GSTDTAP  > 地球科学
DOI10.1175/JAS-D-17-0138.1
Spectral Signatures of Moisture-Convection Feedbacks over the Indian Ocean
Ahmed, Fiaz1; Schumacher, Courtney2
2018-06-01
发表期刊JOURNAL OF THE ATMOSPHERIC SCIENCES
ISSN0022-4928
EISSN1520-0469
出版年2018
卷号75期号:6页码:1995-2015
文章类型Article
语种英语
国家USA
英文摘要

Positive feedbacks between the cloud population and the environmental moisture field are central to theoretical expositions on the Madden-Julian oscillation (MJO). This study investigates the statistical incidence of positive moisture-convection feedbacks across multiple space and time scales over the tropical Indian Ocean. This work uses vertically integrated moisture budget terms from the ECMWF interim reanalysis [ERA-Interim (ERA-I)] in a framework proposed by Hannah et al. Positive moisture-convection feedbacks are primarily a low-frequency, low-wavenumber phenomenon with significant spectral signatures in the 32-48-day time scale. The efficacy of these feedbacks, however, is subject to horizontal moisture advection variations, whose relative importance varies with scale. Wave-filtered Tropical Rainfall Measuring Mission (TRMM) satellite precipitation is used to show that these moisture-convection feedbacks contribute more to moisture increases in the MJO than in other equatorial waves. A moving-window correlation analysis suggests that instances of moisture-convection feedbacks are more frequent in drier conditions, when column water vapor (CWV) is below its climatological mean value, with the implication that positive moisture-convection feedbacks shape the mean CWV field by moistening drier air columns, but that they are less effective in moistening already moist environments. Ground radar observations show that stratiform rain damps local CWV increases on short time scales (< 2 days) and therefore precludes positive moisture-convection feedbacks in high-CWV environments. Vertical coherence structures from ERA-I confirm that relatively bottom-heavy cloud ensembles (i.e., peaks between 700 and 850 hPa) are more effective in inducing low-frequency positive moisture-convection feedbacks than ensembles with other vertical structures. Low-frequency horizontal advective drying damps moisture increases and is strongly coherent with upper-level rising motion.


领域地球科学
收录类别SCI-E
WOS记录号WOS:000434942300013
WOS关键词MADDEN-JULIAN OSCILLATION ; STATIC ENERGY BUDGET ; TEMPERATURE-GRADIENT APPROXIMATION ; TROPICAL DEEP CONVECTION ; COUPLED KELVIN WAVES ; COLUMN WATER-VAPOR ; STRATIFORM INSTABILITY ; EQUATORIAL WAVES ; PART I ; INTRASEASONAL OSCILLATIONS
WOS类目Meteorology & Atmospheric Sciences
WOS研究方向Meteorology & Atmospheric Sciences
引用统计
文献类型期刊论文
条目标识符http://119.78.100.173/C666/handle/2XK7JSWQ/29541
专题地球科学
作者单位1.Univ Calif Los Angeles, Atmospher & Ocean Sci, Los Angeles, CA 90095 USA;
2.Texas A&M Univ, Dept Atmospher Sci, College Stn, TX USA
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Ahmed, Fiaz,Schumacher, Courtney. Spectral Signatures of Moisture-Convection Feedbacks over the Indian Ocean[J]. JOURNAL OF THE ATMOSPHERIC SCIENCES,2018,75(6):1995-2015.
APA Ahmed, Fiaz,&Schumacher, Courtney.(2018).Spectral Signatures of Moisture-Convection Feedbacks over the Indian Ocean.JOURNAL OF THE ATMOSPHERIC SCIENCES,75(6),1995-2015.
MLA Ahmed, Fiaz,et al."Spectral Signatures of Moisture-Convection Feedbacks over the Indian Ocean".JOURNAL OF THE ATMOSPHERIC SCIENCES 75.6(2018):1995-2015.
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