Abstract
Joining together or merging is postulated to be a major way in which convective clouds become larger, enhancing their transports and impacts upon their environment. Cumulus shower merger is defined in terms of echoes from a calibrated digitized 10-cm radar reviewing a 0.9×105 km2 area in south Florida, U. S. A., which encompasses a 1.3×104 km2 experimental area for randomized seeding. A detailed physical and statistical study is reported for three relatively undisturbed untreated days in the summer of 1973, the driest of which was a randomly selected control day for the experiment. Mergers are found to produce more than an order of magnitude more rain than unmerged echoes, while mergers of mergers (second order mergers) produce still an order of magnitude more rain. On the three days studied, merged systems produced about 86% of the rainfall over the area. Duration, echo area and rain depths are also compared for merged and unmerged systems. Each day is then analyzed individually, indicating a correlation between organization and rain amount, confirmed by other research reviewed briefly. The location and time of merger is related to the seabreeze convergence zones as predicted by the University of Virginia Mesoscale Model with overall good agreement. Physical hypotheses suggesting the importance of downdrafts in cumulus merging are developed. The relevance of mergers to hydrology, weather modification and the large-scale impacts of convective clouds is discussed.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1-40 |
| Number of pages | 40 |
| Journal | Archiv für Meteorologie, Geophysik und Bioklimatologie Serie A |
| Volume | 29 |
| Issue number | 1-2 |
| DOIs | |
| State | Published - Mar 1 1980 |
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ASJC Scopus subject areas
- Environmental Science(all)
- Atmospheric Science
- Earth and Planetary Sciences(all)
Cite this
On cumulus mergers. / Simpson, Joanne; Westcott, Nancy; Clerman, R. J.; Pielke, R. A.
In: Archiv für Meteorologie, Geophysik und Bioklimatologie Serie A, Vol. 29, No. 1-2, 01.03.1980, p. 1-40.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - On cumulus mergers
AU - Simpson, Joanne
AU - Westcott, Nancy
AU - Clerman, R. J.
AU - Pielke, R. A.
PY - 1980/3/1
Y1 - 1980/3/1
N2 - Joining together or merging is postulated to be a major way in which convective clouds become larger, enhancing their transports and impacts upon their environment. Cumulus shower merger is defined in terms of echoes from a calibrated digitized 10-cm radar reviewing a 0.9×105 km2 area in south Florida, U. S. A., which encompasses a 1.3×104 km2 experimental area for randomized seeding. A detailed physical and statistical study is reported for three relatively undisturbed untreated days in the summer of 1973, the driest of which was a randomly selected control day for the experiment. Mergers are found to produce more than an order of magnitude more rain than unmerged echoes, while mergers of mergers (second order mergers) produce still an order of magnitude more rain. On the three days studied, merged systems produced about 86% of the rainfall over the area. Duration, echo area and rain depths are also compared for merged and unmerged systems. Each day is then analyzed individually, indicating a correlation between organization and rain amount, confirmed by other research reviewed briefly. The location and time of merger is related to the seabreeze convergence zones as predicted by the University of Virginia Mesoscale Model with overall good agreement. Physical hypotheses suggesting the importance of downdrafts in cumulus merging are developed. The relevance of mergers to hydrology, weather modification and the large-scale impacts of convective clouds is discussed.
AB - Joining together or merging is postulated to be a major way in which convective clouds become larger, enhancing their transports and impacts upon their environment. Cumulus shower merger is defined in terms of echoes from a calibrated digitized 10-cm radar reviewing a 0.9×105 km2 area in south Florida, U. S. A., which encompasses a 1.3×104 km2 experimental area for randomized seeding. A detailed physical and statistical study is reported for three relatively undisturbed untreated days in the summer of 1973, the driest of which was a randomly selected control day for the experiment. Mergers are found to produce more than an order of magnitude more rain than unmerged echoes, while mergers of mergers (second order mergers) produce still an order of magnitude more rain. On the three days studied, merged systems produced about 86% of the rainfall over the area. Duration, echo area and rain depths are also compared for merged and unmerged systems. Each day is then analyzed individually, indicating a correlation between organization and rain amount, confirmed by other research reviewed briefly. The location and time of merger is related to the seabreeze convergence zones as predicted by the University of Virginia Mesoscale Model with overall good agreement. Physical hypotheses suggesting the importance of downdrafts in cumulus merging are developed. The relevance of mergers to hydrology, weather modification and the large-scale impacts of convective clouds is discussed.
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U2 - 10.1007/BF02247731
DO - 10.1007/BF02247731
M3 - Article
AN - SCOPUS:0007129298
VL - 29
SP - 1
EP - 40
JO - Meteorology and Atmospheric Physics
JF - Meteorology and Atmospheric Physics
SN - 0177-7971
IS - 1-2
ER -