scholarly journals On the quality of RS41 radiosonde descent data

2021 ◽  
Author(s):  
Bruce Ingleby ◽  
Martin Motl ◽  
Graeme Marlton ◽  
David Edwards ◽  
Michael Sommer ◽  
...  
Keyword(s):  
Short Range ◽  
Radio Occultation ◽  
Fall Rate ◽  
Pendulum Motion ◽  
Descent Data ◽  
Wind Variability ◽  
Wind Measurements ◽  
Fall Rates ◽  
Radiosonde Ascent

Abstract. Radiosonde descent profiles have been available from tens of stations for several years now – mainly from Vaisala RS41 radiosondes. They have been compared with the ascent profiles, with ECMWF short-range forecasts and with co-located radio-occultation retrievals. Over this time our understanding of the data has grown, and the comparison also shed some light on radiosonde ascent data. It has become clear that the fall rate is very variable and that it is an important factor, with high fall rates being associated with temperature biases, especially at higher altitudes. Ascent winds are affected by pendulum motion, on average descent winds are less affected by pendulum motion and are smoother. It is plausible that the true wind variability in the vertical lies between that shown by ascent and descent profiles. The discrepancy indicates the need for reference wind measurements.

scholarly journals On the quality of RS41 radiosonde descent data

2022 ◽  
Vol 15 (1) ◽  
pp. 165-183
Author(s):  
Bruce Ingleby ◽  
Martin Motl ◽  
Graeme Marlton ◽  
David Edwards ◽  
Michael Sommer ◽  
...  
Keyword(s):  
Short Range ◽  
Radio Occultation ◽  
Pressure Sensors ◽  
Pendulum Motion ◽  
Forecast System ◽  
Wind Variability ◽  
Wind Measurements ◽  
Fall Rates ◽  
Radiosonde Ascent

Abstract. Radiosonde descent profiles have been available from tens of stations for several years now – mainly from Vaisala RS41 radiosondes. They have been compared with the ascent profiles, with ECMWF short-range forecasts and with co-located radio occultation retrievals. Over this time, our understanding of the data has grown, and the comparison has also shed some light on radiosonde ascent data. The fall rate is very variable and is an important factor, with high fall rates being associated with temperature biases, especially at higher altitudes. Ascent winds are affected by pendulum motion; on average, descent winds are less affected by pendulum motion and are smoother. It is plausible that the true wind variability in the vertical lies between that shown by ascent and descent profiles. This discrepancy indicates the need for reference wind measurements. With current processing, the best results are for radiosondes with parachutes and pressure sensors. Some of the wind, temperature and humidity data are now assimilated in the ECMWF forecast system.

scholarly journals Comparison of the fall rate and structure of recent T-7 XBT manufactured by Sippican and TSK

2010 ◽  
Vol 7 (5) ◽  
pp. 1811-1847 ◽  
Author(s):  
S. Kizu ◽  
C. Sukigara ◽  
K. Hanawa
Keyword(s):  
Quadratic Form ◽  
Water Entry ◽  
Rate Coefficients ◽  
Fall Rate ◽  
Current Standard ◽  
Expendable Bathythermograph ◽  
Structural Differences ◽  
Fall Rates ◽  
The Difference ◽  
Temperature Depth

Abstract. The fall rate of recent T-7 expendable bathythermograph (XBT) is evaluated based on a series of concurrent measurement with a calibrated Conductivity Temperature Depth profiler (CTD) in the sea east of Japan. An emphasis is placed on comparing the fall rates of T-7 produced by the two present manufacturers, the Lockheed Martin Sippican Inc., and the Tsurumi Seiki Co. Ltd., which have been believed to be identical but had never been compared directly. It is found that the two manufacturers' T-7 fall at rates different by about 3.5%. The Sippican T-7 falls slower than the current standard equation by Hanawa et al. (1995) gives by about 2.1%, and the TSK T-7 falls faster than it tells by about 1.4%. The fall-rate coefficients estimated based on the present sea test by applying the equation of traditional quadratic form, d(t)=at−bt2 where d is depth in meters and t is the time elapsed, since the water entry of the probe, in seconds, are a=6.553 and b=0.00221 for the LMS T-7, and a=6.803 and b=0.00242 for the TSK T-7. By detail examination of the probes, it is revealed that the two companies' T-7 have different total weight and many structural differences. Because the difference in the fall rate is about twice larger than the difference in weight (about 2%), it is inferred that those structural differences give sizable impact to the difference in their fall rates. Our results clearly show that the recent T-7 of the two companies needs to be discriminated.

GRACE-FO radio occultation data processing – First result

2020 ◽  
Author(s):  
Torsten Schmidt ◽  
Patrick Schreiner ◽  
Byron Iijima ◽  
Chi Ao
Keyword(s):  
Data Processing ◽  
Radio Occultation ◽  
Temperature Data ◽  
Gps Satellites ◽  
Weather And Climate ◽  
First Results ◽  
Software Updates ◽  
Occultation Data ◽  
Radio Occultation Data

<p>An objective of the GRACE-FO mission is the continuation of GRACE radio occultation measurements successfully performed between 2006 and 2017.</p> <p>GRACE and GRACE-FO radio occultations contribute to the overall radio occultation dataset used in weather and climate applications.</p> <p>Since mid-2019 rising occultations from GF1 are available while setting radio occultations from GF2 are still disabled. After several on-board software updates and raw data reader improvements about 280 daily GF1 radio occultations are available since March 2020.</p> <p>Currently GF1 radio occultation data are processed on the basis of different measured variables: For different GPS satellites a combination of L1CA/L2P, L1CA/L2C, or L1CA/L5 is available.</p> <p>In this study first results of GF1 processing are presented. Refractivity and temperature data up to an altitude of 60 km will be compared with ECMWF operational analyses and the quality of the different measured variables will be evaluated.</p>

scholarly journals Comparison of the fall rate and structure of recent T-7 XBT manufactured by Sippican and TSK

Ocean Science ◽  
2011 ◽  
Vol 7 (2) ◽  
pp. 231-244 ◽  
Author(s):  
S. Kizu ◽  
C. Sukigara ◽  
K. Hanawa
Keyword(s):  
Quadratic Form ◽  
Rate Equation ◽  
Total Weight ◽  
Rate Coefficients ◽  
Fall Rate ◽  
Expendable Bathythermograph ◽  
Structural Differences ◽  
Fall Rates ◽  
The Difference ◽  
Temperature Depth

Abstract. The fall rate of recent T-7 expendable bathythermograph (XBT; 760 m) is evaluated based on a series of concurrent measurement with a calibrated Conductivity Temperature Depth profiler (CTD) in the sea east of Japan. An emphasis is placed on comparing the fall rates of T-7 produced by the two present manufacturers, the Lockheed Martin Sippican Inc., and the Tsurumi Seiki Co. Ltd., which have been believed to be identical but had never been compared directly. It is found that the two manufacturers' T-7 fall at rates different by about 3.5%. The Sippican T-7 falls slower than given by the fall-rate equation (FRE) of Hanawa et al. (1995) by about 2.1%, and the TSK T-7 falls faster by about 1.4%. The fall-rate coefficients estimated based on the sea test by applying the equation of traditional quadratic form, d(t)=at−bt2 where d is depth in meters and t is the time elapsed, in seconds, are a=6.553 (m s−1) and b=0.00221 (m s−2) for the LMS T-7, and a=6.803 (m s−1) and b=0.00242 (m s−2) for the TSK T-7. By detail examination of the probes, we found that the two companies' T-7 have different total weight and many structural differences. Because the difference in the fall rate is about twice larger than the difference in weight (about 2%), it is inferred that the structural differences give sizable impact to the difference in their fall rates. Our results clearly show that the recent T-7 of the two companies needs to be discriminated.

Upper wind observing systems used for meteorological operations

1994 ◽  
Vol 12 (8) ◽  
pp. 691-710 ◽  
Author(s):  
J. Nash
Keyword(s):  
Measurement Errors ◽  
Wind Component ◽  
Random Errors ◽  
The United Kingdom ◽  
Radar Systems ◽  
Wind Profiler Radar ◽  
Wind Measurements ◽  
Balloon Measurements ◽  
Observing Systems

Abstract. Methods of upper wind measurements used in operational meteorology have been reviewed to provide guidance to those developing wind profiler radar systems. The main limitations of the various methods of tracking weather balloons are identified using results from the WMO radiosonde comparisons and additional tests in the United Kingdom. Costs associated with operational balloon measurements are reviewed. The sampling and quality of operational aircraft wind observations are illustrated with examples from the ASDAR system. Measurement errors in horizontal winds are quantified wherever possible. When tracking equipment is functioning correctly, random errors in southerly and westerly wind component measurements from aircraft and weather balloons are usually in the range 0.5-2 m s-1.

Thermal Degradation of SiGe Interfaces Studied by X-Ray Reflectivity and Diffraction

1991 ◽  
Vol 239 ◽  
Author(s):  
J. M. Hudson ◽  
A. R. Powell ◽  
D. K. Bowen ◽  
M. Wormington ◽  
B. K. Tanner ◽  
...  
Keyword(s):  
Short Range ◽  
Grazing Incidence ◽  
Sige Layer ◽  
Interface Roughness ◽  
Total Thickness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface And Interface ◽  
Superlattice Structures

ABSTRACTWe demonstrate the use of x-ray diffraction to provide accurate compositional information, together with grazing incidence reflectivity to provide information on layer thicknesses and surface and interface roughnesses, on Si/Si1-xGex superlattice structures of less than 200nm total thickness.The quality of SiGe interfaces has been investigated in superlattices where x varies from 0.1 to 0.5. At low Ge compositions the interfaces are shown to be smooth to a few angstroms. However, as the Ge composition in the SiGe layer approaches 50%, severe roughness is observed at the SiGe to Si interfaces, although the Si to SiGe interfaces remain relatively smooth.Upon annealing for one hour at 850°C the Ge diffuses outwards from the SiGe layers and can be closely modelled by inclusion of a (2.4±0.3)nm linearly graded layer either side of the SiGe layer into a simulation program. The long range roughness at the SiGe to Si interface is lost upon annealing leaving only a short range roughness of similar size to the Si to SiGe interface roughness.Reflectivity measurements have been shown to distinguish between interface roughness and interdiffusion for the annealed system.

Effect of Tai Chi on Physical Function, Fall Rates and Quality of Life Among Older Stroke Survivors

2014 ◽  
Vol 95 (5) ◽  
pp. 816-824 ◽  
Author(s):  
Ruth E. Taylor-Piliae ◽  
Tiffany M. Hoke ◽  
Joseph T. Hepworth ◽  
L. Daniel Latt ◽  
Bijan Najafi ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Physical Function ◽  
Tai Chi ◽  
Stroke Survivors ◽  
Fall Rates

scholarly journals Initial MST radar observations of upper tropospheric-lower stratospheric duct-like structures over Jicamarca, Peru

2012 ◽  
Vol 12 (22) ◽  
pp. 11085-11093 ◽  
Author(s):  
Z. Li ◽  
S. Naqvi ◽  
A. J. Gerrard ◽  
J. L. Chau ◽  
Y. Bhattacharya
Keyword(s):  
Gravity Waves ◽  
Lower Stratosphere ◽  
Physical Nature ◽  
High Quality ◽  
Data Set ◽  
Upper Troposphere ◽  
Atmospheric Fronts ◽  
Mst Radar ◽  
Wind Measurements

Abstract. Persistent wind jet structures along zonal and meridional fields, believed to be caused by stationary gravity waves, were detected in February 1999 in mesosphere-stratosphere-troposphere (MST) radar wind measurements of the troposphere and lower stratosphere over Jicamarca, Peru. Over a continuous seven day span of MST-data analyzed in this study, two days of observations showed signatures of wave-like structures in the upper troposphere/lower stratosphere wind jets associated with the phases of the stationary gravity waves. We believe these wave-like structures are ducted gravity waves. We present these initial observations, their characteristics, and the results of simple numerical simulations used in an attempt to mimic these observed features. Although a fair replication of the observed ducted structure in the numerical model is found, the observed period of ~90 min is nonetheless much longer than what is traditionally observed. As a result, the specific physical nature of the observed structures is not fully established. Nevertheless, given the high quality of the observations, we demonstrate here that continued analysis of this data set and concurrent modeling efforts will allow for a better understanding of Doppler ducts at high spatial and temporal resolution, and the results presented here can ultimately be applied to studies of middle atmospheric fronts, ducts, and bores.

scholarly journals Changing Expendable Bathythermograph Fall Rates and Their Impact on Estimates of Thermosteric Sea Level Rise

2008 ◽  
Vol 21 (21) ◽  
pp. 5657-5672 ◽  
Author(s):  
Susan E. Wijffels ◽  
Josh Willis ◽  
Catia M. Domingues ◽  
Paul Barker ◽  
Neil J. White ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Decadal Variability ◽  
Heat Content ◽  
Time History ◽  
Global Ocean ◽  
Fall Rate ◽  
Rate Minimum ◽  
Fall Rates

Abstract A time-varying warm bias in the global XBT data archive is demonstrated to be largely due to changes in the fall rate of XBT probes likely associated with small manufacturing changes at the factory. Deep-reaching XBTs have a different fall rate history than shallow XBTs. Fall rates were fastest in the early 1970s, reached a minimum between 1975 and 1985, reached another maximum in the late 1980s and early 1990s, and have been declining since. Field XBT/CTD intercomparisons and a pseudoprofile technique based on satellite altimetry largely confirm this time history. A global correction is presented and applied to estimates of the thermosteric component of sea level rise. The XBT fall rate minimum from 1975 to 1985 appears as a 10-yr “warm period” in the global ocean in thermosteric sea level and heat content estimates using uncorrected data. Upon correction, the thermosteric sea level curve has reduced decadal variability and a larger, steadier long-term trend.

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