T ' A_5/?cn-/6_ 77/ NASA-CR-168971 ...,5'._V',,¢,v .z- _.. 19820017797 (2./ O_5"t3_Y FINAL TECHNI CAL REPORT NASA CONTRACT NSG 5357 ° INITIAL STUDI ES OF MI DDLE AND UPPER TROPOSPHERI C STRATI FORM CLOUDS COLORADO STATE UN I VERS I TY DEPARTMENT OF ATMOSPHERI C SCI ENCE PRINCI PAL INVESTIGATOR: STEPHEN K . COX MAY 1 8 _ 1 982 _.:i;!._._i '_'-;;., ._-''; ,.,"',":'-,,, 7, _: o_:!"2 2 ':,,:- 1870 DEPARTMENOTFATMOSPHERICSCIENCE COLORADOSTATEUNIVERSITY FORTCOLLINS,COLORADO TABLE OF CONTENTS FINAL TECHNICAL REPORT , NASA CONTRACT NSG 5357 INITIAL STUDIES OF MIDDLE AND UPPER TROPOSPHERIC STRATIFORM CLOUDS Section I: Statement of Project ObJectives Section 2: Characteristics of Middle and Upper Tropospheric Clouds as Deduced from Rawinsonde Data • Section 3: A Middle and Upper Tropospheric Cloud Model Section 4: A Proposal for Observations of Upper and Middle Tropospheric Clouds Section 5: Calculations of. the Variability of Ice Cloud Radiative Properties at Selected Solar Wavelengths Section 6: A Climate Index Derived from Satellite Measured Spectral Infrared Radiation Appendix I: List of Publications, Meetings m°, S E l_T I ON 1 STATENENT OF PF'OJECT OBJECTIVES: The initial middle and upper tropospheric cloud studies performed under this NASA grant had multiple objectives. These objectives may be summarized as follotus: studies of spatial and temporal occurrence of extended middle and upper tropospheric cloud layers; development of a physical-numerical model to simulate the life cycles of middle and upper tropospheric cloud layers; and the design of an observational program to study" the physical, radiative and dynamical properties of these cloud l.__vers. Our initial intent was to study the spatial and temporal extents of middle and upper tropospheric cloud layers using both rawinsonde data and satellite visible and infrared imagery. We successfully completed the rat,,insonde summary but found the satellite archives available to be lacking in the time continuity required for such a study. Section 2 reproduces the results of the analysis derived from rawinsonde data. Huch of the resources of this grant have gone into the development of a t_vo dimensional model of the middle and upper tropospheric cloud layer. The t,.:iodimensionm.l model is nearly complete and has passed many of the r'equired val idation tests. Final val idation and utilization of the model is only a few months at.gay• Section 3, a portion of a Ph. D. thesis being prepe.red by Flr. David Starr, presents a detailed explanation of the model and its development to date. One of the specific objectives of this grant was the design of an experimental program to complement the climatological and modelling objectives presented in Sections 2 and 3 and referred to above. Section 4 of this final technical report presents the model design for such a program in proposal form. This proposal is being submitted to NASA concurrently t,._iththis report with the aim of implementing such a program of observations within the next two years. Section 5 of this report is a reprint of a paper published in Applied Optics on the variability of the radiative properties of ice clouds across the solar _vavelengths. This work was a precurser to the selection of a realistic, simplified solar radiation algorith for the two dimensional phxsica.l-numerical model described in Section 3. Section 6 is composed of a copy of the Ph. D. thesis of Michael Abel. Dr.. Able is a member of the Air Weather Service vJho attended Colorado b State University from 1978 - 1980. Dr. Able, under the guidance of the principal investigator, pursued a research topic closely identifiable with the !ongterm objectives of the middle and upper tropospheric cloud grant, Dr. Able developed an unconventional method of co!letting a c! imatology of the effects of middle and upper tropospheric clouds on the radiative energy budget of the earth. Cloud height and a composite area-radiative property ma/ be inferred from his technique as well. Dr, Able uJas supported under this grant on1>- to the extent of covering research expenses such as computer time_ materials_ manuscript preparation and correspondence since his satary was paid by the Air- Weather Service. Appendix 1 of this report lists publications and meeting presentations prepared from material generated by research conducted under NASA grant 53477 APPENDIX I - PAPERS AND MEETING PRESENTATIONS BASED UPON MATERIAL FROM NASA GRANT STUDIES Cox, S. K., 1979: Initial studies of middle and upper tropospheric stratiform clouds. Six Month1>" Interim Report for NASA Grant NSG 5357, 72 pp. Welch, R. M., S. K. Cox, and W. G. Zdunkowski, 1980: Calculations of the variability of ice cioud radiative properties at selected solar wavelengths. Appl. Opt., 19, 3057-3067. Starr, D. O'C., and S. K. Cox, 1980: Characteristics of middle and upper tropospheric clouds as deduced from rawinsonde data. Atmospheric Science Paper #327, Colorado State University, Ft. Collins, CO., 71 pp. Abel, M. D., and S. K. Cox, 1981: A climate index derived from satellite measured spectral infrared radiation. Atmospheric Science Paper #335, Colorado State University', Ft. Co!lins, CO. Abel, M. D., and S. K. Cox, 1981: A cl imate index derived from satellite measured spectral infrared radiation. Submitted for publ ication to J. Atmos. Sci., (May). D. SCIENTIFIC MEETINGS.- Papers presented after January 197-? *Cox, S. K. : JOC Study Conference on Parameterization of Extended Cloudiness and Radiation for CI imate Models. Review of parameterizations of radiation and extended cloudiness. 27 September - 4 October 1978, Oxford, U.K. Starr, D. O'C., and S. K. Cox: Numerical experiments on the role of radiative processes in the development and maintenance of upper level clouds. Fourth Conference on Atmospheric Radiation of the American Meteorological Society, June 16-18, 1981, Toronto, Ont., Canada. Abel, M. D., and S. K. Cox: A climate index indicative of cloudiness derived from satellite infrared sounder data. Fourth Conference on Atmospheric Radiation of the American Meteorological Society, June 16-18, 1981, Toronto, Ont., Canada. ,-_ IIliiiiniiiiJ_iiiiiiiillI ' - 3 1176 00504 4178 #1Z5/J ell- /tbf: C; 7/ SECTION 2 S'c::c!/p/72 I g;)00/ 7 )C/7 al 050:2~ q CHARACTERISTICS OF MIDDLE AND .• -. UPPER TROPOSPHERIC CLOUDS .."".j.' AS DEDUCED FROM RAWINSONDE t DATA A By i 1 David O'C. Starr .I And Stephen K. Cox SEP 2 2 1982, Atmospheric Science PAPER NO. 327 US ISSN 0067-0340 DEPARTMENT OF ATMOSPHERIC SCIENCE COLORADO STATE UNIVERSITY FORT COLLINS, COLORADO 2 W .,r, I IP CHARACTERISTICSOF MIDDLEANDUPPERTROPOSPHERICCLOUDS AS DEDUCEDFROMRAWINSONDEDATA by David O'C. Starr and Stephen K. Cox Research supported by National Aeronautics and Space Administration " Goddard Space Flight Center under grant NSG5357 Department of Atmospheric Science Colorado State University Fort Collins, Colorado November, 1980 Atmospheric Science Paper Number 327 Ir t'- ABSTRACT g This study characterizes the static environment of middle and upper tropospheric clouds as deduced from rawinsonde data from 24 loca- tions in the contiguous U.S. for 1977. Computed relative humidity with respect to ice is used to diagnose the presence of cloud layer. The deduced seasonal mean cloud cover estimates based on this technique are shown to be reasonable. Over 3600 cloud cases qualified for the analy- sis. The cases are stratified by season and pressure thickness, i.e. thick and thin. The dry static stability, vertical wind speed shear and Richardson number are computed for three layers for each case, i.e. the sub-cloud and above cloud layers and an in-cloud layer bounded by - the cloud-top level. Mean values for each parameter and, in some in- stances, the corresponding relative frequency distributions are pre- t sented for each stratification and layer. The relative frequency of occurrence of various structures is presented for each stratification, e.g. increasing static stability with height through the three layers. The observed values of each parameter vary over quite large ranges for each layer. The observed structure of each parameter for the layers of a given case is also quite variable. Structures correspond- i ing to any of a number of different conceptual models, which are re- viewed, may be found though some are substantially more commonthan others. It is of note that moist adiabatic conditions are not commonly observed and that the stratification based on thickness yields sub- ,I stantially different results for each group. Summaries of the results are included in the text. ACKNOWLEDGMENTS D The authors gratefully acknowledge the support of the computing i facility at the National Center for Atmospheric Research, which is sponsored by the National Science Foundation. The primary support for this research was provided by the National Aeronautics and Space Administration under a climate-related grant administered by the Goddard Space Flight Center, under grant NSG5357. ii €, TABLEOF CONTENTS " PAGE ABSTRACT i f ACKNOWLEDGMENTS i i TABLEOF CONTENTS iii 1. INTRODUCTION 1 2. DATAANALYSISMETHODOLOGY 4 2.1 Brief Review of Conceptual Models 4 2.2 The Basic Data Set 8 2.3 Data Processing and Analysis Procedures 9 2,4 Rawinsonde Observed Relative Humidity and 18 Cloud Cover 2.5 The Cloud Case Data Set 22 3. RESULTS 25 3.1 Static Stability 25 3.1.a Mean Stability Structures 25 3.1.b Relative Frequency of Various Stability 30 Structures 3.1.b.i Thick Cloud Cases 32 3.1.b.ii Thin Cloud Cases 38 3.1.c Relative Frequency Distributions of Stability 41 3.2 Vertical Wind Shear 47 3.3 Richardson Number 58 4. SUMMARYANDCONCLUSIONS 63 " REFERENCES 69 iii -I- I. INTRODUCTION w This study attempts to characterize certain aspects of the envi- ronment associated with middle and upper tropospheric stratiform clouds. The results will be utilized in the development of simple realistic models of the thermodynamic energy budgets of these cloud forms in a future study.