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D. S. Arndt, M. O. Baringer, and M. R. Johnson

Editors note: For easy download the posted pdf of the State of the Climate for 2009 is a low-resolution file. A high-resolution copy of the report is available by clicking here. Please be patient as it may take a few minutes for the high-resolution file to download.

Abstract

The year was characterized by a transition from a waning La Niña to a strengthening El Niño, which first developed in June. By December, SSTs were more than 2.0°C above average over large parts of the central and eastern equatorial Pacific. Eastward surface current anomalies, associated with the El Niño, were strong across the equatorial Pacific, reaching values similar to the 2002 El Niño during November and December 2009. The transition from La Niña to El Niño strongly influenced anomalies in many climate conditions, ranging from reduced Atlantic basin hurricane activity to large scale surface and tropospheric warmth.

Global average surface and lower-troposphere temperatures during the last three decades have been progressively warmer than all earlier decades, and the 2000s (2000–09) was the warmest decade in the instrumental record. This warming has been particularly apparent in the mid- and high-latitude regions of the Northern Hemisphere and includes decadal records in New Zealand, Australia, Canada, Europe, and the Arctic. The stratosphere continued a long cooling trend, except in the Arctic.

Atmospheric greenhouse gas concentrations continued to rise, with CO2 increasing at a rate above the 1978 to 2008 average. The global ocean CO2 uptake flux for 2008, the most recent year for which analyzed data are available, is estimated to have been 1.23 Pg C yr−1, which is 0.25 Pg C yr−1 smaller than the long-term average and the lowest estimated ocean uptake in the last 27 years. At the same time, the total global ocean inventory of anthropogenic carbon stored in the ocean interior as of 2008 suggests an uptake and storage of anthropogenic CO2 at rates of 2.0 and 2.3 ±0.6 Pg C yr−1 for the decades of the 1990s and 2000s, respectively. Total-column ozone concentrations are still well below pre-1980 levels but have seen a recent reduction in the rate of decline while upper-stratospheric ozone showed continued signs of ongoing slow recovery in 2009. Ozone-depleting gas concentrations continued to decline although some halogens such as hydrochlorofluorocarbons are increasing globally. The 2009 Antarctic ozone hole was comparable in size to recent previous ozone holes, while still much larger than those observed before 1990. Due to large interannual variability, it is unclear yet whether the ozone hole has begun a slow recovery process.

Global integrals of upper-ocean heat content for the last several years have reached values consistently higher than for all prior times in the record, demonstrating the dominant role of the oceans in the planet's energy budget. Aside from the El Niño development in the tropical Pacific and warming in the tropical Indian Ocean, the Pacific Decadal Oscillation (PDO) transitioned to a positive phase during the fall/winter 2009. Ocean heat fluxes contributed to SST anomalies in some regions (e.g., in the North Atlantic and tropical Indian Oceans) while dampening existing SST anomalies in other regions (e.g., the tropical and extratropical Pacific). The downward trend in global chlorophyll observed since 1999 continued through 2009, with current chlorophyll stocks in the central stratified oceans now approaching record lows since 1997.

Extreme warmth was experienced across large areas of South America, southern Asia, Australia, and New Zealand. Australia had its second warmest year on record. India experienced its warmest year on record; Alaska had its second warmest July on record, behind 2004; and New Zealand had its warmest August since records began 155 years ago. Severe cold snaps were reported in the UK, China, and the Russian federation. Drought affected large parts of southern North America, the Caribbean, South America, and Asia. China suffered its worst drought in five decades. India had a record dry June associated with the reduced monsoon. Heavy rainfall and floods impacted Canada, the United States, the Amazonia and southern South America, many countries along the east and west coasts of Africa, and the UK. The U.S. experienced its wettest October in 115 years and Turkey received its heaviest rainfall over a 48-hr period in 80 years.

Sea level variations during 2009 were strongly affected by the transition from La Niña to El Niño conditions, especially in the tropical Indo-Pacific. Globally, variations about the long-term trend also appear to have been influenced by ENSO, with a slight reduction in global mean sea level during the 2007/08 La Niña event and a return to the long-term trend, and perhaps slightly higher values, during the latter part of 2009 and the current El Niño event. Unusually low florida Current transports were observed in May and June and were linked to high sea level and coastal flooding along the east coast of the United States in the summer. Sea level significantly decreased along the Siberian coast through a combination of wind, ocean circulation, and steric effects. Cloud and moisture increased in the tropical Pacific. The surface of the western equatorial Pacific freshened considerably from 2008 to 2009, at least partially owing to anomalous eastward advection of fresh surface water along the equator during this latest El Niño. Outside the more variable tropics, the surface salinity anomalies associated with evaporation and precipitation areas persisted, consistent with an enhanced hydrological cycle.

Global tropical cyclone (TC) activity was the lowest since 2005, with six of the seven main hurricane basins (the exception is the Eastern North Pacific) experiencing near-normal or somewhat below-normal TC activity. Despite the relatively mild year for overall hurricane activity, several storms were particularly noteworthy: Typhoon Morakot was the deadliest typhoon on record to hit Taiwan; Cyclone Hamish was the most intense cyclone off Queensland since 1918; and the state of Hawaii experienced its first TC since 1992.

The summer minimum ice extent in the Arctic was the third-lowest recorded since 1979. The 2008/09 boreal snow cover season marked a continuation of relatively shorter snow seasons, due primarily to an early disappearance of snow cover in spring. Preliminary data indicate a high probability that 2009 will be the 19th consecutive year that glaciers have lost mass. Below normal precipitation led the 34 widest marine terminating glaciers in Greenland to lose 101 km2 ice area in 2009, within an annual loss rate of 106 km2 over the past decade. Observations show a general increase in permafrost temperatures during the last several decades in Alaska, northwest Canada, Siberia, and Northern Europe. Changes in the timing of tundra green-up and senescence are also occurring, with earlier green-up in the High Arctic and a shift to a longer green season in fall in the Low Arctic.

The Antarctic Peninsula continues to warm at a rate five times larger than the global mean warming. Associated with the regional warming, there was significant ice loss along the Antarctic Peninsula in the last decade. Antarctic sea ice extent was near normal to modestly above normal for the majority of 2009, with marked regional contrasts within the record. The 2008/09 Antarctic-wide austral summer snowmelt was the lowest in the 30-year history.

This 20th annual State of the Climate report highlights the climate conditions that characterized 2009, including notable extreme events. In total, 37 Essential Climate Variables are reported to more completely characterize the State of the Climate in 2009.

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H.-M. Zhang, R. W. Reynolds, R. Lumpkin, R. Molinari, K. Arzayus, M. Johnson, and T. M. Smith

This paper describes the optimal design and its research-to-operation transition of an integrated global observing system of satellites and in situ observations. The integrated observing system is used for climate assessment using sea surface temperature (SST). Satellite observations provide superior samplings while in situ observations provide the ground truth. Observing System Simulation Experiments (OSSEs) were used to objectively design an efficient in situ system to reduce satellite biases to a required accuracy. The system design was peer reviewed and was then transitioned into operations as a U.S. contribution to the international Global Climate Observing System (GCOS). A system performance measure was also formulated and operationally tracked under the Government Performance Results Act (GPRA). Additional OSSEs assisted the planning, programming, budgeting, and execution system at the National Oceanic and Atmospheric Administration (NOAA) to maximize design efficiency. This process of research to operation and decision making enables NOAA to strategically target its observing system investments. The principles of this specific example may have potential applicability to the other components of GCOS.

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R. E. Pandya, D. R. Smith, M. K. Ramamurthy, P. J. Croft, M. J. Hayes, K. A. Murphy, J. D. McDonnell, R. M. Johnson, and H. A. Friedman

The 11th American Meteorological Society (AMS) Education Symposium was held from 13 to 15 January 2002 in Orlando, Florida, as part of the 82nd Annual Meeting of the AMS. The theme of the symposium was “creating opportunities in educational outreach in the atmospheric and related sciences.” Drawing from traditional strengths in meteorology and numerous national recommendations, the presentations and posters of the symposium highlighted three opportunities for reform. These opportunities build on partnerships between diverse educational stakeholders, efforts to make science education more like scientific practice, and strategies that place the atmospheric sciences within a larger, multidisciplinary context that includes oceanography, hydrology, and earth-system science.

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Jeffry Rothermel, Dean R. Cutten, R. Michael Hardesty, Robert T. Menzies, James N. Howell, Steven C. Johnson, David M. Tratt, Lisa D. Olivier, and Robert M. Banta

In 1992 the atmospheric lidar remote sensing groups of the National Aeronautics and Space Administration Marshall Space Flight Center, the National Oceanic and Atmospheric Administration/Environmental Technology Laboratory (NOAA/ETL), and the Jet Propulsion Laboratory began a joint collaboration to develop an airborne high-energy Doppler laser radar (lidar) system for atmospheric research and satellite validation and simulation studies. The result is the Multicenter Airborne Coherent Atmospheric Wind Sensor (MACAWS), which has the capability to remotely sense the distribution of wind and absolute aerosol backscatter in three-dimensional volumes in the troposphere and lower stratosphere.

A factor critical to the programmatic feasibility and technical success of this collaboration has been the utilization of existing components and expertise that were developed for previous atmospheric research by the respective institutions. For example, the laser transmitter is that of the mobile ground-based Doppler lidar system developed and used in atmospheric research for more than a decade at NOAA/ETL.

The motivation for MACAWS is threefold: 1) to obtain fundamental measurements of subsynoptic-scale processes and features to improve subgrid-scale parameterizations in large-scale models, 2) to obtain datasets in order to improve the understanding of and predictive capabilities for meteorological systems on subsynoptic scales, and 3) to validate (simulate) the performance of existing (planned) satellite-borne sensors.

Initial flight tests were made in September 1995; subsequent flights were made in June 1996 following system improvements. This paper describes the MACAWS instrument, principles of operation, examples of measurements over the eastern Pacific Ocean and western United States, and future applications.

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Scott Sandgathe, Bonnie R. Brown, Jessie C. Carman, Johnna M. Infanti, Bradford Johnson, David McCarren, and Eileen McIlvain
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EXECUTIVE COMMITTEE, R. G. Fleagle, R. E. Hallgren, R. M. White, J. Simpson, G. R. Hilst, D. S. Johnson, K. C. Spengler, and D. F. Landrigan
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R. E. Carbone, F. I. Harris, P. H. Hildebrand, R. A. Kropfli, L. J. Miller, W. Moninger, R. G. Strauch, R. J. Doviak, K. W. Johnson, S. P. Nelson, P. S. Ray, and M. Gilet
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J. Verlinde, J. Y. Harrington, G. M. McFarquhar, V. T. Yannuzzi, A. Avramov, S. Greenberg, N. Johnson, G. Zhang, M. R. Poellot, J. H. Mather, D. D. Turner, E. W. Eloranta, B. D. Zak, A. J. Prenni, J. S. Daniel, G. L. Kok, D. C. Tobin, R. Holz, K. Sassen, D. Spangenberg, P. Minnis, T. P. Tooman, M. D. Ivey, S. J. Richardson, C. P. Bahrmann, M. Shupe, P. J. DeMott, A. J. Heymsfield, and R. Schofield

The Mixed-Phase Arctic Cloud Experiment (M-PACE) was conducted from 27 September through 22 October 2004 over the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) on the North Slope of Alaska. The primary objectives were to collect a dataset suitable to study interactions between microphysics, dynamics, and radiative transfer in mixed-phase Arctic clouds, and to develop/evaluate cloud property retrievals from surface-and satellite-based remote sensing instruments. Observations taken during the 1977/98 Surface Heat and Energy Budget of the Arctic (SHEBA) experiment revealed that Arctic clouds frequently consist of one (or more) liquid layers precipitating ice. M-PACE sought to investigate the physical processes of these clouds by utilizing two aircraft (an in situ aircraft to characterize the microphysical properties of the clouds and a remote sensing aircraft to constraint the upwelling radiation) over the ACRF site on the North Slope of Alaska. The measurements successfully documented the microphysical structure of Arctic mixed-phase clouds, with multiple in situ profiles collected in both single- and multilayer clouds over two ground-based remote sensing sites. Liquid was found in clouds with cloud-top temperatures as cold as −30°C, with the coldest cloud-top temperature warmer than −40°C sampled by the aircraft. Remote sensing instruments suggest that ice was present in low concentrations, mostly concentrated in precipitation shafts, although there are indications of light ice precipitation present below the optically thick single-layer clouds. The prevalence of liquid down to these low temperatures potentially could be explained by the relatively low measured ice nuclei concentrations.

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John R. Mecikalski, Wayne F. Feltz, John J. Murray, David B. Johnson, Kristopher M. Bedka, Sarah T. Bedka, Anthony J. Wimmers, Michael Pavolonis, Todd A. Berendes, Julie Haggerty, Pat Minnis, Ben Bernstein, and Earle Williams

Advanced Satellite Aviation Weather Products (ASAP) was jointly initiated by the NASA Applied Sciences Program and the NASA Aviation Safety and Security Program in 2002. The initiative provides a valuable bridge for transitioning new and existing satellite information and products into Federal Aviation Administration (FAA) Aviation Weather Research Program (AWRP) efforts to increase the safety and efficiency of project addresses hazards such as convective weather, turbulence (clear air and cloud induced), icing, and volcanic ash, and is particularly applicable in extending the monitoring of weather over data-sparse areas, such as the oceans and other observationally remote locations.

ASAP research is conducted by scientists from NASA, the FAA AWRP's Product Development Teams (PDT), NOAA, and the academic research community. In this paper we provide a summary of activities since the inception of ASAP that emphasize the use of current-generation satellite technologies toward observing and mitigating specified aviation hazards. A brief overview of future ASAP goals is also provided in light of the next generation of satellite sensors (e.g., hyperspectral; high spatial resolution) to become operational in the 2007–18 time frame.

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EXECUTIVE COMMITTEE, Warren M. Washington, David D. Houghton, Robert T. Ryan, Donald R. Johnson, Margaret A. LeMone, Alexander E. MacDonald, Richard E. Hallgren, and Kenneth C. Spengler
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