SOME STATISTICAL OBSERVATIONS1

ABSTRACT: Some of the statistical techniques and results presented in publications in hydrology and water resources are, at best, misleading and, in other cases, plain wrong. The author discusses examples that he has found in recent publications. One reason for the number of doubtful papers may be simply that the total number of papers is increasing so fast; seven new journals in hydrology and water resources have been issued in the last few years.     

Impact of consistent boundary layer mixing approaches between NAM and CMAQ

Discrepancies in grid structure, dynamics and physics packages in the offline coupled NWS/NCEP NAM meteorological model with the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) model can give rise to inconsistencies. This study investigates the use of three vertical mixing schemes to drive chemistry tracers in the National Air Quality Forecast Capability (NAQFC). The three schemes evaluated in this study represent various degrees of coupling to improve the commonality in turbulence parameterization between the meteorological and chemistry models. The methods tested include: (1) using NAM predicted TKE-based planetary boundary height, h, as the prime parameter to derive CMAQ vertical diffusivity; (2) using the NAM mixed layer depth to determine h and then proceeding as in (1); and (3) using NAM predicted vertical diffusivity directly to parameterize turbulence mixing within CMAQ. A two week period with elevated surface O₃ concentrations during the summer 2006 has been selected to test these schemes in a sensitivity study. The study results are verified and evaluated using the EPA AIRNow monitoring network and other ozonesonde data. The third method is preferred a priori as it represents the tightest coupling option studied in this work for turbulent mixing processes between the meteorological and air quality models. It was found to accurately reproduce the upper bounds of turbulent mixing and provide the best agreement between predicted h and ozonesonde observed relative humidity profile inferred h for sites investigated in this study. However, this did not translate into the best agreement in surface O₃ concentrations. Overall verification results during the test period of two weeks in August 2006, did not show superiority of this method over the other 2 methods in all regions of the continental U.S. Further efforts in model improvement for the parameterizations of turbulent mixing and other surface O₃ forecast related processes are warranted.     

Crops,cows or timber? Including carbon values in land use choices

Farm forestry is a very minor land use in the inland agricultural landscapes of Australia. The Australian Government intends to introduce a program to encourage landholders to trade the carbon sequestration value of plantations and this may change the relative profitability of plantations against other agricultural land uses. This research compares the returns from a timber and ‘carbon’ plantation, with those from grazing and a common crop rotation in the Kingaroy area of Queensland.Typical production patterns for all systems were developed from producer and expert knowledge and soil and vegetation sampling were used to estimate sequestration rates. The costs and benefits of all land use systems were converted into monetary terms and discounted to produce net present values. With a standard discount rate and average commodity prices based on recent history, cultivation is the most profitable option, followed by pasture and plantations. After the inclusion of carbon, plantations are the most profitable option, followed by pasture and cultivation. A number of qualifications of these findings are also discussed.