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Tropospheric Warming (tropospheric + warming)

Distribution by Scientific Domains

Earth and Environmental Science	100%

Selected Abstracts

Consistency of modelled and observed temperature trends in the tropical troposphere

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2008
B. D. Santer
Abstract A recent report of the U.S. Climate Change Science Program (CCSP) identified a ,potentially serious inconsistency' between modelled and observed trends in tropical lapse rates (Karl et al., 2006). Early versions of satellite and radiosonde datasets suggested that the tropical surface had warmed more than the troposphere, while climate models consistently showed tropospheric amplification of surface warming in response to human-caused increases in well-mixed greenhouse gases (GHGs). We revisit such comparisons here using new observational estimates of surface and tropospheric temperature changes. We find that there is no longer a serious discrepancy between modelled and observed trends in tropical lapse rates. This emerging reconciliation of models and observations has two primary explanations. First, because of changes in the treatment of buoy and satellite information, new surface temperature datasets yield slightly reduced tropical warming relative to earlier versions. Second, recently developed satellite and radiosonde datasets show larger warming of the tropical lower troposphere. In the case of a new satellite dataset from Remote Sensing Systems (RSS), enhanced warming is due to an improved procedure of adjusting for inter-satellite biases. When the RSS-derived tropospheric temperature trend is compared with four different observed estimates of surface temperature change, the surface warming is invariably amplified in the tropical troposphere, consistent with model results. Even if we use data from a second satellite dataset with smaller tropospheric warming than in RSS, observed tropical lapse rate trends are not significantly different from those in all other model simulations. Our results contradict a recent claim that all simulated temperature trends in the tropical troposphere and in tropical lapse rates are inconsistent with observations. This claim was based on use of older radiosonde and satellite datasets, and on two methodological errors: the neglect of observational trend uncertainties introduced by interannual climate variability, and application of an inappropriate statistical ,consistency test'. Copyright © 2008 Royal Meteorological Society [source]

Changes in Antarctic Peninsula tropospheric temperatures from 1956 to 1999: a synthesis of observations and reanalysis data

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2002
Gareth J. Marshall
Abstract The surface warming at Faraday station in the western Antarctic Peninsula is one of the largest observed anywhere over the last 50 years, yet the physical mechanisms driving this climate change are poorly understood. In this paper we synthesize radiosonde temperature observations from three Peninsula stations and NCEP,NCAR reanalysis data in order to examine contemporaneous regional tropospheric temperature trends (1956,99), which may in turn help us to understand better the causes of the surface warming. The reanalysis data are utilized in two ways: (i) to provide long-term mean monthly offsets between Faraday, which ceased radiosonde observations in 1982, and two other stations in the region having more recent data, Bellingshausen and Marambio, in order to create post-1982 simulated Faraday data; (ii) after having any spurious trends and bias removed, to provide directly a monthly value for Faraday when no equivalent value from regional observations is available. Using available months of overlap, a comparison between temperature observations and simulated data suggests that the latter are a reasonable facsimile of the former. The synthesized time-series of tropospheric temperatures reveal a statistically significant mean annual tropospheric (850,300 hPa) warming above Faraday between 1956 and 1999 of ,0.027±0.022 °C year,1. Winter and summer both show a warming trend, with significance varying with height and season. Annually, the mean tropospheric warming is half that at the surface, Unlike the surface warming, the calculated tropospheric warming trend is no greater than observed at other Antarctic stations, and indeed is not significantly greater than the background global warming trend for most of the period examined. Thus, we cannot dismiss the possibility that the Peninsula surface warming may simply be a response to a global warming magnified by the observed strong regional feedback between sea-ice extent and surface temperature during winter. Copyright © 2002 Royal Meteorological Society. [source]

Antarctic winter tropospheric warming,the potential role of polar stratospheric clouds, a sensitivity study

ATMOSPHERIC SCIENCE LETTERS, Issue 4 2009
T. A. Lachlan-Cope
Abstract Over the last 30 years, Antarctic mid-tropospheric temperatures in winter have increased by 0.5 K per decade, the largest regional tropospheric warming observed. Over this period, amounts of polar stratospheric cloud(PSC) have also increased, as rising CO2 concentrations cooled the stratosphere. By imposing an idealisation of these increases in PSC within the radiation scheme of an atmosphere-only general circulation model, we find that they could have contributed to the observed warming. The present generation of global climate models do not properly represent PSCs, and so these results demonstrate the need to improve the representation of PSCs. Copyright © 2009 Royal Meteorological Society and Crown Copyright [source]