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Tian, B.

Publications and source records attributed to Tian, B..

4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

The Atmospheric Infrared Sounder Version 6 Cloud Products

The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter D(sub e), and ice cloud optical thickness (τ) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of tau are found in the storm tracks and near convection in the tropics, while D(sub e) is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of tau is significantly larger than for the total cloud fraction, ice cloud frequency, and D(sub e), and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

infrared instruments↗
NASA NTRS2010

Modulation of Atlantic Aerosols by the Madden-Julian Oscillation

Much like the better-known EI Nino-Southern Oscillation, the Madden-Julian Oscillation (MJO) is a global-scale atmospheric phenomenon. The MJO involves periodic, systematic changes in the distribution of clouds and precipitation over the western Pacific and Indian oceans, along with differences in wind intensity over even more extensive areas, including the north and subtropical Atlantic Ocean. The lead authors of this paper developed a sophisticated mathematical technique for mapping the spatial and temporal behavior of changes in the atmosphere produced by the MJO. In a previous paper, we applied this technique to search for modulation of airborne particle amount in the eastern hemisphere associated with the "wet" (cloudy) vs. "dry" phases of the MJO. The study used primarily AVHRR, MODIS, and TOMS satellite-retrieved aerosol amount, but concluded that other factors, such as cloud contamination of the satellite signals, probably dominated the observed variations. The current paper looks at MJO modulation of desert dust transport eastward across the Atlantic from northern Africa, a region much less subject to systematic cloud contamination than the eastern hemisphere areas studied previously. In this case, a distinct aerosol signal appears, showing that dust is transported westward much more effectively during the MJO phase that favors westward-flowing wind, and such transport is suppressed when the MJO reduces these winds. Aside form the significant achievement in identifying such an effect, the result implies that an important component of global dust transport can be predicted based on the phase of the MJO. As a consequence, the impact of airborne dust on storm development in the Atlantic, and on dust deposition downwind of the desert sources, can also be predicted and more accurately modeled.

Tian, B.↗
NASA NTRS2007

Intraseasonal Variations of the Tropical Total Ozone and their Connection to the Madden-Julian Oscillation

We investigate the intraseasonal (30-90 day) variations in satellite-observed tropical total ozone (O3) and their connection to the Madden-Julian Oscillation (MJO). Tropical total O3 intraseasonal variations are large (approximately +/- 10 DU) and comparable to those in annual and interannual time scales. These O3 anomalies are mainly evident in the subtropics over the Pacific an eastern; hemisphere and propagate slowly eastward (approximately 5 m s-1). The subtropical negative (positive) O3 anomalies are typically collocated with the subtropical upper troposphere anticyclones (cyclones) generated by equatorial MJO convection and flank or lie to the west of the equatorial enhanced (suppressed) MJO convection. The subtropical O3 are anticorrelated with geopotential height anomalies near the tropopause and thus mainly associated with the O3 variability in the stratosphere rather the troposphere. Over the equatorial regions, total O3 anomalies are small.

Atmospheric Infrared Sounder (AIRS)↗