Editorial Type:
Article
Article Type:
Research Article

Cloud-Top Evolution of Tropical Oceanic Squall Lines from Radar Reflectivity and Infrared Satellite Data

Thomas M. Rickenbach Tropical Rainfall Measuring Mission Office, NASA/Goddard Space Flight Center, Greenbelt, Maryland

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Print Publication:
01 Dec 1999
DOI:
https://doi.org/10.1175/1520-0493(1999)127<2951:CTEOTO>2.0.CO;2
Page(s):
2951–2976
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Abstract

Precipitation estimation over the tropical oceans is commonly performed using passive infrared (IR) measurements of cloud-top brightness temperature from geostationary satellites to infer the location of deep convection. It has been recognized in recent years that the majority of tropical precipitation is produced by mesoscale convective systems (MCSs). However, the relationship between the IR cloud-top patterns associated with MCSs and the underlying precipitation is not well understood. The assumption that the coldest cloud tops are associated with deep, active convection has been central to the characterization of cloud system motion and organization, and to many IR-based rainfall retrievals. Previous studies suggested that this view may be oversimplified when applied to propagating convective systems, such as squall lines. The goal of this study was to understand the evolution of the cold cloud associated with tropical oceanic squall line MCSs, and to discuss the implications for the retrieval of precipitation organization and rainfall rate from satellite IR data.

Shipboard radar reflectivity and Geostationary Meteorological Satellite (Japan) brightness temperature data collected during the Tropical Oceans Global Atmospheres Coupled Ocean–Atmosphere Response Experiment have been used to study the evolution of two tropical oceanic squall line MCSs. Results suggested a complex, evolution-dependent relationship between the radar-derived precipitation pattern associated with mesoscale convective systems and the overlying cloud tops observed by the satellite. The coldest clouds formed in the wake of the leading edge of the propagating lines, following the intensification of deep convection on the leading edge. In an environment of deep tropospheric directional wind shear (e.g., during westerly wind bursts), the cold cloud shield became spatially decoupled from the source convection to form swaths of cold cloud. These cloud swaths were generally normal to the squall line orientation. As convection on the leading edge of the squall line weakened, the cold cloud shield expanded. As a result the coldest clouds were more closely associated with weaker surface precipitation.

These results have implications for the interpretation of the location, shape, and motion of cold cloud features in the tropical western Pacific region. They may also help to explain the poor performance of IR rain retrieval algorithm when applied to instantaneous images. Results from this study may aid in the interpretation of twice-per-day “snapshots ” of MCSs (from IR, microwave, and radar sensors) from the recently launched Tropical Rainfall Measuring Mission satellite.

* Current affiliation: Joint Center for Earth Systems Technology (JCET), University of Maryland, Baltimore County (UMBC), Baltimore, Maryland.

Corresponding author address: Dr. Thomas M. Rickenbach, TRMM Office, Code 910.1, NASA GSFC, Greenbelt, MD 20771.

Email: rickenba@research.umbc.edu

Abstract

Precipitation estimation over the tropical oceans is commonly performed using passive infrared (IR) measurements of cloud-top brightness temperature from geostationary satellites to infer the location of deep convection. It has been recognized in recent years that the majority of tropical precipitation is produced by mesoscale convective systems (MCSs). However, the relationship between the IR cloud-top patterns associated with MCSs and the underlying precipitation is not well understood. The assumption that the coldest cloud tops are associated with deep, active convection has been central to the characterization of cloud system motion and organization, and to many IR-based rainfall retrievals. Previous studies suggested that this view may be oversimplified when applied to propagating convective systems, such as squall lines. The goal of this study was to understand the evolution of the cold cloud associated with tropical oceanic squall line MCSs, and to discuss the implications for the retrieval of precipitation organization and rainfall rate from satellite IR data.

Shipboard radar reflectivity and Geostationary Meteorological Satellite (Japan) brightness temperature data collected during the Tropical Oceans Global Atmospheres Coupled Ocean–Atmosphere Response Experiment have been used to study the evolution of two tropical oceanic squall line MCSs. Results suggested a complex, evolution-dependent relationship between the radar-derived precipitation pattern associated with mesoscale convective systems and the overlying cloud tops observed by the satellite. The coldest clouds formed in the wake of the leading edge of the propagating lines, following the intensification of deep convection on the leading edge. In an environment of deep tropospheric directional wind shear (e.g., during westerly wind bursts), the cold cloud shield became spatially decoupled from the source convection to form swaths of cold cloud. These cloud swaths were generally normal to the squall line orientation. As convection on the leading edge of the squall line weakened, the cold cloud shield expanded. As a result the coldest clouds were more closely associated with weaker surface precipitation.

These results have implications for the interpretation of the location, shape, and motion of cold cloud features in the tropical western Pacific region. They may also help to explain the poor performance of IR rain retrieval algorithm when applied to instantaneous images. Results from this study may aid in the interpretation of twice-per-day “snapshots ” of MCSs (from IR, microwave, and radar sensors) from the recently launched Tropical Rainfall Measuring Mission satellite.

* Current affiliation: Joint Center for Earth Systems Technology (JCET), University of Maryland, Baltimore County (UMBC), Baltimore, Maryland.

Corresponding author address: Dr. Thomas M. Rickenbach, TRMM Office, Code 910.1, NASA GSFC, Greenbelt, MD 20771.

Email: rickenba@research.umbc.edu

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  • Adler, R. F., and A. J. Negri, 1988: A satellite infrared technique to estimate tropical convective and stratiform rainfall. J. Appl. Meteor.,27, 30–51.

  • Arkin, P. A., and B. N. Meisner, 1987: The relationship between large-scale convective rainfall and cold cloud over the Western Hemisphere during 1982–84. Mon. Wea. Rev.,115, 51–74.

  • Chen, S. S., R. A. Houze Jr., and B. E. Mapes, 1996: Multiscale variability of deep convection in relation to large-scale circulation in TOGA COARE. J. Atmos. Sci.,53, 1380–1409.

  • ——, G. M. McFarquhar, and A. J. Heymsfield, 1997: A modeling and observational study of the detailed microphysical structure of tropical cirrus anvils. J. Geophys. Res.,102, 6637–6653.

  • Churchill, D. D., and R. A. Houze Jr., 1991: Effects of radiation and turbulence on the diabatic heating and water budget of the stratiform region of a tropical cloud cluster. J. Atmos. Sci.,48, 903–922.

  • Ebert, E. E., and M. J. Manton, 1998: Performance of satellite rainfall estimation algorithms during TOGA COARE. J. Atmos. Sci.,55, 1537–1557.

  • Fortune, M., 1980: Properties of African squall lines inferred from time-lapse satellite imagery. Mon. Wea. Rev.,108, 153–168.

  • Gamache, J. F., and R. A. Houze Jr., 1982: Mesoscale air motions associated with a tropical squall line. Mon. Wea. Rev.,110, 118–135.

  • Geldmeier, M. F., and G. M. Barnes, 1997: The “footprint” under a decaying tropical mesoscale convective system. Mon. Wea. Rev.,125, 2879–2895.

  • Goldenberg, S. B., R. A. Houze Jr., and D. D. Churchill, 1990: Convective and stratiform components of a winter monsoon cloud cluster determined from geosynchronous infrared satellite data. J. Meteor. Soc. Japan,68, 37–63.

  • Heymsfield, G. M., and R. Fulton, 1994: Passive microwave and infrared structure of mesoscale convective systems. Meteor. Atmos. Phys.,54, 123–139.

  • Hinton, B. B., 1993: Satellite images, satellite sounder data, forecast model grids and SST composites archived by SSEC for TOGA COARE. SSEC, 388 pp. [Available from the Space Science and Engineering Center (SSEC), Univ. of Wisconsin—Madison, 1225 W. Dayton St., Madison, WI 53706.].

  • Hodges, K. I., and C. D. Thorncroft, 1997: Distribution and statistics of African mesoscale convective weather systems based on the ISCCP Meteosat imagery. Mon. Wea. Rev.,125, 2821–2837.

  • Houze, R. A., Jr., 1977: Structure and dynamics of a tropical squall-line system. Mon. Wea. Rev.,105, 1540–1567.

  • ——, 1993: Cloud Dynamics. Academic Press, 573 pp.

  • ——, B. F. Smull, and P. Dodge, 1990: Mesoscale organization of springtime rainstorms in Oklahoma. Mon. Wea. Rev.,118, 613–654.

  • Inoue, T., 1987: An instantaneous delineation of convective rainfall areas using split window data of NOAA-7 AVHRR. J. Meteor. Soc. Japan,65, 469–480.

  • Kummerow, C., and L. Giglio, 1994: A passive microwave technique for estimating rainfall and vertical structure information from space. Part II: Applications to SSM/I data. J. Appl. Meteor.,33, 19–34.

  • LeMone, M. A., D. P. Jorgensen, and B. F. Smull, 1994: The impact of two convective systems on sea-surface stresses in COARE. Preprints, Sixth Conf. Mesoscale Processes, Portland, OR, Amer. Meteor. Soc., 40–44.

  • ——, E. J. Zipser, and S. B. Trier, 1998: The role of environmental shear and thermodynamic conditions in determining the structure and evolution of mesoscale convective systems during TOGA COARE. J. Atmos. Sci.,55, 3493–3518.

  • Lilly, D. K., 1988: Cirrus outflow dynamics. J. Atmos. Sci.,45, 1594–1605.

  • Machado, L. A. T., and W. B. Rossow, 1993: Structural characteristics and radiative properties of tropical cloud clusters. Mon. Wea. Rev.,121, 3234–3260.

  • Maddox, R. A., 1980: Mesoscale convective complexes. Bull. Amer. Meteor. Soc.,61, 1374–1387.

  • Mapes, B. E., and R. A. Houze Jr., 1993: Cloud clusters and superclusters over the oceanic warm pool. Mon. Wea. Rev.,121, 1398–1415.

  • Nachamkin, J. E., R. L. McAnelly, and W. R. Cotton, 1994: An observational analysis of a developing mesoscale convective complex. Mon. Wea. Rev.,122, 1168–1188.

  • Newton, C. W., 1966: Circulations in large sheared cumulonimbus. Tellus,18, 699–712.

  • Rasmussen, E. N., and S. A. Rutledge, 1993: Evolution of quasi-two-dimensional squall lines. Part I: Kinematic and reflectivity structure. J. Atmos. Sci.,50, 2584–2606.

  • Rickenbach, T. M., and S. A. Rutledge, 1998: Convection in TOGA COARE: Horizontal scale, morphology and rainfall production. J. Atmos. Sci.,55, 2715–2729.

  • Rotunno, R., B. Klemp, and M. L. Weisman, 1988: A theory for strong, long-lived squall lines. J. Atmos. Sci.,45, 463–485.

  • Rutledge, S. A., R. A. Houze Jr., M. I. Biggerstaff, and T. Matejka, 1988: The Oklahoma–Kansas mesoscale convective system of 10–11 June 1985: Precipitation structure and single-Doppler radar analysis. Mon. Wea. Rev.,116, 1409–1430.

  • Scofield, R. A., 1987: The NESDIS operational convective precipitation estimation technique. Mon. Wea. Rev.,115, 1773–1792.

  • Short, D. A., P. A. Kucera, B. S. Ferrier, J. C. Gerlach, S. A. Rutledge, and O. W. Thiele, 1997: Shipboard radar rainfall patterns within the TOGA COARE IFA. Bull. Amer. Meteor. Soc.,78, 2817–2836.

  • Smull, B. F., and R. A. Houze, 1985: A midlatitude squall line with a trailing region of stratiform rain: Radar and satellite observations. Mon. Wea. Rev.,113, 117–133.

  • Stumpf, G. J., R. H. Johnson, and B. F. Smull, 1991: The wake low in a midlatitude mesoscale convective system having complex convective organization. Mon. Wea. Rev.,119, 134–158.

  • Sui, C.-H., and K.-M. Lau, 1992: Multi-scale phenomena in the tropical atmosphere over the western Pacific. Mon. Wea. Rev.,120, 407–430.

  • Tokay, A., and D. A. Short, 1996: Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds. J. Appl. Meteor.,35, 355–371.

  • Velden, C. S., and J. A. Young, 1994: Satellite observations during TOGA COARE: Large-scale descriptive overview. Mon. Wea. Rev.,122, 2426–2441.

  • Webster, P. J., and R. Lukas, 1992: TOGA COARE: The coupled ocean–atmosphere response experiment. Bull. Amer. Meteor. Soc.,73, 1377–1416.

  • Williams, M., and R. A. Houze Jr., 1987: Satellite-observed characteristics of winter monsoon cloud clusters. Mon. Wea. Rev.,115, 505–519.

  • Wu, X., and M. A. LeMone, 1999: Fine structure of cloud patterns within the intraseasonal oscillation during TOGA COARE. Mon. Wea. Rev.,127, 2503–2513.

  • ——, W. W. Grabowski, and M. W. Moncrieff, 1998: Long-term behavior of cloud systems in TOGA COARE and their interactions with radiative and surface processes. Part I: Two-dimensional modeling study. J. Atmos. Sci.,55, 2693–2714.

  • Yuter, S. E., and R. A. Houze Jr., 1997: Measurements of raindrop size distributions over the Pacific warm pool and implications for Z–R relations. J. Appl. Meteor.,36, 847–867.

  • —— and R. A. Houze Jr., 1998: The natural variability of precipitating clouds over the western Pacific warm pool. Quart. J. Roy. Meteor. Soc.,124, 53–99.

  • Zipser, E. J., 1988: The evolution of mesoscale convective systems:Evidence from radar and satellite observations. Tropical Rainfall Measurements, J. Theon and N. Fugono, Eds., A. Deepak Publishing, 159–166.

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