Postlaunch calibration and bias characterization of AMSU‐A upper air sounding channels using GPS RO Data

Chen, X.; Zou, Xiaolei

doi:10.1002/2013jd021037

Cited by 8 publications

(5 citation statements)

References 54 publications

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“…Comparisons with collocated radiosondes (detailed in the following section), Vaisala RS90/92 and GRUAN, showed very good agreement with global annualmean temperature differences of less than 0.2 K. Radiosonde daytime radiation biases were identified at higher altitudes (Ladstädter et al 2015;Ho et al 2017). The stability of RO makes it a useful calibration reference for AMSU (Chen and Zou 2014) and radiosondes (Ho et al 2017;Tradowsky et al 2018).…”

Section: ) Gnss Radio Occultation Observationsmentioning

confidence: 74%

Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018

et al. 2020

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Temperature observations of the upper-air atmosphere are now available for more than 40 years from both ground- and satellite-based observing systems. Recent years have seen substantial improvements in reducing long-standing discrepancies among data sets through major reprocessing efforts. The advent of radio occultation (RO) observations in 2001 has led to further improvements in vertically-resolved temperature measurements, enabling a detailed analysis of upper troposphere/lower stratosphere trends. This paper presents the current state of atmospheric temperature trends from the latest available observational records. We analyze observations from merged operational satellite measurements, radiosondes, lidars, and RO, spanning a vertical range from the lower troposphere to the upper stratosphere. The focus is on assessing climate trends and on identifying the degree of consistency among the observational systems. The results show a robust cooling of the stratosphere of about 1–3 K, and a robust warming of the troposphere of about 0.6–0.8 K over the last four decades (1979–2018). Consistent results are found between the satellite-based layer average temperatures and vertically-resolved radiosonde records. The overall latitude-altitude trend patterns are consistent between RO and radiosonde records. Significant warming of the troposphere is evident in the RO measurements available after 2001, with trends of 0.25–0.35 K per decade. Amplified warming in the tropical upper-troposphere compared to surface trends for 2002–2018 is found based on RO and radiosonde records, in approximate agreement with moist adiabatic lapse rate theory. The consistency of trend results from the latest upper-air data sets will help to improve understanding of climate changes and their drivers.

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Section: ) Gnss Radio Occultation Observationsmentioning

confidence: 74%

Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018

et al. 2020

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“…Radiosonde daytime radiation biases were identified at higher altitudes (Ladstädter et al, 2015;Ho et al, 2017). The stability of RO makes this data a useful comparator for AMSU (Chen and Zou, 2014) and radiosondes (Ho et al, 2017;Tradowsky et al, 2017), as well as anchoring post-2006 reanalyses datasets and improving their consistency in the lower and middle stratosphere (Long et al, 2017;Ho et al, 2020). The effective vertical resolution of RO measurements in the upper troposphere and lower stratosphere was found to be up to 100 m at the tropical tropopause (Zeng et al, 2019a), which is favourable for resolving atmospheric variability (Scherllin-Pirscher et al, 2012;Wilhelmsen et al, 2018;Stocker et al, 2019).…”

Section: Dataset Developmentsmentioning

confidence: 99%

Changing State of the Climate System

2023

Climate Change 2021 – The Physical Science Basis

104

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Chapter 2 assesses observed large-scale changes in climate system drivers, key climate indicators and principal modes of variability. Chapter 3 considers model performance and detection/attribution, and Chapter 4 covers projections for a subset of these same indicators and modes of variability. Collectively, these chapters provide the basis for later chapters, which focus upon processes and regional changes. Within Chapter 2, changes are assessed from in situ and remotely sensed data and products and from indirect evidence of longer-term changes based upon a diverse range of climate proxies. The timeevolving availability of observations and proxy information dictate the periods that can be assessed. Wherever possible, recent changes are assessed for their significance in a longer-term context, including target proxy periods, both in terms of mean state and rates of change.The increase in GMST since the mid-19th century was preceded by a slow decrease that began in the mid-Holocene (around 6500 years ago) (medium confidence). {2.3.1.1, Cross-Chapter Box 2.1} Changes in GMST and global surface air temperature (GSAT) over time differ by at most 10% in either direction (high confidence), and the long-term changes in GMST and GSAT are presently assessed to be identical. There is expanded uncertainty in GSAT estimates, with the assessed change from 1850-1900 to 1995-2014 being 0.85 [0.67 to 0.98] °C. {Cross-Chapter Box 2.3} The troposphere has warmed since at least the 1950s, and it is virtually certain that the stratosphere has cooled. In the Tropics, the upper troposphere has warmed faster than the near-surface since at least 2001, the period over which new observational techniques permit more robust quantification (medium confidence). It is virtually certain that the tropopause height has risen globally over 1980-2018, but there is low confidence in the magnitude. {2.3.1.2} Changes in several components of the global hydrological cycle provide evidence for overall strengthening since at least 1980 (high confidence). However, there is low confidence in comparing recent changes with past variations due to limitations in paleoclimate records at continental and global scales. Global land precipitation has likely increased since 1950, with a faster increase since the 1980s (medium confidence). Nearsurface specific humidity has increased over both land (very likely) and the oceans (likely) since at least the 1970s. Relative humidity has very likely decreased over land areas since 2000. Global total column water vapour content has very likely increased during the satellite era. Observational uncertainty leads to low confidence in global trends in precipitation minus evaporation and river runoff. {2.3.1.3} Several aspects of the large-scale atmospheric circulation have likely changed since the mid-20th century, but limited proxy evidence yields low confidence in how these changes compare to longer-term climate. The Hadley circulation has likely widened since at least the 1980s, and extratropical storm tracks have likely shi...

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“…A TB value at a specific channel represents the atmospheric radiation within a layer of the atmosphere near a particular altitude and varies mainly with the atmospheric temperature. The weighting functions of these AMSU‐A sounding channels are evenly distributed in the vertical using the logarithmic pressure coordinate from the surface up to about 0.1 hPa (see Figure 2a in Chen & Zou, 2014). The largest radiation contribution to the channel comes from the altitude where the weighting function peaks.…”

Section: Mwts‐2 and Amsu‐a Channels Limb‐correction Method And Resultsmentioning

confidence: 99%

Northeast China Cold Vortex Observed by FY‐3 MWTS‐2 and MetOp AMSU‐A

Niu

Zou

2021

JGR Atmospheres

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The northeast China cold vortex (NCCV) refers to a closed low‐pressure system over northeast China extending from China‐Siberia to the northwest Pacific coast region. It is cut off from the westerly jet belt in the middle and upper troposphere, has a cold core, lasts several days, and could bring heavy rain events in late spring and summer that are of great challenge to weather forecasters. This study investigates the possibility of observing temperature structures of NCCVs by two microwave temperature sounders, that is, the Microwave Temperature Sounder‐2 (MWTS‐2) and the Advanced Microwave Sounding Unit‐A (AMSU‐A) onboard the two polar‐orbiting operational environmental satellites (POES) Fenyun‐3 satellite FY‐3D and Meteorological Operational satellite MetOp‐B, respectively. The MWTS‐2 and AMSU‐A together provide 3D atmospheric temperatures in the middle and upper troposphere, as well as the lower stratosphere four times daily. Both limb‐corrected direct observations of brightness temperature and retrievals of atmospheric temperature within NCCVs are characterized by cold and warm cores below and above the tropopause, respectively, comparing favorably with the European Centre for Medium‐Range Weather Forecasts ERA5 reanalysis. Compared with the ERA5 reanalysis in June 2019, the MWTS‐2 retrieved atmospheric temperatures have no scan‐dependent biases, the biases are smaller than ±0.2K, and root‐mean‐square errors (RMSEs) are smaller than and 2.0K at all altitudes. This study suggests the possibility of using multiple POES microwave‐temperature‐sounding observations for near‐real‐time monitoring of NCCVs' 3D temperature structures.

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Postlaunch calibration and bias characterization of AMSU‐A upper air sounding channels using GPS RO Data

Cited by 8 publications

References 54 publications

Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018

Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018

Changing State of the Climate System

Northeast China Cold Vortex Observed by FY‐3 MWTS‐2 and MetOp AMSU‐A

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