atmospheric response from the surface to the lower thermosphere to changes in solar and geomagnetic forcing ...over the 11‐year solar cycle. WACCM3 is a general circulation model that incorporates interactive chemistry that solves for both neutral and ion species. Energy inputs include solar radiation and energetic particles, which vary significantly over the solar cycle. This paper presents a comparison of simulations for solar cycle maximum and solar cycle minimum conditions. Changes in composition and dynamical variables are clearly seen in the middle and upper atmosphere, and these in turn affect terms in the energy budget. Generally good agreement is found between the model response and that derived from satellite observations, although significant differences remain. A small but statistically significant response is predicted in tropospheric winds and temperatures which is consistent with signals observed in reanalysis data sets.
It has been known for a long time that the equatorial electrojet varies from day to day even when solar and geomagnetic activities are very low. The quiet time day‐to‐day variation is considered to ...be due to irregular variability of the neutral wind, but little is known about how variable winds drive the electrojet variability. We employ a numerical model introduced by Liu et al. (2013), which takes into account weather changes in the lower atmosphere and thus can reproduce ionospheric variability due to forcing from below. The simulation is run for May and June 2009. Constant solar and magnetospheric energy inputs are used so that day‐to‐day changes will arise only from lower atmospheric forcing. The simulated electrojet current shows day‐to‐day variability of ±25%, which produces day‐to‐day variations in ground level geomagnetic perturbations near the magnetic equator. The current system associated with the day‐to‐day variation of the equatorial electrojet is traced based on a covariance analysis. The current pattern reveals return flow at both sides of the electrojet, in agreement with those inferred from ground‐based magnetometer data in previous studies. The day‐to‐day variation in the electrojet current is compared with those in the neutral wind at various altitudes, latitudes, and longitudes. It is found that the electrojet variability is dominated by the zonal wind at 100–120 km altitudes near the magnetic equator. These results suggest that the response of the zonal polarization electric field to variable zonal winds is the main source of the day‐to‐day variation of the equatorial electrojet during quiet periods.
Key Points
Day‐to‐day variation of the equatorial electrojet (EEJ) is simulatedA current system associated with EEJ variability is revealedThe EEJ variability is dominated by equatorial zonal wind at 110 km
Virtually all fiscal measures influence people's health, through their impacts on behaviour, consumption, income and wealth. A narrow subset of fiscal measures, however, can be more directly aimed at ...improving health by targeting behaviours and risks that are known to be strongly associated with health outcomes. The purpose of this book is to discuss the subject of these measures, which we define as 'health taxes'. The book aims to enumerate key health taxes of interest, explore their positive and negative effects, and how these effects are influenced by the design of these taxes and the context in which they are applied. We ask how and where they can be implemented. Critically, we build an argument throughout the book for why policymakers across government should care about health taxes.
We compare simulations of mesospheric tracer descent in the winter and spring of 2009 with two versions of the Whole Atmosphere Community Climate Model (WACCM), both with specified dynamics. One is ...constrained with data from the Modern‐Era Retrospective Analysis for Research and Applications which extends from 0 to 50 km; the other uses the Navy Operational Global Atmospheric Prediction System‐Advanced Level Physics High Altitude (NOGAPS‐ALPHA) which extends up to 92 km. By comparison with Solar Occultation for Ice Experiment data we show that constraining WACCM to NOGAPS‐ALPHA yields a dramatic improvement in the simulated descent of enhanced nitric oxide (NO) and very low methane (CH4). We suggest that constraining to NOGAPS‐ALPHA compensates for an underestimate of nonorographic gravity wave drag in WACCM. Other possibilities, such as missing energetic particle precipitation or underestimated eddy diffusion, are less likely for the Arctic winter and spring of 2009.
Key Points
Use of high‐altitude analysis for simulating thermosphere‐stratosphere coupling
Descent of nitric oxide and methane in polar night is a sensitive test for whole atmosphere models
High‐altitude analysis can compensate for uncertainties in gravity wave drag parameterizations
PDF
