Search Results
You are looking at 1 - 10 of 40 items for :
- Author or Editor: J. Anderson x
- Bulletin of the American Meteorological Society x
- Refine by Access: All Content x
A simple instrument is described for measuring or recording wind speed, using a 1-in. length of heated platinum wire as the sensing element. As a practical laboratory and field device, its main virtues are its excellent response at low wind speeds and its utility in confined spaces. Calibration techniques are described, and the circuit diagram is included for a three-range instrument.
A simple instrument is described for measuring or recording wind speed, using a 1-in. length of heated platinum wire as the sensing element. As a practical laboratory and field device, its main virtues are its excellent response at low wind speeds and its utility in confined spaces. Calibration techniques are described, and the circuit diagram is included for a three-range instrument.
Measurements on rainfall near Hilo, Hawaii are described. Quartile deviations of drop-size distributions are plotted versus rainfall intensity. Comparison is made with similar data of Laws and Parsons, and certain similarities and differences are pointed out.
Measurements on rainfall near Hilo, Hawaii are described. Quartile deviations of drop-size distributions are plotted versus rainfall intensity. Comparison is made with similar data of Laws and Parsons, and certain similarities and differences are pointed out.
Meteorological equipment for taking detailed temperature and humidity soundings to 3000 ft. altitude is discussed. It consists of a captive balloon wired-sonde system using a ceramic temperature element and an electrolytic hygrometer strip. Similar equipment is also adapted for use in airplane soundings. Calibration techniques and results are discussed, together with a method for correcting the humidity strip to ± 1% R.H. Temperature accuracy is ± 0.1°C. The limitations of the balloon and airplane equipment are discussed and the two are found to be complementary.
Meteorological equipment for taking detailed temperature and humidity soundings to 3000 ft. altitude is discussed. It consists of a captive balloon wired-sonde system using a ceramic temperature element and an electrolytic hygrometer strip. Similar equipment is also adapted for use in airplane soundings. Calibration techniques and results are discussed, together with a method for correcting the humidity strip to ± 1% R.H. Temperature accuracy is ± 0.1°C. The limitations of the balloon and airplane equipment are discussed and the two are found to be complementary.
The equipment described is suitable for measuring lag coefficients, as small as 0.1 second, of temperature recording systems. The sensing element is suspended alternately in two air streams of different temperature. The ratio of indicated to actual temperature difference is used to compute the lag coefficient. Measurements indicate that the lag of the amplifier-recorder is small compared to that of the elements tested.
The equipment described is suitable for measuring lag coefficients, as small as 0.1 second, of temperature recording systems. The sensing element is suspended alternately in two air streams of different temperature. The ratio of indicated to actual temperature difference is used to compute the lag coefficient. Measurements indicate that the lag of the amplifier-recorder is small compared to that of the elements tested.
A new thermocouple psychrometer, designed to indicate true air temperature and humidity in remote locations, is described. In order to minimize maintenance, it utilizes natural ventilation, but provides adequate shielding of sensing elements against radiation. Wet and dry bulb temperature errors of less than + 0.1C° are obtained in winds above 1 mph.
A new thermocouple psychrometer, designed to indicate true air temperature and humidity in remote locations, is described. In order to minimize maintenance, it utilizes natural ventilation, but provides adequate shielding of sensing elements against radiation. Wet and dry bulb temperature errors of less than + 0.1C° are obtained in winds above 1 mph.
A new concept of upper-air data collection utilizes instrumented balloons controlled to float along given constant-pressure surfaces in the atmosphere. A system of instrumentation, named the transosonde (trans-oceanic-sonde) has been developed for implementing this concept. Field tests have established the technical and meteorological feasibility of the system. In the course of the tests, transosonde balloons were tracked over distances of thousands of miles using a network of shore-based high-frequency radio-direction-finder stations. Emphasis has been placed upon the trajectory of the balloon as the primary source of meteorological data. Wind velocities and accelerations can be derived directly from constant-pressure surface trajectories, providing valuable synoptic and research data. Balloon trajectories in passing through major troughs and ridges define these features, giving information of importance for synoptic analysis and long-range forecasting. In addition, a sequence of trajectories provides a measure of the acceleration and deceleration of these entities. The transosonde system has additional data-gathering potentials for temperature, lapse rate, wind shear and other parameters. It is concluded that the system can be employed over those regions of the globe where upper-air data are lacking at a cost competitive with present-day systems.
A new concept of upper-air data collection utilizes instrumented balloons controlled to float along given constant-pressure surfaces in the atmosphere. A system of instrumentation, named the transosonde (trans-oceanic-sonde) has been developed for implementing this concept. Field tests have established the technical and meteorological feasibility of the system. In the course of the tests, transosonde balloons were tracked over distances of thousands of miles using a network of shore-based high-frequency radio-direction-finder stations. Emphasis has been placed upon the trajectory of the balloon as the primary source of meteorological data. Wind velocities and accelerations can be derived directly from constant-pressure surface trajectories, providing valuable synoptic and research data. Balloon trajectories in passing through major troughs and ridges define these features, giving information of importance for synoptic analysis and long-range forecasting. In addition, a sequence of trajectories provides a measure of the acceleration and deceleration of these entities. The transosonde system has additional data-gathering potentials for temperature, lapse rate, wind shear and other parameters. It is concluded that the system can be employed over those regions of the globe where upper-air data are lacking at a cost competitive with present-day systems.
The diversity of small lakes' (size < 50 km) configurations, sizes, surrounding terrain, and land use combined with relative sparsity of observations complicates the observational evaluation of the lake breezes (LB) that are induced by these lakes. In the present article observational data obtained from available documents, data archives, and special projects were surveyed to suggest characterization of the LB features. The observational survey was complemented by conceptual evaluations. A preliminary generalization of the LB intensity and inland penetration in relation to the surrounding land use was inferred. The conceptual evaluation suggested that for a given lake width the prime factor affecting the LB intensity is the magnitude of the surface sensible heat flux over the surrounding land. Cooling related to the lake water temperature was indicated to have usually a secondary effect on the LB intensity for small lakes. Surface observations implied that the onshore penetration of the LB by the early afternoon hours is typically less than the characteristic width of the lake. Lower atmosphere observations indicated that the vertical extent of the LB may reach several hundred meters. Implications of the observed LB features in support of characterization of the real-world vegetation breeze are discussed.
The diversity of small lakes' (size < 50 km) configurations, sizes, surrounding terrain, and land use combined with relative sparsity of observations complicates the observational evaluation of the lake breezes (LB) that are induced by these lakes. In the present article observational data obtained from available documents, data archives, and special projects were surveyed to suggest characterization of the LB features. The observational survey was complemented by conceptual evaluations. A preliminary generalization of the LB intensity and inland penetration in relation to the surrounding land use was inferred. The conceptual evaluation suggested that for a given lake width the prime factor affecting the LB intensity is the magnitude of the surface sensible heat flux over the surrounding land. Cooling related to the lake water temperature was indicated to have usually a secondary effect on the LB intensity for small lakes. Surface observations implied that the onshore penetration of the LB by the early afternoon hours is typically less than the characteristic width of the lake. Lower atmosphere observations indicated that the vertical extent of the LB may reach several hundred meters. Implications of the observed LB features in support of characterization of the real-world vegetation breeze are discussed.
Dynamical Seasonal Prediction (DSP) is an informally coordinated multi-institution research project to investigate the predictability of seasonal mean atmospheric circulation and rainfall. The basic idea is to test the feasibility of extending the technology of routine numerical weather prediction beyond the inherent limit of deterministic predictability of weather to produce numerical climate predictions using state-of-the-art global atmospheric models. Atmospheric general circulation models (AGCMs) either forced by predicted sea surface temperature (SST) or as part of a coupled forecast system have shown in the past that certain regions of the extratropics, in particular, the Pacific–North America (PNA) region during Northern Hemisphere winter, can be predicted with significant skill especially during years of large tropical SST anomalies. However, there is still a great deal of uncertainty about how much the details of various AGCMs impact conclusions about extratropical seasonal prediction and predictability.
DSP is designed to compare seasonal simulation and prediction results from five state-of-the-art U.S. modeling groups (NCAR, COLA, GSFC, GFDL, NCEP) in order to assess which aspects of the results are robust and which are model dependent. The initial emphasis is on the predictability of seasonal anomalies over the PNA region. This paper also includes results from the ECMWF model, and historical forecast skill over both the PNA region and the European region is presented for all six models.
It is found that with specified SST boundary conditions, all models show that the winter season mean circulation anomalies over the Pacific–North American region are highly predictable during years of large tropical sea surface temperature anomalies. The influence of large anomalous boundary conditions is so strong and so reproducible that the seasonal mean forecasts can be given with a high degree of confidence. However, the degree of reproducibility is highly variable from one model to the other, and quantities such as the PNA region signal to noise ratio are found to vary significantly between the different AGCMs. It would not be possible to make reliable estimates of predictability of the seasonal mean atmosphere circulation unless causes for such large differences among models are understood.
Dynamical Seasonal Prediction (DSP) is an informally coordinated multi-institution research project to investigate the predictability of seasonal mean atmospheric circulation and rainfall. The basic idea is to test the feasibility of extending the technology of routine numerical weather prediction beyond the inherent limit of deterministic predictability of weather to produce numerical climate predictions using state-of-the-art global atmospheric models. Atmospheric general circulation models (AGCMs) either forced by predicted sea surface temperature (SST) or as part of a coupled forecast system have shown in the past that certain regions of the extratropics, in particular, the Pacific–North America (PNA) region during Northern Hemisphere winter, can be predicted with significant skill especially during years of large tropical SST anomalies. However, there is still a great deal of uncertainty about how much the details of various AGCMs impact conclusions about extratropical seasonal prediction and predictability.
DSP is designed to compare seasonal simulation and prediction results from five state-of-the-art U.S. modeling groups (NCAR, COLA, GSFC, GFDL, NCEP) in order to assess which aspects of the results are robust and which are model dependent. The initial emphasis is on the predictability of seasonal anomalies over the PNA region. This paper also includes results from the ECMWF model, and historical forecast skill over both the PNA region and the European region is presented for all six models.
It is found that with specified SST boundary conditions, all models show that the winter season mean circulation anomalies over the Pacific–North American region are highly predictable during years of large tropical sea surface temperature anomalies. The influence of large anomalous boundary conditions is so strong and so reproducible that the seasonal mean forecasts can be given with a high degree of confidence. However, the degree of reproducibility is highly variable from one model to the other, and quantities such as the PNA region signal to noise ratio are found to vary significantly between the different AGCMs. It would not be possible to make reliable estimates of predictability of the seasonal mean atmosphere circulation unless causes for such large differences among models are understood.
