J. K. Angell

Climatological characteristics of the tropical tropopause as revealed by radiosondes

A temporally and spatially comprehensive depiction of the tropical tropopause is presented, based on radiosonde data from 83 stations. Climatological statistics for 1961- 1990 are computed for three levels: the conventional lapse-rate tropopause (LRT), the cold-point tropopause (CPT), and the 100 hPa level. Mean values and seasonal and interannual variations of temperature, pressure, height, potential temperature, and water vapor saturation mixing ratio at these levels are compared. The tropopause is higher, colder, and at lower pressure in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH) in NH winter. This pattern reverses in NH summer, except that the tropopause remains colder in the NH than in the SH. The climatological locations of minimum tropopause temperature differ from those of maximum height and minimum pressure: In NH winter the tropopause is coldest over the western tropical Pacific warm pool region, but it is highest and at lowest pressure over the western Atlantic. Correlations of interannual anomalies in zonal-mean characteristics reveal that the height of the tropopause reflects the temperature of the underlying troposphere. Tropopause temperature, on the other hand, shows little association with tropospheric characteristics but is significantly correlated with the temperature and pressure of the lower stratosphere. The 100 hPa level is a poor surrogate for the tropical tropopause. Changes in radiosonde instrumentation limit the potential for detecting tropopause trends. However, the following (nonmonotonic) trends in the tropopause in the deep tropics during 1978 -1997 seem robust: an increase in height of about 20 m decade 21 , a decrease in pressure of about 0.5 hPa decade 21 , a cooling of about 0.5 K decade 21 , little change in potential temperature, and a decrease in saturation volume mixing ratio of about 0.3 ppmv decade 21 .

Comparison of Variations in Atmospheric Quantities with Sea Surface Temperature Variations in the Equatorial Eastern Pacific

Abstract Sea surface temperature (SST) variations in the equatorial eastern Pacific (0–10°S, 180–90°W) are compared with variations in atmospheric temperature, circulation, rainfall and trace-constituent amount. Significant at the 99.9% level (taking into account the serial correlation in the seasonal data) is the zero-lag correlation of −0.62 between this SST and the Southern Oscillation Index (normalized pressure difference between Tahiti and Darwin) during 1932–79, the correlation of 0.72 between this SST and the zonally averaged temperature in the tropical troposphere two seasons later during 1958–79, and the correlation of −0.62 between this SST and Indian summer monsoon rainfall 1–2 seasons earlier during 1868–1977. Significant at the 99% level is the correlation of 0.67 between this SST and rate of increase of CO2 at the South Pole 2–3 seasons later during 1965–76, and significant at the 95% level the correlation or 0.37 between this SST and rate of increase of CO2 at Mauna Loa one season later dur...

Variations and Trends in Tropospheric and Stratospheric Global Temperatures, 1958–87

Abstract Examined in this paper are the variations and trends in tropospheric and low-stratospheric temperature for seven climatic zones, hemispheres, and world for intervals 1958–87 and 1973–87, based on 63 well-distributed radiosonde stations. For the 30-yr interval 1958–87, these data indicate an increase in year-average global temperature at the surface and in the tropospheric 850–300 mb layer of 0.08°C (10 yr)−1 and 0.09°C (10 yr)−1, respectively, just significant at the 5% level. Nevertheless during this interval there is evidence for a slight decrease in year-average temperature at the surface and in the troposphere of the north polar and north temperate zones. The global 300–100 mb temperature is indicated as having decreased by 0.18°C (10 yr)−1 during this 30-yr interval (significant at the 1% level), with a temperature decrease in all seven climatic zones, though largest in the south polar zone (associated with the Antarctic “ozone hole” phenomenon). For the 15-yr interval 1973–87, the global te...

Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) : A new data set of large-area anomaly time series

[1] A new data set containing large-scale regional mean upper air temperatures based on adjusted global radiosonde data is now available up to the present. Starting with data from 85 of the 87 stations adjusted for homogeneity by Lanzante, Klein and Seidel, we extend the data beyond 1997 where available, using a first differencing method combined with guidance from station metadata. The data set consists of temperature anomaly time series for the globe, the hemispheres, tropics (30N–30S) and extratropics. Data provided include annual time series for 13 pressure levels from the surface to 30 mbar and seasonal time series for three broader layers (850–300, 300–100 and 100–50 mbar). The additional years of data increase trends to more than 0.1 K/decade for the global and tropical midtroposphere for 1979–2004. Trends in the stratosphere are approximately 0.5 to 0.9 K/decade and are more negative in the tropics than for the globe. Differences between trends at the surface and in the troposphere are generally reduced in the new time series as compared to raw data and are near zero in the global mean for 1979–2004. We estimate the uncertainty in global mean trends from 1979 to 2004 introduced by the use of first difference processing after 1995 at less than 0.02–0.04 K/decade in the troposphere and up to 0.15 K/decade in the stratosphere at individual pressure levels. Our reliance on metadata, which is often incomplete or unclear, adds further, unquantified uncertainty that could be comparable to the uncertainty from the FD processing. Because the first differencing method cannot be used for individual stations, we also provide updated station time series that are unadjusted after 1997. The Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) data set will be archived and updated at NOAA’s National Climatic Data Center as part of its climate monitoring program.

Quasi-Biennial Variations in Temperature, Total Ozone, and Tropopause Height

Abstract An analysis of mean-monthly temperature and total ozone data suggests that quasi-biennial oscillations extend to the temperate and polar latitudes of both hemispheres. Basically, there is symmetry with respect to the equator, although the oscillations show up most clearly in the Southern Hemisphere, and there is a tendency for the biennial maximum of temperature and total ozone to occur in the spring. Harmonic analysis implies a poleward drift of the biennial maximum of temperature and total ozone at a rate near 0.2 m sec−1, with the drift becoming indistinct poleward of 40°. The quasi-biennial variation in total ozone is very nearly in phase with the quasi-biennial variation in 50-mb temperature. There is also a quasi-biennial variation in tropopause height associated with the temperature oscillation in the lower stratosphere. There is weak evidence for a quasi-biennial variation in beryllium-7 in the lower stratosphere.

Quasi-Biennial and Long-Term Fluctuations In Total Ozone

Abstract Quasi-biennial and long-term fluctuations in total ozone are estimated from stations with more than 4 yr of record in north polar, tropical, south temperate, and south polar latitudes and more than 8 yr of record in north temperate latitudes. The quasi-biennial total-ozone fluctuations tend to be out of phase in tropical and extratropical latitudes, with the extratropical fluctuations better organized in the Southern than Northern Hemisphere. In the Tropics, the quasi-biennial total-ozone and zonal wind oscillations are significantly in phase, but, in extratropical latitudes, the total-ozone fluctuations are alternately in phase and out of phase with the tropical zonal wind oscillation, the out-of-phase relation being the dominant one. There is the suggestion that the Mt. Agung volcanic eruption in 1963 caused a breakdown of the quasi-biennial, total-ozone oscillation in the Southern Hemisphere subtropics, with anomalously high ozone values a few months after the eruption. We derive, for the past...

Surface temperature changes following the six major volcanic episodes between 1780 and 1980

Abstract Examined is the effect on surface temperature of the volcanic eruptions of Asama and Laki in 1783, Tambora in 1815, Coseguina in 1835, Krakatoa in 1883, Santa Maria, Soufriere and Pelee in 1902, and Agung in 1963, using temperature records extending back to 1781. These records include New Haven, Connecticut, in North America; Edinburgh, De Bilt, Copenhagen, Berlin and Vilnius in Northern Europe; Geneva, Basel, Hohen-peissenberg, Vienna and Budapest in Central Europe; the “Central England” data of Manley; and the merged Northern Hemisphere data of Groveman and Landsberg and Jones et al. At New Haven and in Europe there is more evidence of a cooling following eruptions in subtropical and temperate latitudes than in equatorial latitudes (despite the similarity in mean dust-veil index), with a cooling most evident following the Asama and Laki eruptions in Japan and Iceland, and next most evident following the Coseguina eruption in Nicaragua. Following the tremendous Tambora eruption, the eruption wit...

Uncertainty in Signals of Large-Scale Climate Variations in Radiosonde and Satellite Upper-Air Temperature Datasets

There is no single reference dataset of long-term global upper-air temperature observations, although several groups have developed datasets from radiosonde and satellite observations for climate-monitoring purposes. The existence of multiple data products allows for exploration of the uncertainty in signals of climate variations and change. This paper examines eight upper-air temperature datasets and quantifies the magnitude and uncertainty of various climate signals, including stratospheric quasi-biennial oscillation (QBO) and tropospheric ENSO signals, stratospheric warming following three major volcanic eruptions, the abrupt tropospheric warming of 1976‐77, and multidecadal temperature trends. Uncertainty estimates are based both on the spread of signal estimates from the different observational datasets and on the inherent statistical uncertainties of the signal in any individual dataset. The large spread among trend estimates suggests that using multiple datasets to characterize large-scale upperair temperature trends gives a more complete characterization of their uncertainty than reliance on a single dataset. For other climate signals, there is value in using more than one dataset, because signal strengths vary. However, the purely statistical uncertainty of the signal in individual datasets is large enough to effectively encompass the spread among datasets. This result supports the notion of an 11th climate-monitoring principle, augmenting the 10 principles that have now been generally accepted (although not generally implemented) by the climate community. This 11th principle calls for monitoring key climate variables with multiple, independent observing systems for measuring the variable, and multiple, independent groups analyzing the data.

Global Temperature Variations in the Troposphere and Stratosphere, 1958–1982

Abstract A network of 63 well-distributed radiosonde stations has been used to estimate mean-annual temperature variations at the surface and for 85–30 kPa (850–300 mb), 30–10 kPa, 10–5 kPa, 10–3 kPa, and surface- 10 kPa layers for five climatic zones, both hemispheres, and the world for the interval 1958–81. At the surface and in the 85–30 kPa layer there was global cooling of about 0.5°C between 1958 and about 1970, and global warming since, with 1980 and 1981 values approximately 0.1°C warmer than observed in 1958 and 1959. However, an update using seasonal data indicates appreciable cooling again between the northern springs of 1981 and 1982. In the 30–10 kPa layer there has been slight global cooling during most of the interval 1958–81, resulting in an increase in lapse rate in the 85–30 and 30–10 kPa layers during the last decade. In the middle and high stratosphere (26–55 km), Northern Hemisphere rocketsonde data suggest a 3–5°C cooling between 1970 and 1976, but little temperature change since. Th...

Variation in United States Cloudiness and Sunshine Duration between 1950 and the Drought Year of 1988

Abstract The variations in United States cloudiness (percent of sky covered by clouds, as estimated subjectively by observers at 100 National Weather Service stations) and sunshine duration (percent of possible sunshine, as estimated objectively by sunshine recorders at these same 100 stations) are examined for years 1950–88. During this period, the correlation between annual values of cloudiness and sunshine duration within the contiguous United States was −0.86, significant at the 1% level. The years of maximum cloudiness and minimum sunshine duration were 1972 and 1982, when strong El Ninos began. The year of maximum sunshine duration was 1988, but the years of minimum cloudiness were 1952–56 (mini dust bowl); the discrepancy a result of the greater long-term increase in cloudiness than decrease in sunshine duration. In the spring of 1988 them were anomalous values of cloudiness (below average) and sunshine duration (above average) in north central, south central and southeast regions of the United Sta...