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D. R. Johnson
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R. G. Gallimore and D. R. Johnson

Abstract

The impact of GWF satellite data on GLA analyses of the thermal structure of two oceanic extratropical cyclones are presented. The two storms developed nearly simultaneously in the western Pacific and Atlantic oceans during January 1979. In addition to describing the satellite data impact on temperature and static-stability distributions within each storm, implications of the impact on available potential energy and on the baroclinic growth of the cyclone are discussed.

In the comparison of CLA analyses with (SAT) and without (NOSAT) the satellite temperature soundings produced by 1,be NOAA/NESS retrieval method, the results show sizable temperature differences between the two analyses for both storms. Characteristic features include the following: 1) warmer SAT temperature within NOSAT thermal through and colder SAT temperatures within NOSAT thermal ridges 2) a difference in sign or magnitude of the temperature impact between the upper troposphere and the lower troposphere, and 3) an evolution of a significant, satellite-data cold bias located within and paralleling the evolution of the low-tropospheric thermal ridge close to the cyclone center. The satellite temperature impact in the low troposphere increases tropospheric static in the central storm area and decreases troposhperic stability in the cold troughs both to the rear and ahead of the cyclone.

Although the net effect of area-averaged satellite temperature impact for the storms is small, the association of warmer temperature with NOSAT thermal trough and colder temperatures with thermal ridges reduces the areal temperature stability variance within the Pacific storm area. The reduction for the Atlantic storm region is less. For the Pacific storm the satellite temperature impact led to a 10% reduction of available potential energy, a significant reduction in vertical phase tilt of the tropospheric temperature structure, and a potentially greater than 10–20% reduction of the baroclinic rate of cyclone-scale waves. The decreased baroclinic amplification is inferred from stabilization of the highest lapse rates and a reduction of the largest vertical thermal-wind shears in the low troposphere of the storm area. Overall the results stress the need to identify characteristics of satellite temperature-sounding impacts on the baroclinic structure of cyclone waves, which potentially degrade numerical weather prediction of cyclogenesis.

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Ronald D. Townsend and Donald R. Johnson

Abstract

The mass circulation of the zonally averaged global circulation is investigated in isobaric and isentropic coordinates through the use of a FGGE Level IIIa data set. The isobaric mass circulation during the First GARP Global Experiment is consistent with previous results, i.e., direct Hadley cells in low latitudes and indirect Ferrel cells in midlatitudes of both hemispheres.

Within the isentropic framework, the combination of a geostrophic mean mode of mass transport within the baroclinic wave structure of extratropical latitudes, and an ageostrophic mean mode in tropical latitudes, yields an isentropic mass circulation spanning the hemisphere. The asymmetric structure of midlatitude baroclinic waves provides the degree of freedom for a geostrophic mode of mass transport that is fundamental to the direct Hadley-type circulation in isentropic coordinates. This direct Hadley-type circulation is explicitly linked to heat sources and sinks on a planetary scale. The diabatic heating estimated from the mean meridional mass transport through the isentropic continuity equation reveals a realistic distribution for the zonally averaged atmosphere. Within the isentropic perspective, the scale of thermodynamic forcing by diabatic beating explicitly determines the hemispheric scale of atmospheric response for the mean meridional circulation.

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J. D. McQuigg, S. R. Johnson, and J. R. Tudor

Abstract

A method is developed which can be used to produce estimates of electric power load diversity from samples of ambient daily mean temperature observations from a large interconnected power system. This method has several advantages, the most important of which is the comparative case with which homogenous samples of temperature data can be located. The method is believed to have important applications in long-term planning of large interconnected electric power systems.

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J. M. Vergin, D. R. Johnson, and R. Atlas

Abstract

The results of a quasi-Lagrangian diagnostic study of two 72 h Goddard Laboratory for Atmospheric Sciences (GLAS) model cyclone predictions from 0000 GMT 19 February 1976 are presented and compared with observed results. One model forecast (SAT) was generated from initial conditions which included satellite sounding data, and the other model forecast (NOSAT) was generated from initial conditions that excluded satellite sounding data. Examination of the mass and angular momentum budget statistics for the SAT and NOSAT forecasts reveals substantial differences. The improvement in the SAT forecast is established from the more realistic SAT budget statistics, and results from the modifications of initial atmospheric structure due to satellite information.

The assimilation of satellite data caused modifications of the horizontal mass and eddy angular momentum transports at the zero hour. The assimilation of satellite data resulted in colder temperatures and weaker stabilities in the lower layers of the northwest quadrant of the budget volume, and thus an improved structure of the cold polar air mass over a relatively warm ocean surface. In the southwest quadrant of the budget volume, the SAT assimilation produced an increase in the stability of the middle and lower layers and an increase in temperatures throughout much of the troposphere. These modifications in the temperature structure were the primary reasons for the improved mass and eddy angular momentum transports which contributed to the better SAT forecast for the cyclone event.

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D. Johnson, R. Stocker, R. Head, J. Imberger, and C. Pattiaratchi

Abstract

The design of small, compact, low-cost GPS drifters that utilize “off the shelf” components is described. The drifters are intended for use in confined or nearshore environments over time scales of up to several days and are a low-cost alternative for applications that do not require drifters with full ocean-going capabilities.

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R. L. Johnson, D. E. Janota, and J. E. Hay

Abstract

During the spring-summer of 1979, six lightning warning devices were evaluated in a side-by-side comparison study at three test sites. Stock commercial devices were selected based upon distinct concepts of operation. The devices tested included a sferics counter, a corona point, a radioactive probe, a field mill, an azimuth/range locator and a triangulation locator. The test sites were chosen to provide varied thunderstorm conditions: 1) San Antonio, Texas (cold air advection), 2) Kennedy Space Center, Florida (localized surface heating) and 3) Langmuir Laboratory, New Mexico (orographic effects). The evaluation parameters were advance warning time, time to clear after hazard, alarm reliability, and false alarm and failure to alarm probabilities. The triangulation locator provided the best overall performance; however, all systems indicated a need for improvement in the failure to alarm rate.

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K. V. Beard, D. B. Johnson, and A. R. Jameson

Abstract

An energy model is formulated to compare collisional kinetic energy with viscous dissipation for oscillating raindrops as a function of size, raindrop distribution and rainfall rate. A potential energy model is used to calculate oscillation energies, and is coupled with results from a potential flow model to determine the time-average axis ratios for fundamental mode oscillations. The model findings are found to be consistent with observations of mean and extreme axis ratios. It is concluded that there is sufficient collisional energy to produce large-amplitude oscillations in moderate-to-heavy rainfall, and that time-average axis ratios should depart significantly from equilibrium, thereby altering the radar polarization characteristics of rain.

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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. D. Ausfresser, A. C. Johnson, and R. A. Kowalski
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