Wayman E. Baker

Global Numerical Weather Prediction at the National Meteorological Center

In this paper we describe the global numerical weather prediction system of the National Meteorological Center, and review recent improvements, the evolution in skill, and current research projects and plans.

Lidar-Measured Winds from Space: A Key Component for Weather and Climate Prediction

Abstract The deployment of a space-based Doppler lidar would provide information that is fundamental to advancing the understanding and prediction of weather and climate. This paper reviews the concepts of wind measurement by Doppler lidar, highlights the results of some observing system simulation experiments with lidar winds, and discusses the important advances in earth system science anticipated with lidar winds. Observing system simulation experiments, conducted using two different general circulation models, have shown 1) that there is a significant improvement in the forecast accuracy over the Southern Hemisphere and tropical oceans resulting from the assimilation of simulated satellite wind data, and 2) that wind data are significantly more effective than temperature or moisture data in controlling analysis error. Because accurate wind observations are currently almost entirely unavailable for the vast majority of tropical cyclones worldwide, lidar winds have the potential to substantially improve...

LIDAR-MEASURED WIND PROFILES The Missing Link in the Global Observing System

The three-dimensional global wind field is the most important remaining measurement needed to accurately assess the dynamics of the atmosphere. Wind information in the tropics, high latitudes, and stratosphere is particularly deficient. Furthermore, only a small fraction of the atmosphere is sampled in terms of wind profiles. This limits our ability to optimally specify initial conditions for numerical weather prediction (NWP) models and our understanding of several key climate change issues. Because of its extensive wind measurement heritage (since 1968) and especially the rapid recent technology advances, Doppler lidar has reached a level of maturity required for a space-based mission. The European Space Agency (ESA)s Atmospheric Dynamics Mission Aeolus (ADM-Aeolus) Doppler wind lidar (DWL), now scheduled for launch in 2015, will be a major milestone. This paper reviews the expected impact of DWL measurements on NWP and climate research, measurement concepts, and the recent advances in technology that ...

Objective Analysis and Assimilation of Observational Data from FGGE

Abstract An objective analysis scheme developed at the Goddard Laboratory for Atmospheric Sciences (GLAS) to assimilate meteorological data is described. Wind, geopotential height, and relative humidity are analyzed on mandatory pressure levels. Surface pressure and temperature are reduced to sea level and analyzed there. The objective analysis procedure is of the successive correction type, but modified to account for variable data density and quality. A sample analysis is presented for 1200 GMT 19 January 1979 and shows good agreement with the one produced by the European Centre for Medium Range Weather Forecasts (ECMWF). The present analysis/forecast system demonstrates reasonable forecast skill over the Northern Hemisphere for an ensemble of five-day integrations during the First Special Observing Period (SOP-1) of the First GARP (Global Atmospheric Research Program) Global Experiment (FGGE). The vertical motion field shows excellent agreement with the large-scale synoptic pattern for the 1200 GMT 19 ...

Spectral energetics of the observed and simulated Northern Hemisphere general circulation during blocking episodes

Abstract The spectral energetics of the Northern Hemisphere circulation during blocking episodes of the FGGE year is investigated with gridded analyses of observational data and Parallel simulation experiments. The purpose of this study is to describe the energetics distinctions of the observed and simulated blockings in the context of the general circulation and to assess the capability of the model to simulate blockings. In the observed circulation a pronounced winter blocking is developed and maintained by the nonlinear wave-wave interaction L(1) from the kinetic energy source for n = 3–10, where L(n) is the transfer of eddy kinetic energy from all other wavenumbers to wavenumber n. In the case of the. double blocking in the winter, both L(1) and L(2) support the blocking. The kinetic energy source of n=3–10 for upscale input at n = 1 and 2 is supported by the baroclinic conversion at n3–10. The simulated winter circulation shows strong baroclinic conversion at all wavenumbers, including ultralong wave...

A case study of forecast sensitivity to data and data analysis techniques

Abstract In this study we examine the sensitivity of forecast to individual components of the First GARP (Global Atmospheric Research Programme) Global Experiment database as well as to some modifications in the data analysis techniques. Several short assimilation experiments (0000 GMT 18 January 1979 through 0000 21 January) are performed in order to test the effects of each database or analysis change. Forecasts are then generated from the initial conditions provided by these experiments. The 0000 21 January case is chosen for a detailed investigation because or the poor forecast skill obtained earlier over North America for that particular case. Specifically, we conduct experiments to test the sensitivity of forecast skill to: 1) the addition of individual satellite observing system components; 2) temperature data obtained with different satellite retrieval methods; and 3) the method of vertical interpolation between the mandatory pressure analysis levels and the model sigma levels. For the single case...

Planetary-Scale Characteristics of the Atmospheric Circulation During January and February 1979

Abstract The vertical and temporal Structure of the global scale flow in the Goddard Laboratory for Atmospheric Sciences analyses of data from the First GARP Global Experiment are presented. The fields are represented in terms of spherical harmonic expansions of the streamfunction, velocity potential and geopotential. The global scale patterns are obtained from triangular truncations of such series, neglecting terms past the fourth degree. Some modes display prominent high frequency oscillations in the velocity potential and geopotential height that may be related to diurnal cycles of cumulus convection. Such oscillations are not apparent in the streamfunction. Low-order harmonics with nodes only along latitude circles are nearly equivalent barotropic. However, those harmonics that have no nodes between the poles reverse phase with height. The following conclusions are drawn regarding the global scale patterns: 1) Since the divergent component of the meridional flow is not much smaller than the rotational...

The Influence of the Tropics on the Prediction of Ultralong Waves. Part II: Latent Heating

Abstract The influence of tropical latent heating on the short-to-medium-range numerical prediction of ultralong waves is examined. Two integrations of the GLAS general circulation model are made from the came initial state. One forecast utilizes the full model physics, the other contains no latent heating in the tropical belt from 20°S to 20°N. The tropical and subtropical divergence fields react to differences in the latent heating within half a day. Differences in the rotational wind field within these latitudes are noted in about three days, while at mid-latitudes (30°–60°) the influence is not felt until five days. At higher latitudes the five-day predictions of a strong North Atlantic block with and without latent heating are quite similar. Although the greatest changes in the heating field occur in the Southern Hemisphere, the largest temperature, height and wind change take place in the Northern Hemisphere. It appears that the upper troposheric tropical westerlies are sustained in the model by tro...

Global-scale weekly and monthly energetics during January and February 1979

Abstract Time averages of the latitudinal distribution of kinetic energy and terms of the kinetic energy equation are presented as depicted by the Goddard Laboratory for Atmospheric Science (GLAS) analyses of the First GARP Global Experiment (FGGE) during the First Special Observing Period (SOP-1). Monthly averages display peaks in the stationary wave energy at 30°N and in the tropics. Global decompositions of the streamfunction and velocity potential in spherical harmonics are truncated at the fourth degree. The kinetic energy distribution of the associated wind field displays peaks in the tropics and northern mid-latitudes in January, but only a tropical peak in February. The Eliassen-Palm relationship for latitudinal momentum and geopotential wave transport appears to have some support in these analyses, particularly in the mid-latitudes. In the deep tropics, latitudinal convergence of the fully resolved stationary wave momentum transport accompanies latitudinal convergence of stationary wave geopotent...

Utilization of satellite winds for climate and global change studies

Abstract The importance of wind measurements for climate and global change research is reviewed, particularly with respect to the data anticipated from the Laser Atmospheric Wind Sounder (LAWS).