Muhammad Fahim Khokhar

Dr. Muhammad Fahim Khokhar

Institute of Environmental Sciences and Engineering, National University of Science and Technology, Islamabad 24090, Pakistan
orcid

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 November 2018 in Journal of Environmental Management
Verified
Journal Article
Closed access
MAM.N. Anwar
M.N. Anwar
AFA. Fayyaz
A. Fayyaz
NSN.F. Sohail
N.F. Sohail
Muhammad Fahim KhokharMuhammad Fahim Khokhar
Muhammad Fahim Khokhar
MBMujtaba Baqar
Mujtaba Baqar
Abdul-Sattar NizamiAbdul-Sattar Nizami
Abdul-Sattar Nizami

1 April 2020 in Journal of Environmental Management
Verified
Journal Article
Closed access
MAM.N. Anwar
M.N. Anwar
AFA. Fayyaz
A. Fayyaz
NSN.F. Sohail
N.F. Sohail
Muhammad Fahim KhokharMuhammad Fahim Khokhar
Muhammad Fahim Khokhar
MBM. Baqar
M. Baqar
Abdul-Sattar NizamiAbdul-Sattar Nizami
Abdul-Sattar Nizami

1 January 2021 in Journal of Hazardous Materials
Verified
Journal Article
Closed access
MAMuhammad Shehzaib Anjum
Muhammad Shehzaib Anjum
SASyeda Mahnoor Ali
Syeda Mahnoor Ali
MIMuhammad Imad-Ud-Din
Muhammad Imad-Ud-Din
MSMuhammad Ahmed Subhani
Muhammad Ahmed Subhani
MAMuhammad Naveed Anwar
Muhammad Naveed Anwar
Muhammad Fahim KhokharMuhammad Fahim Khokhar
Muhammad Fahim Khokhar

1 August 2021 in Journal of Hazardous Materials
Verified
Journal Article
Closed access
MAMuhammad Naveed Anwar
Muhammad Naveed Anwar
MSMuneeba Shabbir
Muneeba Shabbir
ETEza Tahir
Eza Tahir
MIMahnoor Iftikhar
Mahnoor Iftikhar
HSHira Saif
Hira Saif
Abdul-Sattar NizamiAbdul-Sattar Nizami
Abdul-Sattar Nizami

1 January 2005 in Advances In Space Research
Verified
Journal Article
Closed access
Muhammad Fahim KhokharMuhammad Fahim Khokhar
Muhammad Fahim Khokhar
CFChristian Frankenberg
Christian Frankenberg
MRM. Van Roozendael
M. Van Roozendael
SBS. Beirle
S. Beirle
SKS. Kühl
S. Kühl
TWT. Wagner
T. Wagner

6 May 2020 in Atmospheric Measurement Techniques
Verified
Journal Article
Open access
PDF file
KKKarin Kreher
Karin Kreher
MRMichel Van Roozendael
Michel Van Roozendael
FHFrancois Hendrick
Francois Hendrick
AAArnoud Apituley
Arnoud Apituley
EDErmioni Dimitropoulou
Ermioni Dimitropoulou
XZXiaoyi Zhao
Xiaoyi Zhao
In September 2016, 36 spectrometers from 24 institutes measured a number of key atmospheric pollutants for a period of 17 d during the Second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) that took place at Cabauw, the Netherlands (51.97∘ N, 4.93∘ E). We report on the outcome of the formal semi-blind intercomparison exercise, which was held under the umbrella of the Network for the Detection of Atmospheric Composition Change (NDACC) and the European Space Agency (ESA). The three major goals of CINDI-2 were (1) to characterise and better understand the differences between a large number of multi-axis differential optical absorption spectroscopy (MAX-DOAS) and zenith-sky DOAS instruments and analysis methods, (2) to define a robust methodology for performance assessment of all participating instruments, and (3) to contribute to a harmonisation of the measurement settings and retrieval methods. This, in turn, creates the capability to produce consistent high-quality ground-based data sets, which are an essential requirement to generate reliable long-term measurement time series suitable for trend analysis and satellite data validation. The data products investigated during the semi-blind intercomparison are slant columns of nitrogen dioxide (NO2), the oxygen collision complex (O4) and ozone (O3) measured in the UV and visible wavelength region, formaldehyde (HCHO) in the UV spectral region, and NO2 in an additional (smaller) wavelength range in the visible region. The campaign design and implementation processes are discussed in detail including the measurement protocol, calibration procedures and slant column retrieval settings. Strong emphasis was put on the careful alignment and synchronisation of the measurement systems, resulting in a unique set of measurements made under highly comparable air mass conditions. The CINDI-2 data sets were investigated using a regression analysis of the slant columns measured by each instrument and for each of the target data products. The slope and intercept of the regression analysis respectively quantify the mean systematic bias and offset of the individual data sets against the selected reference (which is obtained from the median of either all data sets or a subset), and the rms error provides an estimate of the measurement noise or dispersion. These three criteria are examined and for each of the parameters and each of the data products, performance thresholds are set and applied to all the measurements. The approach presented here has been developed based on heritage from previous intercomparison exercises. It introduces a quantitative assessment of the consistency between all the participating instruments for the MAX-DOAS and zenith-sky DOAS techniques.