AbstractA detailed analysis of hourly precipitation from 60°N to 60°S for the covariability is performed at 0.25° resolution using the new CMORPH dataset. For all points, correlations are computed ...
This document presents the large scale water budget statistics of a perturbed input-parameter ensemble of atmospheric model runs. The model is Version 5.1.02 of the Community Atmosphere Model (CAM). These runs are the “C-Ensemble” described by Qian et al., “Parametric Sensitivity Analysis of Precipitation at Global and Local Scales in the Community Atmosphere Model CAM5” (Journal of Advances in Modeling the Earth System, 2015). As noted by Qian et al., the simulations are “AMIP type” with temperature and sea ice boundary conditions chosen to match surface observations for the five year period 2000-2004. There are 1100 ensemble members in addition to one run with default inputparameter values.
Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere, despite the transition from an El Ni&#
The climate is changing because of human activities and will continue to do so regardless of any mitigation actions. Available climate observations and information are also changing as technological advances take place. Accordingly, an overview is given of a much-needed potential climate information system that embraces a comprehensive observing system to observe and track changes and the forcings of the system as they occur, and that develops the ability to relate one to the other and understand changes and their origins. Observations need to be taken in ways that satisfy the climate monitoring principles and ensure long-term continuity, and that have the ability to discern small but persistent signals. Some benchmark observations are proposed to anchor space-based observations and trends, including a much-needed step forward in the quality of water vapor observations. Satellite observations must be calibrated and validated, with orbital decay and drift effects fully dealt with if possible, and adequate overlap to ensure continuity. The health of the monitoring system must be tracked and resources identified to address issues. Fields must be analyzed into global products and delivered to users while stakeholder needs are fully considered. Data should be appropriately archived with full and open access, along with metadata that fully describe the observing system status and environment in which it operates. Reanalysis of the records must be institutionalized along with continual assessment of impacts of new observing and analysis systems. Some products will be used to validate and improve models, as well as initialize models and predict future evolution on multiple time scales using ensembles. Attribution of changes to causes is essential, and it is vital to fully assess past changes and model performance and results in making predictions to help appraise reliability and assess impacts regionally on the environment, human activities, and sectors of the economy. In particular, a revolution in the way developing countries use and apply climate information is expected. Such a system will be invaluable and further provides a framework for setting priorities of new observations and related activities. Without the end-to-end process the investments will not deliver adequate return and our understanding will be much less than it would be otherwise.
The heat budget has been computed locally over the entire globe for each month of 1988 using compatible top-of-the-atmosphere radiation from the Earth Radi
No abstract is provided for this article.
Kevin E. Trenberth emphasizes the fundamental role of energy flows in the climate system and anthropogenic climate change. The distribution of heat, or more generally, energy, is the main determinant of weather patterns in the atmosphere and their impacts. The topics addressed cover many facets of climate and the climate crisis. These include the diurnal cycle; the seasons; energy differences between the continents and the oceans, the poles and the tropics; interannual variability such as Nino; natural decadal variability; and ice ages. Human-induced climate change rides on and interacts with all of these natural phenomena, and the result is an unevenly warming planet and changing weather extremes. The book emphasizes the need to not only slow or stop climate change, but also to better prepare for it and build resilience. Students, researchers, and professionals from a wide range of backgrounds will benefit from this deeper understanding of climate change.
While hurricanes occur naturally, human‐caused climate change is supercharging them and exacerbating the risk of major damage. Here using ocean and atmosphere observations, we demonstrate links between increased upper ocean heat content due to global warming with the extreme rainfalls from recent hurricanes. Hurricane Harvey provides an excellent case study as it was isolated in space and time. We show that prior to the beginning of northern summer of 2017, ocean heat content was the highest on record both globally and in the Gulf of Mexico, but the latter sharply decreased with hurricane Harvey via ocean evaporative cooling. The lost ocean heat was realized in the atmosphere as moisture, and then as latent heat in record‐breaking heavy rainfalls. Accordingly, record high ocean heat values not only increased the fuel available to sustain and intensify Harvey but also increased its flooding rains on land. Harvey could not have produced so much rain without human‐induced climate change. Results have implications for the role of hurricanes in climate. Proactive planning for the consequences of human‐caused climate change is not happening in many vulnerable areas, making the disasters much worse.
A detailed analysis of atmospheric temperatures at the South Pole and McMurdo Sound is presented. Missing data are common, especially in the stratosphere, and the usual practice of computing monthly means as an average of all available observations produces unreliable results because the annual cycle is aliased onto the interannual variations and longer term trends. A methodology to rectify this involves computation of the smoothed mean annual cycle for each day of the year and then subsequently analyzing the anomalies. The persistence of the anomalies within each month reveals that regular observations about every three days are required to produce a reliable climate record throughout the troposphere and lower stratosphere. A comparison of station data with lower stratospheric analyzed values from the National Meteorological Center (NMC) reveals big discrepancies at times arising mainly from methods used to produce the NMC analyses. The mean annual cycle of temperature features the coreless winter at low levels at both stations. The largest amplitude annual cycle occurs at 10 mb with maximum temperatures in December. The maximum occurs progressively later at lower levels down to 200 mb, where it occurs in February. The seasonal transition occurs more rapidly in spring than in autumn. Interannual fluctuations are dominated by a quasi-biennial variation. Noticeable downward trends in temperature were found mainly near the time of greatest variability, in late spring. Temperatures decreased between 50 and 100 mb in October and November and at 100 mb in December and January; but only from 1985 to 1987 have monthly means gone outside the range of previous variations. The most extreme anomalies, of as much as −21°C, were found in November 1987. The downward trends arise from a delay in the spring warming apparently brought about by the diminished solar heating due to low ozone amounts associated with the “ozone hole.” Trends from 1979 to 1986 or 1987, which is the period of satellite data on temperatures and ozone, are not representative of the overall record which begins in 1956.
No abstract is provided for this article.
A more complete and new formulation of the orographic forcing and new thermal forcings are included in a steady state model of the Northern Hemisphere planetary waves. When both forcings are included, the simulation produces excellent results which are compared in detail with observations. In particular, the Siberian high, the tropospheric East Asian trough and subtropical tropospheric East Asian jet stream maxima are well reproduced even though the forcing is primarily extratropical in origin. The modes uses a lower boundary condition in which the orographic forcing is determined by the effects of the total flow, not just the zonal mean basic state. Consequently, the net orographic forcing changes when thermal forcing is added and the tow solution is not equal to the linear sum of the solutions with orographic and thermal forcings separately. The thermally induced orographic forcing is found to be very significant and, in the troposphere, there is strong interaction between the two forcings with both of roughly equal importance. However, the Iowa-latitude vertically propagating waves am deflected by the subtropical jet and absorbed in the low-latitude easterlies. Thus only the mid-high latitude planetary waves are important in the stratosphere which seems to be dominated by the thermally forced component. The model is forced with new estimates of diabetic heating from several FGGE analyses. The sensitivity of the results to different heatings and their assumed vertical profile is examined. The amplitude of the lower-troposphere response is very sensitive to the vertical profile but there are much smaller changes at upper levels which are dominated by the remote response. Large differences in the response to the different diabatic heatings are found at high latitudes and over the Pacific Ocean. However, when orographic forcing is also included, these differences diminish indicating a smaller sensitivity to uncertainties in heating, and thus the orographic forcing is acting to constrain the total response. This is in marked contrast to the model results when the traditional lower-boundary condition (in which the waves are decoupled) is used since then the total response is entirely linear. Wave 1 is too weak in the model and this is most likely mainly due to deficiencies in the thermal forcing. The model eddy fluxes of heat and momentum show excellent agreement with observations in location although the poleward heat flux is somewhat weak. These reveal noticeable improvements over the wave-decoupled model which produces too large a response with the lower-tropospheric heat flux too far south at 35°N in association with a degraded simulation of the Siberian high and East Asian trough, in particular.
No abstract is provided for this article.
A pathological problem has been discovered in the NCEP reanalyses in the stratosphere. It is manifested most strongly as a two-delta vertical wave in the divergence of the wind field above steep topography especially where the wind increases with altitude in the stratosphere. It is present primarily above 50 mb at the topmost four levels in the NCEP model used for data assimilation and appears to be directly related to the use of the sigma (terrain following) coordinate system and the upper boundary condition in the assimilating model. Recommendations suggested for addressing the problem include switching to a hybrid coordinate system that transitions to a pressure coordinate in the stratosphere, and with a damping upper boundary condition. Certain climate diagnostics are greatly impacted by these pathologies.
