scholarly journals Spatial and Time Warping for Gauge Adjustment of Rainfall Estimates

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1510
Author(s):  
Camille Le Le Coz ◽  
Arnold Heemink ◽  
Martin Verlaan ◽  
Nick van de van de Giesen
Keyword(s):  
Bias Correction ◽  
Positive Impact ◽  
Sub Saharan Africa ◽  
Rain Event ◽  
Time Warping ◽  
Deformation Method ◽  
Timing Errors ◽  
Position Errors ◽  
Southern Ghana ◽  
Rainfall Estimates

Many satellite-based estimates use gauge information for bias correction. In general, bias-correction methods are focused on the intensity error and do not explicitly correct possible position or timing errors. However, position and timing errors in rainfall estimates can also lead to errors in the rainfall occurrence or the intensity. This is especially true for localized rainfall events such as the convective rainstorms occurring during the rainy season in sub-Saharan Africa. We investigated the use of warping to correct such errors. The goal was to gauge-adjust satellite-based estimates with respect to the position and the timing of the rain event, instead of its intensity. Warping is a field-deformation method that transforms an image into another one. We compared two methods, spatial warping focusing on the position errors and time warping for the timing errors. They were evaluated on two case studies: a synthetic rainfall event represented by an ellipse and a rain event in southern Ghana during the monsoon season. In both cases, the two warping methods reduced significantly the respective targeted (position or timing) errors. In the southern Ghana case, the average position error was decreased by about 45 km by the spatial warping and the average timing error was decreased from more than 1 h to 0.2 h by the time warping. Both warping methods also improved the continuous statistics on the intensity: the correlation went from 0.18 to at least 0.62 after warping in the southern Ghana case. The spatial warping seems more interesting because of its positive impact on both position and timing errors.

Correcting position error in rainfall estimates using temporal and spatial warping

2020 ◽  
Author(s):  
Camille Le Coz ◽  
Arnold Heemink ◽  
Martin Verlaan ◽  
Marie-claire ten Veldhuis ◽  
Nick van de Giesen
Keyword(s):  
Bias Correction ◽  
Monsoon Season ◽  
Position Error ◽  
Rainfall Event ◽  
Sub Saharan Africa ◽  
Registration Method ◽  
Rainfall Events ◽  
Meteorological Observatory ◽  
Sub Saharan ◽  
Rainfall Estimates

<p>An increasing number of satellite-based rainfall estimates, with ever finer resolution, are becoming available. They are particularly valuable in regions with sparse radar and gauge networks. For example, in most of sub-Saharan Africa, the gauge network is not dense enough to represent the high variability of the rainfall during the monsoon season. However, satellite-based estimates can be subject to errors in position and/or timing of the rainfall events, in addition to errors in the intensity.<br>Many satellite-based estimates use gauge measurements for bias correction. Bias correction methods focus on the intensity errors, and do not correct the position error explicitly. We propose to gauge-adjust the satellite-based estimates with respect to the position and time. We investigate two approaches: spatial and temporal warping. The first one is based on a spatial mapping and correct the spatial position while keeping the time constant. The second uses a temporal mapping and keeps the spatial domain unchanged. The mappings are derived through a fully automatic registration method. That is, only the gauge and satellite-based estimates are needed as inputs. There is no need to manually predefine the rain features.<br>The spatial and temporal approaches are both applied to a rainfall event during the monsoon season in southern Ghana. The Trans-African Hydro-Meteorological Observatory (TAHMO) gauge network is used to gauge-adjust the IMERG-Late (Integrated Multi-Satellite Retrievals for GPM) satellite-based estimates. The two approaches are evaluated with respect to the timing, the location and the intensity of the rainfall event.</p>

scholarly journals Correcting Position Error in Precipitation Data Using Image Morphing

2019 ◽  
Vol 11 (21) ◽  
pp. 2557 ◽  
Author(s):  
Camille Le Coz ◽  
Arnold Heemink ◽  
Martin Verlaan ◽  
Marie-claire ten Veldhuis ◽  
Nick van de Giesen
Keyword(s):  
Monsoon Season ◽  
Real Data ◽  
Sub Saharan Africa ◽  
Rain Event ◽  
Spatial Transformation ◽  
Image Morphing ◽  
Rainfall Events ◽  
Position Errors ◽  
First Case ◽  
Meteorological Observatory

Rainfall estimates based on satellite data are subject to errors in the position of the rainfall events in addition to errors in their intensity. This is especially true for localized rainfall events such as the convective rainstorms that occur during the monsoon season in sub-Saharan Africa. Many satellite-based estimates use gauge information for bias correction. However, bias adjustment methods do not correct the position errors explicitly. We propose to gauge-adjust satellite-based estimates with respect to the position using a morphing method. Image morphing transforms an image, in our case a rainfall field, into another one, by applying a spatial transformation. A benefit of this approach is that it can take both the position and the intensity of a rain event into account. Its potential is investigated with two case studies. In the first case, the rain events are synthetic, represented by elliptic shapes, while the second case uses real data from a rainfall event occurring during the monsoon season in southern Ghana. In the second case, the satellite-based estimate IMERG-Late (Integrated Multi-Satellite Retrievals for GPM ) is adjusted to gauge data from the Trans-African Hydro-Meteorological Observatory (TAHMO) network. The results show that the position errors can be corrected, while preserving the higher spatial variability of the satellite-based estimate.

scholarly journals Video-Based Intervention for Improving Maternal Retention and Adherence to HIV Treatment: Patient Perspectives and Experiences

2021 ◽  
Vol 18 (4) ◽  
pp. 1737
Author(s):  
Steven Masiano ◽  
Edwin Machine ◽  
Mtisunge Mphande ◽  
Christine Markham ◽  
Tapiwa Tembo ◽  
...  
Keyword(s):  
Positive Impact ◽  
Low Cost ◽  
Hiv Treatment ◽  
Sub Saharan Africa ◽  
Hiv Care ◽  
Structured Interviews ◽  
Convenience Sample ◽  
Long Term Conditions ◽  
Art Initiation ◽  
Retention In Hiv Care

VITAL Start is a video-based intervention aimed to improve maternal retention in HIV care and adherence to antiretroviral therapy (ART) in Malawi. We explored the experiences of pregnant women living with HIV (PWLHIV) not yet on ART who received VITAL Start before ART initiation to assess the intervention’s acceptability, feasibility, fidelity of delivery, and perceived impact. Between February and September 2019, we conducted semi-structured interviews with a convenience sample of 34 PWLHIV within one month of receiving VITAL Start. The participants reported that VITAL Start was acceptable and feasible and had good fidelity of delivery. They also reported that the video had a positive impact on their lives, encouraging them to disclose their HIV status to their sexual partners who, in turn, supported them to adhere to ART. The participants suggested using a similar intervention to provide health-related education/counseling to people with long term conditions. Our findings suggest that video-based interventions may be an acceptable, feasible approach to optimizing ART retention and adherence amongst PWLHIV, and they can be delivered with high fidelity. Further exploration of the utility of low cost, scalable, video-based interventions to address health counseling gaps in sub-Saharan Africa is warranted.

Improvement in rainfall estimates using bias correction with the IAP-DCP Global Model

2020 ◽  
Vol 171 ◽  
pp. 26-35
Author(s):  
Usa Humphries ◽  
Pramet Kaewmesri ◽  
Pariwate Varnakovida ◽  
Prungchan Wongwises
Keyword(s):  
Bias Correction ◽  
Global Model ◽  
Rainfall Estimates

Blended Learning in Nigeria

2011 ◽  
pp. 190-207 ◽  
Author(s):  
Nwachukwu Prince Ololube
Keyword(s):  
Blended Learning ◽  
Quantitative Assessment ◽  
Positive Impact ◽  
University Education ◽  
Sub Saharan Africa ◽  
Chi Square ◽  
Assessment Design ◽  
Sub Saharan ◽  
And Performance ◽  
University Setting

Blended learning requirements are increasing, in part because of the population explosion and policies pertaining to the democratization of education. Yet, thousands of students and faculty remain deficient in the use of blended learning to advance technology in developing countries, especially sub-Saharan Africa. This research employed a quantitative assessment design aimed at improving best available practices, processes, and performance in terms of the blended learning offered in a university setting. A six-point Likert-type questionnaire was used to gather data. Multiple statistical procedures were employed in the subsequent analysis—percentage, mean point values, chi-square, and ANOVA. Majority of the respondents to the questionnaire agreed that the teaching of MIS to students is effective and has a positive impact on their academic achievements. This groundbreaking research presents a realistic resource for the practical application of blended learning in university education in Nigeria, as well as a comprehensive view of the benefits and problems of the applicability of blended learning.

scholarly journals Evaluation of High-Resolution Satellite Rainfall Products through Streamflow Simulation in a Hydrological Modeling of a Small Mountainous Watershed in Ethiopia

2012 ◽  
Vol 13 (1) ◽  
pp. 338-350 ◽  
Author(s):  
Menberu M. Bitew ◽  
Mekonnen Gebremichael ◽  
Lula T. Ghebremichael ◽  
Yared A. Bayissa
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Bias Correction ◽  
Hydrological Modeling ◽  
Rain Gauge ◽  
Hydrologic Model ◽  
Model Simulations ◽  
Mountainous Watershed ◽  
Satellite Rainfall ◽  
Rainfall Estimates

Abstract This study focuses on evaluating four widely used global high-resolution satellite rainfall products [the Climate Prediction Center’s morphing technique (CMORPH) product, the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) near-real-time product (3B42RT), the TMPA method post-real-time research version product (3B42), and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) product] with a spatial resolution of 0.25° and temporal resolution of 3 h through their streamflow simulations in the Soil and Water Assessment Tool (SWAT) hydrologic model of a 299-km2 mountainous watershed in Ethiopia. Results show significant biases in the satellite rainfall estimates. The 3B42RT and CMORPH products perform better than the 3B42 and PERSIANN. The predictive ability of each of the satellite rainfall was examined using a SWAT model calibrated in two different approaches: with rain gauge rainfall as input, and with each of the satellite rainfall products as input. Significant improvements in model streamflow simulations are obtained when the model is calibrated with input-specific rainfall data than with rain gauge data. Calibrating SWAT with satellite rainfall estimates results in curve number values that are by far higher than the standard tabulated values, and therefore caution must be exercised when using standard tabulated parameter values with satellite rainfall inputs. The study also reveals that bias correction of satellite rainfall estimates significantly improves the model simulations. The best-performing model simulations based on satellite rainfall inputs are obtained after bias correction and model recalibration.

scholarly journals Is overseas volunteering beneficial to the NHS? The analysis of volunteers’ responses to a feedback questionnaire following experiences in low-income and middle-income countries

BMJ Open ◽  
2017 ◽  
Vol 7 (10) ◽  
pp. e017517 ◽  
Author(s):  
Daniel Yeomans ◽  
Grace Le ◽  
Hemant Pandit ◽  
Chris Lavy
Keyword(s):  
Professional Development ◽  
Low Income ◽  
Personal Development ◽  
Positive Impact ◽  
Sub Saharan Africa ◽  
Middle Income ◽  
Middle Income Countries ◽  
Feedback Questionnaire ◽  
Sub Saharan ◽  
The Uk

IntroductionLocally requested and planned overseas volunteering in low-income and middle-income countries by National Health Service (NHS) staff can have benefits for the host or receiving nation, but its impact on the professional development of NHS staff is not proven. The Knowledge and Skills Framework (KSF) and Leadership Framework (LF) are two tools used by employers as a measure of individuals' development. We have used dimensions from both tools as a method of evaluating the benefit to NHS doctors who volunteer overseas.Methods88 NHS volunteers participating with local colleagues in Primary Trauma Care and orthopaedic surgical training courses in sub-Saharan Africa were asked to complete an online self-assessment questionnaire 6 months following their return to the UK. The survey consisted of questions based on qualities outlined in both the KSF and LF.Results85 completed responses to the questionnaire were received. In every KSF domain assessed, the majority of volunteers agreed that their overseas volunteering experience improved their practice within the NHS. Self-assessed pre-course and post-course scores evaluating the LF also saw a universal increase, notably in the ‘working with others’ domain.DiscussionThere is a growing body of literature outlining the positive impact of overseas volunteering on NHS staff. Despite increasing evidence that such experiences can develop volunteers’ essential skills, individuals often find it difficult to gain support of their employers. Our study, in line with the current literature, shows that overseas volunteering by NHS staff can provide an opportunity to enhance professional and personal development. Skills gained from volunteering within international links match many of the qualities outlined in both KSF and LF, directly contributing to volunteers’ continued professional development.

Impact of globalization on human rights: evidence from Sub-Saharan Africa

2020 ◽  
Vol 47 (12) ◽  
pp. 1453-1480
Author(s):  
Aman Takiyar ◽  
N.V.M. Rao
Keyword(s):  
Human Rights ◽  
Positive Impact ◽  
Social Dimension ◽  
Sub Saharan Africa ◽  
Political Dimension ◽  
Economic Dimension ◽  
Content Type ◽  
Multiple Dimensions ◽  
Sub Saharan ◽  
The Impact

PurposeThe purpose of this study is to examine the impact of globalization and its multiple dimensions on human rights in Sub-Saharan Africa.Design/methodology/approachThe study extends the Poe and Tate (1994) model, which enumerates the various determinants of human rights. Ordered probit estimation is used to estimate the impact of globalization and its dimensions. For the purpose of empirical analysis, the period has been divided into three phases: short, medium and long term. This helps in understanding how the impact of the different dimensions of globalization has evolved over a period of time. Furthermore, analysis has been carried out to detect causality between human rights and globalization.FindingsAs per the results, overall globalization and social dimension of globalization do have a positive impact on human rights in long and medium term and, also, Granger-cause human rights. The political dimension of globalization has a positive relation with human rights, though there exists no causality between the two. On the other hand, the economic dimension of globalization fails to have a statistically significant impact on human rights. Impact of the social dimension of globalization dominates that of other dimensions of globalization.Originality/valueThis is one of the few studies that examine, in an empirical fashion, the impact of globalization on human rights in Sub-Saharan Africa.

scholarly journals Bias correction of radar rainfall estimates based on a geostatistical technique

ScienceAsia ◽  
2012 ◽  
Vol 38 (4) ◽  
pp. 373 ◽  
Author(s):  
Ratchawatch Hanchoowong ◽  
Uruya Weesakul ◽  
Siriluk Chumchean
Keyword(s):  
Bias Correction ◽  
Radar Rainfall ◽  
Rainfall Estimates
Sign in / Sign up

Export Citation Format

Share Document