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20 August 2009

Empirical analysis of the solar contribution to global mean air surface temperature change

Copyright © 2009 Elsevier Ltd All rights reserved.

Empirical analysis of the solar contribution to global mean air surface temperature change

Nicola Scafettaa,

aDepartment of Physics, Duke University, Durham, NC 27708, USA


Received 4 March 2009; revised 16 July 2009; accepted 23 July 2009. Available online 3 August 2009.

Abstract

The solar contribution to global mean air surface temperature change is analyzed by using an empirical bi-scale climate model characterized by both fast and slow characteristic time responses to solar forcing: and or . Since 1980 the solar contribution to climate change is uncertain because of the severe uncertainty of the total solar irradiance satellite composites. The sun may have caused from a slight cooling, if PMOD TSI composite is used, to a significant warming (up to 65% of the total observed warming) if ACRIM, or other TSI composites are used. The model is calibrated only on the empirical 11-year solar cycle signature on the instrumental global surface temperature since 1980. The model reconstructs the major temperature patterns covering 400 years of solar induced temperature changes, as shown in recent paleoclimate global temperature records.

Keywords: Solar variability; Climate change; Solar-terrestrial link

15 August 2009

Ocean heat content and Earth's radiation imbalance

Physics Letters A
Volume 373, Issue 36, 31 August 2009, Pages 3296-3300

Ocean heat content and Earth's radiation imbalance

David H. Douglassa and Robert S. Knox

Dept. of Physics and Astronomy, University of Rochester, PO Box 270171, Rochester, NY 14627-0171, USA


Received 26 June 2009; revised 8 July 2009; accepted 9 July 2009. Communicated by V.M. Agranovich. Available online 14 July 2009.

Abstract

Earth's radiation imbalance is determined from ocean heat content data and compared with results of direct measurements. Distinct time intervals of alternating positive and negative values are found: 1960–mid-1970s (−0.15), mid-1970s–2000 (+0.15), 2001–present (−0.2 W/m2), and are consistent with prior reports. These climate shifts limit climate predictability.

Keywords: Climate; Radiative imbalance; Ocean heat content

14 August 2009

Influence of the Southern Oscillation on tropospheric temperature

Influence of the Southern Oscillation on tropospheric temperature

J. D. McLean

Applied Science Consultants, Croydon, Victoria, Australia

C. R. de Freitas

School of Geography, Geology and Environmental Science, University of Auckland, Auckland, New Zealand

R. M. Carter

Marine Geophysical Laboratory, James Cook University, Townsville, Queensland, Australia

Abstract
Time series for the Southern Oscillation Index (SOI) and global tropospheric temperature anomalies (GTTA) are compared for the 1958−2008 period. GTTA are represented by data from satellite microwave sensing units (MSU) for the period 1980–2008 and from radiosondes (RATPAC) for 1958–2008. After the removal from the data set of short periods of temperature perturbation that relate to near-equator volcanic eruption, we use derivatives to document the presence of a 5- to 7-month delayed close relationship between SOI and GTTA. Change in SOI accounts for 72% of the variance in GTTA for the 29-year-long MSU record and 68% of the variance in GTTA for the longer 50-year RATPAC record. Because El Niño−Southern Oscillation is known to exercise a particularly strong influence in the tropics, we also compared the SOI with tropical temperature anomalies between 20°S and 20°N. The results showed that SOI accounted for 81% of the variance in tropospheric temperature anomalies in the tropics. Overall the results suggest that the Southern Oscillation exercises a consistently dominant influence on mean global temperature, with a maximum effect in the tropics, except for periods when equatorial volcanism causes ad hoc cooling. That mean global tropospheric temperature has for the last 50 years fallen and risen in close accord with the SOI of 5–7 months earlier shows the potential of natural forcing mechanisms to account for most of the temperature variation.

Received 16 December 2008; accepted 14 May 2009; published 23 July 2009.

Citation: McLean, J. D., C. R. de Freitas, and R. M. Carter (2009), Influence of the Southern Oscillation on tropospheric temperature, J. Geophys. Res., 114, D14104, doi:10.1029/2008JD011637.

11 August 2009

A large discontinuity in the mid-twentieth century in observed global-mean surface temperature

Letter

Nature 453, 646-649 (29 May 2008) | doi:10.1038/nature06982; Received 28 January 2008; Accepted 4 April 2008

A large discontinuity in the mid-twentieth century in observed global-mean surface temperature

David W. J. Thompson1, John J. Kennedy2, John M. Wallace3 & Phil D. Jones4

1. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USA
2. Met Office Hadley Centre, Exeter EX1 3PB, UK
3. Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, USA
4. Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK


Abstract

Data sets used to monitor the Earth's climate indicate that the surface of the Earth warmed from approx1910 to 1940, cooled slightly from approx1940 to 1970, and then warmed markedly from approx1970 onward1. The weak cooling apparent in the middle part of the century has been interpreted in the context of a variety of physical factors, such as atmosphere–ocean interactions and anthropogenic emissions of sulphate aerosols2. Here we call attention to a previously overlooked discontinuity in the record at 1945, which is a prominent feature of the cooling trend in the mid-twentieth century. The discontinuity is evident in published versions of the global-mean temperature time series1, but stands out more clearly after the data are filtered for the effects of internal climate variability. We argue that the abrupt temperature drop of approx0.3 °C in 1945 is the apparent result of uncorrected instrumental biases in the sea surface temperature record. Corrections for the discontinuity are expected to alter the character of mid-twentieth century temperature variability but not estimates of the century-long trend in global-mean temperatures.


Correspondence to: David W. J. Thompson1 Correspondence and requests for materials should be addressed to D.W.J.T. (Email: davet@atmos.colostate.edu).

08 August 2009

On the Madden Julian Oscillation – Atlantic Hurricane Relationship

Colorado State University
On the Madden Julian Oscillation – Atlantic Hurricane Relationship

Philip J. Klotzbach*
Department of Atmospheric Science

Fort Collins CO 80523e

Submitted to Journal of Climate: 11 Decembr 2008
Revised: 24 June 2009
Second Revision: 3 August 2009

Abstract
The large-scale equatorial circulation known as the Madden-Julian Oscillation (MJO)has been shown to impact tropical cyclone activity in several basins around the globe. In this paper, we utilize an MJO index created by Wheeler and Hendon to examine its impacts on tropical genesis and intensification in the Atlantic. Large differences in frequency and intensity of tropical cyclone activity are seen, both in the tropical Atlantic as well as in the northwest Caribbean and Gulf of Mexico depending on the MJO phase. Coherent changes in upper-and lower-level winds and relative humidity are likely responsible for these differences. Since the MJO shows potential predictability out to about two weeks, the relationships discussed in this paper may be useful for short-term predictions of the probability of tropical cyclone activity in the Atlantic as a complement to the already available longer-term seasonal predictions.

07 August 2009

The Last Glacial Maximum

Science 7 August 2009:
Vol. 325. no. 5941, pp. 710 – 714
DOI: 10.1126/science.1172873


Research Articles

The Last Glacial Maximum

Peter U. Clark,1,* Arthur S. Dyke,2 Jeremy D. Shakun,1 Anders E. Carlson,3 Jorie Clark,1 Barbara Wohlfarth,4 Jerry X. Mitrovica,5 Steven W. Hostetler,6 A. Marshall McCabe7

We used 5704 14C, 10Be, and 3He ages that span the interval from 10,000 to 50,000 years ago (10 to 50 ka) to constrain the timing of the Last Glacial Maximum (LGM) in terms of global ice-sheet and mountain-glacier extent. Growth of the ice sheets to their maximum positions occurred between 33.0 and 26.5 ka in response to climate forcing from decreases in northern summer insolation, tropical Pacific sea surface temperatures, and atmospheric CO2. Nearly all ice sheets were at their LGM positions from 26.5 ka to 19 to 20 ka, corresponding to minima in these forcings. The onset of Northern Hemisphere deglaciation 19 to 20 ka was induced by an increase in northern summer insolation, providing the source for an abrupt rise in sea level. The onset of deglaciation of the West Antarctic Ice Sheet occurred between 14 and 15 ka, consistent with evidence that this was the primary source for an abrupt rise in sea level ~14.5 ka.

1 Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
2 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada.
3 Department of Geology and Geophysics, University of Wisconsin, Madison, WI 53706, USA.
4 Department of Geology and Geochemistry, Stockholm University, SE-10691, Stockholm, Sweden.
5 Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
6 U.S. Geological Survey, Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
7 School of Environmental Science, University of Ulster, Coleraine, County Londonderry, BT52 1SA, UK.

A Unified Modeling Approach to Climate System Prediction

A Unified Modeling Approach to Climate System Prediction
James Hurrell*1, Gerald A. Meehl1, David Bader2, Thomas L. Delworth3, Ben Kirtman4,
and Bruce Wielicki5
1National Center for Atmospheric Research, Boulder, CO
2Lawrence Livermore National Laboratory, Livermore, CA
3Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ
4 Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL and Center for Ocean-Land-Atmosphere Studies, Calverton, MD
5 NASA Langley Research Center, Hampton, VA

Bulletin of the American Meteorological Society

Revised: 17 February, 2009
Final Revision: 26 June 2009

Abstract
There is a new perspective of a continuum of prediction problems, with a blurring of the distinction between short-term predictions and long-term climate projections. At the heart of this new perspective is the realization that all climate system predictions, regardless of time scale, share common processes and mechanisms; moreover, interactions across time and space scales are fundamental to the climate system itself. Further, just as seasonal to interannual predictions start from an estimate of the state of the climate system, there is a growing realization that decadal and longer term climate predictions could be initialized with estimates of the current observed state of the atmosphere, oceans, cryosphere, and land surface. Even though the prediction problem itself is seamless, the best practical approach to it may be described as unified: models aimed at different time scales and phenomena may have large commonality but place emphasis on different aspects of the system. The potential benefits of this commonality are significant and include improved predictions on all time scales and stronger collaboration and shared knowledge, infrastructure and technical capabilities among those in the weather and climate prediction communities.

05 August 2009

Cosmic ray decreases affect atmospheric aerosols and clouds

D R A F T June 12, 2009, 3:13pm
GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/,

Cosmic ray decreases affect atmospheric aerosols and clouds

Henrik Svensmark, Torsten Bondo, and Jacob Svensmark
National Space Institute, Technical University of Denmark, Juliane Marie
Vej 30, 2100 Copenhagen Ø, Denmark


Close passages of coronal mass ejections from the sun are signaled at the Earth’s surface by Forbush decreases in cosmic ray counts. We find that low clouds contain less liquid water following Forbush decreases, and for the most influential events the liquid water in the oceanic atmosphere can diminish by as much as 7%. Cloud water content as gauged by the Special Sensor Microwave/ Imager (SSM/I) reaches a minimum about 7 days after the Forbush minimum in cosmic rays, and so does the fraction of low clouds seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) and in the International Satellite Cloud Climate Project (ISCCP). Parallel observations by the aerosol robotic network AERONET reveal falls in the relative abundance of fine aerosol particles which, in normal circumstances, could have evolved into cloud condensation nuclei. Thus a link between the sun, cosmic rays, aerosols, and liquid-water clouds appears to exist on a global scale.

EARTH’S HEAT SOURCE - THE SUN

To be published in: Energy & Environment 20 (2009) 131-144
131
EARTH’S HEAT SOURCE - THE SUN
Oliver K. Manuel
Emeritus Professor, Space and Nuclear Studies
University of Missouri, Rolla, MO 65401
Associate, Climate & Solar Science Institute
625 Broadway, Cape Girardeau, MO 63701
E-mail: omatumr@yahoo.com
Website: http://www.omatumr.com

ABSTRACT
The Sun encompasses planet Earth, supplies the heat that warms it, and even shakes it. The United Nation’s Intergovernmental Panel on Climate Change (IPCC) assumed that solar influence on Earth’s climate is limited to changes in solar irradiance and adopted the consensus opinion of a hydrogen-filled Sun—the Standard Solar Model (SSM). They did not consider the alternative solar model and instead adopted another consensus opinion: Anthropogenic greenhouse gases play a dominant role in climate change. The SSM fails to explain the solar wind, solar cycles, and the empirical link of solar surface activity with Earth’s changing climate. The alternative solar model—molded from an embarrassingly large number of unexpected observations that space-age measurements revealed since 1959—explains not only these puzzles but also how closely linked interactions between the Sun and its planets and other celestial bodies induce turbulent cycles of secondary solar characteristics that significantly affect Earth’s climate.

Keywords: Earth’s Climate, Earth-Sun Connection, IPCC Policies, IPCC Procedures, Solar Inertial Motion, Solar Orbit, Solar System Center of Mass, Solar Density, Core of Sun, Neutron Repulsion, Solar Composition, Origin of Solar System, Solar Luminosity, Solar Interior, Mass Fractionation, Iron Sun.

Tropospheric temperature series from satellites

Nature 432, (2 December 2004) | doi:10.1038/nature03208; Published online 1 December 2004

Atmospheric science: Tropospheric temperature series from satellites

Simon Tett1 & Peter Thorne2

Abstract

Arising from: Q. Fu et al. Nature 429, 55–58 (2004); see also communication from Gillett et al.; Fu et al. reply

There has been considerable debate about changes in the temperature of the troposphere1 measured using the Microwave Sounding Unit (MSU) instrument2, 3 or radiosondes4, 5. Fu et al.6 linearly combine time series from two MSU channels to estimate vertically integrated 850–300-hPa temperatures and claim consistency between surface and free-troposphere warming for one MSU record. We believe that their approach overfits the data, produces trends that overestimate warming and gives overly optimistic uncertainty estimates. There still remain large differences between observed tropospheric temperature trends and those simulated by a climate model.

02 August 2009

Does a polar coronal hole’s flux emergence follow a Hale-like law?

Does a polar coronal hole’s flux emergence follow a Hale-like law?
A. Savcheva1, J.W. Cirtain2, E.E. DeLuca1, L. Golub1
asavcheva@cfa.harvard.edu

ABSTRACT
Recent increases in spatial and temporal resolution for solar telescopes sen-sitive to EUV and X-ray radiation have revealed the prevalence of transient jetevents in polar coronal holes. Using data collected by the X-Ray Telescope on Hinode, Savcheva et al. (2007) confirmed the observation, made first by the SoftX-ray Telescope on Yohkoh, that some jets exhibit a motion transverse to the jet outflow direction. The velocity of this transverse motion is, on average, 20 kms−1. The direction of the transverse motion, in combination with the stan-dard reconnection model for jet production (e.g. Shibata et al. 1992), reflects the magnetic polarity orientation of the ephemeral active region at the base of the jet. From this signature, we find that during the present minimum phase of the solar cycle the jet-base ephemeral active regions in the polar coronal holes had a preferred east-west direction, and that this direction reversed during the cycle’s progression through minimum. In late 2006 and early 2007, the preferred direction was that of the active regions of the coming sunspot cycle (Cycle 24), but in late 2008 and early 2009 the preferred direction has been that of the ac-tive regions of sunspot cycle 25. These findings are consistent with the results of Wilson et al. (1988) that there is a high latitude expansion of the solar activity cycle.

Subject headings: Sun: corona, Sun: UV radiation, Sun: x-ray jets, Sun: polar coronal hole, Sun: flux emergance