Publications Published in JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY

1. Comment on Alpert P., N. Halfon, and Z. Levin, 2008: Does air pollution really suppress precipitation in Israel?. Amir Givati, Daniel Rosenfeld.
   JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY: 2009
   DOI: 10.1175/2009JAMC1902.1
   Notes
   Alpert et al. (2008) from here on referred to as AHL08, challenged the quantification of the suppression of orographic precipitation that was shown by Givati and Rosenfeld (2004 and 2005, from here on referred to as GR04 and GR05) to occur in Israel. Their main claim was that the results were determined by the selection of the rain gauges. In this comment we demonstrate that when an objective selection of the rain gauges is applied to all the rain gauges that were used by AHL08, GR04 and GR05, the outcome replicates the results of GR04 and GR05, and provides additional insights. At the final account our comment here further enhances the confidence that orographic precipitation has been suppressed over Israel. The direct evidence to the cause is still lacking.
   
   
   
2. Errors in Estimating Raindrop Size Distribution Parameters Employing Disdrometer and Simulated Raindrop Spectra. QING CAO, GUIFU ZHANG.
   JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY: 2008
   DOI: 10.1175/2008JAMC2026.1
   Notes
   There have been debates and differences of opinion over the validity of using drop size distribution (DSD) models to characterize precipitation microphysics and to retrieveDSDparameters from multiparameter radar measurements. In this paper, simulated and observed rain DSDs are used to evaluate moment estimators. Seven estimators for gamma DSD parameters are evaluated in terms of the biases and fractional errors of five integral parameters: radar reflectivity (ZH), differential reflectivity (ZDR), rainfall rate (R), mean volume diameter (Dm), and total number concentration (NT). It is shown that middle-moment estimators such as M234 (using the second-third-fourth moments) produce smaller errors than lower- and higher-moment estimators if the DSD follows the gamma distribution. However, if there are model errors, the performance of M234 degrades. Even though the DSD parameters can be biased in moment estimators, integral parameters are usually not. Maximum likelihood (ML) and L-moment (LM) estimators perform s
   
   
   
3. Influence of Cloud Condensation Nuclei on Orographic Snowfall. STEPHEN M. SALEEBY, WILLIAM R. COTTON, DOUGLAS LOWENTHAL, RANDOLPH D. BORYS, MELANIE A. WETZEL.
   JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY: 2008
   DOI: 10.1175/2008JAMC1989.1
   Notes
   Pollution aerosols acting as cloud condensation nuclei (CCN) have the potential to alter warm rain clouds via the aerosol first and second indirect effects in which they modify the cloud droplet population, cloud lifetime and size, rainfall efficiency, and radiation balance from increased albedo. For constant liquid water content, an increase in CCN concentration (Nccn) tends to produce an increased concentration of droplets with smaller diameters. This reduces the collision and coalescence rate, and thus, there is a local reduction in rainfall. While this process applies to warm clouds, it does not identically carry over to mixed-phase clouds in which crystal nucleation, crystal riming, crystal vs. droplet fallspeed and collection efficiency play active roles in determining precipitation amount. Sulfate-based aerosols serve as very efficient cloud nuclei but are not effective as ice forming nuclei. In clouds where precipitation formation is dominated by the ice phase, Nccn influences precipitation growth by altering the efficiency of droplet collection by ice crystals and the fall trajectories of both droplet and crystal hydrometeors. The temporal and spatial variation in both crystal and droplet populations determines the resultant snowfall efficiency and distribution. Results of numerical simulations in this study suggest that CCN can play a significant role in snowfall production by winter, mixed-phase cloud systems when liquid and ice hydrometeors coexist. In sub-freezing conditions, a precipitating ice cloud overlaying a supercooled liquid water cloud allows growth of precipitation particles via the seeder-feeder process, in which nucleated ice crystals fall through the supercooled liquid water cloud and collect droplets. Enhanced Nccn from sulfate pollution by fossil fuel emissions modify the droplet distribution and reduce crystal riming efficiency. Reduced riming efficiency inhibits the rate of snow growth, producing lightly-rimed snow crystals that fall slowly and advect further downstream prior to sur ace deposition. 3 Simulations indicate that increasing Nccn along the orographic barrier of the Park Range in northcentralColorado results in a modification of the orographic cloud such that the surface snow water equivalent amounts are reduced on the windward slopes and enhanced on the leeward slopes. The inhibition of snowfall by pollution aerosols (ISPA) effect has significant implications for water resource distribution in mountainous terrain.
   
   
   
4. Reply to comment by A. Givati and D. Rosenfeld On the paper by Alpert, P., N. Halfon and Z. Levin: Does air pollution really suppress precipitation in Israel?. Alpert, P., N. Halfon, Z. Levin.
   JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY: 2009
   DOI: 10.1175/2009JAMC1943.1
   
   
5. The role of climate forecasts in Western US power planning. Voisin, N.; Hamlet, A. F.; Graham, L. P.; Pierce, D. W.; Barnett, T. P.; Lettenmaier, D. P..
   JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY: 2006
   Notes
   The benefits of potential electric power transfers between the Pacific Northwest (PNW) and California ( CA) are evaluated using a linked set of hydrologic, reservoir, and power demand simulation models for the Columbia River and the Sacramento-San Joaquin reservoir systems. The models provide a framework for evaluating climate-related variations and long-range predictability of regional electric power demand, hydropower production, and the benefits of potential electric power transfers between the PNW and CA. The period of analysis is 1917-2002. The study results show that hydropower production and regional electric power demands in the PNW and CA are out of phase seasonally but that hydropower productions in the PNW and CA have strongly covaried on an annual basis in recent decades. Winter electric power demand and spring and annual hydropower production in the PNW are related to both El Nino-Southern Oscillation (ENSO) and the Pacific decadal oscillation (PDO) through variations in winter climate. Summer power demand in CA is related primarily to variations in the PDO in spring. Hydropower production in CA, despite recent covariation with the PNW, is not strongly related to ENSO variability overall. Primarily because of strong variations in supply in the PNW, potential hydropower transfers between the PNW and CA in spring and summer are shown to be correlated to ENSO and PDO, and the conditional probability distributions of these transfers are therefore predictable with long lead times. Such electric power transfers are estimated to have potential average annual benefits of $136 and $79 million for CA and the PNW, respectively, at the year-2000 regional demand level. These benefits are on average 11%-27% larger during cold ENSO/PDO events and are 16%-30% lower during warm ENSO/PDO events. Power transfers from the PNW to CA and hydropower production in CA are comparable in magnitude, on average.