-------------------------------------------------------------------- (c) Lazaros Oreopoulos 7/99 Last modified 10/99 -------------------------------------------------------------------- The 2D cloud field for this experiment is based on extinction retrievals from the MMCR (Millimiter Cloud Radar) and the MWR (microwave radiometer)at the ARM CART site in Lamont, OK on Feb. 8, 98. These retrievals were performed by Sally McFarlane of the University of Colorado and kindly provided to us by Frank Evans (also at U. of Col). The field consists of 640 columns along the x-direction, which were set to have a 50 m horizontal width (for the 10 sec. measurements this corresponds to the observed wind speed of ~5 m/s), and each column is resolved into 54 vertical layers which are 45 meters thick (z-direction). For our radiative transfer calculations we will assume that the the cloud is infinite along the y-direction. The cloud field can be viewed in mmcr_tau020898_32km.jpg and can be downloaded as mmcr_tau_32km_020898.gz. The vertically integrated version of the cloud field can be viewed in mmcr_tau020898_32km_integr.jpg. A sample Fortran code that reads the cloud field follows: c----------------------------------------------------- c Read in MMCR optical depth field parameter (nz=54, nx=640) real tau(nz, nx) open (1, file='mmcr_tau_32km_020898', status='old') c Start reading from the top of the cloud c (high to low z-coordinates) do iz=nz,1,-1 c Read from low to high x-coordinates read (1, '(640f8.3)') (tau(iz,ix), ix=1,nx) enddo close(1) c------------------------------------------------------ Description of experiments -------------------------- ASSUMPTIONS: 1) No atmospheric effects 2) Periodic boundary conditions (cloud field is repeated an infinite number of times along the x direction) 3) Black surface, and Lambertian surface with albedo (As) of 0.4. 4) Henyey-Greenstein phase function (PF) with g=0.85 and C.1 (Dermeindjian 1969) PF downloadable as file C.1_PF.gz (plotted in C.1_PF.plot.jpg).Legendre expansion coefficients are also available as in file C.1_PF.leg_coef.gz. 5) Single scattering albedos w0=1 and w0=0.99 (with the same PF and extinction field). SOLAR GEOMETRY: 1) Sun at (SZA of) zero degrees 2) Sun at 60 degrees and 0 azimuth (Sun shining from low x coordinates) From all possible combinations for the above assumption and conditions, output for the following experiments is requested: Exp. # 1: SZA = 0, w0 = 1, As = 0, PF = HG 2: SZA = 60, w0 = 1, As = 0, PF = HG 3: SZA = 0, w0 = 0.99, As = 0, PF = HG 4: SZA = 60, w0 = 0.99, As = 0, PF = HG 5: SZA = 60, w0 = 1, As = 0.4, PF = HG 6: SZA = 0, w0 = 1, As = 0, PF = C1 7: SZA = 60, w0 = 1, As = 0, PF = C1 8: SZA = 60, w0 = 1, As = 0.4, PF = C1 Required output --------------- 1) Mean, and higher order moments of: albedo (R) transmittance (T) absorptance (wherever applicable) (A) net horizontal flux (H) defined as H=1-R-T(1-As)-A nadir reflectivity (Iu) defined as pi*Nu/(F*mu0) where Nu is the upward exiting radiance at 0 degrees, mu0 is the cosine of the solar zenith angle, and F(=1) is the incident solar flux zenith transmissivity (Id) defined as pi*Nd/(F*mu0) where Nd is the net downward exiting radiance at 180 degrees !!! This quantity is requested only when SZA=60!!! Higher order moments are calculated as sum_i(x_i-x_mean)^k/N, k=2,6 and N=640, i=1,N. The accuracy of all output mean should be at least 0.001 (feel free to perform calculations of higher accuracy, and whenever possible please document your uncertainty values). All the above quantities (except A and H) are registered at cloud boundaries: cloud top for albedo and reflectivity and cloud base for transmittance and transmissivity. For this case cloud top is defined as the topmost level of where a cloud cell with non-zero extinction is encountered (2.43 km) and cloud base is defined as the last level where a cloudy cell is encountered (0.63km). Directional tolerance (angular width of radiation "pencil") for reflectivity and transmissivity is left up to the user, but must be documented and provided when the results are submitted. Plan also for a file that will include CPU time for each experiment. In order to evaluate code performance as opposed to hardware performance we'll need to normalize with your machine's SPECfp_base95; you can look up your computer at http://www.specbench.org/osg/cpu95/results/cfp95.html, click at the HTML link for it and pull out the SPECfp_base95 number. Please submit the SPECfp_base95, and the CPU and "wall clock" (real elapsed) times for each experiment. For UNIX platforms CPU time can be obtained by using the time or timex commands; see your man pages for specific options. Formats and file name conventions can be found below. ************************** How to submit your results ************************** ------------------------Name convention------------------------ a) Fields of radiative quantities ================================= Create a separate file for each experiment and output field. Use the following name convention: I3RC_RQ_case_exp#.inst[n] where: i) "RQ" is the radiative quantity contained the file. RQ takes the following values: RQ=R (reflectance) RQ=T (transmittance) RQ=A (absorptance) RQ=H (net horizontal flux) RQ=Iu (nadir reflectivity) RQ=Id (zenith transmissivity) ii) "case" is the cloud field case For phase I the cloud field cases have been assigned the following numbers: case=1 step cloud case=2 MMCR-retrieved cloud case=3 Landsat-retrieved cloud Thus, for this field, put case=2 iii) "exp#" is the experiment number as listed above; valid numbers are 1-8 for this case iv) "inst" is the four-letter code that has been assigned to each institution participating in the experiment. The codes are listed in filename_TBD . v) "[n] is an index number following the institution whenever there are more than one participant or codes from the same institution. There is is no number for institutions with one participant and one code. We have already notified participants that have index numbers. ****Examples**** 1) The nadir reflectivity field of experiment 5, MMCR cloud case submitted by a participant affiliated with institution AESC should have the following filename: I3RC_Iu_2_5.AESC 2) The reflectance field of experiment 8, MMCR cloud case submitted by the 2nd participant of institution UMBC should be put in the following file: I3RC_R_2_8.UMBC2 b) Statistics of radiative quantities ===================================== Create a separate file for each experiment. This file will contain the statistics of all radiation quantities. Use the following convention: I3RC_fname_case_exp#.inst[n] where fname="stats" (without the quotes) and the rest is as before. c) Mean and pixel-level errors ========================================= Create a separate file for each experiment. This file will contain the mean pixel-level error and the error to the mean. Use the following convention: I3RC_fname_case_exp#.inst[n] where fname="errors" (without the quotes) and the rest is as before. d) Computing performance ======================== Create a single file for the experiment. This file will contain CPU time information for each experiment. Use the following convention: I3RC_fname_case_inst[n] where fname="CPER" (uppercase, without the quotes) and the rest is as before. ------------------------Output format------------------------- 1) For each field create a file using output format as the one produced by the following Fortran code --------------------------------------------------------------- parameter (nx=640) real R(nx) open (11, file='I3RC_R_2_1_UCOL1', status='unknown') do ix=1,nx write (11, '(f10.4)') R(ix) enddo ----------------------------------------------------------------