Extension of explicit radiance observations by the Stratospheric Sounding Unit into the lower stratosphere and lower mesosphere

Nash, John F.

doi:10.1002/qj.49711448213

Cited by 17 publications

(19 citation statements)

References 16 publications

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“…Figure 15 compares monthly temperature anomalies from JRA-25, JRA-55 and two independent observational datasets for the middle, upper, and top stratosphere, averaged over 75°N to 75°S. The independent datasets are the Met Office SSU dataset (Nash and Forester 1986;Nash 1988;Shine et al 2008) and the National Oceanic and Atmospheric Administration (NOAA) the Center for Satellite Application and Research (STAR) SSU dataset version 1.0 (Wang et al 2012). These two SSU datasets display strikingly different time series, suggesting a clear need for better understanding observational characteristics of the SSUs to obtain more reliable estimates of stratospheric temperature trends (Thompson et al 2012).…”

Section: B Lower Troposphere To Lower Stratospherementioning

confidence: 99%

The JRA-55 Reanalysis: General Specifications and Basic Characteristics

Kobayashi

Ota

Harada

et al. 2015

Journal of the Meteorological Society of Japan

3,822

2,524

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The Japan Meteorological Agency (JMA) conducted the second Japanese global atmospheric reanalysis, called the Japanese 55-year Reanalysis or JRA-55. It covers the period from 1958, when regular radiosonde observations began on a global basis. JRA-55 is the first comprehensive reanalysis that has covered the last half-century since the European Centre for Medium-Range Weather Forecasts 45-year Reanalysis (ERA-40), and is the first one to apply four-dimensional variational analysis to this period. The main objectives of JRA-55 were to address issues found in previous reanalyses and to produce a comprehensive atmospheric dataset suitable for studying multidecadal variability and climate change. This paper describes the observations, data assimilation system, and forecast model used to produce JRA-55 as well as the basic characteristics of the JRA-55 product.JRA-55 has been produced with the TL319 version of JMA's operational data assimilation system as of December 2009, which was extensively improved since the Japanese 25-year Reanalysis (JRA-25). It also uses several newly available and improved past observations. The resulting reanalysis products are considerably better than the JRA-25 product. Two major problems of JRA-25 were a cold bias in the lower stratosphere, which has been diminished, and a dry bias in the Amazon basin, which has been mitigated. The temporal consistency of temperature analysis has also been considerably improved compared to previous reanalysis products. Our initial quality evaluation revealed problems such as a warm bias in the upper troposphere, large upward imbalance in the global mean net energy fluxes at the top of the atmosphere and at the surface, excessive precipitation over the tropics, and unrealistic trends in analyzed tropical cyclone strength. This paper also assesses the impacts of model biases and changes in the observing system, and mentions efforts to further investigate the representation of low-frequency variability and trends in JRA-55.

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Section: B Lower Troposphere To Lower Stratospherementioning

confidence: 99%

The JRA-55 Reanalysis: General Specifications and Basic Characteristics

Kobayashi

Ota

Harada

et al. 2015

Journal of the Meteorological Society of Japan

3,822

2,524

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“…The SSU data set consists of 101 zonal brightness temperature anomalies from three observed (25, 26, and 27) and five synthetically derived (47X, 36X, 35X, 26X, and 15X) channels having their maximum sensitivity at different altitudes as given in Table 1. The weighting functions for the SSU channels are typically 10-15 km wide (Nash, 1988) with long tails, while the weighting functions for the synthetic channels using the off-nadir (51) mode are somewhat sharper, see, for example, Fig. 1 of Randel et al (2009).…”

Section: Description Of the Ssu Seriesmentioning

confidence: 99%

“…Peak altitudes of weighting functions of the SSU channels: near nadir viewing, and synthetic (combined near nadir and 351 scans) extracted fromNash (1988).…”

mentioning

confidence: 99%

An evaluation of uncertainties in monitoring middle atmosphere temperatures with the ground-based lidar network in support of space observations

Keckhut

Randel

Claud

et al. 2011

Journal of Atmospheric and Solar-Terrestrial Physics

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International audienceThe capability of the longest lidar data sets to monitor long-term temperature changes have been evaluated through comparisons with the successive Stratospheric Sounder Units (SSU) onboard NOAA satellites. Cross-consistency investigations between SSU and the lidar network can be considered as a first attempt to demonstrate how the synergistic use of space and ground-based instruments could provide reliable monitoring of the temperature of the middle atmosphere. The breakdown of the temperature cooling trend, and the following flattening observed in the satellite temperature series, are qualitatively confirmed by the lidars. However, there are still large differences that can either be due to SSU continuity (orbit drifts or weighting function modifications) or lidar operation changes (time of measurements, accuracy, sampling, etc.). SSU vertical weighting functions have been taken into account for comparisons. Some discontinuity events cannot be explained by the SSU weighting function drifts due to CO2. For the upper channels of SSU (peaking around 50 km) the results are probably sensitive to the mesospheric part of the lidar profiles that can explain some discontinuities. Tropical lidar stations show clear inter-annual differences with the SSU channels covering the lowest altitude range that need further investigations to understand if the origin is instrumental or geophysical. An attempt to derive non-linear trends with combinations of linear, hockey stick, and quadratic functions has been made. While the quadratic term is not highly significant, this approach allows the derivation of a better quantification of the linear trend terms

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“…These channels have weighting function peaks at about 29, 38 and 44 km, respectively (see Figure 1), and sample relatively broad layers of the stratosphere (∼10–15 km thick). In addition, a number of so‐called synthetic channels (henceforth X channels) [see Nash , 1988] are available which use the differences between near‐nadir and 35° scans and combinations of channels to construct weighting functions that increase the vertical resolution of the derived temperatures. These are referred to as 15X, 26X, 36X and 47X (which peak at about 23, 35, 45 and 50 km, respectively).…”

Section: Data Sets and Trend Calculationsmentioning

confidence: 99%

“…This paper uses the only available time series of corrected SSU brightness temperatures currently available. These are an extension of the series derived by Nash and Forrester [1986] and Nash [1988] [see also Ramaswamy et al , 2001]. These brightness temperatures are available as monthly zonal mean anomalies from a long‐term climatology, on a 10° latitude grid covering 70°N to 70°S.…”

Section: Data Sets and Trend Calculationsmentioning

confidence: 99%

An update of observed stratospheric temperature trends

et al. 2009

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An updated analysis of observed stratospheric temperature variability and trends is presented on the basis of satellite, radiosonde, and lidar observations. Satellite data include measurements from the series of NOAA operational instruments, including the Microwave Sounding Unit covering 1979-2007 and the Stratospheric Sounding Unit (SSU) covering 1979-2005. Radiosonde results are compared for six different data sets, incorporating a variety of homogeneity adjustments to account for changes in instrumentation and observational practices. Temperature changes in the lower stratosphere show cooling of ~0.5 K/decade over much of the globe for 1979-2007, with some differences in detail among the different radiosonde and satellite data sets. Substantially larger cooling trends are observed in the Antarctic lower stratosphere during spring and summer, in association with development of the Antarctic ozone hole. Trends in the lower stratosphere derived from radiosonde data are also analyzed, for a longer record (back to 1958); trends for the presatellite era (1958-1978) have a large range among the different homogenized data sets, implying large trend uncertainties. Trends in the middle and upper stratosphere have been derived from updated SSU data, taking into account changes in the SSU weighting functions due to observed atmospheric CO2 increases. The results show mean cooling of 0.5-1.5 K/decade during 1979-2005, with the greatest cooling in the upper stratosphere near 40-50 km. Temperature anomalies throughout the stratosphere were relatively constant during the decade 1995-2005. Long records of lidar temperature measurements at a few locations show reasonable agreement with SSU trends, although sampling uncertainties are large in the localized lidar measurements. Updated estimates of the solar cycle influence on stratospheric temperatures show a statistically significant signal in the tropics (~30°N-S), with an amplitude (solar maximum minus solar minimum) of ~0.5 K (lower stratosphere) to ~1.0 K (upper stratosphere)

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Extension of explicit radiance observations by the Stratospheric Sounding Unit into the lower stratosphere and lower mesosphere

Cited by 17 publications

References 16 publications

The JRA-55 Reanalysis: General Specifications and Basic Characteristics

The JRA-55 Reanalysis: General Specifications and Basic Characteristics

An evaluation of uncertainties in monitoring middle atmosphere temperatures with the ground-based lidar network in support of space observations

An update of observed stratospheric temperature trends

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