Planetary boundary layer heights from GPS radio occultation refractivity and humidity profiles

Ao, C. O.; Waliser, Duane E.; Chan, S.; Li, Jui-Lin; Tian, Baijun; Xie, Feiqin; Mannucci, A. J.

doi:10.1029/2012jd017598

Cited by 141 publications

(179 citation statements)

References 46 publications

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“…The h can be estimated as the level of the minimum vertical gradient of relative humidity (h RH ) or specific humidity (h q ) with a significant reduction in atmospheric moisture (Ao et al, 2008;Seidel et al, 2010). Additionally, atmospheric refractivity (N), which combines the information of temperature and humidity (defined in Eq.…”

Section: Comparison Of the Existing Methods To Determine Hmentioning

confidence: 99%

Estimation of atmospheric mixing layer height from radiosonde data

Wang

2014

Atmos. Meas. Tech.

103

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Abstract. Mixing layer height (h) is an important parameter for understanding the transport process in the troposphere, air pollution, weather and climate change. Many methods have been proposed to determine h by identifying the turning point of the radiosonde profile. However, substantial differences have been observed in the existing methods (e.g. the potential temperature (θ ), relative humidity (RH), specific humidity (q) and atmospheric refractivity (N) methods). These differences are associated with the inconsistency of the temperature and humidity profiles in a boundary layer that is not well mixed, the changing measurability of the specific humidity and refractivity with height, the measurement error of humidity instruments within clouds, and the general existence of clouds. This study proposes a method to integrate the information of temperature, humidity and cloud to generate a consistent estimate of h. We apply this method to high vertical resolution (∼ 30 m) radiosonde data that were collected at 79 stations over North America during the period from 1998 to 2008. The data are obtained from the Stratospheric Processes and their Role in Climate Data Center (SPARC). The results show good agreement with those from N method as the information of temperature and humidity contained in N ; however, cloud effects that are included in our method increased the reliability of our estimated h. From 1988 to 2008, the climatological h over North America was 1675 ± 303 m with a strong east-west gradient: higher values (generally greater than 1800 m) occurred over the Midwest US, and lower values (usually less than 1400 m) occurred over Alaska and the US West Coast.

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Section: Comparison Of the Existing Methods To Determine Hmentioning

confidence: 99%

Estimation of atmospheric mixing layer height from radiosonde data

Wang

2014

Atmos. Meas. Tech.

103

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“…Several studies have utilized such features in RO refractivity profile for detecting the ABL height by locating the height of maximum refractivity gradient (MRG) in GPS RO profiles with some differences in algorithm implementation (e.g., Sokolovskiy et al, 2006;Ao et al, 2008;Basha and Ratnam, 2009;Guo et al, 2011;Ao et al, 2012). For a well-defined ABL (e.g., over VOCALS region), the refractivity gradient method is consistent with other conventional definitions (e.g., gradient method based on temperature or humidity profiles) (Basha and Ratnam, 2009;Seidel et al, 2010;von Engeln and Teixeira, 2011;Ao et al, 2012).…”

Section: Typical Abl Structure Over Vocals Regionmentioning

confidence: 97%

“…It is important to note that the implementation of the open-loop tracking technique on the COS-MIC RO receivers significantly improves the quality of RO soundings in the moist ABL, as compared with the early GPS RO missions that used phase-locked loop (PLL) tracking technique (Sokolovskiy 2001;Ao et al, 2009). Several studies have demonstrated the values of RO soundings in detecting the ABL height (e.g., Sokolovskiy et al, 2006;Sokolovskiy et al, 2007;Ao et al, 2008;Basha and Ratnam, 2009;Guo et al, 2011;Ao et al, 2012). However, probing the ABL interior with RO remains to be challenging.…”

Section: F Xie Et Al: Advances and Limitations Of Abl Observations mentioning

confidence: 99%

Advances and limitations of atmospheric boundary layer observations with GPS occultation over southeast Pacific Ocean

Xie

et al. 2012

Atmos. Chem. Phys.

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Abstract. The typical atmospheric boundary layer (ABL) over the southeast (SE) Pacific Ocean is featured with a strong temperature inversion and a sharp moisture gradient across the ABL top. The strong moisture and temperature gradients result in a sharp refractivity gradient that can be precisely detected by the Global Positioning System (GPS) radio occultation (RO) measurements. In this paper, the Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) GPS RO soundings, radiosondes and the high-resolution ECMWF analysis over the SE Pacific are analyzed. COSMIC RO is able to detect a wide range of ABL height variations (1-2 km) as observed from the radiosondes. However, the ECMWF analysis systematically underestimates the ABL heights. The sharp refractivity gradient at the ABL top frequently exceeds the critical refraction (e.g., −157 N-unit km −1 ) and becomes the so-called ducting condition, which results in a systematic RO refractivity bias (or called N -bias) inside the ABL. Simulation study based on radiosonde profiles reveals the magnitudes of the N-biases are vertical resolution dependent. The N -bias is also the primary cause of the systematically smaller refractivity gradient (rarely exceeding −110 N-unit km −1 ) at the ABL top from RO measurement. However, the N-bias seems not affect the ABL height detection. Instead, the very large RO bending angle and the sharp refractivity gradient due to ducting allow reliable detection of the ABL height from GPS RO. The seasonal mean climatology of ABL heights derived from a nine-month composite of COSMIC RO soundings over the SE Pacific reveals significant differences from the ECMWF analysis. Both show an increase of ABL height from the shallow stratocumulus near the coast to a much higher trade wind inversion further off the coast. However, COSMIC RO shows an overall deeper ABL and reveals different locations of the minimum and maximum ABL heights as compared to the ECMWF analysis. At low latitudes, despite the decreasing number of COSMIC RO soundings and the lower percentage of soundings that penetrate into the lowest 500-m above the mean-sea-level, there are small sampling errors in the mean ABL height climatology. The difference of ABL height climatology between COSMIC RO and ECMWF analysis over SE Pacific is significant and requires further studies.

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“…A few studies have been done by using Global Positioning System radio occultation (GPS RO) measurements (Ratnam and Basha, 2010;Guo et al, 2011;Ao et al, 2012) or Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) (McGrath-Spangler and Denning, 2013). GPS RO provides a valuable global view of the height-resolved refractivity or moisture structure of ABL.…”

Section: Introductionmentioning

confidence: 99%

Lidar-based remote sensing of atmospheric boundary layer height over land and ocean

2014

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Abstract. Atmospheric boundary layer (ABL) processes are important in climate, weather and air quality. A better understanding of the structure and the behavior of the ABL is required for understanding and modeling of the chemistry and dynamics of the atmosphere on all scales. Based on the systematic variations of the ABL structures over different surfaces, different lidar-based methods were developed and evaluated to determine the boundary layer height and mixing layer height over land and ocean. With Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) micropulse lidar (MPL) and radiosonde measurements, diurnal and season cycles of atmospheric boundary layer depth and the ABL vertical structure over ocean and land are analyzed. The new methods are then applied to satellite lidar measurements. The aerosol-derived global marine boundary layer heights are evaluated with marine ABL stratiform cloud top heights and results show a good agreement between them.

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Planetary boundary layer heights from GPS radio occultation refractivity and humidity profiles

Cited by 141 publications

References 46 publications

Estimation of atmospheric mixing layer height from radiosonde data

Estimation of atmospheric mixing layer height from radiosonde data

Advances and limitations of atmospheric boundary layer observations with GPS occultation over southeast Pacific Ocean

Lidar-based remote sensing of atmospheric boundary layer height over land and ocean

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