scholarly journals Climatic Bases and Analysis of Proposed Cloud Attenuation Model for Satellite Links Application

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mustapha Adewusi
Keyword(s):  
Elevation Angle ◽  
Radiosonde Data ◽  
Daily Maximum ◽  
Climatic Data ◽  
Attenuation Model ◽  
Cloud Attenuation ◽  
Total Attenuation ◽  
Cloud Models ◽  
Need To Evaluate ◽  
Southwest Nigeria

Consistently required lager bandwidth at lower cost induce increases in magnitude of transmission frequency for satellite signal. This is phenomenally accompanied by proportional hydrometeors attenuation. Hence, there is need to evaluate cloud attenuation impact in every climatic region periodically. This report is one of the outcomes of experimental communication research carried out at tropical Ota (6.7oN, 3.23oE) station, southwest, Nigeria. The station spectrum analyzer measures its received beacons total attenuation at 12.245 GHz and elevation angle 59.9o to Astra satellites located at 28.2oE. Daily maximum, minimum and mean temperatures; rain amount, wind speed and direction as well as time of occurrence of each of these weather parameters were also measured. Then the radiometric data including acquired radiosonde data were analysed under rainy and non-rainy conditions, to obtain cloud attenuation contribution from the total attenuation measured per minute. The various data used range in measurement periods between four and fifty-eight years. The outputs were used to compute the station cumulative distributions for the existing cloud models and for the integrated station’s data. Statistical analysis comparing the two cumulative distributions show a high difference between the measured data and existing models’ predicted values. Hence a cloud attenuation computation algorithm and its simulation program were developed and used to derive a new tropical cloud attenuation model. The results of climatic data and analysis were used to justify the well corroborated new cloud attenuation model.

scholarly journals Validation of GOME-2/Metop total column water vapour with ground-based and in situ measurements

2016 ◽  
Vol 9 (4) ◽  
pp. 1533-1544 ◽  
Author(s):  
Niilo Kalakoski ◽  
Jukka Kujanpää ◽  
Viktoria Sofieva ◽  
Johanna Tamminen ◽  
Margherita Grossi ◽  
...  
Keyword(s):  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Relative Difference ◽  
Radiosonde Data ◽  
Climatic Data ◽  
National Climatic Data Center ◽  
Data Processor ◽  
Data Source ◽  
Relative Differences ◽  
Total Column

Abstract. The total column water vapour product from the Global Ozone Monitoring Experiment-2 on board Metop-A and Metop-B satellites (GOME-2/Metop-A and GOME-2/Metop-B) produced by the Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M SAF) is compared with co-located radiosonde observations and global positioning system (GPS) retrievals. The validation is performed using recently reprocessed data by the GOME Data Processor (GDP) version 4.7. The time periods for the validation are January 2007–July 2013 (GOME-2A) and December 2012–July 2013 (GOME-2B). The radiosonde data are from the Integrated Global Radiosonde Archive (IGRA) maintained by the National Climatic Data Center (NCDC). The ground-based GPS observations from the COSMIC/SuomiNet network are used as the second independent data source. We find a good general agreement between the GOME-2 and the radiosonde/GPS data. The median relative difference of GOME-2 to the radiosonde observations is −2.7 % for GOME-2A and −0.3 % for GOME-2B. Against the GPS, the median relative differences are 4.9 % and 3.2 % for GOME-2A and B, respectively. For water vapour total columns below 10 kg m−2, large wet biases are observed, especially against the GPS retrievals. Conversely, at values above 50 kg m−2, GOME-2 generally underestimates both ground-based observations.

scholarly journals High-Resolution ITU-R Cloud Attenuation Model for Satellite Communications in Tropical Region

2019 ◽  
Vol 67 (9) ◽  
pp. 6115-6122 ◽  
Author(s):  
Feng Yuan ◽  
Yee Hui Lee ◽  
Yu Song Meng ◽  
Shilpa Manandhar ◽  
Jin Teong Ong
Keyword(s):  
High Resolution ◽  
Satellite Communications ◽  
Tropical Region ◽  
Attenuation Model ◽  
Cloud Attenuation

Identifying Rogue Air Temperature Stations Using Cluster Analysis of Percentile Trends

2005 ◽  
Vol 18 (8) ◽  
pp. 1275-1287 ◽  
Author(s):  
Scott M. Robeson ◽  
Jeffrey A. Doty
Keyword(s):  
Cluster Analysis ◽  
Air Temperature ◽  
Large Body ◽  
Large Temperature ◽  
Daily Maximum ◽  
Climatic Data ◽  
Single Linkage ◽  
Frequency Distributions ◽  
Temperature Trends ◽  
Average Linkage

Abstract A new and efficient method for identifying “rogue” air temperature stations—locations with unusually large air temperature trends—is presented. Instrumentation problems and spatially unrepresentative local climates are sometimes more apparent in air temperature extremes, yet can have more subtle impacts on variations in mean air temperature. As a result, using data from over 1300 stations in North America, the tails of daily air temperature frequency distributions were examined for unusual trends. In particular, linear trends in the 5th percentile of daily minimum air temperature during the winter months and the 95th percentile of daily maximum air temperature during the summer were analyzed. Cluster analysis then was used to identify stations that were distinct from other locations. Both single- and average linkage clustering were evaluated. By identifying individual stations along the entire periphery of the percentile trend space, single-linkage clustering appears to produce better results than that of average linkage. Average linkage clustering tends to group together several stations with large trends; however, only a handful of these stations appear distinctly different from the large body of trends toward the center of the percentile trend space. Maps of the rogue stations show that most are in close proximity to numerous other stations that were not grouped into the rogue cluster, making it unlikely that the unusually large temperature trends were due to regional climatic variations. As with all approaches for evaluating data quality, time series plots and station history information also must be inspected to more fully understand inhomogeneous variations in historical climatic data.

Projection of future streamflow changes of the Pearl River basin in China using two delta-change methods

2015 ◽  
Vol 47 (1) ◽  
pp. 217-238 ◽  
Author(s):  
Fei Yuan ◽  
Yeou-Koung Tung ◽  
Liliang Ren
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Future Climate Change ◽  
Pearl River ◽  
Daily Maximum ◽  
Climatic Data ◽  
Pearl River Basin ◽  
Delta Change ◽  
The Pearl River ◽  
The Pearl River Basin

Considerable biases in precipitation simulations in climate models have required the adoption of delta-change approaches to construct future precipitation scenarios for hydrological climate change impact studies. However, different delta-change methods yield different future precipitation scenarios that might significantly affect the projected future streamflow. To assess these effects, two delta-change methods were compared: the simple delta-change (SDC) method with a constant scaling factor and the quantile-quantile delta-change (QQDC) method with a quantile mapping-based non-uniform delta factor. The Xinanjiang (XAJ) hydrological model was applied using historical climatic data and two future precipitation scenarios for streamflow simulations in the Pearl River basin, China. The results show that the two delta-change methods have significant influences on future precipitation and streamflow projections, and these impacts become more distinct at finer and extreme event time scales. For instance, the QQDC method projects the 20-year daily maximum precipitation to be 8.1–98.6% higher than the SDC method. Consequently, the XAJ model with the QQDC future precipitation produces the 20-year daily maximum streamflow to be approximately 7.0–65.0% higher than that using the SDC precipitation. It implies that future precipitation transformation methods are a source of uncertainty, affecting future discharge projections. Such uncertainty should be considered in water resources management and flood control strategies for future climate change adaptations.

scholarly journals Climatic Change in Australia Since 1880

1953 ◽  
Vol 6 (2) ◽  
pp. 209 ◽  
Author(s):  
EL Deacon
Keyword(s):  
High Pressure ◽  
Climatic Change ◽  
Atmospheric Pressure ◽  
Annual Variation ◽  
Summer Rainfall ◽  
Subtropical High ◽  
Daily Maximum ◽  
Climatic Data ◽  
Maximum Temperatures

Australian climatic data show that, for the period 1911?1950, the summer rainfall over much of the southern part of the continent was considerably greater than in the previous 30 years and, for the same season, mean daily maximum temperatures in the interior were appreciably lower. A difference in character of the annual variation of atmospheric pressure between these periods also suggests a shift of mean position of the subtropical high pressure belt.

Changing Temperature Inversion Characteristics in the U.S. Southwest and Relationships to Large-Scale Atmospheric Circulation

2011 ◽  
Vol 50 (6) ◽  
pp. 1307-1323 ◽  
Author(s):  
Adriana Bailey ◽  
Thomas N. Chase ◽  
John J. Cassano ◽  
David Noone
Keyword(s):  
Air Quality ◽  
Large Scale ◽  
Salt Lake ◽  
American Southwest ◽  
Radiosonde Data ◽  
Climatic Data ◽  
Large Scale Circulation ◽  
Near Surface ◽  
Inversion Frequency ◽  
Global Telecommunication System

AbstractContinental temperature inversions significantly influence air quality, yet little is known about their variability in frequency and intensity with time or sensitivity to dynamical changes with climate. Inversion statistics for six upper-air stations in the American Southwest are derived for the period 1994–2008 from radiosonde data reported by the Global Telecommunication System (GTS) and National Climatic Data Center (NCDC), which use different significant level standards. GTS data indicate that low-level elevated inversions have increased in frequency at four of six sites, consistent with enhanced regional stagnation projected by models. NCDC data, in contrast, show remarkable declines in weak, near-surface inversions through 2001, indicating local surface conditions may counteract atmospheric dynamics in regulating inversion activity and air quality. To further test the sensitivity of inversion activity to climate, associations between wintertime inversion frequency and large-scale circulation are quantified using the self-organizing map technique. Twenty-four representative circulation patterns are derived from North American Regional Reanalysis (NARR) 500-hPa geopotential height fields, and these patterns are correlated with inversion frequency at each site. Inversion activity in Salt Lake City, Utah, and Albuquerque and Santa Teresa, New Mexico, is found to correspond well with large-scale anticyclonic ridging; however, sensitivities to large-scale circulation in Denver, Colorado, and Flagstaff and Tucson, Arizona, are weak. Denver stands out in exhibiting a higher percentage of near-surface inversions in winter than the other southwestern sites. These findings indicate that dynamical changes with climate will not uniformly influence inversions and hence urban air quality conditions in the American Southwest.

scholarly journals Climate Change and Cereal Production Evolution Trend in the Sahel: Case Study in Mali from 1951 to 2010

2019 ◽  
Vol 8 (2) ◽  
pp. 68
Author(s):  
M. Kouressy ◽  
B. Sultan ◽  
M. Vaksmann ◽  
J. F. Belières ◽  
L. Claessens ◽  
...  
Keyword(s):  
Climate Change ◽  
Crop Production ◽  
Daily Maximum ◽  
Climatic Data ◽  
Positive Trend ◽  
Synoptic Weather ◽  
Cereal Production ◽  
Food Crop Production ◽  
Maximum Temperatures

Mali is a Sahelian country with a large climatic contrast from North to South. The current climatic and production evolutionary study is focused on the six major agro-climatic cereal production zones ranging from Kayes (400 mm) to Sikasso (>1000 mm) of rainfalls. Climatic data are rainfall records, daily maximum and minimum temperatures from 60 years of the six major synoptic weather observation stations. Data were analyzed on comparing average decades of the two normal periods of 30 years (1951-1980) and (1981-2010). Annual agronomic production data for millet, sorghum, maize and rice are derived from Mali's agricultural statistics base from 1984 to 2013. Main climatic results analyses indicate that climate change resulted in a decrease of 100 mm isohyets between the 2 periods of 30 years. The structure of the rainy season was little changed between these two periods since the average start of the season was delayed by 6 days and the average end date of the season became earlier by 4 days. Maximum temperatures increased significantly from + 0.44°C to + 1.53°C and minimum temperatures significantly increased from + 1.05°C to + 1.93°C in varying way depending on the sites. Statistics of major agronomic food crop production in Mali from 1984 to 2013 indicate an average increase of 985 to 4492 thousand tones, or 22% increase per year. There is a positive upward in saw tooth trend in Malian production from 1984 to 2013. This positive trend is the result of a combination of agricultural extension, agronomic research application and the management of small farmer holder in the Sahel. This evolution needs better study for drawing necessary right conclusions.

scholarly journals Impacts of Some Climatic Variables on the Seasonal Productivity of Aman Rice at Dhaka Region, Central Part of Bangladesh

2016 ◽  
Vol 8 (2) ◽  
pp. 7-10
Author(s):  
SMSA Tuhin ◽  
MA Farukh ◽  
BS Nahar ◽  
MA Baten
Keyword(s):  
Crop Production ◽  
Climatic Variability ◽  
Climatic Variables ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Daily Maximum ◽  
Climatic Data ◽  
Average Maximum ◽  
Average Maximum Temperature ◽  
Daily Sunshine

An agro-climatic study was conducted at Dhaka region of Bangladesh using 43 years (1970-2012) of climatic data (daily maximum temperature, seasonal total rainfall, daily average humidity, and daily sunshine hour) to observe the climatic variability and their impacts on the productivity of Aman rice. The average maximum temperature increased by 0.04°C in Aman season in Dhaka region. The average sunshine hours decreased by 0.05 in the season. The average humidity decreased by 0.14% in the season. The average seasonal rainfall increased slightly by 0.09 mm in the season. The Aman rice production increased by 0.03 t ha-1 in the region. The production year 2003 shows highest productivity due to less climatic devastation impact on the seasonal productivity of the rice. The climatic variables impact ( Savg > Havg > Tmax ) implies the seasonal productivity of Aman rice was mostly and inversely correlated with average sunshine (Savg) hour. However, most of the time the production showed increasing trend except some devastating natural calamities in the year of 1988 and 1998 which affected crop production seriously.J. Environ. Sci. & Natural Resources, 8(2): 7-10 2015

scholarly journals Magnitude and frequency of heat and cold waves in recent decades: the case of South America

2016 ◽  
Vol 16 (3) ◽  
pp. 821-831 ◽  
Author(s):  
Guido Ceccherini ◽  
Simone Russo ◽  
Iban Ameztoy ◽  
Claudia Patricia Romero ◽  
Cesar Carmona-Moreno
Keyword(s):  
South America ◽  
Heat Waves ◽  
Extreme Temperature ◽  
Daily Maximum ◽  
Cold Wave ◽  
Climatic Data ◽  
Data Set ◽  
Cold Waves ◽  
National Climatic Data Center ◽  
Temperature Records

Abstract. In recent decades there has been an increase in magnitude and occurrence of heat waves and a decrease of cold waves, both of which may be related to the anthropogenic influence. This study describes the extreme temperature regime of heat waves and cold waves across South America over recent years (1980–2014). Temperature records come from the Global Surface Summary of the Day (GSOD), a climatological data set produced by the National Climatic Data Center that provides records of daily maximum and minimum temperatures acquired worldwide. The magnitude of heat waves and cold waves for each GSOD station are quantified on an annual basis by means of the Heat Wave Magnitude Index and the Cold Wave Magnitude Index. Results indicate an increase in intensity and in frequency of heat waves, especially in the last 10 years. Conversely, no significant changes are detected for cold waves. In addition, the trend of the annual temperature range (i.e. yearly mean of Tmax – yearly mean of Tmin) is positive – up to 1 °C per decade – over the extratropics and negative – up to 0.5 °C per decade – over the tropics.

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