MAE 207/255: BOUNDARY LAYER AND RENEWABLE ENERGY METEOROLOGY

Instructor: Prof. Jan Kleissl, jkleissl at ucsd Lectures: Mon, Wed, Fri 1200-1250 (WLH 2206) Office Hours: Fri 120-3, EBU-2 580 Homework (50% or 75% of grade, depending on option below) Project and presentation: 5-15 page project report by group (50%) or 5-10 minute paper presentation (25% of grade).

Books


• Stull I: Meteorology for Scientists and Engineers: Simple text for background and basics (on reserve).
• Stull II: Introduction to Boundary Layer Meteorology: Advanced book by the same author: fluid mechanics, scaling relationships, profiles of atmospheric variables (on reserve).
• Kaimal and Finnigan: Atmospheric Boundary Layer Flows: Their structure and measurement Advanced book on ABL structure, spectral analysis, flow over hills, and sensors and measurement techniques (on reserve).
• Markvart and Castaner: Practical Handbook of Photovoltaics: Fundamentals and Applications Solar resource assessment, PV technologies.

All presentations online. Thanks for a great quarter!

Course Content:


1. Introduction to the atmosphere
2. Solar Energy
   • Solar radiation: Solar constant, solar geometry. Atmospheric transmissivity: gases and aerosols, clouds. Global horizontal, diffuse, and direct radiation. Solar resource assessment, sensors and instrumentation. Albedo. Reading: Stull I Chapter 2,18, Diak satellite insolation model, National Solar Radiation Database, NREL Specs for insolation measurements
   • Solar energy systems: Types of systems: photovoltaic, concentrating solar power, solar hot water. Solar intermittency. Economics of solar energy. Required reading: Crabtree and Lewis (2007) solar energy conversion (), Curtright and Apt (2008) solar intermittency (D. Uehling & M Nguyen 4/17), Hawkins (CAISO) presentation, Denholm and Margolis (2007) Renewable Penetration (J. Stromsoe, M. Sankur 4/17). Other presentation topics (not required reading): explain and demo NREL PVWatts (J. Kerins & R. Kapadia, 4/15/2009), CA Center for Sustainable Energy Solar Hot Water Basics for Homeowners
3. Surface Energy Balance (longwave/thermal): Stefan's law, emissivity. Greenhouse effect. Surface energy balance: net radiation, ground heat flux, sensible and latent heat flux. Sensors and instrumentation. Other applications: Building heating, ventilation, and air conditioning (HVAC). Evapotranspiration and irrigation, Reading: Stull I Chapter 2 p. 36-38, Chapter 3, Kaimal p. 225 - 232
4. Atmospheric boundary layer: Structure. Friction velocity and roughness. Stability, stratified flow, Obuhkov length, Richardson number. Moisture and heat in the atmosphere, thermodynamic diagrams, atmospheric soundings. Reading: Stull I Chapters 3-6; Stull II Chapter 7
5. Turbulence and Dispersion in the ABL: Turbulence kinetic energy (TKE). Conservation equs for heat and momentum fluxes. Advection-diffusion equation. Gaussian plume model. Atmospheric measurements and instrumentation. Reading: Stull I chapters 4, 17, Stull II chapters 2, 5; Kaimal & Finnigan chapter 6
6. Wind power meteorology: Mean velocity profile. Wind resource assessment. Flow over hills. Low-level jet. Sensors and instrumentation. Reading: Kaimal & Finnigan Ch 5, American Meteorological Society Meeting 2009: Summarize session on Modeling Tools for Energy Production in Urban and Complex Terrain, DOE Report Research Needs for Wind Resource Characterization, Hoogwijk renewable penetration, Nanahara et al. 2004: Coherence of wind power (Anson B.)
7. Urban energy efficiency: urban surface energy balance; urban heat islands and mitigation; thermal effects of artificial turf; building energy use. Reading: ASHRAE Fundamentals: Ch 27-29: Residential cooling and heating load, ventilation and infiltration; Ch 30-32: Non-residential cooling and heating load, energy estimation and modeling. Older version available in library; Taha et al 2007 Simulation of the effect of urban surface modification on climate in LA; Ihara et al. 2007 UHI mitigation; Suehrcke et al 2008 Effect of roof reflectance on heat gain; Akbari et al. 2000 Roof reflectance and building energy use (Kenny Lee and David Yu); Rosenfeld and Akbari 1998 Costs and benefits of cool communities ; Kruger and Pearlmutter, 2008 Cooling of urban areas through evapotranspiration and effect on building energy use (Kassandra M. and Jason O.);

Homeworks
Comment on the result of each problem

• Homework 1: Radiation, due April 8, 2009
  1. Using the simple algorithm in the ASCE evapotranspiration equations graph the hourly extraterrestrial and clear sky irradiance at the surface over a year and over a day. Explanation of the algorithm. Disregard the part that deals with evaporation.
  2. Compare the results to global horizontal irradiance observation from a DEMROES station (go to 'Textual' and click on a station name to see raw data). Note that all times are Pacific Standard Time (PST=Pacific Daylight Savings Time - 1 hour). Multiply the radiation given in the file by the following calibration factors:

     Station	RIMC	Powell Solar_Radiation	Powell SEVar3, SEVar4	EBU2	CMRR	Hubbs	MoCC	BMSB	Tioga
     Factor	1	.9388	1	1.0090	1	1.0135	.9883	.9856	.9766

  3. Consider this formula for the air mass X = 1 / [sin (pi/2 - SZA) + 0.025 exp(-11 sin (pi/2 - SZA))] (Rozenberg 1966), where SZA is the solar zenith angle (SZA = 90^o - theta). Use DEMROES measurements (not the ASCE model) together with airmass and extraterrestrial irradiance to determine the clear sky transmissivity of the atmosphere on different days. Here we define the transmissivity of the atmosphere for incident irradiance normal to the earth's surface (and atmosphere).
  4. Design an experimental protocol to obtain the direct and diffuse horizontal solar irradiance through measurements with a single pyranometer by (a) shading the sensor and (b) (independently from a) measuring at different angles to the sun. Compare the results to DEMROES measurements at the Powell (PoSL) station (column SEVar3_Avg: global horizontal irradiance [W/m2], SEVar4_Avg: diffuse horizontal irradiance [W/m2]; disregard the units given in the file).
  Comments: increase font size on graph: set(0,defaultaxesfontsize',12); when comparing to DEMROES data, download data and graph in the same plot; when conducting measurements, note down serial number and calibration constant for your sensor; specify time zone; .
• Homework 2: Solar Energy Systems due April 20, 2009
  1. (5 pts) Assuming that the Powell diffuse measurements were correct, reanalyze your dataset (considering that DEMROES data is horizontal and in PST, calibration factor of your pyranometer) collected in homework 1.4 to calculate atmospheric transmissivity, and to determine whether the global radiation measured by your pyranometer at different angles can be modeled as direct + diffuse radiation. Sun azimuth and zenith angle can be calculated with this m file.
  2. (10 pts) Using a solar photovoltaic panel from the lab under near-standard conditions (1000 W/m2, 25^oC) measure open circuit voltage with a voltmeter.
     Also measure power output in a circuit with a PV panel connected to a 12V battery (you can use a voltmeter or a current sense resistor circuit attached to a CR1000 datalogger. Note that the CR1000 dataloggers can only measure voltages up to 2.5 VDC). Determine the solar conversion efficiency.
     Compare both results to those given by Prabakhar Bandaru during his lecture on April 3.
  3. (15 pts) Consider data from the solar PV system on Powell Structures Laboratory [kW] and DEMROES data (RIMC.SlrW_Avg.data and RIMC.time) from RIMAC. The Powell solar array is a 13 kW array, half of which is flat and the other half is tilted at 4.4 degrees.
     1. Determine which of the two arrays (or two columns in the file) is the flat array.
     2. Apply the model distributed by email (Markvart & Castaner: Photovoltaics, pp. 44-65) to calculate the output of the tilted array and flat array given the DEMROES Powell diffuse and GHR data and compare the results to the actually observed power output. Assume reflectance = albedo = 0.2. Determine the solar conversion efficiency.
  4. (10 pts) Solve the problem 3.12 in D.G. Andrews: "An introduction to atmospheric physics". The last part of the question was cut off. It is "Evaluate the reflection and transmission coefficients for omega = 0.9997, f = 0.9, and xi_1^* = 10, 20, and 30. Note that R+T <1: what is the physical reason for this? Find also the reflection coefficient for an infinitely deep cloud with these values of omega and f.
• Homework 3: Solar Intermittency / Surface Energy Balance due May 6, 2009. Datalogger program for 3.2 and 3.3
  1. Using DEMROES station data from Hubbs Hall (variables Hubb.time and Hubb.SlrW_Avg.data) and EBU2 (same variables) conduct a study of intermittency at these 2 sites using quantities discussed in class (or more of your own choice). Also see Curtright and Apt (2008).
  2. Design and conduct an outdoor experiment using a infrared radiometer (Apogee IRR-P assumes emissivity = 0.95) and air temperature data from a nearby DEMROES station that demonstrates that bare metal has a lower emissivity than concrete.
     Then determine the emissivity by adding a thermistor to measure temperature of the surface. Neglect radiance coming directly from air into the radiometer (the 'path radiance').
  3. Using a Kipp & Zonen net radiometer (NR-Lite in program), conduct net radiation measurements at 3 different sites during daytime (ideally close to noon) and at night. Discuss the reasons for the observed differences between day and night and between the different sites.
• Homework 4: Surface Energy Balance / Convective Fluxes, Stability due May 18, 2009.
  1. Datalogger program. Material on practical issues and some theory Conduct measurements with a Campbell Scientific 3D sonic anemometer (CSAT3) and the NR-Lite at a non-watered site (e.g. concrete or asphalt) during daytime (ideally midday) and after sunset. To avoid excessive data plug in datalogger power only once you are ready to take data. Download the tables 'stats' (for net radiation) and 'HighFreq' for (u,v,w,Tv). During setup consider the following:
     • CSAT3 should face into the wind (so that the air can reach the measurement area without obstructions); note that a vector (u,v,w)=(1,0,0) indicates a wind blowing into the CSAT (as desired)
     • CSAT3 axis should be perpendicular to the surface
     • assure (as much as possible) a homogeneous surface for a long distance upwind of the sensor
     • measure for at least 10 minutes starting at :00, :10, :20, :30, :40, or :50 at a frequency of 10 Hz
     • Tv is the virtual temperature derived from the speed of sound measured by the CSAT. Assume T' = Tv' = \theta'
     1. What are the reasons for the setup considerations?
     2. Plot the 2x 10 minute time series of u, v, w, Tv (ideally in one plot with four horizontal subplots) using the same y axis limits for daytime and nighttime measurements. Comment on the magnitude of TKE for day & night
     3. Compute the average of [u, w, w, Tv] and plot the time series of fluctuations (one plot with four horizontal subplots). Comment on the value obtained for mean(w).
     4. Compute the covariance (covar) and correlation coefficient (corrcoef) for (u,w) and (t,w). What can you infer from the sign and the value of r(t,w)? What is the physical meaning of covar(t,w)?
     5. Compute the mean and turbulent parts of the vertical kinematic heat flux [K m/s] (see Reynolds averaging of \overbar{wT} demonstrated in class). Compute the sensible heat flux [W/m2] and comment on its relation to net radiation.
     6. Assuming neutral conditions compute and plot the profile \bar{M}(z) of the mean horizontal velocity M = (sqrt(u.^2+v.^2).
     7. Compute the flux Richardson number using d\bar{M}/dz from the previous question. Also compute the Obukhov length L.
  2. Obtain a daytime radiosounding from http://raob.fsl.noaa.gov [note that time is UTC. PST lags UTC by 8 hours.] for an inland location in California (e.g. Edwards Air Force Base). The columns in the file are p [.1 mbar], z [m] above mean sea level, T [.1 oC], dewpoint T[.1 oC], wind direction [^o], wind speed [as selected]
     1. Interpolate missing data (9999) using surrounding values. Plot the data up to a height of 5 km.
     2. Compute and plot the potential temperature. Designate the static stability of each layer.
     3. Compute the gradient Richardson and classify the dynamic stability and existence of turbulence.
• Homework 5: Wind power due June 5, 2009.
  1. Consider your daytime CSAT3 measurements for homework 4. Assume that the measurements were carried out at z = 20 m over a suburban surface with building heights of 8m.
     1. Using the power spectra density of the horizontal velocity sqrt(u2+v2)discuss the intermittency of wind power.
     2. At what height would a typical wind turbine (choose one from internet) produce power output at 50% of its rated capacity?
     3. How does the surface energy balance over this suburban area differ from that for a desert shrubland? What is the impact on wind power?
  2. Give constructive feedback on the class (1/2 - 1 page; you can use the cape forms as a guide for what to comment on). What did you learn? What would you have liked to learn? What else could be improved to promote learning? Please email this to rzhuang@ucsd.edu who will grade it but withhold it from me until after final grades are assigned.

Lecture Notes and Resources

• Meteorological Measurements:
  • Datalogger and measurement instructions
  • Simple datalogger program to aquire 1 second data with a pyranometer. Enter calibration factor for your pyranometer in line 4.
  • Free Campbell Scientific starter software for use on your own laptop.
  • MATLAB file to read and plot output from CR1000 datalogger
• Intro to Atmosphere and Radiation
• Solar maps