Meteorological Monographs

METEOROLOGICAL MONOGRAPHS

VOLUME 29 JANUARY 2003 NUMBER 51

Edited by

Dr. Wei-Kuo Tao Dr. Robert Adler

American MeteorologicalSociety 45 BeaconStreet, Boston, Massachusetts 02108 @ Copyright 2003 by the American Meteorological Society. Per- mission to use figures, tables,and brief excerpts from this monograph in scientific and educationalworks is herebygranted provided the source is acknowledged.All rights reserved. No part of this publication may be reproduced,stored in a retrieval system, or transmitted, in any form or by any means,electronic, mechanical, photocopying, recording, or otherwise, without the prior written permissionof the publisher.

ISBN 1-878220-54-3 ISSN 0065-9401 Support for this monographhas beenprovided by the Cooperative ResearchCentre for SouthernHemisphere Meteorology, Australia, and NASA Goddard SpaceFlight Center.

Published by the American Meteorological Society 45 Beacon St., Boston, MA 02108

Printed in the United Statesof America by Allen Press,Inc., Lawrence,KS TABLE OF CONTENTS

Preface. v List of Contributors vi Part I. JoanneSimpson's Career Chapter The Research of Dr. Joanne Simpson: Fifty Years Investigating Hurricanes, Tropical Clouds, and Cloud Systems -W.-K. TAO, J. HALVERSON,M. LEMoNE, R. ADLER, M. GARSTANG,R. HOUZE JR., R. PIELKE SR., AND W. WOODLEY

Chapter 2. Joanne Simpson: An Ideal Model of Mentorship -ROGER A. PIELKESR. """" 17 Part II. Cloud Systems-Observations

Chapter3 What We Have Learned about Field Programs -MARGARET A. LEMoNE 25 Chapter 4. From Hot Towers to TRMM: Joanne Simpson and Advances in Tropical Convection Research -ROBERTA. HoUZE JR. 37 Chapter 5. Some Views on "Hot Towers" after 50 Yearsof Tropical Field Programsand Two Yearsof TRMM Data -EDWARD J. ZIPSER 49

Chapter 6. Spaceborne Inferences of Cloud Microstructure and Precipitation Processes:

Synthesis, Insights, and Implications Isotopic Variations -DANIEL and ROSENFELDInternal Storm AND DynamicsWILLIAM in L. the WOODLEYAmazon Basin 59 Chapter7.

-ISABELLA ANGELINI, MICHAEL GARSTANG, STEPHEN MACKO, ROBERT SWAP, DEREK STEWART, AND HILLANDIA B. CUNHA.. 81 Part III. Cloud Systems-Modeling Chapter 8. Cloud Models: Their Evolution and Future Challenges -WILLIAMR.COlTON 95 Chapter 9. GoddardCumulus Ensemble(GCE) Model: Application for Understanding PrecipitationProcesses -WEI-KuoTAO Part IV. Hurricanes Chapter10. Hot Towers and Hurricanes:Early Observations,Theories, and Models -RICHARDA.ANTHES Chapter On the TransverseCirculation of the Hurricane -WILLIAM M. GRAY Chapter 12. Some Aspectsof Midlevel Vortex Interaction in Tropical Cyclogenesis -ELIZABETHA. RITCHIE 165 METEOROLOGICAL MONOGRAPHS VOL. 29, No. 51

Part V, TRMM-History and Management

Chapter 13. My View of the Early History of TRMM and Dr. Joanne Simpson's Key Role in Winning Mission Approval -JOHNS. THEON 175

Chapter 14. Dr. JoanneSimpson and the Beginning of the TRMM Project -TOM KEATING 181

Chapter 15 Working with Dr. JoanneSimpson while Managing the TRMM Project -THOMAS LA VIGNA 183 Part VI. TRMM-Science Aspects

Chapter 16. A Short History of the TRMM PrecipitationRadar -KEN' ICHI OKAMOTO 187

Chapter 17 The TRMM Measurement Concept -THOMAS WILHEIT . 197

Chapter 18. GATE and TRMM -GERALD R. NORTH 201

Chapter 19. Performance Evaluation of Level-2 TRMM Rain Profile Algorithms by

Intercomparison and Hypothesis Testing

Status of TRMM -ERIC MonthlyA. SMITHEstimates AND THROYof Tropical D. HOLLIS.Precipitation 207

Chapter 20. -ROBERT E ADLER, CHRISTIAN KUMMEROW, DAVID BOLVIN, SCOTTCURTIS,ANDCHRIsKiDD 223 CHAPTER 2 PIELKE

Chapter 2

Joanne Simpson: An Ideal Model of Mentorship

ROGER A. PIELKE JR. Department ofAtmospheric Science. Colorado State University. Fort Collins. Colorado

ABSTRACT The role of cumulus clouds in local, regional, and global weather and climate that is understood today is based to a large extent on the pioneering work of Joanne Simpson. Her involvement in this work is illustrated through the experiences as my career developed. She also was, and is, an ideal model of mentorship. This paper illustrates this model using my interactions during the 1970s and early 1980s. and how they have influenced research articles up to the present.

1. Experimental Meteorology Lab Years ative slowness,only one hourof simulationwas possible In 1971, Dr. Simpson was director of the Experi- eachday. Tenhours of simulatedtime required tendays! mental Meteorology Laboratory (EML) when I joined Dr. Simpson,however, felt strongly that studentsand as a graduatestudent.! Her original papers (Stem and researchstaff should not just be theoreticalmodelers. Malkus 1953,Ma1kus and Stem 1953)provided a frame- They needto also experiencereal weather.For this rea- work to develop a sea-breezenumerical model and to sonopportunities were provided for my participation in apply this tool to better understandmesoscale and cu- the Florida Area Cumulus Experiment(FACE; Simpson mulus dynamics in south Florida. Figure 1 from her and Woodley 1975; Biondini et al. 1977; Woodley et work demonstratesthe concept of the "equivalent al. 1977; see Fig. 2.3 for a caricature I drew during mountain," which results from surface heating of land FACE). This experimentinvolved randomizedcumulus (Fig. 2.1) Air is lifted, as a result, as it passesover the cloud seeding(Simpson 1977). As part of Joanne'smen- land. This provided an original explanationof why cu- torship, I flew on severalFACE cloud seedingexperi- mulus clouds preferentially developover and downward ments, both with the seeding aircraft and in a separate of tropical islands even in the absenceof topographical aircraft that often flew at just a few hundred feet above relief. Figure 2.2 illustrates this preference for rain the ground! I was also permitted (and encouraged)to showersdownwind of such islands (in this caseGrand fly a hurricane Storm Fury flight (into Ginger in 1971). Bahama,Eleuthera, and Andros Islands in the Bahamas, This ability to participate in a variety of research where the large-scale wind is southeasterly). When programswas facilitated by the leadershipof the gov- Joanne'swork was performed,such direct observations ernment agencies that managed the weather research of cloud fields were not available. groups(the National Hurricane ResearchLab and EML) Since computers were available in the early 1970s, and the National WeatherService [National Hurricane EML provided resourcesto constructa model of the sea Center(NHC)]. Thesegroups were collocated in a single breezes.Fortunately, the computerwas sufficient to run multistory building (Fig. 2.4) with the Departmentof a three-dimensionalmodel of the seabreezes over south Atmospheric Sciences at the University of Miami in Florida. Using 11-km horizontal grid intervals over a Coral Gables,Florida. This vertical linkage permitted a 33 X 36 grid meshwith sevenvertical levels,the model free exchangeamong academic, research,and opera- just fit on a CDC 6600 computer at the National Me- tional weathercommunities. teorological Center [NMC; now called the National This exposureto operational weather,which was per- Centers for Environmental Prediction (NCEP)]. Given mitted by the perceptiveleadership of Joanne'shusband, the restraint on accessto the computerand its compar- Dr. Robert H. Simpson,allowed researchersto experi- ence the cold reality of making actual forecasts that affected lives and properties. We were permitted to I Dr. Bill Cotton, a graduate student when I first met him (and watch NHC forecastersprepare hurricane watchesand shared an office) at Penn State in 1968, had been previously hired by Joanne, and recommended me for a two-year tour of duty to warnings, which allowed us to better relate our studies complete my Ph.D. My personal and professional interactions with to actual public need. Bill continue to this day at Colorado State University. Joanneis an observational meteorologist,as well as 17 18 METEOROLOGICAL MONOGRAPHS VOL. 29, No. 51

FIG. 2.1. Equivalent mountain for Nantucket Island on 9 Aug 1950 [case 3 studied by Malkus and Bunker (1952)]. Observed temperature profile along ground, 7"(x), is given by the heavy solid line. Heating function along the ground divided by specific heat at constant pressure, Volcp, was calculated from observed surface values of VaT'lax and is shown by the dashed line. Extent of island is indicated by the hatched region (from Stern and Malkus 1953). a modeler.She provided resourcesto instrument 10 lo- tions, and from a set of volunteerobservers that were cations across south Florida with recording surface recruited for FACE, resulted in severalpapers (Pielke weather stations. Made by MRI Inc., these stations, and Cotton 1977;Pielke and Mahrer 1978).Among the which archived data on strip charts, were among the results found was the prominentrole of sea-breezehor- first applications of such portable automated weather izontal wind convergencein establishingfavorable en- stations. Such exposureof a studentto real data helps vironments for thunderstormsand their merger.An ex- establish a reality check when developing theoretical ample of observedand modeledwinds acrossthe east- models.Figure 2.5 illustrates one of theseobservational west cross section that containedthe MRI sites is dis- platforms. The data from these mechanicalweather sta- played in Fig. 2.6. The wind convergencelocally in- creasedconvective available potential energy (CAPE)

FIG. 2.2. Radar echo coverage at 1901 UTC 19 Aug 1971 as seen FIG. 2.3. Caricature drawn by R. A. Pielke during FACE of by the Miami WSR-S7 10-cm radar (from Pielke 1974). participants, including JoanneSimpson. CHAPTER 2 PIELKE 19

FIG. 2.4. Pholograph of the building that hou!;ed the National Hur- FIG. 2.5. Photograph of one of the MRI, Inc., weather stations (in ricane Re!;earch Lab, EML, and the National Weather Service at the the J. W. Corbett Wildlife Refuge west of the West Palm Beach, FL), University of Miami in Coral Gables, FL. which included a tipping bucket rain gauge, cup anemometer, wind vane, and a temperature sensor. and physically moved cumulus clouds toward each oth- er. As discussed in Simpson et al. (1980), Wescott (1994), and more recently in Simpson et al. (1993), a facilitator for studentresearch, rather than a manager. merged cumulus clouds rain much more than the in- Students who graduate from such a program benefit ~ II dividual clouds would separately. This concept of cu- greatly from this combination of scienceexposure and i! collegial interaction. Among the major achievements I mulus cloud merger originated from Joanne's dynamic I cloud seeding hypothesis (Cotton and Pielke 1995) and was one of the first soil-vegetation-atmospheretransfer . is an important reason for the high correlation between (SVAT) schemesthat formed part of Mike McCumber's sea-breezeconvergence zones and thunderstorms (Ulan- Ph.D. dissertation (McCumber 1980; McCumber and ski and Garstang 1978a,b; Cooper et al. 1982; Pielke et Pielke 1981). al. 1991; Garstang and Fitzgerald 1999; see also Fig. An essentialcomponent of Joanne'sleadership ethic 2.7). was her treatment of support staff. Always requiring excellence,she still treatedeach person as anindividual. They were as much a part of the researchteam as the 2. The University of Virginia years scientific staff. As part of Joanne's position at the Center for Ad- It was during these years that my professionalasso- vanced Studies at the University of Virginia, I was hired ciation with Robert Simpsondeepened. He was (and is) as an assistant professor of environmental sciences in a sourceof strengthfor Joanneand is also anoutstanding 1974. In this capacity, she continued to mentor my re- scientist on his own. I may be the only personwho has search and to aid in the development of an academic separatelypublished papers with both Simpsons.2This program. Among her major efforts was the recruitment involvement with Bob also resulted in my involvement of Dr. Ytzhaq Mahrer of the University of Jerusalem in with both of them in the Typhoon Moderation (TY- Rehovot. This was a fruitful collaboration that permitted MOD) Project, which discussedthe possibility of cloud additional developments of the EML sea-breeze model seedingwestern Pacific typhoons (Simpsonet al. 1978). to include topography (Mahrer and Pielke 1975, 1976) and improved computational solution techniques (Mah- rer and Pielke 1978). Professor Mike Garstang and I 3. Subsequentyears also met during this time period, and developed a close research collaboration (e.g., see Pielke et al. 1987). After I left the University of Virginia, my research Joanne was responsible for bringing Mike and I together, continued to be greatly influenced by Joanne's pio- where, as an experimentalist and a numerical modeler, neering work. At Colorado State University, a new mod- we were able to successfully pool our different exper- eling system was developed that built on the EML sea- tise. This was another example of where Joanne rec- breeze model and the model developed independently ognized the need for combined observational and mod- by Bill Cotton. This new model was called the Regional eling studies. In my role as an assistant professor and later associate professor, I adopted Joanne's philosophy of serving as 2 My paper with Robert Simpson was Simpson and Pielke (1976). 20 METEOROLOGICAL MONOGRAPHS VOL. 29, No. 51

0 5 10 IV'" Lj-J WINDS AT J.. ~ IOC-l 'WESTERLYFLOW ~ REGIO~STFIONGER OF SESIGNIFICANTLY WI~S (l~msK,) ..-' --. "00 //// """,,////:~"'.,//////I;\"x'" ., Ij"~, ,,""..:,, , ,.""",, ".;:;..."~ . '100 //

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I CHAPTER 2 PIELKE 21

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FIG. 2.7. (left) Vertical velocity prediction, 9.5 h after simulated sunrise, and (right) composite radar map at equivalent time for 29 Jun 1971 (from Pielke 1974).

Atmospheric Modeling System (RAMS; Pielke et al. County, Florida, where I lived while working at EML. 1992).3 Our explicit modeling of deepthunderstorms in the eye- My interest in hurricanes was intensified as a result wall and in the spiral bands of a hurricane (using hor- of my collaboration with both Joanne and Bob. Thus it izontal grid incrementsof 5 km) wasthe key to properly was natural that we would apply RAMS to simulate simulating intensification of Andrew (Eastman et al. these tropical cyclones. We chose Hurricane Andrew 1996). Such high spatial resolution is neededto accu- (1992) since its intensification was underforecast and it rately evacuatemass from the eyewall region. This was made landfall over the same area in southern Dade the first simulation of a specific hurricane with explicit microphysics at such fine spatial resolution. The early observationalpapers by the Simpsonspro- vided an essential assessmentof the credibility of our hurricane model results. Malkus (1958), for example, provides an observed characterizationof eyewall-eye dynamics, such as the influence of large-scaleenviron- mental shear(Fig. 2.8). In Nicholls and Pielke (1995), we investigated,using RAMS, the importanceof wind shearassociated with idealized hurricanes.Among our conclusionsis that weak vertical wind shearcan actually enhancethe ability of a hurricane to intensify. Figure 2.9 illustrates the eye and eyewall structureas modeled by RAMS for a mature hurricane (Pielke and Pielke W .'ST'.. 'T, -LL~U.,.., 'T-;- "STO" 'T' -LL E 1997, p. 78). Pielke (1990) used the Robert Simpson FIG. 2.8. Schematic illustration of asymmetry in eye structure when decision tree for hurricane developmentand intensifi- tropical easterly current has pronounced negative shear. The velocities cation to illustrate the forecastprocedure for thesetwo given by the arrows illustrate a hypothetical set of winds (coordinates aspectsof tropical cyclones. In Pielke and Pielke (1997) fixed to ground) resulting when a storm circulation with inflow at low levels and outflow aloft is superposed on a trade current of 10 we referred to several early papers by Bob (Simpson m S-I at the ground decreasing to 2 m S-I in the stratosphere (from 1946; 1954; 1971; Simpsonand Riehl 1981) that con- Malkus 1958). tinue to provide a fundamentalbasis for prediction research. 3 Cotton summarizes the RAMS development and lists a spectrum On the global scale, the Riehl and Malkus (1958) of papers which resulted from the application of this modeling tool paper is a major landmark in the study of the energy in chapter 8 of this monograph. and water budgetof the earth'satmosphere. The concept

. 22 METEOROLOGICAL MONOGRAPHS VOL. 29, No.5]

; :

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, , ;::j~::::1: , I l." , v., @Z) ~ 40 I 90 40

FIG.2.9. A model simulation of the eye and eyewall region of a maturehurricane. The contours show wind speedin miles per hour. The solid contoursrepresent winds moving into the page and dashedcontours represent winds moving out of the page. The shadedregion illustrates the locations of clouds. This figure was provided by Dr. Mel Nicholls of Colorado State University (from Pielke and Pielke 1997).

of undilute ascentin thunderstormsin the intertropical ilarly affect higher latitudes. Pitman and Zhao (2000) convergencezone, as one segment in the Hadley cir- and Pitman et al. (1999) confirm the major role of land- culation, revolutionized the conceptof how the atmo- use change affecting the Hadley circulation, and higher spheretransfers mass and energy.The Riehl and Malkus latitude weather. In one of my numerous fruitful col- study indicated that between 1500and 5000 active un- laborations with Bill Cotton, we published Cotton and dilute cumulus convective towers (i.e., "hot towers") Pielke (1995), where we connected our experiences as- are all that is neededfor the equatorialside of the ver- sociated with weather modification studies at EML with tical transport associatedwith the Hadley circulation. the current overselling of the ability to predict future Satellite images that subsequentlybecame available climate. Land-use change was one of the issues that we confirmed this hypothesis and illustrate that massand used to illustrate that climate predictability inherently energyare transportedpoleward within high upper-tro- may be more limited than has been traditionally thought. posphericjet streams,which are referred to as subtrop- The role of the hot towers is critical to this human- ical jets. Thesejets are aneffective mechanismfor long- caused climate sensitivity. Even though the location of distancerapid communicationof weather,a conceptre- the hot towers covers only a relatively small percentage ferred to as teleconnection. of the earth's surface, large climate change effects can This fundamentalwork is the basisfor the conclusions occur! This overlooked climate change issue is built on of Chase et al. (1996, 2000) that tropical land-use Joanne's early pioneering work. changecan alter the patterningof wherethese hot towers occur. Deforestationresults in a drying and warming, 4. Conclusions suchthat cumulonimbusconvection tends to occurmore over nondeforestedregions and over tropical oceanar- The richness of Joanne Simpson's research accom- eas. This pattern shift results in alterations in the tele- plishments are best appreciated by tracking our current connectionswith higher latitudes,such that weatherpat- knowledge of the atmosphere to where these concepts terns may be permanently changed. ENSO events, were first discussed in the peer-reviewed literature. Her which also affect the patterning of thunderstorms,sim- breadth of contribution is impressive and ranges from

I)j'tWWi;~~~;tlf;:v.1::,1'~~[1~:;j~f!'..~~i~~1 CHAPTER 2 PIELK

the cumulus cloud to global scale. Early in her career, Eastman, J. L., M. E. Nicholls, and R. A. Pielke, 1996: A numerical she recognized the critical role of cumulus clouds in the simulation of Hurricane Andrew. Presented at Second Interna- earth's atmosphere, and now she continues to build on tional Symposium ,m Computational Wind EnKineerinK. Fort Collins, CO. Japan Association for Wind Engineering and the her innovative and broad expertise in such programs as U.S. Wind Engineering Research Council. the Tropical Rainfall Measuring Mission (TRMM; Garstang, M., and D. R. Fitzjarrald, 1999: Observations of Surface Kummerow et al. 1998) and the Tropical Ocean Global to Atmo.vphere Interaction.v in the Tropics. Oxford University Atmosphere Coupled Ocean-Atmosphere Response Ex- Press, 405 pp. Halverson, J., B. S. Ferrier, T. M. Rickenbach, J. Simpson. and W.- periment (TOGA COARE; Halverson et al. 1999). K. Tao, 1999: An ensemble of convective systems on II Feb- When one uncovers the origin of many of our most basic ruary 1993 during TOGA COARE: Morphology, rainfall char- concepts in atmospheric science, it is quite impressive acteristics. and anvil cloud interactions. Mon. Wea. Rev., 127, how much of this knowledge is founded in her original 1208-1228. Kummerow, C., W. Barnes, T. Kozu. J. Shuie, and J. S. Simpson, work! 1998: The Tropical Rainfall Measuring Mission (TRMM) sensor Finally, while completing pioneering research results, package. J. Atmos. Oceanic Technol.. 15,809-8]7. she also recognized the need to mentor the next gen- Mahrer, Y., and R. A. Pielke, 1975: The numerical study of the air eration of scientists. Her sacrifices are candidly sum- flow over mountains using the University of Virginia mesoscale marized in Simpson (1973), a publication that was also model. J. Atmos. Sci.. 32, 2144-2155. extremely informative concerning the prejudices against -, and -, ]976: The numerical simulation of the airflow over Barbados. Mon. Wea. Rev.. 104, ]392-1402. women in science. Joanne's publication has sensitized -, and -, 1978: The meteorological effect of the changes in many men to this obstacle. surface albedo and moisture. Isr. Meteor. Res. Pap., 2,55-70. Joanne's career has spanned all aspects of our pro- Malkus, J. S., 1958: On the structure and maintenance of the mature fession, from research and mentorship to teaching and hurricane eye. J. Meteor.. 15, 337-349. -, and A. Bunker, 1952: Observational Studies of the Air Flow service. Her guidance as American Meteorological So- over Nantucket Island during the Summer of 1950. Papers in ciety publication commissioner and scientific and tech- Physical Oceanography and Meteorology, No. 12, Massachusetts nological activities commissioner and president has ef- Institute of Technology and Woods Hole Oceanographic Insti- fectively led the society to its current very high level tution, 50 pp. of achievement. She was also involved with Robert -, and M. Stern, 1953: The flow of a stable atmosphere over a heated island, Part I. J. Meteor., 10,30-41, Simpson in setting up a private company (Simpson McCumber, M., 1980: A numerical simulation of the influence of Weather Associates), which transfers research knowl- heat and moisture fluxes upon mesoscale circulations. Ph.D. dis- edge to help solve real-world problems. This respon- sertation, University of Virginia, 255 pp. sibility of university professors is not widely recog- -, and R. A. Pielke, 1981: Simulation of the effects of surface nized, yet this is a prime mechanism that can be used fluxes of heat and moisture in a mesoscale numerical model- Part I: Soil layer. J. Geophys. Res., 86, 9929-9938. to interface with societal needs. Nicholls, M. E., and R. A. Pielke, 1995: A numerical investigation All the best to Joanne on an extremely valuable career of the effect of vertical wind shear on tropical cyclone inten- that is still continuing full throttle! sification. Preprints, 21st Can! on Hurricanes and Tropical Me- teorology. Miami, FL, Amer. Meteor. Soc., 339-341. Acknowledgments.This paper was preparedas part Pielke, R. A., 1974: A three-dimensional numerical model of the sea breezes over south Florida. Mon. Wea. Rev., 102, 115-139. of an invited contributionto celebrateJoanne Simpson's -, 1990: The Hurricane. Routledge Press, 228 pp. career.The oral versionwas presented at the Symposium -, and W. R. Cotton, 1977: A mesoscale analysis over south Flor- on Cloud Systems,Hurricanes and TRMM: Celebration ida for a high rainfall event. Mon. Wea. Rev., 105, 343-362. of Dr. JoanneSimpson's Career-The First Fifty Years. -, and Y. Mahrer, 1978: Verification analysis of the University of Dallas Staley and Michelle McClaren ably handledthe Virginia three-dimensional mesoscale model prediction over south Florida for I July 1973. Mon. Wea. Rev., 106, 1568-1589. typing and the editing of the contribution. -, and R. A. Pielke Sr., 1997: Hurricanes: Their Nature and Impacts on Society. John Wiley and Sons, 279 pp. -, M. Garstang, C. Lindsey, and J. Gudsorf, 1987: Use of a syn- REFERENCES optic classification scheme to define seasons. Theor. Appl. Cli- Biondini, R., J. S. Simpson,and W. Woodley, 1977: Empirical pre- matol., 38, 57-68. dictors for natural and seededrainfall in the Florida Area Cu- -, A. Song, P. J. Michaels, W. A. Lyons, and R. W. Arritt, 1991: mulus Experiment(FACE) 1970-1975.J. Appl. Meteor.,16, 12- The predictability of sea-breeze generated thunderstorms. At- 97. mosfera. 4,65-78. Chase,T. N., R. A. Pielke, T. G. F. Kittel, R. Nemani, and S. W. -, and Coauthors, 1992: A comprehensive meteorological mod- Running, 1996: The sensitivity of a general circulation model eling system-RAMS. Meteor. Atmos. Phys., 49,69-91. to global changesin leaf areaindex. J. Geophys.Res., 101,7393- Pitman, A. J., and M. Zhao, 2000: The relative impact of observed 7408. change in land cover and carbon dioxide as simulated by a cli- -, -, -, -, and -, 2000: Simulated impacts of his- mate model. Geophys. Res. Lett.. 27, 1267-1270. toricalland cover changes on global climate in northern winter. -, R. Pielke, R. Avissar, M. Claussen, J. Gash, and H. Dolman, Climate Dyn.. 16,93-105. 1999: The role of the land surface in weather and climate: Does Cooper, H. J., M. Garstang, and J. S. Simpson. 1982: The diurnal the land surface matter? IGBP Newslett., 39,4-11. interaction between convection and peninsular-scale forcing over Riehl, H., and J. S. Malkus, 1958: On the heat balance in the equatorial south Florida. Mon. Wea. Rev., 110,486-503. trough zone. Geophysica, 6, 503-535. -, and R. A. Pielke, 1995: Human Impacts on Weather and Cli- Simpson, J. S" 1973: Meteorologist. Ann. New York Acad. Sci.. 208, mate. Cambridge University Press, 288 pp. 41-46.

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-, 1977: Empirical predictors for natural and seeded rainfall in -, and H. Riehl, 1981:The Hurricane and Its Impact. Louisiana the Florida Area Cumulus Experiment (FACE), 1970-1975. J. State University Press,398 pp. Appl. Meteor.. 16, 585-594. -, and Coauthors, 1978:TYMOD: TyphoonModeration. Virginia -, and W. L. Woodley, 1975: Florida Area Cumulus Experiments Technology,Inc. Final report for PAGASA, Republicof the Phil- 1970-1975 rainfall results. J. Appl. Meteor.. 14,734-744. ippines. -, N. E. Westcott, R. J. Clerman, and R. A. Pielke, 1979: On Stern, M., and J. S. Malkus, 1953: The flow of a stable atmosphere cumulus mergers. Arch. Meteor. Geophys. Bioklim.. 29A, 1-40. over a heatedisland, Part II. J. Meteor., 10, 105-120. -, Th. D. Keenan, B. Ferrier, R. H. Simpson, and G. J. Holland, Ulanski, S., and M. Garstang,1978a: The role of surfacedivergence 1993: Cumulus mergers in the maritime continent region. Me- and vorticity in the lifecycle of convectiverainfall. Part I: Ob- teor. Atmos. Phys., 51, 73-99. servation and analysis.J. Atmos. Sci., 35, 1047-1062. -, and -, 1978b: The role of surfacedivergence and vorticity Simpson, R. G., and R. A. Pielke, 1976: Hurricane development and in the lifecycle of convectiverainfall. PartII: Descriptivemodel. movement. Appl. Mech. Rev.. 29,601-609. J. Armos. Sci., 35, 1063-1069. Simpson, R. H., 1946: On the movement of tropical cyclones. Trans. Wescott,N. E., 1994:Merging of convectiveclouds: Cloud initiation, Amer. Geophys. Union. 27,641-655. bridging, and subsequentgrowth. Mon. Wea. Rev., 122, 780- -, 1954: Hurricanes. Sci. Amer.. 190,32-37. 790. -, 1971: The decision process in hurricane forecasting. NOAA Woodley,W. L., and Cumulus Group, 1977: Rainfall results, 1970- Tech. Memo. NWS SR-53, Fort Worth, TX, 35 pp. 1975: Florida Area Cumulus Experiment(FACE). Science,195, 735-742.